1986 MICHIGAN POTATO RESEARCH REPORT VOLUME 18 MICHIGAN STATE UNIVERSITY AGRICULTURAL EXPERIMENT STATION IN COOPERATION WITH THE MICHIGAN POTATO INDUSTRY COMMISSION THE MICHIGAN POTATO INDUSTRY COMMISSION March 20, 1987 TO ALL MICHIGAN POTATO GROWERS AND SHIPPERS: The Michigan Potato Industry Commission and the Agricultural Experiment Station of Michigan State University are happy to provide you with a copy of the results of the 1986 potato research projects. This years report includes research projects funded by the MPIC as well as projects funded through a special federal grant that the Michigan Potato Industry Commission helped secure. The federal grant data completes the second year of a five year project. Also included are reports on projects carried out by MSU which were not subsidized by the industry. Providing research funding and direction to researchers is a major function of the MPIC on behalf of Michigan growers and shippers. Input from the industry regarding research is most welcome at any time. Sincerely, The Michigan Potato Industry Commission THE MICHIGAN POTATO INDUSTRY COMMISSION • 13109 SCHAVEY RD., SUITE 7 • DEWITT, Ml 48820 • (517) 669-8377 TABLE OF CONTENTS INTRODUCTION AND ACKNOWLEDGEMENTS, WEATHER, AND GENERAL MANAGEMENT 1 1986 POTATO VARIETY EVALUATIONS R.W. Chase, G.H. Silva, R.B. Kitchen, R. Leep and R. Hammerschmidt 4 Page THE EFFECTS OF PRE-CUTTING AND FUNGICIDE TREATMENT OF POTATO SEED R.W. Chase, G.H. Silva and R. B. Kitchen 25 EVALUATION OF PRODUCTION MANAGEMENT INPUTS TO IMPROVE QUALITY AND YIELD OF THREE MSU SEEDLINGS G. H. Silva, R.W. Chase and R. B. Kitchen 27 EFFECTS OF RESPOND TREATMENTS ON YIELD AND QUALITY OF POTATOES R.W. Chase, G.H. Silva and R.B. Kitchen 33 EVALUATION OF CULTIVARS FOR FROZEN PROCESSING R.W. Chase, G.H. Silva and R.B. Kitchen 35 SUSTAINABLE AGRICULTURE — POTATOES Robert Lucas and Richard Bay 41 IMPROVED PRODUCTION AND UTILIZATION TECHNOLOGY FOR MICHIGAN POTATOES F. J. Pierce, R.W. Chase and K. A. Renner 44 WEED CONTROL ON MUCK SOILS AND VARIETY RESPONSE TO HERBICIDE APPLICATION AND TIME OF HILLING K. A. Renner and R.W. Chase 51 NITROGEN STUDIES ON RUSSET BURBANK POTATOES IN THE UPPER PENINSULA R.H. Leep and D.L. Pellegrini 63 NITROGEN USE EFFICIENCY STUDY WITH RUSSET BURBANK M.L. Vitosh, D.A. Hyde, B.P. Darling and J. Thorburn 65 THE INFLUENCE OF METHAM CHEMIGATION AND NITROGEN ON YIELD AND QUALITY OF RUSSET BURBANK POTATOES M.L. Vitosh and G.W. Bird 69 Page CONTROL OF SCAB AND RHIZOCTONIA DISEASES R. Hammerschmidt and M.L. Vitosh 80 MANAGEMENT OF COLORADO POTATO BEETLE E. Grafius, L. Connington and D. Herrington 88 1986 POTATO NEMATODE RESEARCH REPORT G.W. Bird 97 EFFECT OF SPRAY SCHEDULE AND POTATO CULTIVAR ON DEVELOPMENT OF EARLY BLIGHT AND EFFECT OF EARLY BLIGHT ON YIELDS M.L. Lacy 107 INFLUENCE OF ENVIRONMENTAL FACTORS ON WOUND HEALING OF POTATO TUBERS IN RELATION TO STORAGE DISORDERS R. Hammerschmidt and A. Cameron 111 SIMULATED POTATO STORAGE RESEARCH: 1985-1986 Burt Cargill and Todd Forbush 115 A PILOT STUDY INVESTIGATING SPROUT INHIBITING AND VINE KILLING METHODS — 1985-86 SEASON B.F. Cargill, T.D. Forbush, R.L. Ledebuhr, G.R. VanEe and H.S. Potter 124 THE EFFECTS OF PRESTORAGE CHEMICAL TREATMENTS ON THE MARKET QUALITY OF 1985 ATLANTIC POTATOES — 1985-86 B.F. Cargill, T.D. Forbush, R. L. Ledebuhr, G. R. VanEe and H.S. Potter 133 POTATO PROCESSING AND UTILIZATION FOR IMPROVED MARKETING Jessy N. Cash and Ron Morgan 145 APPLICATION OF POTATO CARBOHYDRATE ANALYSIS AND CIPC INTERACTION IN A COMMERCIAL GROWING AND STORAGE OPERATION J.N . Cash, R. Chase and A. Cameron 148 MARKET AND ECONOMIC FEASIBILITY OF PRECOOKED (RETORT POUCH) POTATO PRODUCTS Thomas R. Pierson and Donald Hinman 158 A COMPARATIVE ANALYSIS OF POTATO PACKING COSTS: ASSORTED VERSUS CLOSELY SIZED PACKS Thomas R. Pierson and Lisa Allison 160 1986 POTATO RESEARCH REPORT 1 R.W. Chase, Coordinator Department of Crop and Soil Sciences Michigan State University INTRODUCTION AND ACKNOWLEDGEMENTS The 1986 Potato Research Report has been expanded to include many additional reports of potato research projects in addition to those conducted at the Montcalm Research Station. We are also using this report to include the research of the projects funded under the special Federal Grant, in addition to those funded by the MPIC and other sources. As you review the various reports, you will note that we have attempted to identify the source of the support for those projects funded by the special Federal Grant and by the MPIC. I wish to acknowledge the excellent support that the MPIC and the Michigan potato industry have given to MSU potato research. We also want to acknowledge the many contributions made in fertilizers, chemicals, seed, equipment, technical assistance, personal services and monetary grants. Appreciation is also expressed to Dick Kitchen and Theron Comden in the coordination and production management needs of the Montcalm Research Station. ***Dr. Burt Cargill *** We also want to acknowledge the loss of one of our very dedicated and sincere research and extension colleagues, Dr. Burt Cargill. Burt was well known for the hard work, sincerity and dedication that he put forth for the betterment of the Michigan potato industry. Burt was very creative in his storage management ideas and principles and the results of his efforts will long be remembered. WEATHER The 1986 Montcalm Research Farm rainfall and temperature data from April to September, as compared with the 15 year average, are summarized in Tables 1 and 2. Temperature during April and May (particularly April) were above the average which resulted in warm soils and allowed for early planting. In June, July, August and September, temperature resembled closely the 15-year average. Rainfall in August was well below the average. In September, however, record levels of rainfall (18.6 inches) were received. All the rain occurred after September 9, starting with 7.8 inches on September 10. 1 Printing and distribution of this 1986 Potato Research Report was made possible by the Michigan Potato Industry Commission. SOIL TESTS Soil test results for the general plot area were: (lbs/A) (lbs/A) P K (lbs/A) Ca (lbs/A) Mg % Organic Matter 407 232 842 175 2.10 (lbs/A) pH 6.0 FERTILIZERS USED The previous crop was corn for the 2 ranges where the variety trials were conducted. For the entire 1986 research area, winter rye was planted in late fall of 1985. Except for the specific fertility studies where the fertilizers are specified in the report, the following fertilizers were used on the potato plot area: plowdown 0-0-60 200 lbs/A banded at planting 15-10-15-12S 500 lbs/A sidedress with irrigation 46-0-0 225 lbs/A HERBICIDES AND HILLING Most of the hillings were completed by the end of May. The procedure used was to delay the herbicide application until the potatoes were just cracking the ground. The potatoes were then hilled by building a wide and flattened hill and placing just enough soil over the top of the ridge to protect them. Immediately after hilling, a tank mix of metolachlor (Dual) 2 lbs/A plus metrabuzin (Lexone 4L) 1/2 lb/A was applied. No further tillage was required until harvest. IRRIGATION Twelve supplementary irrigations were applied on June 23, July 2, 7, 10, 18, 23, August 2, 7, 15, 19, 22 and 26. Irrigation was based on the Michigan State University irrigation scheduling program. The minimum profile moisture content allowed was 50%. The amount of water applied ranged from 0.3 to 1.0 inches per application. Urea was incorporated into irrigation on June 23, July 2, 18 and 29. INSECT AND DISEASE CONTROL Aldicarb (Temik 15G) was applied at planting at 20 lbs/A with the fertilizer. The foliar fungicide applications were initiated on June 20 and 9 applications were made throughout the balance of the season. Fungicides used were Bravo (3 applications) and Dithane M45 (5 applications). One applicatiin of Ridomil MZ-58 was made on August 21. Foliar insecticides used were Imidan on June 30, Furadan on July 21 and Pydrin on July 23. The principal insect problems were Colorado potato beetles, cutworms and flea beetles. Table 1. The 15 year summary of average and minimum temperatures during the growing season at the Montcalm Research Farm. Year April Max April Min May Max May Min June Max June Min July Max July Min August Max August Min September September Min Max 6-Month Average Max 6-Month Average Min 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 15-YR. AVG. 47 54 57 48 58 62 50 50 49 56 53 47 54 58 60 53 30 36 36 28 35 37 31 33 31 35 28 28 34 38 36 34 70 63 62 73 63 80 67 66 69 64 72 60 60 70 70 67 47 42 41 48 41 47 45 44 42 39 46 38 39 44 46 43 72 77 73 75 79 76 78 74 73 73 70 76 77 71 77 75 50 58 52 56 57 50 50 55 50 50 44 49 54 46 50 52 79 79 81 80 81 85 81 82 81 77 80 85 78 81 82 81 57 60 57 57 58 61 56 57 58 51 53 57 53 55 59 56 76 80 77 79 80 77 82 77 81 78 76 82 83 75 77 79 57 60 56 58 53 52 57 55 58 53 48 57 55 54 51 55 69 73 68 65 70 70 75 76 70 67 66 70 69 70 72 70 49 48 45 44 46 53 52 47 49 47 44 46 45 50 50 48 73 74 70 70 71 75 72 71 71 69 70 70 70 71 73 71 48 51 48 49 48 50 49 49 48 46 44 46 47 48 49 48 Table 2. The 15 year summary of precipitation (inches per month) recorded during the growing season at the Montcalm Research Farm. Year April May June July August September Total 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 15-YR. AVG. 1.35 3.25 4.07 1.81 3.27 1.65 2.34 2.58 3.53 4.19 1.43 3.47 2.78 3.63 2.24 2.77 1.96 3.91 4.83 2.05 4.03 0.46 1.35 1.68 1.65 3.52 3.53 4.46 5.14 1.94 4.22 2.97 2.51 4.34 4.69 4.98 4.22 1.66 2.55 3.77 4.37 3.44 5.69 1.19 2.93 2.78 3.20 3.45 3.83 2.36 2.39 2.71 1.50 2.39 1.89 1.09 2.64 1.23 5.53 2.44 3.76 2.58 2.36 2.57 7.28 3.94 6.18 11.25 1.44 2.61 5.90 3.69 3.21 3.48 1.96 2.21 1.97 4.72 2.10 4.13 2.60 1.33 1.81 3.07 1.40 8.62 2.77 0.04 6.59 3.82 3.24 5.34 3.90 3.30 18.60 4.42 19.53 19.13 23.97 25.87 15.86 17.39 16.80 12.85 21.99 19.68 21.38 19.11 20.48 18.95 32.72 20.31 Funding: Federal Grant 1986 POTATO VARIETY EVALUATIONS R.W. Chase, G.H. Silva, R.B. Kitchen, R. Leep and R. Hammerschmidt Departments of Crop and Soil Sciences and Botany and Plant Pathology The potato variety evaluation program is designed: (a) to search for improved cultivars well-adapted to Michigan for fresh pack, chip and frozen processing industry; and (b) to conduct intensive evaluations of selected varieties to determine the production management inputs that improve potato quality. In variety evaluations, special attention was given to quality parameters such as tuber size distribution, appearance, dry matter, internal defects, chip color and after cooking darkening. Other characteristics monitored were overall vigor in relation to emergence and plant stand, resistance to important diseases, notably scab, early blight and tuber bruising. Tuber samples were kept in 3 storage environments (40, 46, 52°F) for subsequent quality evaluations. A. DATES-OF-HARVEST TRIAL The 1986 dates-of-harvest trial was conducted at the Montcalm Research Farm. Eighteen selected varieties were tested for their marketable maturity and adaptability to Michigan. These included 9 released varieties and 9 advanced selections. The performances of these varieties were evaluated at 3 harvest dates, 99, 120, and 142 days after planting. Four replications of a randomized complete block design were harvested at each harvest date. Plots were 23 ft x 34 Inches in size and the within row spacing was 12 inches. The trial was planted on April 30. The previous crop was corn and a winter rye cover crop. Fertilizers used were 200 lbs/A 0-0-60 plowdown, 500 Ibs/A 15-10-15-12S in the planter and a sidedressing of 100 lbs N as urea in 4 split applications with irrigation water. Aldicarb (Temik 15G) was applied at 20 lbs/A at planting. The hilling and herbicide application were all made just as the potatoes were emerging which was done on May 18. Immediately after hilling, a tank mix of Dual at 2 lbs/A plus Lexone at 1 Ib/A were applied for weed control and no further tillage was performed until harvest. The crop was irrigated 13 times, according to the MSU irrigation scheduling program. The minimum profile moisture content allowed was 50%. The amount of water applied ranged from 0.3 to 1.0 inch per application. Results The yield, size distribution and quality of the potato varieties at the 3 harvest dates are presented in Tables 1, 2 and 3. In general, 1986 was a exceptionally good year for potatoes. Inspite of the heavy rainfall (13 inches) received between the second and third harvests, the specific gravity of the tubers remained high at the third harvest. With the exception of rainfall, weather conditions were generally favorable through the growing season. The vigor, maturity and early blight data are presented in Table 4. The culinary quality of after cooking darkening recorded on November 10 is summarized in Table 5. Peeled halves of 3 tubers selected at random and cooked uniformly in steam were evaluated 0, 1 and 24 hours for darkening. The chip color ratings after 120 days of storage at 50-55°F, as compared to those at harvest are presented in Table 6. Susceptibility to blackspot bruising was evaluated in artificially bruised and check treatments. Artificial bruising was done by placing potatoes inside a wooden drum and turning 10 revolutions at a moderate speed. In the check treatments, potatoes were tested without artificial bruising, so that any blackspot observed are only those incurred at the harvesting and handling operations. The results of blackspot evaluation are summarized in Table 7. The tendency to develop internal defects in oversized potatoes was determined by cutting 40 tubers of diameter >3 1/4 inches from each variety at the 120- and 142-day harvests. The results of this study are presented in Table 8. Among the early maturing varieties, Onaway produced the highest U.S. #1 yield and was free of internal defects. However, it had a low gravity, and a tendency to produce a higher % of oversize tubers and growth cracks. Conestoga produced average yields but was highly susceptible to early blight. Among the medium maturing varieties, MS 700—83, MS 704-10, MS 716-15, Atlantic and Krantz performed well. MS 700-83 produced good yields with a higher % of U.S. #1 tubers. MS 704-10 is a golden flesh variety with a high specific gravity. MS 716-15 produced above average yields of excellent quality and high gravity. It had the best chip color among all varieties. Atlantic had the highest gravity but was susceptible to internal necrosis. Krantz produced acceptable yields but its gravity was lower than Russet Burbank. Norking Russet had a poor marketable yield. In MS 702-91, tuber type was too variable and dry matter was insufficient for chips. Among the late maturing varieties, MS 700-70 was a prolific yielder with the highest U.S. #1 yield at both 120- and 142-day harvests. A 76147-2 was another prolific yielder but with a slightly lower gravity than Russet Burbank. Acadia Russet produced above average yields with high gravity and good internal quality. Russet Burbank produced a poor marketable yield and an undesirably high % of undersize and knobby tubers. In the culinary tests, undesirable levels of after cooking darkening occurred in MS 700—83, MS 700—79, ND 534-4, Onaway and Atlantic. In previous years, some of these varieties, particularly MS 700-83, had showed little or no after cooking darkening. Seasonal effects, such as heavy rainfall and fertilization, seem to have influenced this test. The chip color following 120 days of storage at 50-55°F was excellent in MS 716-15, MS 702-80, MS 702-91, Krantz and Atlantic. Acceptable chip color was found in MS 700-70, MS 704-10, MS 700-79, Conestoga and Sunrise. The results of the bruising study indicated that in artificially bruised tubers, the varieties that were highly resistant to blackspot were ND 534-4 and Norking Russet. Moderate levels of resistance were found in MS 702-80, MS 700-83, Onaway, Sunrise, A 76147-2, MS 702-91 and Conestoga. Krantz and Acadia Russet were found to be very susceptible. In the check treatments, most varieties showed no blackspot. The varieties that exhibited the least amount of internal defects in oversized tubers were MS 716-15, ND 534-4, Norking Russet, Krantz, Onaway and Russet Burbank. These varieties had less than 10% hollow heart and internal necrosis symptoms at the last two harvest dates. Variety Characteristics MS 700-79 - Round white, mid-season maturity with average yields and specific gravity. Has some scab resistance, but is susceptible to hollow heart. This seedling will be deleted from further tests. MS 700-83 - Round white, mid-season maturity and above average yields with medium gravity. Does chip out of field. In some years, after cooking darkening can be a problem. Possesses some scab resistance. MS 702-80 - Round white, mid-season maturity and average yields with medium gravity. Chips well and has good scab tolerance. MS 702-91 - Round white, mid-season maturity and high yield potential. Tuber shape tends to be variable and the gravity is too low for chipping. Has moderate scab resistance. This seedling will be deleted from further tests. MS 704-10 - Round tubers with yellow flesh. Mid-season maturity. Produces average yields with high specific gravity. Sets heavy and produces a golden color chip when processed from field and short term storage. MS 716-15 - Round white, medium-late maturity and above average yields with high gravity. Well shaped, smooth general appearance and has excellent chip color. MS 700-70 - Round white, late maturity and very high yields. Tubers have high gravity and good general appearance. Chip color is acceptable. A 76147-2 - Long, light russet, late maturity and very high yields with medium gravity. Good external appearance and minimal internal defects. Has potential for count pack market. ND 534-4 - Oblong to long russet, early to mid-season maturity and produced below average yields. Tubers have very smooth external appearance with gravity lower than Russet Burbank. Good resistance to blackspot and minimal internal defects in 1986. Has potential for count pack market. Norking Russet - Oblong russet, medium-late maturity with very poor sizing in 1986. Yields below average with gravity higher than ND 534-4 but lower than Russet Burbank. Has good scab tolerance. Very smooth external appearance and minimal internal defects in 1986. Has potential for count pack market. Acadia Russet - Long russet, late maturity and above average yields with high gravity. Fair general appearance, minimal internal defects in 1986. It is susceptible to scab and blackspot. Krantz - Oblong russet, mid-1ate season maturity with average yields and gravity. Minimal internal defects in 1986. Onaway - Round white, early maturity and above average yields with low gravity. Susceptible to early blight and growth cracks. Minimal internal defects. Atlantic - Round white, mid-late season maturity and above average yields at all 3 harvest dates with high gravity. Has good chip color, however, hollow heart and internal necrosis is a problem. It is susceptible to scab. Conestoga - Round-oblong white, early maturity with average yields and gravity. Produces an acceptable chip. Very susceptible to early blight. Shepody - Long white, mid-late season maturity and average yields. Matures 2-3 weeks earlier than Russet Burbank but has similar gravity. Slow early establishment in the field. Sets fewer tubers than Russet Burbank but sizes quickly. Some susceptibility to scab but minimal internal defects in 1986. Good for French fry industry. Sunrise - Round-oblong, early maturity with average yields and low gravity. Chip color is acceptable. Susceptible to growth cracks and scab. Russet Burbank - Long russet, late maturity with very poor sizing and type. Below average yields but high gravity. Minimal internal defects in 1986. B. UPPER PENINSULA TRIAL Sixteen potato varieties were tested in a randomized complete block design with 4 replications in the Upper Peninsula. The trial was planted on May 22 and harvested on September 29, 1986. The results of this trial are presented in Table 9. The varieties MS 704-10, Acadia Russet, Onaway, A 76147-2 and MS 700-83 produced the highest US. #1 yields. The size distribution and dry matter content of most varieties in this trial were excellent. C. NORTH CENTRAL REGIONAL TRIAL This trial is conducted in 14 states and provinces with entries from various breeding programs to obtain data from a wide range of adaptability prior to the release decision. Two MSU seedlings, MS 700-83 and MS 704-10 were included in the 1986 trial. Twenty varieties (10 round whites, 6 reds, 4 russets) were tested in a randomized complete block design with 4 replications. The results of this trial are presented in Tables 10 and 11. The round whites that performed well in the trial were MS 700—83, W 832, MN 12161 and ND 651-9. W 879 had the highest gravity (1.090) but the tuber shape (very flattened) was unacceptable. The highest U.S. #1 yield was produced by W 848R, a red variety which also had a high specific gravity. Two russets that appeared promising were NE 165.75-2 and NEA 71.72-1, with high gravity and smooth tuber appearance. On a general merit rating based on appearance alone (disregarding maturity, yield and gravity), the 5 best varieties were ND 671-4 Russ, MN 12567, MS 704-10, NEA 71.72-1 and W 832. Chip color was excellent in MS 700-83 and ND 860—2, and was acceptable in MS 704-10, W 832, MN 12161 and MN 82328. D. PRELIMINARY TRIAL Six varieties reported to have good chipping characteristics were tested for yield and quality in a randomized complete block design with 4 replications. Plot size, fertilizer use and pest management were the same as for the dates-of-harvest study. The results are summarized in Table 12. The US. #1 yields were high in F 72004, F 74123 and A 7411-2. Although F 72004 and F 7411-2 had sufficient dry matter for chipping, only F 7411-2 produced an acceptable chip color and warranted further testing. BR 7093-24 was late maturing and susceptible to hollow heart. ND 1538-1 and ND 651-9 had low U.S. #1 yields owing to poor sizing. E. EIGHT-HILL SELECTIONS FROM NEW SEEDLING INTRODUCTIONS New seedling introductions, 16 from Michigan State University, 51 from North Dakota, 35 from New York and 65 from USDA-Aberdeen (Ore-Ida Foods, Inc.) were tested in 8-hill single plots. At harvest, 41 lines were selected on the basis of external appearance, size distribution and scab resistance in the field. These lines were further evaluated for dry matter, internal defects, chip color and after cooking darkening. Characteristics of the lines selected from MSU, North Dakota and New York are presented in Tables 13, 14 and 15, respectively. Those seedlings that meet the industry requirements for fresh market, chip and frozen processing will be further tested in 1987 in larger plots. F. VARIETY EVALUATIONS FOR SCAB Potato scab continues to be of concern with several of the newer varieties. Each year Dr. Ray Hammerschmidt conducts evaluations of varieties and advanced seedlings to assess their tolerance or susceptibility to scab. Locations are selected on cooperators farms where scab is known to have been a problem. Table 16 classes the several varieties evaluated for their reactions to scab in 1986. Table 1. First date of harvest yield data (99 days). Harvested August 7, 1986. Variety Yield cwt/A 1 U.S. #1 Yield cwt/A 1 Total % Size Distribution U.S. #1 % Size Distribution <2 % Size Distribution 2-3 1/4 % Size Distribution >3 1/4 % Size Distribution Specific Gravity Pick Outs A 76147-2 MS 700-83 Onaway MS 702-91 Atlantic MS 700-70 MS 716-15 MS 704-10 Conestoga Sunrise Krantz MS 702-80 ND 534-4 Shepody MS 700-79 Acadia Russet Norking Russet Russet Burbank Average 397 392 386 365 346 335 333 327 327 320 296 295 278 274 254 218 189 181 306 489 446 477 433 406 425 392 423 385 395 389 347 383 356 315 381 327 361 396 81 88 81 84 85 79 85 77 85 81 76 85 72 77 81 57 58 50 16 10 10 9 13 18 14 22 13 13 17 15 23 20 16 41 40 45 67 85 71 75 79 78 78 75 76 73 68 82 64 67 77 56 57 50 14 3 10 9 6 1 7 2 9 8 8 3 8 10 4 1 1 0 3 2 9 7 2 3 1 1 2 6 7 0 5 3 3 2 2 5 empty table cell empty table empty table cell cell empty table empty table cell cell 1.069 1.073 1.068 1.071 1.081 1.079 1.079 1.077 1.076 1.071 1.069 1.072 1.069 1.078 1.073 1.076 1.078 1.078 1.074 1 BLSD for U.S. #1 = 51 cwt/A. CV = 8.8%. 2 20 tubers cut to determine internal defects. 3 PC/SFA 1-5 scale, 1 = lightest; 5 = darkest. Chip 3 Score 2.5 1.5 3.0 1.5 1.5 1.5 1.0 1.5 1.5 1.5 2.0 1.5 2.0 2.0 1.5 2.5 2.0 2.0 empty table cell Internal Defects 2 HH Internal Defects 2 Vas. Dis. Internal Defects 2 Int. Necrosis 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 2 0 4 1 1 0 0 0 4 0 0 1 0 0 4 empty table empty table empty table cell cell cell Table 2. Second date of harvest yield data (120 days). Harvested August 28, 1986. Variety Yield cwt/A 1 U.S. #1 Yield cwt/A 1 Total % Size Distribution U.S. #1 % Size Distribution <2 Specific % Size Distribution % Size Distribution % Size Distribution Gravity 2-3 1/4 >3 1/4 Pick Outs MS 700-70 A 76147-2 Atlantic MS 700-83 Onaway Shepody MS 716-15 MS 702-91 MS 704-10 Acadia Russet Krantz MS 702-80 Conestoga Sunrise ND 534-4 MS 700-79 Russet Burbank Norking Russet Average 550 543 460 445 432 401 396 383 381 374 355 345 332 319 300 287 233 187 374 618 664 510 503 550 523 458 453 487 534 457 420 397 418 411 347 458 357 476 89 82 90 88 79 77 86 85 78 70 78 82 83 76 74 83 52 53 7 12 8 9 11 12 10 8 18 24 13 10 12 15 20 13 31 43 65 49 67 67 63 51 62 67 64 61 56 64 73 58 49 75 49 47 24 33 23 21 16 26 24 18 14 9 22 18 10 18 25 8 3 6 4 6 2 2 11 11 3 7 3 6 9 7 4 8 6 4 17 4 empty table cell empty table empty table cell cell empty table empty table cell cell 1.088 1.076 1.088 1.074 1.066 1.086 1.085 1.072 1.082 1.086 1.071 1.073 1.071 1.067 1.070 1.076 1.086 1.082 1.078 1 BLSD for US. #1 = 71 cwt/A. CV = 13.6%. 2 20 tubers cut to determine internal defects. 3 PC/SFA 1-5 scale, 1 = lightest; 5 = darkest. Chip 3 Score 1.5 2.5 1.5 1.5 3.5 1.5 1.0 1.5 1.5 3.5 2.0 1.5 1.5 1.5 2.5 2.0 2.0 2.0 empty table cell Internal Defects 2 HH Internal Defects 2 Vas. Dis. Internal Defects 2 Int. Necrosis 2 0 0 0 0 2 0 2 2 0 5 0 0 0 0 1 0 2 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 2 0 0 2 1 1 2 0 0 0 4 0 2 2 0 1 0 1 0 3 1 empty table empty table empty table cell cell cell Table 3. Third date of harvest yield data (142 days). Harvested September 22, 1986. Variety Yield cwt/A 1 U.S. #1 Yield cwt/A 1 Total % Size Distribution U.S. #1 % Size Distribution <2 % Size Distribution % Size Distribution 2-3 1/4 >3 1/4 Specific % Size Distribution Pick Gravity Outs MS 700-70 A 76147-2 Atlantic Acadia Russet MS 716-15 MS 702-91 MS 700-83 Onaway Shepody MS 702-80 MS 704-10 ND 534-4 Krantz Sunrise Russet Burbank Conestoga MS 700-79 Norking Russet Average 620 611 521 504 488 488 468 445 430 428 394 372 363 354 347 341 311 250 430 676 747 569 663 545 534 522 547 558 473 499 485 468 429 567 400 376 395 525 92 82 91 76 89 91 89 81 77 90 79 76 78 82 61 85 83 63 empty table cell 6 12 6 20 7 7 9 6 14 8 17 17 14 10 25 12 14 35 empty table cell 66 51 65 65 64 67 63 66 54 69 69 51 61 66 51 69 69 60 empty table cell 26 31 26 11 25 24 26 15 23 21 10 26 17 16 10 16 14 3 empty table cell 2 6 3 4 4 2 2 9 9 2 4 6 8 8 14 3 3 2 empty table cell 1.084 1.077 1.090 1.086 1.086 1.073 1.074 1.072 1.083 1.076 1.080 1.073 1.075 1.072 1.086 1.076 1.077 1.078 1.079 1 BLSD for U.S. #1 = 83 cwt/A. CV = 13.8%. 2 20 tubers cut to determine internal defects. 3 PC/SFA 1-5 scale, 1 = lightest; 5 = darkest. Chip 3 Score 2.0 3.0 1.5 4.5 1.5 1.5 2.0 4.0 2.0 1.5 1.5 3.0 2.0 1.5 2.5 1.5 2.0 2.0 empty table cell Internal Defects 2 HH Internal Defects 2 Vas. Dis. Internal Defects 2 Int. Necrosis 5 4 6 0 0 0 0 1 1 3 1 0 0 1 0 0 2 1 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 3 0 empty table cell 2 sl 1 sl 1 sl 4 sl 1 sl 1 sl 2 sl 2 sl 2 sl 0 2 1 sl 3 sl 0 3 sl 3 sl 1 sl 0 empty table cell empty table cell Table 4. The vigor, maturity and early blight ratings of potato varieties in the dates of harvest trial. Variety Vigor 1 Maturity 2 Early Blight 3 MS 700-79 MS 700-83 MS 702-80 MS 702-91 MS 704-10(Y) MS 716-15 MS 700-70 A 76147-2 ND 534-4 Norking Russet Acadia Russet Krantz Onaway Atlantic Conestoga Shepody Sunrise Russet Burbank 3.8 4.5 3.7 3.8 4.3 4.5 5.0 4.4 3.8 4.3 4.7 4.7 4.9 5.0 4.3 4.6 4.1 4.3 3.0 2.8 3.5 2.8 2.8 3.7 4.0 4.0 2.2 2.5 4.2 3.1 2.0 3.8 1.0 4.0 2.0 4.5 1.0 1.1 1.0 1.3 1.2 1.0 1.0 1.0 1.7 1.3 1.0 1.4 2.1 1.0 3.3 1.1 1.4 1.0 1 Vigor: When tops have reached maximum size, before visible signs of maturity. Taken 68 days after planting. Scale of 1-5, 1 = poor; 5 = excellent. 2 Maturity: When tops show differences in maturity. Taken 93 days after planting. Scale of 1-5, 1 = early; 5 = very late. 3 Early Blight Rating: Scale of 1-5 = resistant; 5 = highly susceptible. Table 5. After-cooking-darkening 1 of potato varieties grown in the 1986 dates- of-harvest trial. Variety 0 Hours 1 Hour 24 Hours Comments MS 700-79 MS 700-83 MS 702-80 MS 702-91 MS 704-10 MS 716-15 MS 700-70 A 76147-2 ND 534-4 Norking Russet Acadia Russet Krantz Onaway Atlantic Conestoga Shepody Sunrise Russet Burbank 1.5 2.0 1.5 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.5 1.5 1.0 1.5 1.0 2.5 3.0 1.5 1.5 1.0 1.5 1.5 1.5 2.0 1.0 1.5 1.0 1.0 2.0 1.5 1.0 1.5 1.0 2.5 3.5 1.5 1.5 1.0 1.5 1.5 2.0 2.0 1.0 1.5 1.0 1.0 2.0 1.5 1.0 2.0 1.0 All 3 tubers darkened All 3 tubers darkened 1 with dark end 1 with dark end empty table cell Some sloughing empty table cell empty table cell dark color overall empty table cell dark color overall empty table cell empty table cell 2 dark stem ends 2 dark stem ends empty table cell 3 dark ends empty table cell 1 Tubers stored at 50-55°F since harvest. Rating scale 1-5, 1 = no darkening; 5 = severe darkening (black) overall. Table 6. The chip color of potato varieties at harvest and after 120 days of storage at 55°F. Variety Chip Score 1 At Harvest Chip Score 1 120 Days MS 700-79 MS 700-83 MS 702-80 MS 702-91 MS 704-10 MS 716-15 MS 700-70 A 76147-2 ND 534-4 Norking Russet Acadia Russet Krantz Onaway Atlantic Conestoga Shepody Sunrise Russet Burbank 2.0 1.5 1.5 1.5 1.5 1.0 1.5 2.5 2.5 2.0 3.5 2.0 3.5 1.5 1.5 1.5 1.5 2.0 1 Chip Score: PC/SFA scale 1-5, 1 = lightest; 5 = darkest. 1.5 2.0 1.0 1.0 1.5 1.0 1.5 2.5 3.5 2.0 3.5 1.0 3.5 1.0 1.5 2.0 1.5 2.0 Table 7. Blackspot susceptibility of potato varieties in the dates-of-harvest trial 1. Variety Artificially Bruised % Tubers with Blackspot Artificially Bruised Severity 2 Index Check % Tubers with Blackspot Check Severity 2 Index MS 702-91 MS 700-79 MS 716-15 MS 702-80 MS 704-10 MS 700-83 Norking Russet Krantz Russet Burbank Acadia Russet Onaway Shepody Sunrise A 76147-2 Conestoga ND 534-4 Atlantic 20 30 30 20 40 20 10 40 30 80 20 30 20 20 20 0 30 0.2 0.4 0.5 0.2 0.4 0.2 0.1 0.4 0.6 2.5 0.2 0.3 0.2 0.2 0.3 0.0 0.6 0 0 0 0 10 0 0 0 0 10 10 0 0 10 0 0 0 0 0 0 0 0.1 0 0 0 0 0.1 0.2 0 0 0.1 0 0 0 1 Potatoes were stored at 40°F for 120 days following harvest. The bruised tubers and the check treatments were placed at 55°F for one week before peeling. 2 Severity Index: Number of blackspot bruises per tuber. Table 8. Internal defects in oversized tubers at 2 dates of harvest. Variety % Tubers Hollow Heart 120 Days % Tubers Hollow Heart 142 Days % Tubers Internal Necrosis 120 Days % Tubers Internal Necrosis 142 Days MS 700-79 MS 700-83 MS 702-80 MS 702-91 MS 704-10 MS 716-15 MS 700-70 A 76147-2 ND 534-4 Norking Russet Acadia Russet Krantz Onaway Atlantic Conestoga Shepody Sunrise Russet Burbank 12 10 6 5 13 5 10 5 3 4 10 0 0 16 3 3 12 0 28 10 4 5 22 8 5 10 5 3 8 0 0 13 16 10 11 6 4 5 3 20 3 0 10 0 6 0 4 0 3 10 13 0 3 0 12 10 14 16 8 2 12 2 5 0 0 0 0 12 5 2 2 0 Table 9. Tuber yield, size distribution and specific gravity of potato varieties in the Upper Peninsula. Variety Yield cwt/A U.S. #1 Yield cwt/A Total % Size Distribution U.S. #1 % Size Distribution <2 % Size Distribution 2-3 1/4 Specific % Size Distribution % Size Distribution Pick Outs >3 1/4 Gravity MS 704-10 Acadia Russet Onaway A 76147-2 MS 700-83 Russet Burbank Krantz ND 534-4 MS 702-80 Atlantic MS 716-15 MS 702-91 MS 700-70 NorKing Russet Conestoga Nooksack Average 352 336 317 303 302 270 267 266 259 250 243 243 230 213 187 163 263 369 382 328 326 323 325 288 288 274 272 253 266 246 230 190 175 283 95 88 97 93 93 83 93 92 94 92 96 92 93 92 99 93 4 6 3 3 4 8 4 5 5 7 4 3 7 5 1 5 52 53 30 32 50 54 54 53 50 52 50 60 47 62 78 69 44 35 66 61 43 29 39 40 45 39 46 32 46 30 21 24 0 5 0 4 3 9 3 3 1 1 0 5 0 3 0 2 empty table cell empty table empty table cell cell empty table empty table cell cell 1.087 1.081 1.079 1.072 1.081 1.080 1.081 1.079 1.082 1.090 1.088 1.082 1.081 1.080 1.081 1.084 1.082 Table 10. Tuber yield, solids, maturity and chip quality of potato varieties in the North Central Regional Trial. Most 2/ Representa­ tive Scab Area-Type EARLY CWT/A Aver. Yield EARLY CWT/A Aver. Yield US #1 EARLY Aver. Percent US #1 EARLY (Not Solids/a) Aver. Total Solids EARLY Aver. 1/ Mat. EARLY Gen. 3/ Merit Rating EARLY Chip 4/ Color EARLY Early 5/ Blight Reading EARLY EARLY 376 493 339 459 1.0 2.0 1.0 3.0 MEDIUM TO LATE Comments and General Notes empty table cell2.5 empty table cell2.5 empty table cell1.0 1.5 MEDIUM TO LATEMEDIUM TO LATE 3.0 3.0 3.0 4.0 MEDIUM TO LATE 16.5 18.6 18.8 19.9 5 315 383 259 405 MEDIUM TO LATEMEDIUM TO LATE MEDIUM TO LATE 84 77 76 89 MEDIUM TO LATE Selection Number or Variety EARLY Norland ND651-9 ND860-2 W832 MEDIUM TO LATE MS700-83 MS704-10 MN12161 MN12567 MN82328 NE165.75-2 NEA71.72-1 BN9803-1 ND671-4Russ NDT9-1068-11R W879 W948R Red Pontiac Russet Burbank Norgold Russet Norchip La12-59 1/ 1-Very Early-Norland maturity; 2-Early-Irish Cobbler maturity; 3-Medium-Red Pontiac maturity; 4-Late-Katahdin maturity; Nice tuber appearance. Flesh br. yellow, high % <2" empty table cell empty table cell Sprouts early. High % of oversize tubers. Nice smooth tubers. Rough, irregular shape, knobs. High % of tubers <4 oz. Prominent growth cracks. Flat tubers, irregular shape. empty table cell empty table cell High % of tubers <4 oz. High % of tubers <4 oz. empty table cell empty table cellempty table cell 1.0 1.5 empty table cell1.5 2.5 empty table cell1.5 empty table cell2.5 2.5 empty table cell2.0 2.5 empty table cell3.5 empty table cell2.0 empty table cell2.5 empty table cell3.5 empty table cell3.0 empty table cell4.0 empty table cell2.0 empty table cell empty table cell empty table cell High % of oversize tubers. MEDIUM TO LATE 19.0 20.1 19.9 18.6 19.2 19.4 19.4 20.5 18.4 16.9 21.8 19.9 17.5 21.2 18.2 19.9 468 311 361 388 297 390 361 316 311 504 377 557 388 283 197 356 - 541 471 485 506 427 453 448 410 490 593 445 655 473 613 347 441 - 3.7 3.7 4.0 4.0 4.0 5.0 4.5 4.0 3.7 3.5 3.7 4.0 4.2 4.2 3.7 3.5 3.0 3.0 3.5 3.8 3.5 4.5 3.5 3.0 2.8 3.2 3.0 3.0 3.5 4.5 3.0 3.0 empty table cellempty table cellempty table cell 87 66 75 77 70 86 81 77 63 85 85 85 82 46 57 80 - empty table cellempty table cell 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 MEDIUM TO LATE empty table cell 3 2 4 1 1-1 1-2 5-Very Late-Kennebec or Russet Burbank maturity. 2/ AREA - T-less than 1%; 1 - 1020%; 2 - 21-40%; 3 - 41-60%; 4 - 61-80; 5 - 81-100%. TYPE - 1. Small, superficial; 2. Larger, superficial; 3. Larger, rough pustules; 4. Larger pustules, shallow holes; 5. Very large pustules, deep holes. 3/ Place top five among all entries including check varieties; disregard maturity classification. (Rate first, second, third, fourth and fifth (in order) for overall worth as a variety). 4/ Chip Color - PCII Color Chart or Agtron. 5/ Early Blight - 1-suspectible; 5-highly resistant. SFA Score 1 = lightest, 5 = darkest. Table 11. Summary of external and internal grade defects of potato varieties in the North Central Regional Trial. * Sun Green EARLY Total (4) Tubers Free of External EARLY Defects MEDIUM TO LATE MEDIUM TO LATE MEDIUM TO LATE 92 76 88 90 2 0 0 4 2 0 4 0 EARLY EARLY Soab (3) EARLY Normal Tubers (5) Hollow Heart EARLY Internal Neorosis EARLY Growth Cracks EARLY Second Growth EARLY Vasoular Discoloration MEDIUM TO LATEMEDIUM TO LATE Disregard Disregard Disregard Disregard MEDIUM TO LATE 100 92 98 100 4 sl 24 sl 2 s, 6 sl 4 s, 2 sl MEDIUM TO LATEMEDIUM TO LATE 0 0 0 0 MEDIUM TO LATEMEDIUM TO LATE Selection Number or Variety EARLY Norland ND651-9 ND860-2 W832 MEDIUM TO LATE MS700-83 MS704-10 MN12161 MN12567 MN82328 NE165.75-2 NEA71.72-1 BN98O3-1 ND671-4RUSS NDT9-1068-11R W879 W948R Red Pontiac Russet Burbank Norgold Russet Norchip La12-59 (1) Based on four 25 tuber samples (one from each replication). Percentage based on number of tubers. (2) Based on four 25 tuber samples (one from each replication). Percentage based on number of tubers. (3) Includes all tubers with scab lesions whether merely surface, pitted or otherwise and regardless of area. Be sure to 6 sl 2 s, 6 sl 0 36 sl 4 sl 4 s, 6 sl 6 sl 2 sl 2 sl 4 s, 6 sl 6 sl 20 sl 12 sl 4 sl 0 6 sl - 96 96 100 98 100 96 100 90 100 90 100 100 94 84 96 92 - 76 86 100 62 94 84 80 72 98 88 94 78 74 92 96 94 4 0 0 0 0 2 10 24 0 2 0 0 14 0 2 0 - 14 6 0 2 2 4 4 2 0 0 0 2 0 4 2 0 - 0 0 0 0 0 4 0 8 0 4 0 0 0 14 2 6 Disregard Disregard Disregard Disregard Disregard Disregard Disregard Disregard 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 - 0 8 2 0 2 4 0 2 0 0 0 2 0 6 0 0 4 2 2 2 - Disregard Disregard Disregard Disregard Disregard Disregard Disregard Disregard - - count tubers with any amount of scab in this category. (4) This total - tubers free from any external defect of any sort. (5) Percentage normal tubers are those showing no internal defects. internal defects. Some individual tubers will have more than one type of (6) Percent pick-outs (knobs, growth crack) determined at time of field grading and percentage of total weight. Pick outs are discarded so are not included in sample when external and internal defects are determined. % Pic Outs (6) EARLY 1 2 1 4 1 3 2 1 2 6 1 8 3 7 4 1 5 22 8 5 - Table 12. Yield, size distribution and quality of potato varieties tested in the preliminary trial. Variety Yield cwt/A U.S. #1 2 Yield cwt/A Total % Size Distribution U.S. #1 % Size Distribution <2 % Size Distribution 2-3 1/4 % Size Distribution >3 1/4 % Size Distribution Pick Outs Specific Gravity Chip 3 Score Maturity 4 Early Blight 5 Internal Internal Defects 1 Defects 1 Vas. HH Dis. Internal Defects 1 Int. Necrosis F 72004 F 74123 A 7411-2 BR 7093-24 ND 1538-1 ND 651-9 Average 523 462 442 363 330 260 397 564 554 515 436 455 428 492 93 83 86 83 73 61 empty table cell empty table cell 5 11 10 13 25 39 67 68 59 67 66 61 empty table cell 26 15 27 16 7 0 2 6 4 4 2 0 empty table cell empty table cell 1.081 1.072 1.091 1.079 1.079 1.072 1.079 2.5 2.5 1.5 2.0 2.5 1.5 empty table cell 1 20 tubers cut to determine internal defects. 2 LSD for U.S. #1 = 57 cwt/A. CV = 9.5%. 3 PC/SFA scale 1-5, 1 = lightest; 5 = darkest. 4Maturity: 1 = early, 5 = very late maturity. 5Early Blight: 1 = resistant, 5 = susceptible to early blight 3.1 2.5 3.8 4.6 2.2 2.9 2.0 1.8 2.2 1.2 2.0 2.0 0 3 3 8 1 0 empty table cell empty table cell empty table cell 2 0 0 0 0 2 empty table cell 1 3 2 2 0 2 empty table cell Table 13. Characteristics of MSU seedlings selected from 8-hill plots. Variety Yield (lbs) No. 1 Yield (lbs) Total % Size Distribution % Size Distribution 2-3 1/4 #1 % Size Distribution % Size Distribution >3 1/4 <2 % Size Distribution Pick Outs Specific Gravity Internal Mat 1 EB 2 Internal Internal Defects Defects Defects VD IN HH Chip 3 Color ACE MS 401-5 MS 401-2 MS 401-3 MS 402-7 MS 401-7 MS 402-3 MS 402-1 MS 402-6 MS 401-6 MS 401-8 MS 402-5 MS 402-8 MS 401-1 MS 402-2 MS 402-4 Russet Burbank MS 401-4 27.5 29.5 27.5 26.5 23.0 25.3 26.0 23.0 28.0 22.7 23.2 21.7 21.0 23.0 22.5 20.0 18.2 17.5 16.0 17.8 19.0 16.0 16.0 15.0 21.0 15.0 14.0 16.5 18.0 12.5 16.2 10.5 8.0 13.5 7 93 96 4 91 8 88 12 81 18 94 6 92 4 89 2 96 4 90 8 84 16 94 6 71 29 85 15 69 28 65 34 59 41 83 93 85 73 78 91 59 89 63 70 76 72 71 85 69 65 59 10 3 6 15 3 3 33 0 33 20 8 22 0 0 0 0 0 0 0 1 0 1 0 4 9 0 2 0 0 0 0 3 1 0 1.090 1.090 1.086 1.078 1.091 1.082 1.079 1.076 1.086 1.086 1.078 1.076 1.086 1.077 1.074 1.088 1.082 5.0 4.0 3.0 2.5 3.5 ? 3.0 2.0 3.0 2.5 2.0 2.0 2.0 2.0 1.5 5.0 1.5 2 2 2 2 1 ? 2 2 1 2 2 2 2 1 1 1 1 2 0 0 9 0 0 0 1 0 1 0 1 0 0 8 2 1 s1 6 1 s1 4 1 s1 2 0 6 1 s1 0 8 0 0 0 18 1 s1 2 2 s1 0 0 0 4 0 3 3 1 1 s1 0 0 1 s1 0 1 1 s1 1 3 1.5 1.5 2.0 3.5 2.5 3.0 3.0 2.5 2.0 1.5 4.0 2.5 1.0 2.5 2.5 3.0 2.0 1. 1. 2 1. 1. 1. 1. 1 1 1 1 1 1 1 1 1 1 1 Maturity: 1 = early, 5 = very late maturity. 2 Early Blight: 1 = resistant, 5 = highly susceptible. 3 PC/SFA 1-5 scale: 1 = lightest, 5 = darkest. 4 After cooking darkening score after 1 hour: 1 = no darkening, 5 = very dark Table 14. Characteristics of North Dakota seedlings selected from 8-hill plots. Variety Yield (lbs) No. 1 Yield (lbs) Total % Size Distribution #1 % Size Distribution % Size Distribution > 3 1/4 <2 % Size Distribution % Size Distribution Pick 2-3 1/4 Outs Specific Gravity Mat 1 Internal Internal EB 2 Internal Defects Defects Defects VD IN HH Chip 3 Color ACD 4 27.0 ND 1719-5 ND 1725-13 26.5 ND 2233-2 25.0 24.0 ND 2112-2 ND 2126-11 21.5 ND 1859-3 21.0 ND 2135-3-R 20.0 20.0 ND 2179-10 19.0 Atlantic ND 862-8 18.5 ND 2126-7 17.7 17.0 ND 2109-7 15.2 ND 1215-1 12.7 ND 2212-9 11.0 ND 1850-5 28.5 34.0 26.0 25.8 25.0 23.5 27.0 23.0 24.5 23.0 26.7 23.5 20.7 17.7 15.0 95 5 78 21 96 4 93 6 86 14 89 11 74 19 87 13 78 22 80 20 66 34 72 28 73 27 72 11 73 27 84 69 85 76 80 89 74 74 78 80 64 60 67 48 60 11 9 11 17 6 0 0 13 0 0 2 12 6 24 13 0 1 0 1 0 0 7 0 0 0 0 0 0 17 0 1.079 1.082 1.081 1.078 1.081 1.087 1.076 1.084 1.094 1.068 1.077 1.083 1.076 1.072 1.073 2.0 2.5 3.5 1.5 1.5 3.0 2.0 2.0 3.5 1.5 3.0 2.5 3.5 2.0 1.5 2 2 3 2 2 3 2 2 3 2 2 2 3 2 2 0 1 0 0 0 0 1 0 0 0 0 0 0 1 0 0 1 s1 1 1 s1 1 2 s1 0 1 s1 1 1 s1 2 1 s1 0 0 1 1 s1 1 1 s1 2 1 s1 3 1 s1 0 1 s1 1 1 s1 0 0 0 2 s1 3.5 1.0 3.0 1.5 2.0 3.0 3.5 3.5 1.5 2.0 1.5 1.0 2.0 3.5 3.0 1.0 1.5 1.0 2.0 1.0 1.0 1.5 1.5 1.0 1.0 1.0 2.0 1.0 1.5 1.0 1 Maturity: 1 = early, 4 After cooking darkening score after 1 hour: 1 = 1-5 scale: very late maturity.2 Early Blight: resistant, highly susceptible. 3 PC/SFA darkest. lightest, 5 = 1 = 5 = 5 = 1 = no darkening, 5 = very dark. Table 15. Characteristics of New York seedlings selected from 8-hill plots. Variety Yield (lbs) No. 1 Yield (lbs) Total % Size Distribution % Size Distribution #1 2-3 1/4 % Size Distribution % Size Distribution > 3 1/4 <2 % Size Distribution Pick Outs Specific Gravity Mat 1 Internal Internal EB 2 Internal Defects Defects Defects VD IN HH Chip 3 Color ACD 4 NY 191-2 NY 123-4 NY 191-1 NY 85-10 NY 130-4 NY 130-5 NY 140-2 NY 195-11 NY 143-9 NY 125-6 NY 164-9 NY 195-3 Russet Burbank 42.0 38.0 36.0 34.0 33.6 27.6 25.5 30.5 25.5 30.0 26.0 25.5 25.2 29.7 24.0 21.2 28.2 20.5 19.5 23.5 21.7 19.0 23.2 18.2 10.0 16.0 90 10 94 3 82 18 84 16 85 13 2 98 85 13 88 12 73 26 83 17 87 12 79 17 63 25 83 72 73 77 72 83 71 76 73 74 78 76 63 7 22 9 7 13 15 14 12 0 9 9 3 0 0 3 0 0 2 0 2 0 1 0 1 0 12 1 Maturity: 1 = early, 5 = very late maturity. 1.065 1.071 1.079 1.075 1.082 1.085 1.075 1.088 1.084 1.090 1.092 1.089 1.090 3.5 2.5 4.0 5.0 3.0 5.0 2.0 3.0 3.0 3.0 2.5 2.5 5.0 2 2 1 1 1 2 2 2 2 3 2 2 1 0 2 0 0 0 2 3 2 0 0 2 0 1 3.5 1 1 3.0 0 1 3.5 0 0 3.0 1 1 s1 1.0 0 5 2.0 3 1 s1 2.5 0 1 s1 1.0 0 1 1 1 s1 4.0 1.5 0 3 1.5 0 3 1.5 2 1 s1 3.0 0 1 l.0 1.0 l.0 l.0 1.0 1.5 1.0 1.0 1.0 1.5 1.5 1.0 1.0 2 Early Blight: 1 = resistant, 5 = highly susceptible. 3 PC/SFA 1-5 scale: 1 = lightest, 5 = darkest. 4 After cooking darkening score after 1 hour: 1 = no darkening, 5 = very dark Table 16. Variety reactions to scab. Resistant Intermediate Susceptible Islander Nooksack MS 700-83 MS 702-91 Alasclear Krantz Norking Russet Onaway Ontario Pungo Rideau Russet Burbank Superior MS 700-79 MS 702-80 MS 714-10 Acadia Russet Atlantic Chipbelle Conestoga Crystal Denali Jemseg Katahdin Monona Oceania Rosa Sebago Shepody Simcoe Snowchip Yukon Gold Yankee Chipper Yankee Supreme MS 700-70 MS 701-22 MS 704-10(Y) MS 716-15 MS 718-16 THE EFFECTS OF PRE-CUTTING AND FUNGICIDE TREATMENT OF POTATO SEED Funding: Federal Grant R.W. Chase, G.H. Silva, and R.B. Kitchen Department of Crop and Soil Sciences Michigan State University Pre-cutting of seed has been suggested as a remedy for potato varieties that are slow to emerge and establish in the field. Shepody and Yukon Gold are examples of such varieties that are grown commercially in Michigan. The germination is often slow and erratic resulting in poor vigor and uneven plant stands. Also, the delayed emergence predispose the seed pieces to rot organisms in the soil. In 1986, a 2 x 2 factorial experiment was conducted at the Montcalm Experiment farm to investigate the merits of: (a) Pre-cut (2 weeks before planting) vs. fresh-cut seed. (b) Fungicide (Tops-2.5D®) treatment of seed pieces vs. no treatment. Two cultivars, Shepody and Yukon Gold were used in the study. For pre-cutting, the seed potatoes were taken out of storage two weeks before the planting date and hand-cut to produce seed pieces between 50-60 grams. Fresh-cut seed was cut and planted on the same day. Fungicide treatment was done immediately after cutting at the recommended rate (1 lb Tops-2.5D®/100 lbs cut seed. The treatments were tested in a randomized complete block design with four replications. The trial was planted on May 5, 1986. The fertilizers applied were 200 lbs/A 0-0-60 at plowdown, 500 lbs/A 15-10-15-12S with planter, and 75 lbs/A N as urea as sidedressing (June 17, 198(6). Management practices were similar to those applied for the dates-of-harvest study. The trial was harvested on September 16, 1986. Data on emergence, plant stand, tuber yield and quality were recorded. The results obtained with cultivar Shepody are presented in Table 1. Plants from pre-cut seed emerged earlier and produced a higher plant stand compared with fresh-cut seed. The uniformity and the vigor of the pre-cut treatment was very evident at the early stage of the crop. Analysis of variance showed that the combined yield produced by the pre-cut seed (with and without fungicide treatment) was significantly higher than the fresh-cut seed. Treatment of cut seed with Tops-2.5D® produced no significant advantages in plant stand and tuber yield. The interaction between time of cutting and fungicide treatment was not significant. Quality parameters such as specific gravity and size distribution of potatoes were not substantially different among treatments. The results obtained with Yukon Gold are not presented here because of poor plant stands in the trial. The seed used for this trial was of inferior quality and the overall germination was only about 50%. Therefore the data was not logistically analyzed In this trial, treatment with Tops-2.5D® helped to alleviate some of the germination problems associated with Yukon Gold. The preliminary results are encouraging for the use of pre-cutting and possibly fungicide treatment of cut seed as a means of overcoming the slow and poor establishment of some potato varieties. These experiments are to be expanded and repeated in 1987 to further validate the 1986 findings. Table 1. Yield of Shepody in relation to time of cutting and fungicide treatment of seed. Treatment Yield (cwt/A) U.S. #1 1 Yield (cwt/A) Total % Size Distribution U.S. #1 % Size Distribution <4 % Size Distribution 4-10 % Size Distribution % Size Distribution Pick Outs >10 Specific Gravity Days 50% Emergence % Stan Pre-cut/No Tops Pre-cut/Tops Fresh-cut/No Tops Fresh-cut/Tops 417 a 410 ab 373 bc 367 c 515 509 457 466 81 81 82 79 17 19 18 20 67 68 72 69 14 13 10 10 2 0 0 1 1.086 1.086 1.089 1.090 22 23 24 24 97 97 93 93 1 Means followed by the same letter are not significantly different (Duncan's multiple range test at 5% level). Time of cutting : significant Tops treatment : not significant Interaction : none CV = 6.7% Funding: Federal Grant EVALUATION OF PRODUCTION MANAGEMENT INPUTS TO IMPROVE QUALITY and yield of three msu seedlings G.H. Silva, R.W. Chase, and R.B. Kitchen Department of Crop and Soil Sciences Michigan State University Three new potato seedlings from Michigan State University, MS 716-15, MS 700-83 and MS 704-10 have done consistently well in Michigan and in several other states, and are being considered for variety releases from MSU. MS 716-15 is a round white, medium-late maturing seedling with above average yields and high specific gravity. Tubers have a smooth general appearance and excellent chip quality. MS 700-83 is a round white, mid-season maturing seedling with above average yield and medium gravity. It has a good general appearance and has potential for fresh market and chipping out of field. MS 704-10 is a yellow flesh variety that sets heavy and produces average yields with high specific gravity. It has potential for fresh market and chipping out of field and short term storage. The management practices recommended for new releases are generally based on standard practices adapted for commonly grown varieties. In 1986, the nitrogen and spacing requirements of the three MSU seedlings were studied using three levels of nitrogen (100, 150, 200 lbs/A) and three within-row spacings (6”, 9”, 12") in a factorial experiment. The treatments were tested in a randomized complete block design with four replications. In addition to determining the optimum requirements of nitrogen and spacing, the economics of each input level were investigated. MS 716-15 In this study both nitrogen and spacing effects were significant (Table 1). The highest nitrogen level (200 lbs) and the closest spacing (6") produced significantly higher yields than all other treatments. At 12" spacing, there was a slight tendency to produce a higher % of oversized tubers. The specific gravity of the potatoes, although not significantly different between treatments, were higher at lower nitrogen levels and closer spacings. The cost/revenue analysis showed that the higher yield produced at 200 lbs of N and 6" spacing far outweighed the costs associated with increased nitrogen and seed for closer spacing at this input level (Table 2). MS 700-83 In this study only nitrogen effects were significant and spacing effects were not significant. Although the highest U.S. #1 yield was produced at 200 lbs N and 6" spacing, yield differences were not significantly different from seven other treatment combinations. At closer spacing, there was a slight tendency to produce a higher % of undersized tubers with a corresponding decrease in the % U.S. #1 tubers. The specific gravity again was slightly higher in low nitrogen, closely spaced treatments. The cost/revenue analysis showed that a combination of 150-200 lbs N and a wider spacing of 12" was the most appropriate for MS 700-83. MS 704-10 In this study the yield differences between treatments was somewhat similar to those obtained with MS 700-83. Only nitrogen effects were significant and spacing effects were not significant. Although the highest US. #1 yield was again produced at 200 lbs N and 6" spacing, the yield differences were not significant from seven other treatment combinations. At closer spacing, there was a tendency to produce a higher % of undersized tubers with a corresponding decrease in % U.S. #1 tubers. The cost/revenue analysis showed that a nitrogen, level of 150 lbs/A and a spacing of 12” was the most desirable input combination for MS 704-10. The combined specific gravities of the three seedlings at the three different N levels and spacings are presented in Figures 1 and 2. Increasing levels of nitrogen resulted in a reduced specific gravity, and to a lesser degree, there was a trend to a lower specific gravity with a wider in-row spacing. Table 1. Influence of nitrogen and spacing on tuber yield of MS 716-15. Nitrogen 1 (lbs/A) Spacing 1 (inches) Yield (cwt/A) U.S. #1 2 Yield (cwt/A) Total % Size Distribution U.S. #1 % Size Distribution <2" % Size Distribution 2-3 1/4 % Size Distribution > 3 1/4 % Size Distribution Pick Outs Specific Gravity 200 200 150 150 150 200 100 100 100 9 7 12 7 9 7 12 10 8 1 Both nitrogen and spacing effects were significant. 532 a 480 b 446 bc 437 bcd 433 bcd 415 cd 407 cd 397 cd 390 d 593 521 510 480 482 467 466 451 426 90 91 87 91 90 91 87 89 91 6 9 6 12 9 12 6 9 12 76 80 79 76 81 64 81 83 79 14 11 8 15 9 27 6 6 12 1 1 1 2 1 2 1 1 1 1.092 1.091 1.093 1.091 1.091 1.090 1.093 1.092 1.092 2 Means followed by the same letter are not significantly different (Duncan's multiple range test at 5% ). CV = 7.4% Table 2. Nitrogen and seed costs/acre analysis for MS 716-15. N Applied 1 (lbs/A) 200 200 150 150 150 200 100 100 100 N + Application 2 Cost ($) A 52 52 39 39 39 52 26 26 26 Spacing (inches) 6 9 6 12 9 12 6 9 12 Seed 3 Cost ($) B 266 182 266 133 182 133 266 182 133 N + Seed Cost($) Yield (cwt/A) A+B 318 234 305 172 221 185 292 208 159 532 480 446 437 433 415 407 397 390 Gross 4 Revenue ($) C Net ($) C-(A+B) 3499 3149 2919 2876 2836 2759 2659 2594 2561 3181 2915 2614 2704 2615 2574 2367 2386 2402 1 Nitrogen 100, 150, and 200 lbs applied in 2, 3, and 4 applications. 2 Niltrogen cost = $0.20/lb. Cost per application = $3.00/A. 3 Seed cost = $7.00/cwt. 4 Revenue on the basis of $6.50/cwt for tubers 2-31/4" and $7.00/cwt for tubers >31/4 Table 3. Influence of nitrogen and spacing on tuber yield of MS 700—83. Nitrogen 1 (lbs/A) Spacing (inches) 2 Yield (cwt/A) U.S. #1 3 Yield (cwt/A) Total % Size Distribution U.S. #1 % Size Distribution <2" % Size Distribution 2-3 1/4 % Size Distribution % Size Distribution Pick Outs >3 1/4 Specific Gravity 200 200 150 150 150 100 200 100 100 6 12 6 9 12 6 9 12 9 455 a 446 a 442 ab 437 ab 436 ab 423 ab 422 ab 409 ab 397 b 555 516 539 503 504 501 508 466 468 82 87 82 87 87 84 83 88 84 16 11 17 13 13 15 17 12 15 78 73 77 80 80 82 76 82 80 5 14 5 7 7 2 7 6 4 1 0 1 0 0 1 0 0 1 1.079 1.079 1.081 1.080 1.079 1.082 1.080 1.080 1.082 1 Nitrogen effect : significant. 2 Spacing effect : not significant. 3 Means followed by the same letter are not significantly different (Duncan's multiple range test at 5%) . CV = 7.9% Table 4. Nitrogen and seed costs/acre for MS 700—83. N Applied 1 (lbs/A) N + Application 2 Cost($) A Spacing (inches) Seed 3 Cost ($) B N + Seed Cost ($) Yield (cwt/A) A+B Gross 4 Revenue ($) c Net ($) C-(A+B) 200 200 150 150 150 100 200 100 100 3007 2934 2887 2858 2851 2754 2761 2672 2590 1 Nitrogen 100, 150, and 200 tbs applied in 2, 3, and 4 applications. 455 446 442 437 436 423 422 409 397 318 185 305 221 172 292 234 159 208 266 133 266 182 133 266 182 133 182 52 52 39 39 39 26 52 26 26 6 12 6 9 12 6 9 12 9 2689 2759 2582 2637 2679 2462 2527 2513 2382 2 Nitrogen cost = $0.20/lb. Cost per application = $3.00/A. 3 Seed cost = $7.00/cwt. 4 Revenue on the basis of $6.50/cwt for tubers 2-3 1/4” and $7.00/cwt for tubers >3 1/4" Table 5. Influence of nitrogen and spacing on tuber yield of MS 704-10. Nitrogen 1 (lbs/A) Spacing 2 (inches) Yield (cwt/A) U.S. #1 3 Yield (cwt/A) Total % Size Distribution U.S. #1 % Size Distribution <2" % Size Distribution 2-3 1/4 % Size Distribution >3 1/4 % Size Distribution Pick Outs Specific Gravity 200 150 200 150 200 150 100 100 100 6 12 9 6 12 9 12 9 6 315 a 302 ab 301 ab 301 ab 300 ab 293 ab 289 ab 266 ab 253 b 437 403 406 427 395 403 382 360 368 72 75 75 70 76 73 76 74 69 22 19 19 27 19 22 21 24 28 63 65 62 61 65 63 71 67 64 9 10 13 9 11 10 5 7 5 6 6 6 3 5 5 3 2 3 1.084 1.085 1.086 1.084 1.086 1.086 1.088 1.086 1.088 1 Nitrogen effect : significant. 2 Spacing effect : not significant. 3 Means followed by the same letter are not significantly different: (Duncan's multiple range test 5%). CV = 11.3% Table 6. Nitrogen and seed costs/acre for MS 704-10. N Applied 1 (lbs/A) N + Application 2 Cost($) Spacing (inches) 200 150 200 150 200 150 100 100 100 A 52 39 52 39 52 39 26 26 26 6 12 9 6 12 9 12 9 6 Seed 3 Cost ($) B 266 133 182 266 133 182 133 182 266 A+B 318 172 234 305 185 221 159 208 292 N + Seed Cost ($) Yield (cwt/A) Gross 4 Revenue ($) c Net ($) C-(A+B) 315 302 301 301 300 293 289 266 253 2067 1983 1982 1976 1972 1925 1888 1741 1653 1749 1811 1748 1671 1787 1704 1729 1533 1361 1 Nitrogen 100, 150, and 200 tbs applied, in 2, 3, and 4 applications. 2 Nitrogen cost = $0.20/lb. Cost per application = $3.00/A. 3 Seed cost = $7.00/cwt. 4 Revenue on the basis of $6.50/cwt for tubers 2-3 1/4" and $7.00/cwt for tubers >3 1/4” Figure 1. Relationship between N and specific gravity. Figure 2. Relationship between spacing and specific gravity. Title: EFFECTS of respond® treatments on yield and quality of potatoes Investigators: R.W. Chase, G.H. Silva and R.B. Kitchen Department of Crop and Soil Sciences, Michigan State University (Supported by Grower Services, Inc., Lansing) Cultivar: Atlantic Treatments: The experiment compared 5 treatments: #1 - Respond 1% solution applied in-furrow, at planting #2 - Respond 0.5% solution applied in-furrow, at planting #3 - Respond at 24 oz/A applied to foliage, at hook stage #4 - Respond at 12 oz/A applied to foliage, at hook stage #5 - Control treatment, with no Respond application Design; The treatments were field tested in a randomized complete block design with 5 replications. Individual plots were 23 feet x 34 inches in size. Plants were spaced 9 inches apart in the row. Location: Montcalm Experiment Station, Michigan State University Soil Type: McBride Sandy Loam Date of Planting: May 8, 1986 Date of Harvest: September 16, 1986 Fertilizer application: 200 lbs/A 0-0-60 plowdown 500 lbs/A 15-10-15-12S with planter 75 lbs/A N as urea as sidedressing (June 17, 1986) Respond Application: The in-furrow application for treatments #1 and 2 was made at the time of planting. The application was done with a knapsack sprayer to single drop seed before closing of the furrow. No surfactant was used. The temperature and relative humidity at application was 55°F and 60%, respectively. The foliar application for treatments #3 and 4 was done on June 9, 1986 (31 days after planting) to correspond with the early hook storage. The temperature and relative humidity at application was 65°F and 55%, respectively. Observations: The data on emergence, plant stand, maturity, tuber yield, size distribution and specific gravity were collected. Results and Conclusions: The results are summarized in Table 1. Analysis of variance on US. #1 yield data indicated no significant differences between treatments. The highest U.S. #1 yield (466 cwt/A) was obtained with Respond 24 oz furrow application. The control treatment produced 456 cwt/A. In this experiment, a yield difference of at least 35 cwt/A was required to produce statistical significance between treatments. Days for 50% emergence, % stand and maturity date showed no substantial differences between treatments. Quality parameters such as specific gravity and size distribution of the tubers also were not affected by the Respond treatment. Under 1986 conditions, Respond application did not appear to produce any desirable or undesirable effects on tuber yield and quality in Atlantic variety. However, a complete understanding of the effects of Respond treatment on potatoes requires further tests extended over several seasons and different cultivars. Table 1. Effects of Respond® treatments on potato yield and quality. Treatment Yield cwt/A 1 Yield cwt/A 1 Total U.S. #1 % Size Distribution % Size Distribution 2-3 1/4 U.S. #1 % Size Distribution % Size Distribution S.G. 2 >3 1/4 <2 Days 50% % Size Distribution Pick Outs Emer- gence % Stand Matu- 3 rity Furrow, 24 oz Control (No Respond) Foliar, 24 oz Foliar, 12 oz Furrow, 12 oz 466 536 87 11 456 453 451 446 540 531 536 527 84 85 84 85 12 13 13 12 77 76 77 71 71 10 8 8 13 14 2 4 2 3 3 1.092 1.093 1.093 1.094 1.091 19 21 19 20 21 93 96 93 90 93 3.5 3.5 3.5 3.5 3.5 1 Average of 5 replications. The U.S. #1 yield not significantly different between treatments. In this experiment, a difference of at least 35 cwt/A was required for treatments to become statistically significant. 2 Specific gravity determined by weight in air/water method. 3 Maturity, 1 = early; 5 = very late. Foliar treatments applied at hook stage. CV = 7.8% EVALUATION OF CULTIVARS FOR FROZEN PROCESSING R.W. Chase, G.H. Silva, and R.B. Kitchen Department of Crop and Sool Sciences In Cooperation with Jim Fuller, Ore-Ida Foods, Inc. Advanced potato seedlings from USDA-Aberdeen potato breeding program were evaluated at early and late harvests in collaboration with Ore-Ida Foods, Inc. All trials were planted on May 6. Eight selections were planted in the early harvest trial and harvested on August 28. Ten selections were planted in the late harvest trial and harvested on September 24. In addition, eight selections from the 1985 8-hill screening test were planted in a preliminary adaptation trial. For the 1986 8-hill screening trial, 65 new selections were introduced and tested. The early and late harvest trials were conducted in a randomized complete block design with four replications. The preliminary adaptation trial had two replications. For the screening test, the 65 selections were tested in 8-hill, single plots. The management practices applied to these trials were similar to those used for the dates-of-harvest trial. EARLY TRIAL RESULTS Table 1 summarizes the performances of varieties tested in the early harvest trial. A description of the variety characteristics is given below: A76147-2 - Showed early emergence with good vine growth and vigor. Maturity is considered to be late. Produced the highest U.S. #1 and total yield in the trial. Solids are a little lower than desired for frozen processing. Has potential for count pack market. Onaway - Used as a reference variety, particularly for yield, It is not considered a processing potato. A79239-8 - Showed early emergence with good vine growth and early vigor. Maturity is considered late and similar to Russet Burbank. Produced above average yields with high solids. Produced smooth tubers with excellent appearance. Has excellent potential. A78242-5 - Good early is considered mid-season and produced average yields with high gravity. susceptible to hollow heart. growth and vigor. Maturity to be It is A79357-17 - Good early growth and vigor. Maturity is very late. Produced average yields with high gravity. It is also susceptible to hollow heart. Shepody - Slow emergence and less vigorous in the early stages of growth. Maturity is medium-late but reaches maturity about two weeks before Produced average yields with high gravity. Russet Burbank. Excellent potential for frozen processing. ND534-4 - Slow emergence and less vigorous in the early stages of growth. Maturity is early to mid-season and produced below average yields with low solids. Tubers are smooth with excellent general appearance. Specific gravity is too low for frozen processing but has potential for count pack fresh market. Sizing was not adequate in this trial. Russet Burbank - Used as a reference variety. Very poor sizing and type in 1986. High % solids content is good for frozen processing. LATE TRIAL The performances of varieties tested in the late harvest trial is summarized in Table 2. A description of the variety characteristics are given below: A79239-8 - Produced the highest US. #1 and total tuber yield in the trial. Vine and tuber characteristics are similar to those described for early trial. Excellent potential for frozen processing. A79357-17 - Good early growth and vigor. Late maturity but produced high yields with high solids. As in the early trial, hollow heart was a problem. A78242-5 - Good early growth and vigor. Late maturity with above average yields. Solids are sufficient for frozen processing. Pentland Dell - A major variety used for frozen processing in Europe. Vigorous early growth and very late maturity. Produced average yields with high gravity. Percent U.S. #1 was low because of poor sizing. Krantz - Good early growth and mid-season to late maturity. Produced average yields with good type but the specific gravity is somewhat less than desired for frozen processing. Has potential for a count pack. Russet Burbank - Used as a reference variety. Produced below average yields because of poor sizing and type. A80222-2 - Slow emergence and less vigorous growth at the early phase of growth. Very late maturity and has a tendency to produce a higher % of oversize tubers. Tubers had alligator's skin in 1986. Has limited potential in Michigan. ND534-4 - Slow emergence and less vigorous growth at the early stage. Vine and tuber characteristics are similar to those described in the early trial. Solids content is too low for frozen processing. A77101-18 - Slow emergence and less vigorous growth at the early stage. Produced below average yields because of higher % of U.S. #2 oversized tubers. Tubers are susceptible to hollow heart. Norking Russet - Slow emergence and less vigorous growth at the early stage. Mid-season maturity with very low yields because of poor sizing. Potential for frozen processing is limited because of poor sizing, based on this trial. PRELIMINARY TRIAL The performances of varieties tested in the preliminary trial are summarized in Table 3. A description of the variety characteristics is given below: A79341-3 - Produced the highest U.S. #1 and total yields in the trial. Very late maturing and has high solids. Hrs a tendency to produce a high % of oversized tubers. Tubers are susceptible to hollow heart. A81556-1 - Good early season growth with mid-season maturity. Produced above average yields but the solids are too low for frozen processing. A79340-8 - Good early season growth and mid-season maturity. Produced above average yields with high solids. Tubers were not susceptible to hollow heart but showed a high frequency of bud end necrosis. A80621-8 - Slow early season growth and mid-season maturity. Produced above average yields but the gravity is too low for frozen processing. Russet Burbank - Used as a reference variety. Produced a low % of U.S. #1 tubers because of poor sizing and type. A7869—44 - Slow emergence and vigor at the early stage. Late maturing and produced below average yields with high gravity. A81394-9 - Slow emergence and growth at the early stage of growth. Late maturing and produced below average yields due to poor plant stand. Tubers were of poor type owing to a higher % of U.S. #2 tubers. Solids insufficient for frozen processing. Tubers are susceptible to hollow heart. A81389-4 - Lowest yield due to poor plant stand establishment. Late maturing and low gravity. Tubers are susceptible to hollow heart. Table 1. Ore-Ida early trial, 1986. Variety Yield cwt/A U.S. #1 Yield cwt/A Total Percent Size Distribution Percent Size Distribution Percent Size Distribution U.S. #1 U.S. #1 U.S. #1 #1 6-10 <4 Percent Size Distribution Percent Size Distribution U.S. #1 U.S. #1 > 10 oz 4-6 Internal Percent Size Distribution Percent Size Distribution % Solids Internal Defects 1 Defects 1 U.S. #2<10 oz U.S. #2 >10 oz HH IN Mat 2 EB 3 A76147-2 Onaway A79239-8 A78242-5 A79357-17 Shepody ND534-4 Russet Burbank Average 478 420 390 369 362 342 264 206 354 605 590 506 513 595 447 377 79 71 77 72 61 76 70 14 18 13 15 14 16 23 35 22 17 18 17 12 21 25 21 418 50 506 empty table cell empty table cell empty table cell 25 empty table cell 37 42 35 39 23 42 29 20 12 24 16 26 13 16 4 4 8 5 7 12 5 3 13 3 3 5 6 13 3 4 2 empty table cell empty table cell empty table cell 19.6 17.7 21.0 20.4 20.5 21.2 18.4 2 0 4 11 9 5 1 21.4 1 20.0 empty table cell empty table cell 2 0 0 0 1 0 0 1 3.5 2.5 4.5 3.0 4.5 4.0 3.0 2.0 2.5 2.0 2.0 1.5 2.0 2.0 4.5 empty table cell 1.5 empty table cell 1 Internal defects evaluated by cutting 40 tubers of size >10 oz. 2 Mat: 1 = early; 5 = very late maturity. 3 EB: 1 = Early Blight resistant; 5 = susceptible. CV (U.S. #1) = 13.1% Table 2. Ore-Ida late trial, 1986. Variety Yield (cwt/A) Yield (cwt/A) Total U.S. #1 Percent Size Distribution Percent Size Distribution Percent Size Distribution Percent Size Distribution Percent Size Distribution Percent Size Distribution % Solids U.S. #1 U.S. #1 U.S. #1 U.S. #1 U.S. #1 U.S. #2 #1 >10 oz <10 oz 6-10 4-6 <4 Percent Size Distribution U.S. #2 >10 oz Internal Defects 1 HH Internal Defects 1 IN Mat 2 EB 3 A79239-8 A79357-17 A78242-5 Pentland Dell Krantz Russet Burbank A80222-2 ND534-4 A77101-18 Norking Russet Average 488 468 363 355 329 286 282 247 193 160 317 606 662 526 611 454 489 363 383 366 306 477 80 71 69 58 72 59 78 64 54 14 12 23 36 20 28 16 28 8 16 13 20 32 24 23 19 22 7 53 empty table cell 44 empty table cell 28 empty table cell 37 33 33 24 31 30 34 30 18 24 empty table cell 27 16 16 2 17 6 23 12 29 1 4 6 6 6 4 11 3 6 10 3 2 2 2 0 4 2 3 2 28 0 empty table cell empty table cell empty table cell 21.5 20.7 19.7 21.3 18.5 21.3 19.3 17.7 19.5 4 10 2 2 0 7 6 0 11 19.5 0 19.9 empty table cell empty table cell 0 0 2 2 1 1 0 0 0 1 4.0 2.0 4.0 1.5 2.0 4.5 4.5 1.5 2.0 3.5 5.0 1.0 1.0 5.0 2.0 3.0 4.0 1.3 3.0 empty table cell 2.0 empty table cell 1 Internal defects evaluated by cutting 40 tubers of size >10 oz. 2 Mat: 1 = early; 5 = very late maturity. 3 EB: 1 = Early Blight resistant; 5 = susceptible. CV (U.S. #1) = 12.6% Table 3. Ore-Ida preliminary trial, 1986. Variety Yield (cwt/A) U.S. #1 Yield (cwt/A) Total Percent Size Distribution U.S #1 <4 Percent Size Distribution U.S #1 #1 Percent Size Distribution U.S #2 <10 oz Percent Size Distribution U.S #1 4-6 Percent Size Distribution U.S #1 >10 oz Percent Size Distribution U.S #1 6-10 Percent Size Distribution U.S #1 #2 >10 oz % Solids Internal Defects 1 HH Internal Defects 1 IN Mat 2 EB 3 A79341-3 A81556-1 A79340-8 A80621-8 Russet Burbank A7869-44 A81394-9 A81389-4 Average 481 362 352 346 289 284 177 139 304 613 608 566 501 585 387 306 195 470 78 60 62 69 8 15 19 13 9 15 16 22 24 28 29 21 45 17 17 26 3 12 12 11 49 74 58 71 empty table cell 31 13 21 21 empty table cell 24 14 13 17 empty table cell 21 35 24 32 empty table cell 4 25 21 . 22 empty table cell 12 6 8 8 empty table cell 11 13 7 7 8 7 13 0 empty table cell 21.0 11.9 20.4 18.1 13 9 0 5 21.4 2 21.2 5 17.1 9 12 17.9 19.4 empty table cell 1 1 7 1 0 0 0 0 empty table cell 4.5 3.0 3.5 3.5 2.0 2.0 1.5 1.0 5.0 4.5 5.0 5.0 empty table cell 1.0 1.5 1.0 1.0 empty table cell 1 Internal defects evaluated by cutting 40 tubers of size >10 oz. 2 Mat: 1 = early; 5 = very late maturity. 3 EB: 1 = Early Blight resistant; 5 = susceptible. CV (US. #1) = 20.1% SUSTAINABLE AGRICULTURE — POTATOES Robert Lucas and Richard Bay Department of Crop and Soil Sciences Michigan State University A project was carried out at the Kellogg Biological Station (KBS) in Kalamazoo County which compared four different management systems which could be practical for small scale market gardeners. The soil type is classified as a Kalamazoo loam with less than two percent slope. The site had been well manured and fertilized for many years. In 1983 the soil tested: pH - 6.9, phosphorus - 235, potassium - 460, calcium - 2000 and magnesium - 383 pounds per acre (2 million pounds of soil) . The management systems compared were: 1) High Energy (H. Eng.). This description was given in 1983 when fossil fuel resources were more of an input. The management system might better be called a preventive program where liberal amounts of commercial fertilizers and pesticides are used. 2) Integrated Crop Management (ICM) . This system is similar to H. Eng. but uses chemicals only when a need is apparent. This system requires scouting for nutrient and pest problems. Risks are greater but total production costs are lower than the H. Eng. inputs system. 3) Bioagriculture (Bio). This system is called "organic" by some. It uses no chemical products except those designated as bioproducts. When needed, ground rock phosphate, bone meal, green sand, granite dust or similar materials are used as sources of phosphorus and potassium. 4) Bioagriculture with Farm Manure (Bio-M). This system uses similar chemicals as used for the Bio system. In addition, 12 tons of farm manure from the KBS dairy loose bedding barn was used as the manure source. Site In addition to potatoes, snap beans, cucumbers and sweet corn were grown. Each vegetable crop followed either an alfalfa or some other vegetable crop. Irrigation water was available when needed. Potatoes In 1985, Yankee Chipper was planted April 26 and harvested August 19 and in 1986, Yankee Supreme was planted April 22 and harvested August 12. The rows were spaced three feet apart and the seed spaced 10 inches apart in the row. Temik (aldicarb) was applied on top of the row after planting in April and then covered lightly with soil. Before applying, the Temik was mixed with some soil in a bucket to help obtain a more even application. The N-P-K fertilizer for the two chemical systems was applied in each row before planting the seed. Some of the nitrogen was sidedressed in June. The data in Table 1 shows the crop yields. Of the seven vegetables under study, potatoes were the most responsive to the H. Eng. and ICM management systems because of serious potato leaf-hopper burn. Of these two systems, yields show no significant differences in 1985 but the H. Eng. yields were significantly better in 1986. The data in Table 2 shows the grade size and specific gravity values. Table 3 reports the various inputs for the four systems. Table 1. Yield of potatoes grown under four different management systems. Management System High Energy Integrated Crop Management Bioagriculture Bio and Manure LSD (5%) 1985 After Beans cwt/a 1985 After Alfalfa 1986 After Beans 1986 After Alfalfa cwt/A cwt /A cwt/A 370 370 216 229 305 321 217 245 36 empty table cell 342 292 164 212 338 280 200 212 54 empty table cell Table 2. Yield and specific gravity of potatoes (Yankee Chipper) grown in 1985. Management System High Energy After vegetables After alfalfa High Energy ICM After vegetables ICM After alfalfa Bio After vegetables Bio After alfalfa Bio-M After vegetables Bio-M After alfalfa Average After vegetables After alfalfa Average LSD (5%) A Size cwt/A A and B Size cwt/A A Size Specific Gravitycwt/A 231 256 288 277 119 122 124 140 191 199 empty table cell 37 370 305 370 321 216 217 229 245 321 322 1.075 1.074 1.082 1.077 1.082 1.078 1.077 1.076 1.079 1.076 N.S. Table 3. Inputs for potatoes growing under four management systems. Inputs 1 1985 H. Eng. ICM 1985 Bio 1985 Bio-MPlow and Drag 1986 H. Eng. ICM 1986 Bio 1986 Bio-MPlow and Drag 1985 1986 Primary Tillage Nutrients Plow and Drag — Plow and Drag — Plow and Drag — Manure - Ton/A Rock Phosphate - lb/A Nutrients Green Sand - lb/A Nutrients Fertilizer N - lb/A Nutrients Fertilizer P2O5 - lb/A Nutrients Fertilizer K2O - lb/A Nutrients Herbicide 3 Lexone Insecticide Temik 5 Sevin Insecticide Rotenone Insecticide Fungicide Dithane M-45 Tri. B. Copper Fungicide Cultivation Fungicide Irrigation Hand Weeding Hours/A — — — — 100-70 2 95-55 50 180 100 180 1x 4 lx 2x — 4x 2x 4x 6 — 1x lx 2x — 2x — 2x 4x 6 2000 — 2000 — — — — — — — — — — — 2x 2x — 2x 4x 4x 20 — 2x 4x 4x 20 — — 12 — — Plow and Drag Plow and Drag — Plow and Drag — — 100-50 60 120 — — 100-50 30 60 lx lx — — 2x — 4x — 5 lx lx — — lx 4x — 5 — — — — — — — — — — — 3x — lx 4x — 34 12 — — — — — — 3x — lx 4x — 34 1 - All "after vegetable" plots were plowed, dragged and planted to rye in late September. Alfalfa was seeded in late August, left in sod the following year and then plowed down in April just prior to planting to potatoes. 2 The first value designates the nitrogen applied after vegetables and the second value for the N applied after alfalfa. 3 All pesticides are applied at rates recommended in Michigan State University Extension Bulletins E-312 and E-433. 4 "1x" indicates one application. 5 Temik-15 G applied at planting time in row at the rate of 15 lb per A. Funding: Federal Grant Annual Report Improved Production and Utilization Technology for Michigan Potatoes USDA Project ORD. NO. 38543 and 40818 Sub Report: Tillage Management Systems F. J. Pierce, R. W. Chase and K. A. Renner Crop and Soil Sciences Department Introduction Quality improvement of potatoes represents the major objective of potato growers in Michigan. A major factor affecting potato quality is the physical condition of the soil in the zone of rooting and tuber development. Wind and water erosion are serious problems on the sandy and organic soils which dominate potato acreage in Michigan. Conventional practices for potato production in Michigan use cover crops for overwinter protection of soil and limit plowing to spring primary followed directly by planting to avoid excessive tillage and soil structure degradation. Michigan farmers, therefore, are well aware of the potential limitations of poor soil physical conditions and soil erosion. However, the potential for serious problems related to poor soil physical condition and erosion remain. Excessive traffic, often with heavy axle loads repeated over several years, has created compact soil conditions below the. depth of normal tillage and degraded soil structure in the tillage zone. Soil erosion potential in Michigan from wind and water is highest during the period from tillage and planting to hilling or canopy closure when the soil is bare and unprotected. The objective of this research is to develop and evaluate aternatives to existing tillage systems on sandy soils in Michigan that reduce potential for soil erosion and improve tuber quality and yield of potatoes. This is the second year of the study and results for both years are discussed. Experimental Methods and Results: 1985 Tillage tools designed to subsoil in the row were evaluated in replicated experiments with conventional potato production methods. The intention was to restrict tillage in these systems to the zone in the potato row (zone tillage) and leave the interrow area untilled with a cover of standing rye as protection against wind and water erosion. The tillage treatments evaluated were as follows: 1. Conventional tillage - light disking, moldboard plowing followed immediately by planting 2. Conventional tillage preceded by subsoiling in the row with a Kelly subsoil unit 3. Bush Hog Ro-till - one pass (this is at in-the-row subsoiler equiped with surface tillage tools) 4. Bush Hog Ro-till - two passes 5. Paraplow in-the-row (a subsoiler that fractures the soil with minimal surface disturbance). Results for 1985 were reported in the research report for the Montcalm Station for 1985. While not significant at the 5 percent level, showed trends for yields and tuber quality of Russet Burbank potatoes to increase with the use of zone tillage, with the paraplow showing the highest average yields (385 cwt/ac) and conventional tillage with in-the- row subsoiling the lowest yields (348 cwt./acre). A check of > 10 oz No. 1 potatoes showed an increased incidence of hollow heart. tissue analysis of potato petioles showed a significant increase in uptake of Zn and Mn in the Bush Hog Ro-till treatments. Measurements of population densities of root lesion nematodes (Paratylenchus penetrans) showed no effect of tillage treatments. 1986 Three experiments were initiated in fall of 1985 and spring of 1986 to further develop and evaluate these "zone tillage" systems for potato production. Tillage Management Tillage treatments were expanded from those used in 1985 to include the timing of zone tillage (spring vs fall), the use of surface rotary cultivation in-the-row after passage of the paraplow, and the use of a ridge cultivator for use in hilling potatoes. Treatments were as follows: 1. Paraplow fall in-the row. 2. Paraplow spring in-the row. 3. Paraplow spring with surface rotary cultivation both in-the row. 4. Bush Hog Ro-till in-the-row fall. 5. Bush Hog Ro-till in-the-row spring. 6. Bush Hog Ro-till in-the-row spring, hilling with ridge cultivator. 7. Conventional tillage - spring, light disking, moldboard plow. Yields were higher in 1986 than in 1985. As was the case in 1985, yield of Russet Burbanks were improved with the use of zone tillage systems. Yields in the Paraplow (#1) and the Bush Hog (#4) spring treatments were highest, 424 and 413 cwt./ac respectively, and yields in the conventional tillage treatments were lowest, 346 cwt./ac. Conventional tillage was significantly lower at the 5 percent level than all other treatments. These data are summarized in Table 1. Tuber quality was reduced over that recorded for 1985. Percent No 1's ranged from 55 % for the spring Bush Hog treatment (#5) to 49 % for conventional tillage compared to 70 and 63 %, respectively, for 1985. Tillage affected the distribution of tuber sizes. Conventional tillage produced smaller potatoes although the percentage of No 1 potatoes was not significantly different from other tillage systems. The trends in the data, while not significant, showed a tendency for fall zone tillage to produce higher total yields but spring zone tillage produced higher yields of No 1 potatoes. Seeding Rate Study The results from the 1985 tillage experiment suggested that seeding rate may be imppotant when soil is prepared with zone tillage. Therefore, two seeding rates, 10 inch and 14 inch spacings, were evaluated in a split-plot design field experiment with tillage as the main plots. Tillage included conventional, Bush Hog Ro-till, and Paraplow treatments with all tillage done in the spring. Yields (Table 2) in this study showed no statistical difference between tillage treatments but Bush Hog and conventional treatments were higher than the paraplow, 507, 524, and 468 cwt./ac, respectively. There were no yield differences due to seeding rate, 504 and 496 cwt/ac for the 10 and 14 inch spacings, respectively. Yields were higher in this experiment than the tillage management study where potatoes have been grown more frequently and more recently in the rotation cycle at the Moncalm farm. Tuber quality was affected by both tillage and seeding rate as shown in Table 3. Seeding rate tended to alter the size distribution of tubers with the 10 " seeding rate producing more tubers in the smaller size ranges and less in the No. 1 > 10 oz size. Conventional tillage methods produced a significantly higher percentage of No 2 > 10 oz potatoes. Quality of potatoes was higher in this experiment than the tillage experiment where yield of No. 1 potatoes averaged 62 percent. Rye-Kill Experiment It was apparent from the 1985 experiment that the condition of the rye cover crop in terms of growth and degree of kill affected the performance of the tillage machinery. Therefore, in 1986 an experiment was set out to evaluate the timing and method of killing the rye. Zone tillage was performed with the Bush Hog Ro-till. Treatments included two rates of Roundup herbicide (3/8 and 3/4 pint) applied either 14 days preplant or immediately after planting and one rate of Paraquat applied either 2 days preplant or immediately after planting. Visual rye injury and percent moisture evaluations were taken at planting and at hilling. Results are summarized in Table 4. Glyphosate applications fourteen days before planting gave the most visual rye injury and greatest rye moisture reduction. Paraquat application two days before planting gave 73% visual injury. Glyphosate and paraquat applications immediately after planting did not give complete control or the rye cover crop. Visual observations were made of machinery performance confirmed observations made in 1985 that partial killing of the rye just prior to planting hindered performance of the tillage equipment. Where rye was killed with Roundup 14 days prior to planting, rye was completely killed and experienced little growth. Therefore, machinery was not affected by the rye. Where rye was killed after planting, machinery performed well with the exception of plots in low areas where soil moisture was high. It was our opinion that early killing of the rye was best for machinery performance but was both expensive and did not allow for sufficiency rye growth to insure erosion control. In all methods, all rye was gone after the hilling operation. There were no significant effects of rye kill on potato yield as summarized in Table 5. Significant differences were evident and due to wet conditions in the lower areas of the field. The fourth rep of the experiment was not harvested due to excessive wet conditions and rotting of the potatoes in this area of the field. Table 1. Yield of Russet Burbank as affected by tillage system in 1986. Component < 4 oz 4 - 6 oz PPF \1 CWT/ACRE PPS CWT/ACRE RTF CWT/ACRE RTS CWT/ACRE PPSRC CWT/ACRE CONV CWT/ACRE RTSDR CWT/ACRE 52.1 56.3 56.3 63.8 54.5 54.5 57.8 64.0 54.1 58.9 58.0 61.8 53.9 60.5 6 - 10 oz 56.0a 53.1a 57.0a 63.1a 52.0a 40.6b 53.8a > 10 oz 27.1a 25.3a 26.5a 19.4a 18.5a 9.1b 22.1a No2 <10 oz 43.4ab 42.6ab 44.8ab 40.3ab 49.8a 39.8ab 37.1 b No2 >10 oz 40.9a 26.4 bc 31.9ab 22.6 bc 25.3 bc 19.3 c 28.3 bc Total yield 424a 411a 413a 410a 397a 346 b 393a Yield No 1 214.0a 218.3a 212.0a 225.0a 198.9a 171.3 b 209.5a % No 1 50.5 53.2 51.2 54.7 50.0 49.2 53.5 \1 See treatment descriptions in text under tillage management study for 1986. Numbers with the same letter within a row are not significantly different at the 5 % level using LSD criterion. Table 2. Yield of Russet Burbank as affected by tillage and seeding rate in 1986. Component < 4 oz 4-6 oz 6-10 oz > 10 oz No2 <10 oz No2 >10 oz Tillage Conv. cwt/ac Tillage Conv. cwt/ac 74.0a 60.1b Tillage Tillage Bush Hog Bush Hog cwt/ac cwt/ac 98.8a 75.1b Tillage Paraplow cwt/ac Tillage Paraplow cwt/ac 90.7a 68.4b 107.8 98.8 117.2 111.8 112.2 95.9 129.9 124.3 137.4 138.2 116.7 120.7 75.1a 97.2b 66.7a 86.3b 49.8a 73.0b 50.2 55.5 56.3 49.2 54.6 55.7 67.2a 74.0a 55.3b 55.2b 52.1c 47.9c Total yield cwt/ac 504 510 532 515 476 461 No 1 % 61.2 62.3 65.2 64.8 58.6 62.7 Numbers with the same letter within a row are not significantly different at the 5 % level using LSD criterion. Table 3. Yield of Russet Burbank as affected by seed spacing in 1986. Component < 4 oz 4 - 6 oz 6 - 10 oz > 10 oz No2 <10 oz No2 >10 oz No 1 Plant Spacing 10 inch % 17.6a 22.3 25.3 12.4a 10.8 11.6 61.7 Plant Spacing 14 inch % 13.9b 20.6 25.7 17.0b 11.0 11.9 63.3 Total yield cwt/ac 504 496 Numbers with the same letter within a row are not significantly different at the 5 % level using LSD criterion. TABLE 4. Control of Rye-Cover Crop in Till-Planted Potatoes. 4-25-86 4-25-86 6-16-86 6-16-86 Rate (LB AI/A) 0.38 1/2% 0.75 1/2% 0.38 1/2% 0.75 1/2% 0.50 1/4% 0.50 1/4% Visual* Rye Injury 90 a 90 a 0 c 0 c 73 b 0 c Appl. Time 14 DBP 14 DBP 14 DBP 14 DBP AP AP AP AP 2 DBP 2 DBP AP AP Herbicide GLYPHOSATE X-77 GLYPHOSATE X-77 GLYPHOSATE X-77 GLYPHOSATE X-77 PARAQUAT X-77 PARAQUAT X-77 % Moisture Rye 36 c Visual Rye Injury 100 A % Moisture Rye 42 40 c 100 A 67 A 67 A 58 B 38 c 63 B 93 A 67 A 33 c 44 56 55 44 58 9-18-86 Yield** (cwt/a) 390 425 433 453 451 463 * % MOISTURE OF ALL RYE PRESENT IN 2 SQ FT AREA. ** AVERAGE OF 3 REPS. ONLY. Statistical comparisons are not valid between columns. Table 5. Yield of Russet Burbank as affected by method and timing of rye kill in a zone tillage system in 1986. Treatments: 1. R3/8Pr Roundup + X-77 at 3/8 # + 1/2 % 14 days preplant 2. R3/8Pr Roundup + X-77 at 3/4 # + 1/2 % 14 days preplant 3. R3/8Pr Roundup + X-77 at 3/8 # + 1/2 % post plant 4. R3/8Pr Roundup + X-77 at 3/4 # + 1/2 % post plant 5. P3/4P Paraquat + X-77 at 1/2 # + 1/4 % 2 days preplant 6. P3/4Po Paraquat + X-77 at 1/2 # + 1/4 % post plant Component Herbicide Treatment R3/8Pr Herbicide Treatment CWT/ACRE Herbicide Treatment R3/4PrCWT/ACRE R3/8Po CWT/ACRE Herbicide Treatment Herbicide Treatment R3/4Po CWT/ACRE P3/4P CWT/ACRE P3/4Po Herbicide Treatment CWT/ACRE < 4 oz 99.9 90.5 86.3 89.7 99.7 112.7 4 - 10 oz 180.1 219.6 217.0 226.3 228.0 226.3 > 10 oz No. 2 27.9 82.0 Total yield 390 empty table cell % 42.0 72.8 425 41.8 87.6 433 % 53.3 84.0 453 32.3 90.7 451 % % %% < 4oz 4 - 10 oz > 10 oz No. 2 No. 1 26.1 46.5 6.7 20.7 53.2 21.4 51.6 9.6 17.3 61.2 19.7 50.0 9.7 20.6 59.7 19.8 49.9 11.7 18.5 61.7 22.4 50.2 7.0 20.4 57.2 25.6 98.4 463 24.3 48.8 5.5 21.3 54.4 Funding: MPIC Weed Control on Muck Soils and Variety Response to Herbicide Application and Time of Hilling 1986 Report to the Michigan Potato Industry Commission K. A. Renner and R. W. Chase, Dept, of Crop and Soil Sciences Preliminary Report (Year 1 of 2 year study) Research in 1986 was conducted to: 1. Establish herbicide efficacy on muck soils 2. Evaluate swamp smartweed suppression in potatoes 3. Evaluate the interactions between hilling, potato variety response, and time of herbicide application on mineral soils. Summary of Results: 1. 2. Cinch (2.0 lb ai/A), Command (1.0 lb ai/A), and CGA-180937 (3.0 lb ai/A) provided acceptable season long grass control when applied preemergence (PRE) (at planting) or delayed preemergence (DPRE) (at potato cracking) (Table 1). Command injured the Frito Lay variety at the Allegan Co. location, but no injury occurred where the Atlantic variety was planted in Clinton Co (Table 2). Yields were not taken in Allegan Co. because of flooded conditions resulting in rotting of initial tubers and new tuber set. Sencor (Lexone) provided better redroot pigweed and bardyarngrass control than Lorox when these herbicides were applied PRE or DPRE (Table 3). Optimum Sencor (Lexone) timing appeared to be either a single DPRE application, or a split application of Sencor, with the grass herbicide tank-mixed with the DPRE application of Sencor (Table 4). Another year of research is needed for verification of these weed control results, and to determine tolerance of potatoes to Command herbicide. Sencor (Lexone) when soil applied at 1.0 lb ai/A gave the best suppression of swamp smartweed (Table 5). Roundup and Banvel applied at various rates, timings, and combinations will be evaluated for swamp smartweed regrowth in the spring of 1917. Planned September applications were not made due to saturated soil conditions. 3. Ealy hilling on mineral soils followed by DPRE or postemergence herbicide applications gave excellent control of bardyarngrass, redroot pigweed, common lambsquarters, and Pennsylvania smartweed (Tables 6, 7, 8, and 9). On July 11, nine weeks after planting, there was no interaction between the time of hilling and the herbicide treatments for weed control evaluations. However a significant interation between the time of hilling and herbicide treatments occurred for weed control evaluations taken in August and September. Barnyardgrass and common lambsquarters control was poor in August and September where Eptam (3.0 lb ai/A) was incorporated prior to planting followed by early hilling (EH) (at potato emergence) and then a delayed preemergence (DPRE) application of Lorox (1.0 lb ai/A) or Cobra (0.25 lb ai/A). When Sencor (Lexone) (0.5 lb ai/A) was applied DPRE after Eptam, weed control did not decrease when the treatment was early hilled. Sencor (Lexone) provided better barnyardgrass and common lambsquarters control than Lorox or Cobra when the Eptam activity on these weeds had declined. A preemergence application of Dual + Lorox (2.0 + 1.0 lb ai/A) gave 37% control when early hilled, and 77% control when late hilled (40 days after planting, conventional practice). When this same treatment was applied DPRE (just prior to potato emergence) control of common lambsquarters was excellent throughout the season. All herbicide treatments provided excellent redroot pigweed control throughout the growing season except where Dual + Lorox was applied preemergence and early hilled (Table 8). Sencor (Lexone) was superior to Lorox or Cobra for Pennsylvania smartweed control when applied either DPRE or postemergence with Poast + COC (Table 9). When potatoes were EH a DPRE or postemergence treatment was necessary for maintaining broadspectrum weed control throughout the growing season. However the reduced weed control that began to occur with some treatments by late July was not reflected in potato yield. Eady visual injury on potatoes was noted for al Eptam treatments on the 'Atlantic' variety, especially when the Eptam was followed by Cobra (Table 10). This injury was not reflected in potato yield. There was no significant difference between yields of the 'Atlantic' variety in the seven herbicide treatments, but all herbicide treated plots yielded significantly greater than the untreated check. 'Russet Burbank' yields were significantly greater when herbicides were applied compared to the yield of the hilled-only check. However the yield of the 'Russet Burbank' in the Eptam plus Cobra treatments was significantly lower than the other herbicide treated plots. Double application rates of Dual + Sencor (Lexone) did not injure either potato variety in 1986. There was not a significant interaction between the time of hilling and herbicide treatment when potato yields were evaluated (Table 11). The increased weed growth evident in some of the herbicide treatments that were early hilled did not significantly reduce potato yield. It appeared that if weeds were controlled for the first 8 to 10 weeks after potato planting and then allowed to infest the potatoes, yields were not reduced. Further research in 1987 is necessary to determine if in fact weeds that emerge after mid July have no significant competitive effect on potatoes that is reflected in yield, and to determine if hilling time interactions with herbicice applications will repeat in 1987. Table 1: Herbicide Efficacy and Potato Yield on Organic Soils. * Herbicide Treatment Rate (LB AI/A) 6-11 ANGR 9-9 ANGR (% CONTROL) (% CONTROL) 6-11 RRPW (% CONTROL) 9-9 RRPW (% CONTROL) YIELD (CWT/A) Dual + Sen/Lex Command + Sen/Lex Cinch + Sen/Lex Cinch + Sen/Lex CGA-180937 + Sen/Lex SAN-582 + Sen/Lex SEN/LEX + (POAST + COC) 2.5 + 1.0 1.0 + 1.0 1.0 + 1.0 2.0 + 1.0 3.0 + 1.0 1.5 + 1.0 1.0 + (0.2 +1 QT) 97 AB 90 AB 93 AB 93 AB 90 ABC 83 bc 97 AB 77 ABC 80 AB 77 ABC 70 ABC 83 AB 63 BC 90 AB 100 A 100 A 100 A 100 A 100 A 100 A 100 A 93 A 87 A 93 A 100 A 100 A 90 A 100 A 269 a-f 254 A-H 209 F-I 267 A-F 318 AB 283 A-E 290 A-E 0.5 + (0.5 + 0.2 + 1 QT) SEN/LEX + (SEN/LEX + POAST + COC) Check * All herbicides applied PRE. ( ) denotes POST application. Statistical comparisons are not valid between columns. 27 DE 90 ABC 87 AB 100 A - 0 E 93 A 247 C-H 0 c 0 D 75 I Table 2: Potato Tolerance to New Grass Herbicides. AppL. Rate Herbicide * (lb ai/a) 6-11-86 6-11-86 Clinton Appl. Allegan Time% Visual Injury Co.% Visual Injury Co.% Visual Injury 2.5 1.0 2.0 1.0 DUAL CINCH CINCH COMMAND CGA 180937 SAN-582 0 D 0 D 0 D 0 D 0 D 0 D 17 B 30 A PRE DPRE PRE DPRE PRE DPRE PRE DPRE PRE PRE 3.0 1.5 0 D 3 D 10 BC 0 D 3 CD 0 D 0 D 7 CD 0 D 0 D 0 D 2 D * 1.0 lb ai/a of Sencor (Lexone) was applied with all herbicide treatments. Statistical comparisons between columns are valid. Table 3: Herbicide Efficacy and Potato Yield on Organic Soils. Rate Herbicide (LB AI/A) Appl. TIME 6-11 ANGR 9-9 ANGR 6-11 9-9 Yield RRPW% RRPW% (cwt/a) Sen/Lex Lorox Sen/Lex Lorox Check 1.0 1.5 1.0 1.5 — % 77 C 50 D 100 A 93 AB 0 E % 47 CD 23 DC 83 AB 62 bc 27 DE 93 A 77 B 100 A 100 A 0 c PRE PRE DPRE DPRE — 90 A 63 c 97 A 93 a 0 D 198 g-i 193 hi 246 C-h 228 D-I 75 I Statistical comparisons are not valid between column. TABLE 4: SENCOR (LEXONE) TIMING ON ORGANIC SOILS. Appl. Rate (LB AI/A) Appl. Time 6-11-86 6-11-86 9-9-86 9-9-86 ANGR% CONTROL RRPW ANGR 9-18-86 Yield (cwt/a) 250 A 286 A 268 a RRPW % CONTROL 93 A 98 A 82 B 1.0 1.0 * G + 0.5 + (0.5) 0.5 + (G + 0.5) % CONTROL 97 B 100 A 100 A % CONTROL 76 B 95 A 83 AB PRE 93 B DPRE 100 A PRE + DPRE 99 A PRE + DPRE 100 A 100 A 86 B 93 A 265 A * G = GRASS HERBICIDE. Statistical comparisons between columns are not valid. Table 5: Suppression of swamp smartweed on fallow ground. * Treat- Number Pesticide Name Rate LB/A Application Timing 7/23/86 SWSM 8/11/86 SWSM 9/25/86 SWSM 01 02 03 04 05 06 07 08 * 09 09 09 * 10 10 10 11 12 13 13 14 * 15 15 15 * 16 16 16 17 Lorox DF Lexone DF Command Cinch Roundup Roundup Roundup Banvel II Roundup Banvel X-77 Roundup Banvel X-77 Roundup Roundup Roundup Roundup Banvel Roundup Banvel X-77 Roundup Banvel X-77 1.50 1.00 1.00 2.00 3 QT 4 QT 2 QT 1 QT 1 QT 1 QT 1/2% 2 QT 1 QT 1/2% 3 QT 4 QT 2 QT 2 QT 1 QT 1 QT 1 QT 1/2% 2 QT 1 QT 1/2% No Treatment - May May May May June June June June June June June June June June August August August September August August August August August August August - * Treatment 1-8, 11-14 - 23 gpa, 30 psi. Treatment 9-10, 15-16 - 11.5 gpa, 30 psi. 0.0 3.3 0.0 0.0 6.8 8.1 8.0 10.0 4.0 7.0 3.0 0.7 9.5 9.7 9.7 9.5 3.3 6.7 1.7 0.8 8.5 9.0 8.8 8.7 empty table cellempty table cellempty table cell empty table cellempty table cellempty table cell 9.3 10.0 9.7 9.7 empty table cellempty table cellempty table cell empty table cellempty table cellempty table cell 9.7 9.2 8.8 9.3 7.8 10.0 10.0 9.8 - - - - - - - - - - empty table cellempty table cellempty table cell empty table cellempty table cellempty table cell empty table cellempty table cellempty table cell - - empty table cellempty table cellempty table cell empty table cellempty table cellempty table cell 0.0 0.0 0.0 Table 6: Barnyardgrass Control During the Growing Season Herbicide Eptam + (Sen/Lex) Eptam + (Lorox) Eptam + (Cobra) Dual + Sen/Lex + (Dual + Sen/Lex) Dual + Lorox [Poast + Sen/Lex + COC *] (Dual + Lorox) Hill only Rate (lb ai/a) Appl Time % Control 7-11-86 EHLH Control 8-14-86 EH 8-14-86 LH % Control 9-9-86 % Control 9-9-86 EH LH % % Control 3.0 + (0.5) PPI + (DPRE) 3.0 + (1.0) PPI + (DPRE) 3.0 + (0.25) PPI + (DPRE) 2.0 + 0.5 + (2.0 + 0.5) 2.0 + 0.5 [0.2 + 0.5 + 1 PT] (2.0 + 1.0) PRE + (DPRE) PRE — [POST] (DPRE) — 97 A 93 A 90 A 98 A 73 B 47 c 97 A 95 A 87 AB 85 AB 62 B 20 CD 92 A 93 A 78 AB 100 A :100 A 87 AB 100 A 100 A 97 A 100 A 87 A 100 A 90 A 100 A 97 A 12 B 93 A 93 A 17 D 95 A 100 A 33 cd 92 A 95 A 0 D 75 AB 99 A 27 c * COC = Crop Oil Concentrate. Statistical comparisons are valid only between columns 2 and 3, and columns 4 and 5. Table 7: Redroot Pigweed Control During the Growing Season. Herbicide Eptam + (Sen/Lex) Eptam + (Lorox) Eptam + (Cobra) DUAL + SEN/LEX + (DUAL + SEN/LEX) Dual + Lorox [POAST + SEN/LEX + *] COC (Dual + Lorox) Hill only Rate (LB ai/a) Appl TIME 7-11-86 % Control EHLH 3.0 + (0.5) PPI + (DPRE) 100 A PPI + (DPRE) 100 A 3.0 + (1.0) 3.0 + (0.25) PPI + (DPRE) 100 A PRE + DPRE 100 A 2.0 + 0.5 + (2.0 +0.5) % Control 8-14-86 % Control 8-14-86 EH LH 9-9-86 % Control EHLH 100 A 95 A 97 A 100 A 100 A 100 A 100 A 100 A 93 A 86 A 96 A 98 A 2.0 + 0.5 [0.2 + 0.5 + 1 PT] PRE [POST] 93 A 100 A 50 B 100 A 87 A 100 A 68 B 94 A (2.0 + 1.0) (DPRE) - - 100 A 23 B 97 A 17 D 100 A 33 c 92 a 13 C * COC = Crop Oil Concentrate. Statistical comparison are valid only between columns 2 and 3. Table 8: Common Lambsquarters Control During The Growing Season. Rate (lb ai/a) Appl Time % Control 7-11-86 EHLH Herbicide Eptam + (Sen/Lex) Eptam + (Lorox) Eptam + (Cobra) Dual + Sen/Lex + (Dual + Sen/Lex) Dual + Lorox [Poast + Sen/Lex + COC *] (Dual + Lorox) Hill only 3.0 + (0.5) PPI + (DPRE) 100 A 3.0 + (1.0) PPI + (DPRE) 100 A 3.0 + (0.25) PPI + (DPRE) 100 A 2.0 + 0.5 + (2.0 + 0.5) 2.0 + 0.5 [0.2 + 0.5 + 1 PT] (2.0 + 1.0) PRE + (DPRE) PRE [POST] (DPRE) — — % Control % Control 8-14-86 8-14-86 % Control 9-9-86 EH LH EH % Control 9-9-86 LH 100 A 100 A 57 BC 100 A 100 A 100 A 100 A 100 A 60 bc 98 A 100 A 98 A 100 A 37 CD 97 A 77 AB 100 A 43 cd 100 A 78 AB 100 A 100 A 17 D 100 A 100 A 33 D 100 A 100 A 0 E 98 A 99 A 27 D 100 A 87 B 100 A 100 A 11 c * COC = Crop Oil Concentrate. Statistical comparisons are valid only between columns 2 and 3, and columns 4 and 5. Table 9: Pennsylvania Smartweed Control During the Growing Season. Herbicide Eptam + (Sen/Lex) Eptam + (Lorox) Eptam + (Cobra) Dual + Sen/Lex + (Dual + Sen/Lex) Dual + Lorox [Poast + Sen/Lex + COC *] (Dual + Lorox) Hill only Rate (LB AI/A) Appl Time 7-11-86 % Control EHLH % Control 8-14-86 EH % Control % Control 8-14-86 LH 9-9-86 % Control 9-9-86 EH 98 A 57 CD 7 FG LH 98 A 78 ABC 65 BCD 100 A 70 B 23 CD 100 A 98 A 80 B 3.0 + (0.5) PPI + (DPRE) 100 A PPI + (DPRE) 3.0 + (1.0) 97 A 3.0 + (0.25) PPI + (DPRE) 93 A 2.0 + 0.5 + (2.0 + 0.5) 2.0 + 0.5 [0.2 + 0.5 + 1 PT ] (2.0 + 1.0) PRE + (DPRE) PRE [POST] (DPRE) 100 A 97 A 100 A 100 A 28 b - - 100 A 37 C 100 A 40 C 100 A 43 DE 100 A 33 E 100 A 83 AB 17 D 100 A 100 A 33 cd 100 A 78 ABC 0 G 93 A 88 AB 27 EF * COC = Crop Oil Concentrate. Statistical comparisons are valid only between columns 2 and 3, and columns 4 and 5. Table 10: Injury Evaluation and Potato Yield. Herbicide Eptam + (Sen/Lex) Eptam + (Lorox) Eptam + (Cobra) Dual + Sen/Lex + (Dual + Sen/Lex) Dual + Lorox [Poast + Sen/Lex + COC *] (Dual + Lorox) Hill only Rate (LB AI/A) Appl. Time 3.0 + (0.5) 3.0 + (1.0) 3.0 + (0.25) 2.0 + 0.5 + (2.0 + 0.5) 2.0 + 1.0 [0.2 + 0.5 + 1 PT] (2.0 + 1.0) — PPI + (DPRE) PPI + (DPRE) PPI + (DPRE) PRE + (DPRE) PRE [POST] (DPRE) — % Visual Injury ATL 10 B 12 B 20 a 3 c 0 c 8 c 0 c 0 c 6-2-86 % Visual injury 6-2-86 RB Yield Yiel (cwt/A) d (cwt/A) 10-3-86 10-3-86 ATL RB 515 AB 513 AB 527 A 523 AB 505 AB 453 CD 494 ABC 495 ABC 496 ABC 474 BCD 513 AB 525 AB 444 D 528 A 487 ABCD 339 E 0 c 0 c 2 c 3 c 0 c 0 c 0 c 0 c * COC = Crop Oil Concentrate. Statistical comparisons are valid between columns 1 and 2, and between columns 3 and 4. Table 11: Timing of hilling had no significant effect on potato yield. Herbicide (LB AI/A) Appl. Time Yield (cwt/A) Atlantic EH Yield (cwt/A) Russet B EH Yield (cwt/A) Russet B LH Yield (cwt/A) Atlantic LH Eptam + (Sen/Lex) 3.0 + (0.5) PPI + (DPRE) Eptam + (Lorox) 3.0 + (1.0) PPI + (DPRE) Eptam + (Cobra) 3.0 + (0.25) PPI + (DPRE) Dual + Sen/Lex + (Dual + Sen/Lex) Dual + Lorox 2 + 0.5 + (2.0 + 0.5) 2.0 + 1.0 [Poast + Sen/Lex + COC *] [0.2 + 0.5 + 1 PT] PRE + (DPRE) PRE [POST] (Dual + Lorox) (2.0 + 1.0) (DPRE) Hill Only — - 501 494 495 487 474 542 521 433 528 532 559 502 516 483 529 456 501 512 435 493 469 525 487 307 544 497 472 498 478 532 488 372 * COC = Crop oil concentrate. Statistical comparisons are valid between columns 1 and 2, and between columns 3 AND 4. Funding: MPIC NITROGEN STUDIES ON RUSSET BURBANK POTATOES IN THE UPPER PENINSULA R.H. Leep and D.L. Pellegrini Michigan State University The objective of this study is to determine the effect of nitrogen rates on Russet Burbank potatoes grown in the Upper Peninsula. The end result of this study will determine the most efficient rate of applied nitrogen upon Russet Burbank potatoes grown in rotations following either alfalfa or clover plowdown. Variables which are being analyzed include tuber yield, size distribution, specific gravity, nitrogen concentration, foliage growth and quality. The study was established on the Valare VanDamme farm in Delta County on an Onaway loam. The previous plowdown crop was a mixture of alfalfa and clover. The nitrogen carrier used was ammonium nitrate and was applied on June 10 at first cultivation shortly after emergence. No preplant nitrogen was applied, however, 1,500 pounds/acre of 0-20-20 was applied to this field. Specific treatments are given in Tables 1 and 2. Each treatment was replicated four times. Plot size was four rows by 50 feet. Tissue sampling of young mature leaves was done on July 21 and August 18 and analyzed for nitrate-N content. The nitrate-N content of the tissue was not significantly affected by nitrogen treatments in the first sampling, however, it was significantly affected in the second sampling. Since the normal rate of nitrogen losses due to leaching was the same for all treatments the data would suggest that more nitrogen is available later in the growing season from the higher nitrogen rates. Increasing nitrogen rates above 50 pounds N/acre did not significantly increase total yield. Specific gravity decreased with increasing nitrogen rates. These data indicate that increasing nitrogen rates above 50 pounds Nacre did not increase yields significantly at the general yield levels of 300 cwt/acre. However, plant stands in this field were not optimum with several ''skips" occurring which resulted in overall lowered yields. Poor stands resulted from extreme dry soil conditions in the area where this study was conducted. In summary, potato yields were not affected by increasing nitrogen rates above 50 pounds N/acre immediately following a legume mixture of alfalfa­ clover. Specific gravity decreased significantly only with the 400 lb nitrogen rate. Nitrate concentration in leaves increased with increasing rates of applied nitrogen. Because of poor stands overall yields were lower than expected. Table 1. Influence of nitrogen fertilizer rates on nitrate-N concentration in petioles-leaves of potatoes grown in the Upper Peninsula a. Nitrogen Rate b lb. N/A 50 100 200 400 LSD (.05) Nitrate N in Leaves and Petioles Nitrate N in Leaves and Petioles Mg NO3-N/Kg Dry Tissue Mg NO3-N/Kg Dry Tissue 6575 7865 7517 8275 n.s. 1755 2867 3627 4125 358 a The youngest mature leaves were collected on July 21 and August 18, respectively. B All nitrogen was applied sidedressed as ammonium nitrate on June 10 just as potatoes had emerged. Table 2. Influence of nitrogen fertilizer rates upon the yield, size distribution and specific gravity upon Russet Burbank potatoes in the Upper Peninsula. Nitrogen Rate a lb. N/A Yields cwt/A Total Yields cwt/A No. 1 Percent Size Distribution Percent Size Distribution Percent Size Distribution Over 3 1/4" 2" to No. 1 3 1/4" Percent Size Distribution Under 2" Percent Size Distribution Pick Outs Specific Gravity 50 100 200 400 297 312 292 316 220 244 209 219 73 77 71 68 6 7 7 6 44 51 39 43 29 26 33 25 LSD (.05) n.s. n.s. n.s. n.s. n.s. n.s. 21 16 21 26 9 1.080 1.076 1.073 1.071 .008 a All nitrogen was applied sidedressed as ammonium nitrate on June 10 just as potatoes had emerged. Funding: MPIC NITROGEN USE EFFICIENCY STUDY WITH RUSSET BURBANK ML. Vitosh, D.A. Hyde, B.P. Darling, and J. Thorburn Introduction Nitrate contamination of groundwater is a very critical issue facing the Michigan potato growers. Before legislation is enacted to limit the amount of nitrogen fertilizer used on potatoes, there is a need to demonstrate alternatives methods of supplying nitrogen to the potato crop to improve nitrogen use efficiency and decrease potential leaching of nitrates to groundwater. Current research data is needed to show that certain strategies of nitrogen fertilization all result in minimal contamination of groundwater. Potatoes are a shallow rooted crop fertilized with relatively high rates of nitrogen fertilizer. This problem is of great concern to the potato growers as well as each of their neighbors. The primary objective of the study are to develop alternative strategies for meeting the nitrogen requirements of the potato crop. Procedure A long term study was initiated in 1986 at the Montcalm Research farm to evaluate different strategies for nitrogen management. A rotation sequence of potatoes-corn-small grain will be established. The potato part of the rotation was established in 1986. There. were 6 nitrogen treatments (2 nitrogen rates and 4 splits). The split applications were; May 8, June 13, July 14, and August 13. In 1987 corn will be grown in the same area without additional nitrogen fertilizer and without irrigation to pick up any residual N that might be left from the 1986 potato crop. Sool samples were taken to a depth of 3 feet prior to the experiment and after the experiment. They were analyzed for ammonium and nitrate to determine residual N levels in the soil prior to planting and to determine how much N fertilizer was left at the end of the season. 1986 Results The potato yield data is shown in Table 1. Very little response was shown to N fertilizer additions over the first 120 lb rate. Through statistical analysis it was determined that only off-type tuber yield was affected by nitrogen. At the 240 lb rate, the August 15 application of N fertilizer appeared to cause an increase in off-type tubers. No differences due to the late application on August 15 were observed at the 180 lb N rate. There was a great deal of variability in large size tubers (over 10 oz.) and in the 4-10 oz. class. The coefficients of variation for large size tubers was 38 percent, making it impossible for us to predict significant differences. Some of this variability may be explained by a relatively thin stand as indicated by the stand counts on June 20. These data are shown in Table 2. Although the stands appear to be relatively uniform this count per 100 feet represents a 15 inch spacing. Due to wet, cool conditions soon after planting some seed pieces were lost due to decay. Table 2 also contains information about petiole nitrate contents on August 13 just trior to the last application of N fertilizer. The differences detected by our statistical analysis can not be easily explained. Treatments 1 and 3 as well as 2 and 4 had identical treatments at the time of sampling but yet they show significantly different levels of nitrates in the petioles. The July 15 application showed an increase in nitrate concentration for only 1 of the 3 treatments. Tuber nitrate was very low and unaffected by rate or timing of nitrogen fertilizer. Specific gravity of tubers was unaffected by the treatments. Table 3 shows soil nitrate and ammonium data for both the spring and fall samplings. Relatively small amounts of nitrate and ammonium were found in the 3 foot profile prior to any additions of nitrogen fertilizer. On the average, 1.4 ppm of NO3-N and 1.1 ppm NO4-N was found in the experimental area to a depth of 3 feet. This represents 17 lbs of NO3-N and 13 lbs of NH4 or a total of 30 lbs of residual N per acre. Most of this nitrogen was found at the 0-12 inch level, which would have been readily available to the 1986 potato crop. This may help to explain why no response was obtained to N additions above the 120 lb rate. The fall samplings were taken on October 1 after nearly 16 inches of rain in September. Yet, the data shows even greater of nitrate in the 3 foot profile. On the average the experimental site gained 15 ppm of NO3-N or 18 lbs of N leaving 35 lbs (17 + 18) of NO3-N in the profile after harvest. These plots will be sampled again in the spring to see how much of the 35 lbs of N remains. The amount of NO4-N decreased and it will be interesting to see if it will build back up by spring of 1987. In conclusion, significant responses to N fertilizer were not obtained in this study even though relatively low levels of residual N were left in the profile from the previous year. The advantages or disadvantages of the various split application will need further study. Table 1. The effect of nitrogen rate and time of application on yield a quality of Russet Burbank potatoes. . Time of Nitrogen Application 1 Time of Nitrogen Application Time of Nitrogen Time of Nitrogen Time of Nitrogen Application 1 6-15 lb N/acre 5-15 lb N/acre Application Application 1 Total lb N/acre Off2/ Size Distribution Type cwt/acre Size Distribution Under 4 oz. cwt/acre Size Distribution 4-10 oz. Size Distribution Over 10 oz. Size Distribution U.S. No. 1 cwt/acre Size Distribution Total Yield cwt/acre 1 7-15 lb N/acre 1 8-15 lb N/acre - 60 60 60 60 120 120 60 - 60 60 60 60 60 60 — 60 60 - — 60 60 — 60 120 180 180 240 240 240 47 53 41 61 40 72 cwt/acre cwt/acre 116 126 120 112 129 96 208 189 205 211 198 199 28 19 24 30 31 40 235 208 229 240 229 239 398 386 390 414 399 407 1/ All treatments received 60 lb of N/acre through the planter at planting time all other amounts of N fertilizer were topdressed as ammonium nitrate over the row. 2/ Means followed by the same letter are not significantly different as determined by the Duncans Multiple Range test (p=.05). Table 2. The effect of nitrogen rate and time of application on plant stand, tuber and petiole nitrate content and specific gravity of Russet Burbank potatoes. Time of Nitrogen Application Time of Nitrogen Application Time of Nitrogen Time of Nitrogen Time of Nitrogen Application 1/ Total 1/ 5-15 lb N/acre 1 6-15 lb N/acre Application Application lb N/acre Plant 2/ Stand Petiole 3/ Nitrate Tuber Nitrate Tuber Specific Gravity 1/ 7-15 lb N/acre 1/ 8-15 lb N/acre plt/100' -ppm- -ppm- g/cc 60 60 60 60 120 120 60 — 60 60 — 60 60 60 60 60 60 — — — 60 60 — 60 120 180 180 240 240 240 78 79 78 79 80 77 15325 15225 11350 17775 12275 19075 8.25 9.75 6.25 6.50 6.75 9.00 1.077 1.075 1.077 1.076 1.077 1.075 1/ All treatments received 60 lb of N/acre through the planter at planting time all other amounts of N fertilizer were topdressed as ammonium nitrate over the row. 2/ Plant stand was taken on June 20, 1986. 3/ Means followed by the same letter are not significantly different as determined by the Duncans Multiple Range test (p=.05). Table 3. Spring and fall soil nitrate and ammonium levels as influenced by rates and time of nitrogen fertilizer applications to potatoes. Dates of application Dates of application Dates of application 5/8 lb/acre 6/14 Dates of application 8/13 Total N lb/acre Spring 1/ Spring 1/ Fall 2/ Fall 2/ Difference 3/ nce 3/ Differe Soil Depth NO3-N NH4-N NO3-N NH4-N NO3-N NH4-N lb/acre lb/acre 60 empty table cell120 empty table cell empty table cell empty table cell 120 120 120 60 60 60 60 60 60 60 0 0 0 0 60 60 60 60 0 60 0 0 0 0 0 0 60 60 60 0 0 0 60 60 60 0 0 0 60 60 60 60 0 60 0 0 180 180 180 180 180 180 180 180 240 240 240 240 180 180 180 180 240 240 240 240 0-12 12-24 24-36 2.21 0.97 0.81 Average 1.33 0-12 12-24 24-36 2.48 1.53 1.49 Average 1.83 0-12 12-24 24-36 2.56 1.10 1.00 Average 1.55 0-12 12-24 24-36 2.32 1.20 1.27 Average 1.60 0-12 12-24 24-36 2.67 1.32 1.16 Average 1.72 0-12 12-24 24-36 2.53 0.96 0.70 2.05 0.61 0.35 1.00 1.52 0.68 0.34 0.85 1.83 0.80 0.37 1.00 1.91 0.62 0.37 0.97 1.74 0.71 0.36 0.94 2.27 0.64 0.32 Average 1.40 1.08 3.80 2.20 1.53 2.51 5.50 3.76 3.55 4.27 3.86 2.28 1.39 2.51 3.58 2.64 1.99 2.74 4.14 2.34 1.13 2.54 4.25 2.79 1.77 2.94 0.38 0.28 0.39 0.35 0.27 0.27 0.31 0.28 0.34 0.34 0.42 0.37 0.38 0.19 0.56 0.38 0.32 0.23 0.29 0.28 0.53 0.26 0.39 0.39 1.59 1.23 0.72 -1.66 -0.34 0.04 1.18 -0.65 3.02 2.23 2.06 -1.25 -0.41 -0.02 2.43 -0.56 1.30 1.18 0.39 -1.50 -0.46 0.06 0.96 -0.63 1.27 1.43 0.72 -1.53 -0.42 0.19 1.14 -0.59 1.47 1.02 -1.42 -0.48 -0.03 -0.07 0.82 -0.66 1.72 1.83 1.07 -1.74 -0.37 0.07 1.54 -0.68 6/13 lb/acre 60 60 60 60 60 60 60 60 60 60 60 60 60 60 60 60 60 60 60 60 60 60 60 60 1 20 120 120 120 120 120 120 120 60 60 120 120 120 120 120 120 120 120 60 60 60 60 60 60 1/ Sampled April 14, 1986. 2/ Sampled October 1, 1986. 3/ Gain or loss of soil N between the spring and fall sampling dates. Funding: MPIC THE INFLUENCE OF METHAM CHEMIGATION AND NITROGEN ON YIELD AND QUALITY OF RUSSET BURBANK POTATOES Department of Crop and Soil Sciences and Entomology M. L. Vitosh and G. W. Bird The objectives of this study were: 1. to determine the nitrogen Fertilizer requirements of Russet Burbank potatoes treated with metham by chemigation and 2. to study the interaction effects of nitrogen and metham on tuber size and quality. Two Farm cooperater's were selected who had applied metham in the Fall oF 1985 by chemigation. Both sites were located in Montcalm County on irrigated sandy soils. Rye was the previous crop at both locations. Vapam was applied at 50 gallons per acre to one half or more of the pivot area. Plots were established on both treated and untreated areas shortly after plant emergence. Plots were selected with uniform stands. one row was selected for each replication so that all nitrogen treatments were randomized within each row or replication. A large area between chemigated and unchemigated plots was not used to make sure there was no mixing of treated and untreated areas. The experiment was analyzed as a split plot design, where the Fumigant treatments were considered as whole plots and nitrogen treatments were the sub-plots. At experimental site # 1 , 1000 1b 6-24-24 fertilizer per acre was applied at planting with Thimet as the systemic insecticide. At site # 2, 150 lb N per acre was applied at planting with Thimet as the systemic insecticide. The entire experimental area was staked and no additional N was applied to the area by the grower. All sidedress N was applied just prior to hilling. All plots received sidedress N as ammonium nitrate expect one which received calcium nitrate. This treatment supplied 300 or 188 lb calcium per acre for sites 1 and 2, respectively. The last N treatment received an equivalent amount of calcium From Gypsum. Plant petiole samples were taken For nitrate analysis on July 14. Tubers were sampled on August 4 and analyzed For nitrates using the nitrate paper test. Yields were hand harvested on October 8-10 and sized. Specific gravity and nitrate analysis were determined later in the laboratory. RESULTS AND DISCUSSION TUBER YIELD AND SIZETuber are shown in Tables 1 and 2. yield and size distribution data for the two studies EXPERIMENT SITE # 1 (Table 1.) Metham had a very significant affect on plant growth which was evident shortly after plant emergence. The increased plant growth also resulted in an increase in large tubers over 10 oz., 4-10 oz. size tubers , U.S. # 1 tubers and total yield. Metham increased the U. S. No. 1 yield by 127 cwt per acre. Nitrogen response was considerable less, giving only a significant increase in large size tubers and U. S. No. 1 tubers of the increase in size was observed with the 60 and 120 lb N rates. Small size tubers (less than 4 oz.) were greatest with no sidedress N. EXPERIMENT SITE # 2 (Table 2.) Metham had a similar effect at this site, significantly increasing large size tubers, U. S. No. 1 tubers, 4-10 oz. tubers and total yield. U. S. No. 1 yield was increased with metham by 78 cwt. per acre. The yield of small tubers was significantly decreased with metham. Significant Nitrogen responses were again limited. The zero N rate and the calcium nitrate treatment had the smallest yield of larger sizer tubers. Signífícant interactions between N and metham were detected for off-type and large size tubers. Increasing the N rate significantly increased off-type tubers without metham but not when metham was applied. Gypsum significantly increased large size tubers when metham was present but not. when it. was absent. NITRATE CONTENT AND SPECIFIC GRAVITY Tables 3 and 4 contain data for, nitrate content of potato petioles during mid-season, nitrate content of tubers at harvest time and specific gravity of tubers at harvest. EXPERIMENTAL SITE # 1 (Table 3.) Petiole nitrate content was significantly increased by 180 and 240 lb N over the three lower N rates. Metham did not significantly affect petiole or tuber nitrate content. Calcium nitrate significantly increased the nitrate content of potato tubers, but all nitrate levels are considered to be very low. Specific gravity was not. affected by the N treatments, but metham increased the specific gravity greatly (.005 g/cc increase). EXPERIMENTAL SITE # 2 (Table 4.) The nitrate content of potato petioles was considerably higher at this site, probably due to the higher rate of N at planting time. Petiole nitrate content of the zero sidedress N rate was significantly lower than the other N rates. Petiole nitrate content was not. affected by chemigation of metham. Specific gravity was again significantly increased by metham (.005 g/cc increase). Tuber nitrate was very low and unaffected by any of the treatments. ECONOMIC ANALYSIS Tabes 5 and 6 contain economic information on these two experiment. Net income represents total income minus the cost of the treatments applied in the study. Treatment costs were calculated using $.20 /lb for N from ammonium nitrate and $.30 /lb for N from Calcium nitrate, $10.00 per acre for Gypsum and $200 per acre for Vapam. The prices used for potatoes were $8.00 /cwt for tuber over 10 oz., $5.50 /cwt for 4-10 oz. tubers, $3.00 /cwt for off-type tubers and $1.50 /cwt for tuber less the 4 oz. No adjustment was made for specific gravity. EXPERIMENTAL SITE # 1 (Table 5.) Even though the cost of the chemigation treatment appears to be very costly, it proved to be very profitable on this farm. When averaged of all N treatments a profit of $631 per acre was realized. Maximum profit was obtained with metham and 240 lb N from either ammonium nitrate or calcium nitrate. This represents a net return of more than $1000 for an investment of $248 for metham and ammonium nitrate EXPERIMENTAL SITE # 2 (Table 6.) Because of the lower yields, the net income for this study was considerably less ($458 to $1008 less) than the previous study. Nevertheless, metham was profitable in this study. When averaged over all N treatments, a profit of $254 was obtained. The calcium nitrate in this study appeared to be the least profitable treatment due to it's higher cost and lack of yield improvement over the other N treatments. The Gypsum treatment with metham gave the maximum profit but none of values are statistically significant at the 95% probability level. SOFT ROT EVALUATION Tubers from the highest N rate treatments were injected with a small amount of the soft rot organism, E. caratovora and incubated in a plastic bag for 96 hours. The diameter of decay was then measure. A combined analysis of variance was made on the data for the two experiments. The data are shown in Table 7. Tubers from experimental site # 1 had significantly more decay. Soil calcium levels ranged From 640 and 960 lb Ca/acre for site # 1 and from 800 to 1360 lb Ca/acre for site #2. Wisconsin has reported significant improvement in resistance to infection due to calcium additions to the soils testing less than 700 lb Ca/acre. Calcium from either calcium nitrate fertilizer or Gypsum decreased the amount of decay. Metham did not significantly affect the amount of decay. Addition research on the influence of calcium for reducing the infection of soft rot is needed to determine how significant these findings are. SUMMARY 1. Metham significantly increased tuber size, specific gravity and yield at both locations. Nitrogen requirements For potatoes treated with or without metham were similar. 2. Although the cost of chemigation with metham is expensive, net income was more than enough to pay for the cost of the material in these two studies. 3. The response to nitrogen in both of these studies was small compared to the response from metham. The greatest, response to nitrogen was obtained when metham was used. Nitrogen had it's greatest affect on increasing tuber size. 4. Calcium from calcium nitrate fertilizer or Gypsum did not significantly affect tuber size or yield at either location. Calcium additions did increase the resistance to decay by soft rot. 5. Tuber nitrate was unaffected by any of the treatments used in these experiments. 6. The first increment of sidedress N fertilizer increased the petiole nitrate level. Additional N did not increase the petiole nitrate 7. Specific gravity of tubers was unaffected by any of the N treatments. 60 120 180 240 240 240 0 With Without Without Without Without Without Without With With With With With With 60 120 180 240 240 240 empty table cell A. N. A. N. A. N. A. N. A. N. C. N. A. N.+Gypsum A. N. A. N. A. N. A. N. A. N. C. N. A. N.+Gypsum cwt/acre cwt/acre 125 88 104 74 71 85 92 135 92 96 97 84 83 98 252 265 278 270 241 285 301 325 354 361 344 360 327 315 2 12 20 45 38 44 30 38 56 79 95 107 127 89 255 277 299 315 278 328 330 362 410 439 439 467 454 404 384 381 421 412 392 430 450 505 531 551 544 555 558 514 91 98 270 a 341 b 27 b 84 a 298 b 410 b 425 a 537 a 130 a 90 b 100 b 86 b 77 b 84 b 95 b 289 310 320 307 301 306 308 20 d 34 cd 49 bc 70 ab 72 ab 85 a 59 ab 444 309 b 344 ab 456 369 a 486 377 a 478 373 a 473 391 a 494 368 a 482 4.7 15.2 18.0 22.7 43.3 16.6 27.2 6.4 29.3 15.5 8.6 4.1 21.1 12.0 21.1 13.9 5.5 22.2 16.7 15.6 23.7 18.8 19.6 Table 1. The effect of metham and sidedress nitrogen on yield and quality of Russet Burbank potaotes. Experimental site # 1. Metham 2/ Nitrogen Source 3/ Off Type cwt/acre 4-10 Under 4 Oz. cwt/acre Oz. Over 10 Oz. U. S. No. 1 cwt/acre Total Yield cwt/acre Sidedress N 1/ lb N/acre 0 Without empty table cell Treatment Means 4/ Without Metham empty table cell Treatment Means 4/ Without Metham empty table cell Treatment Means 4/ 0 60 Treatment Means 4/ Treatment Means 4/ 120 180 Treatment Means 4/ 240 Treatment Means 4/ 240 Treatment Means 4/ 240 Treatment Means 4/ A. N. A. N. A. N. A. N. A. N. C. N. A. N.+Gypsum — — — — — — — 1/ 60 lbs of N/acre was applied at planting time. 2/ Metham in this experiment was applied as Vapam at 50 gals./acre. 3/ Nitrogen sources were A. N.(Ammonium Nitrate) and C. N.(Calcium Nitrate). Gypsum and Calcium Nitrate supplied 300 lb Ca/acre. 4/ Means followed by different letters are significantly different as determined by the Duncan's Multiple Range Test (p = .05). Table 2. The effect of metham and sidedress nitrogen on yield and quality of Russet Burbank potatoes. Experimental site # 2. Sidedress N 1/ lb N/acre Metham 2/ Nitrogen Source 3/ Off Type cwt/acre Under Oz 4 Oz cwt/acre 4-10 Over 10 Oz U. S. No. 1 cwt/acre Total Yield cwt/acre cwt/acre cwt/acre Without Without Without Without With With With With 0 With 50 100 150 150 150 With A. N. A. N. A. N. A. N. C. N. 0 Without 50 100 150 150 150 Without A. N. A. N. A. N. A. N. C. N. 11.1 bcd 13.3 bcd 11.5 bcd 15.6 bc 22.6 ab A. N.+Gypsum 32.2 a 87 74 70 68 75 83 165 162 182 163 171 162 18 bc 15 bc 29 bc 22 bc 14 c 9 c empty table cell Treatment Means 4/ Without metham A. N.+Gypsum empty table cell 0.4 d 125 103 4.3 cd 10.9 bcd 102 6.2 cd 79 5.1 cd 105 3.9 cd 85 17.7 a 76 241 233 228 244 212 243 167 b 18 b 13 c 37 b 25 bc 29 bc 12 c 61 a 183 177 211 185 185 171 253 270 253 273 223 304 281 264 293 268 282 286 379 377 366 358 333 392 185 b 279 b empty table cell Treatment Means 4/ With metham empty table cell 5. 1 b 0 Treatment Means 4/ 50 Treatment Means 4/ 100 Treatment Means 4/ 150 Treatment Means 4/ Treatment Means 4/ 150 Treatment Means 4/ 150 A. N. 5.7 A. N. 8.8 A. N. 11.1 A. N. 10.9 C. N. 13.9 A. N.+Gypsum 18.1 — — - — - — 100 106 88 86 74 90 84 233a 29 a 263 a 367 a 203 197 205 203 191 202 15 b 26 ab 27 ab 25 ab 13 b 35 a 218 223 232 229 204 238 330 320 329 313 307 339 1/ 150 lbs of N/acre was applied at planting tme. 2/ Metham in this experiment was applied as Vapam at 50 gals./acre. 3/ Nitrogen sources were A. N.(Ammonium Nitrate) and C. N.(Calcium Nitrate). Gypsum and Calcium Nitrate supplied 188 lb Ca/acre. 4/ Means followed by different letters are significantly different as determined by the Duncan's Multiple Range Test (p = .05). Table 3. The effect of metham and sidedress nitrogen on petiole and tuber nitrate content and specific gravity of Russet Burbank potatoes. Experimental site #1. Sidedress N 1/ lb N/acre Metham 2/ Nitrogen Source 3/ Petiole Nitrate Tuber Nitrate Specific Gravity ppm ppm g/cc 0 Without 60 120 180 240 240 240 0 With Without Without Without Without Without Without With With With With With With A. N. A. N. A. N. A. N. A. N. C. N. A. N.+Gypsum A. N. A. N. A. N. A. N. A. N. C. N. A. N.+Gypsum 60 120 180 240 240 240 empty table cell empty table cell Treatment Means 4/ Without Metham empty table cell Treatment Means 4/ With Metham empty table cell Treatment Means 4/ 0 60 Treatment Means 4/ 120 Treatment Means 4/ Treatment Means 4/ 180 240 Treatment Means 4/ Treatment Means 4/ 240 240 Treatment Means 4/ A. N. A. N. A. N. A. N. A. N. C. N. A. N.+Gypsum — — — — — — — 14,750 15,100 15,750 22,750 21,600 — — 14,750 13,400 15,050 17,900 18,850 — — 17,990 15,990 14,750 b 14,250 b 15,400 b 20,325 a 20,225 a — — 6.9 7.8 7.6 8.9 8.8 15.5 9.6 7.3 7.2 7.5 7.7 7.9 9.0 8.5 9.3 7.9 7. 1 b 7.5 b 7.6 b 8.3 b 8.4 b 12.3 a 9. 1 b 1.079 1.078 1.078 1.076 1.077 1.077 1.079 1.083 1.082 1.084 1.084 1.083 1.081 1.081 1.078 b 1.083 a 1.081 1.800 1.081 1.080 1.080 1.079 1.080 1/ 60 lbs of N/acre was applied at planting time. 2/ Metham in this experiment was applied as Vapam at 50 gals./acre. 3/ Nitrogen sources were A. N. (Ammonium Nitrate) and C. N.(Calcium Nitrate). Gypsum and Calcium Nitrate supplied 300 lb Ca/acre. 4/ Means followed by different letters are significantly different as determined by the Duncan's Muitiple Range Test (p = .05). Table 4. The effect of metham and sidedress nitrogen on petiole and tuber nitrate content and specific gravity of Russet Burbank potatoes. Experimental site # 2. Metham 2/ Nitrogen Source 3/ Petiole Nitrate Tuber Nitrate Specific Gravity ppm ppm 18,000 27,150 27,000 27,000 -- -- 18,050 27,500 29,900 30,600 -- -- 24,788 26,513 18,025 b 27,325 a 28,450 a 28,800 a -- -- 10.4 11.0 11.6 11.6 10.4 14.8 10.4 10.8 11.2 9.4 13.0 10.4 11.6 10.9 10.4 10.9 11.4 10.5 11.7 12.6 g/cc 1.080 1.080 1.081 1.079 1.080 1.080 1.085 1.085 1.085 1.085 1.084 1.084 1.080 b 1.085 a 1.083 1.083 1.083 1.082 1.082 1.082 Sidedress N 1/ lb N/acre 0 Without 50 100 150 150 150 Without Without Without Without Without A. N. A. N. A. N. A. N. C. N. A. N.+Gypsum 0 With 50 100 150 150 150 empty table cell With With With With With A. N. A. N. A. N. A. N. C. N. A. N.+Gypsum empty table cell Treatment Means 4/ Without Metham empty table cell Treatment Means 4/ With Metham empty table cell Treatment Means 4/ 0 50 Treatment Means 4/ Treatment Means 4/ 100 Treatment Means 4/ 150 Treatment Means 4/ 150 Treatment Means 4/ 150 A. N. A. N. A. N. A. N. C. N. A. N.+Gypsum — — — — — — 150 lbs of N/acre was applied at planting time. 1/ 2/ Metham in this experiment was applied as Vapam at 50 gals./acre. 3/ Nitrogen sources were A. N.(Ammonium Nitrate) and C. N.(Calcium Nitrate). Gypsum and Calcium Nitrate supplied 188 lb Ca/acre. 4/ Means followed by different letters are significantly different as determined by the Duncan's Multiple Range Test (p = .05). Table 5. The effect of metham and sidedress nitrogen on net income and income over the check treatment. Experimental site # 1. Sidedress N 1/ lb N/acre Metham 2/ Nitrogen Source 3/ Net Income 4/ Net Income Over Check 5/ $/acre $/acre 0 Without 60 120 180 240 240 240 0 With With With With With With With With With With With With With A. N. A. N. A. N. A. N. A. N. C. N. A. N.+Gypsum A. N. A. N. A. N. A. N. A. N. C. N. A. N.+Gypsum 60 120 180 240 240 240 empty table cell empty table cell Treatment Means 6/ Without Metham empty table cell Treatment Means 6/ With Metham empty table cell — 6/ 0 Treatment Means 6/ 60 - Treatment Means Treatment Means 6/ 120 6/ 180 Treatment Means 6/ 240 Treatment Means Treatment Means 6/ 240 Treatment Means 6/ 240 — — — — — A. N. A. N. A. N. A. N. A. N. C. N. A. N.+Gypsum $1,608 $1,723 $1,881 $1,993 $1,815 $2,020 $2,056 $2,111 $2,410 $2,579 $2,588 $2,727 $2,730 $2,371 $1,871 b $2,502 a $1,860 b $2,067 ab $2,230 a $2,290 a $2,271 a $2,375 a $2,214 a $0 $115 $273 $385 $207 $412 $448 $503 $802 $971 $980 $1,119 $1,122 $763 $0 b $631 a $0 b $207 ab $370 a $430 a $411 a $515 a $354 a 1/ 60 lbs of N/acre was applied at planting time. 2/ Metham in this experiment was applied as Vapam at 50 gals./acre. 3/ Nitrogen sources were A. N.(Ammonium Nitrate) and C. N. (Calcium Nitrate). Gypsum and Calcium Nitrate supplied 300 lb Ca/acre. 4/ Net income after Treatment expenses: N from A. N. @ $.20/acre and from C. N. @ $.30/acre, Gypsum @ $10.00/acre, Vapam @ $200.00/acre Tuber >10 oz @ $8.00, Tubers 4-10 oz @ $ 5.50, Off-type Tubers @ $3.00, Tuber <4 oz @ $ 1.50. 5/ Check = No sidedress Nitrogen and no Vapam. 6/ Means followed by different letters are significantly different as determined by the Duncan's Multiple Range Test (p = .05). Table 6. The effect of metham and sidedress nitrogen on net income and income over the check treatment. Experimental site # 2. Sidedress N 1/ lb N/acre Metham 2/ Nitrogen Source 3/ Net Income 4/ Net Income Over Check 5/ $/acre $/acre 0 Without 50 100 150 150 150 Without Without Without Without Without 0 With 50 100 150 150 150 empty table cell With With With With With A. N. A. N. A. N. A. N. C. N. A. N.+Gypsum A. N. A. N. A. N. A. N. C. N. A. N.+Gypsum empty table cell Treatment Means 6/ Without Methamempty table cell Treatment Means 6/ With Methamempty table cell - — — — 0 Treatment Means 6/ 50 Treatment Means 6/ 100 Treatment Means 6/ 150 Treatment Means 6/ Treatment Means 6/ 150 - 150 Treatment Means 6/ A. N. A. N. A. N. A. N. C. N. A. N.+Gypsum — $1,214 $1,150 $1,352 $1,189 $1,184 $1,143 $1,414 $ 1,533 $1,419 $1,480 $1,184 $1,722 $1,205 b $1,459 a $1,314 $1,341 $1,385 $ 1,334 $1,184 $1,432 $0 ($64) $138 ($25) ($30) ($71) $200 $319 $205 $266 ($30) $508 $0 b $254 a $0 $27 $71 $20 ($130) $118 150 lbs of N/acre was applied at planting time. 1/ 2/ Metham in this experiment was applied as Vapam at 50 gals./acre. 3/ Nitrogen sources were A. N.(Ammonium Nitrate) and C. N.(Calcium Nitrate). Gypsum and Calcium Nitrate supplied 188 lb Ca/acre. 4/ Net income after treatment. expenses: N from A. N. @ $.20/acre and from C. N. @ $.30/acre, Gypsum @ $10.00/acre, Vapam @ $200.00/acre Tuber >10 oz @ $8.00, Tubers 4-10 oz @ $ 5.50, Off-type Tubers @ $3.00, Tuber <4 oz @ $ 1.50. 5/ Check = No sidedress Nitrogen and no Vapam. 6/ Means followed by different letters are significantly different as determined by the Duncan's Multiple Range Test (p = .05). Table 7. The effect of metham and sidedress nitrogen on soft rot infection of Russet Burbank potatoes. Combined analysis for. two experiments. Sidedress N 1/ lb N/acre Metham 2/ Nitrogen Source 3/ Soft Rot Infection Diameter 4/ Experimental Site No. #1 Soft Rot Infection Diameter 4/ #2 cm #2 cm Soft Rot Infection Diameter 4/ Mean 240 or 150 Without 240 or 150 240 or 150 Without Without A. N. C. N. A. N.+ Gypsum 240 or 150 With 240 or 150 240 or 150 empty table cell With With A. N. C. N. A. N.+ Gypsum 0.72 0.57 0.59 0.72 0.57 0.61 0.51 0.44 0.39 0.49 0.46 0.36 Treatment Means 5/ empty table Experimental site No. 1.empty table cell Experimental site No. 2.empty table cell empty table cell empty table cell empty table cell With Methamempty table cell Without Methamempty table cell 240 or 150 240 or 150 240 or 150 — — - A. N. C. N. A. N.+ Gypsum 0.63 a cell 0.44 bempty table cell Treatment Means 5/ 0.54 empty table cell Treatment Means 5/ 0.54 empty table cell Treatment Means 5/ 0.61 a empty table cell Treatment Means 5/ 0.51 b empty table cell Treatment Means 5/ 0.49 bempty table cell Treatment Means 5/ 0.62 0.50 0.49 0.61 0.52 0.48 empty table cell empty table cell empty table cell empty table cell empty table cell empty table cell empty table cell 1/ 60 lb N/acre and 150 lbs of N/acre was applied at planting time to site's 1 and 2, respectively. 2/ Metham in this experiment was applied as Vapam at 50 gals./acre. 3/ Nitrogen sources were A. N.(Ammonium Nitrate) and C. N.(Calcium Nitrate). Gypsum and Calcium Nitrate supplied 300 lb Ca/acre. 4/ Diameter of decay after injection and incubation for 96 hours. 5/ Means followed by the different letters are significantly different as determined by the Duncan's Multiple Range Test (p = .05). Funding: MPIC CONTROL OF SCAB AND RHIZOCTONIA DISEASES R. Hammerschmidt and M.L. Vitosh Department of Botany and Plant Pathology Department of Crop and Soil Sciences INTRODUCTION Scab and Rhizoctonia diseases continue to be a problem in potato production. Research was carried out this yeas to further evaluate possible control measures and to begin to understand the survival and population dynamics of the scab pathogen. Irrigation and N form: Last years research indicated that a combination of acid forming fertilizer and maintaining soil wetter than 50 cb of tension gave very good control of scab. In this experiment we further evaluated the control benefits of ammonium sulfate and irrigation. The research was carried out at the MSU soils farm. N was applied to the plots in four different forms and these treatments were superimposed on high vs. low irrigation regimes. The N treatments were urea/urea, ammonium sulfate/ammonium sulfate, urea/ammonium sulfate, calcium nitrate/calcium nitrate, and urea+gypsum/urea+gypsum as the starter/topdress, respectively (Table 1). One set of N treatments was maintained by irrigation (when needed) at 50 cb of tension or less. The other set of plots received irrigation only every other time the other plot was irrigated (i.e. this plot was often drier than 50 cb). Tensiometers were installed at the time of tuber initiation (i.e. when stolon tips were swelled to ca. twice the diameter of the rest of the stolon). Results: Higher than average amounts of precipitation resulted in less scab than would be expected in drier years. This year, the first irrigation to lower the tension below 50 cb occurred about six weeks after tuber initiation as compared to only about two weeks in the previous year. However, the effect of maintaining the higher water level in controlling scab was evident (although not as great a difference as last year) (Table 2). Ammonium sulfate at both irrigation levels gave the best control of scab, while plots given only urea as the N form exhibited the most scab (Table 2). There were some effects on the N form with regard to total yield. Ammonium sulfate as the N form resulted in the best yields (at both irrigation levels) while Calcium Nitrate produced the poorest yields (Table 3). There were no effects on specific gravity (Table 4). Population of Streptomyces in the soil: Little is known about how many propagules of S. scabies are required to cause a significant amount of disease. Experiments were carried out in which the populations of total Streptomycetes were determined at the time of planting and at the time of tuber initiation and then compared to the amount of disease observed in the plots. Soil samples were collected at three locations at each of the ammonium sulfate and urea treated plots at the times indicated in table 5. After air drying the samples, one gram samples were extracted with sterile water and appropriate dilutions made onto water agar. Total Streptomycetes were counted 14 days after plating. Results: Populations of streptomycetes in each of the plots at the two sampling times are given in Table 5. A decrease in the total population was observed in the Ammonium sulfate plots while a slight increase in total population was observed in the urea treated plots. Amount of disease in the two N form plots is listed next to the Streptomyces population. Less disease was found where the populations were lowered by ammonium sulfate treatments. No good correlation was found between initial population and final amount of disease observed. Infection of alternate crops and colonization of crop residue by Streptomyces species: The survival mechanism used by Streptomyces species in the soil mint be understood in order to develop long-term control strategies for this disease. In these experiments seedlings of plants were grown in the presence of a putative pathogenic Streptomyces strain and then evaluated for infection of root tissue. In addition, partly decomposed crop residue samples were assayed for presence of streptomycetes. This was carried out to assess the possible role that this type of organic matter may serve as a nutrient base for streptomycetes in the absence of the potato. To evaluate the infection of roots of other plants, a pathogenic strain of Streptomyces was mixed with warm, melted soil extract agar and then poured into sterile beakers. Germinated seeds of corn, wheat, soybean, and radish were placed onto the surface of the agar. The plants were allowed to grow for two weeks and the roots were then examined for evidence of infection. Partly decomposed corn stalk and potato vine and root residue was collected from a field that had a history of scab problems. Some of the residue, after surface sterilization, was homogenized in sterile water and plated out onto water agar to check for the presence of Streptomycetes. The rest of the residue was chopped into small pieces and placed around seed pieces of potato (var. Yukon Gold) that were planted in steamed soil. After 10 weeks of growth, the tubers were harvested and examined for scab. Streptomycetes were also tested for their ability to utilize pectin and polygalacturonic acid (polysaccharides that are found in plant tissues) by growing the organism in liquid culture with the polysaccharides as the only carbon source. Results Roots of soybean, wheat and radish exhibited browning of their tissues when grown in the presence of the pathogenic strain of Streptomyces. The development of these symptoms took about ten days to develop. The non-pathogenic strain did not cause these symptoms. Corn roots did not exhibit any signs of infection in these tests. Plating out the crop residue onto water agar demonstrated that some streptomycetes were present along with several other bacteria and fungi. Microscopic observation of the plates showed that many of the streptomycetes could be seen growing directly out of the pieces of plant residue, thus suggesting that these organisms were growing inside of the tissue. Growing Yukon Gold potato in the presence of the crop residues resulted in the development of a slight amount of scab in the potatoes grown in the presence of corn residue and slightly more in the presence of the potato crop residue. This suggests that it is possible that the scab pathogen may survive from potato crop to potato crop by living as a saprophyte in crop residue as do non-pathogenic Streptomycetes. Several Streptomyces isolated from the residue were tested for their ability to grow on complex polysaccharides such as those found in crop residue. The islates were able to utilize pectin and polygalacturonic acid as the sole carbon source (although at a much slower rate than on a more standard carbon source such as glucose). This suggests that the organisms have the enzymes necessary to decompose residue. These types of enzymes may also be important in the establishment of infection by the pathogen in growing tuber tissue. Seed piece treatment studies: Several formulations of seed piece treatments were evaluated on Russet Burbank. The experiment was carried out at the Montcalm Station and planting was on May 14. Treatments were applied to the cut seed pieces immediately after cutting. Treated tubers were planted on the same day of treatment. Plants were evaluated for per cent emergence and vigor, no yield data or Rhizoctonia evaluations could be made on the tubers due to loss of plots from the excessive rains in September. Results: Treatment of seed with the CGA formulation resulted in a decrease in stand which was related to phytotoxicity of the material under the wet soil conditions during and after planting, this type of result has been observed in other trials conducted by Ciba-Geigy (personal communication with company). Stand and vigor was good with the other treatments as compared to the untreated control (Table 6). TABLE 1. SOIL TESTS AND NUTRIENTS USED Soil Test pH 6.9 P 128 267 K Ca 1840 Mg 33 6 Type Spinks Loam Sand FERTILIZER TREATMENTS UREA/UREA AMSO4/AMSO4 UREA/AMSO4 CaNO3/CaNO3 UREA+GYP/UREA+GYP 225+100+100+129 Ca + 98 225-100-100 225-100-100+114 S 225-100-100+57 S 225-100-100+129 Ca TABLE 2. SCAB CONTROL TREATMENTS IRRIGATION High IRRIGATION Low N FORM U/U N FORM AS/AS N FORM U/AS N FORM CaN/CaN N FORM U+Gyp/U+Gyp N FORM X IRRIG. HIGH IRRIG. U/U AS/AS N FORM X IRRIG. HIGH IRRIG. N FORM X IRRIG. HIGH IRRIG. U/AS N FORM X IRRIG. HIGH IRRIG. CaN/CaN U+Gyp/U+Gyp N FORM X IRRIG. HIGH IRRIG. Low Irrig. U/U Low Irrig. AS/AS U/AS Low Irrig. Low Irrig. CaN/CaN Low Irrig. U+Gyp/U+Gyp %<5% SCAB % SCAB FREE 92.3A 86.9B 86.6B 97.6A 86.9B 90.3AB 86.9B 92.6ABC 67.8BC 100.0A 87.8BCD 93.2ABC 87.9BCD 80.6D 95.2AB 85.9BCD 87.3BCD 85.9BCD 76.8 75.0 64.9C 87.4A 74.7BC 72.7BC 79.8AB 87.2A 73.8ABC 73.9ABC 81.1AB 61.9C 87.7A 75.6ABC 71.5BC 78.5AB *High irrig = soil depleted no more than 50 cb. U=urea, AS=ammonium sulfate, CaN=calcium nitrate, Gyp=gypsum. TABLE 3. YIELD TREATMENT * IRRIGATION High IRRIGATION Low N FORM U/U N FORM AS/AS N FORM U/AS N FORM CaN/CaN N FORM U+Gyp/U+Gyp N FORM X IRRIG. High Irrig. U/U AS/AS N FORM X IRRIG. High Irrig. U/AS N FORM X IRRIG. High Irrig. CaN/CaN N FORM X IRRIG. High Irrig. U+Gyp/U+Gyp N FORM X IRRIG. High Irrig. Low Irrig. U/U AS/AS Low Irrig. Low Irrig. U/AS CaN/CaN Low Irrig. U+Gyp/U+Gyp Low Irrig. * Same as Table 2. ** CWT/A. TOTAL YIELD ** % No.l 410.6 375.6 404.9AB 442.7A 389.5AB 334.6B 395.8AB 435.4AB 470.5A 404.0ABC 351.6CD 395.6ABC 374.5BCD 414.9ABC 374.9BCD 317.6D 395.9ABC 87.8 87.7 88.8 87.9 86.1 86.9 89.1 90.1 88.7 84.9 87.9 87.5 87.4 87.2 87.2 85.9 90.6 TABLE 4. SPECIFIC GRAVITY TREATMENT * IRRIGATION High IRRIGATION Low N FORM U/U N FORM AS/AS N FORM U/AS CaN/CaN N FORM U+Gyp/U+Gyp N FORM N FORM X IRRIG. HIGH IRRIG. U/U N FORM X IRRIG. HIGH IRRIG. AS/AS N FORM X IRRIG. HIGH IRRIG. U/AS N FORM X IRRIG. HIGH IRRIG. CaN/CaN N FORM X IRRIG. HIGH IRRIG. U+Gyp/U+Gyp Low Irrig. U/U Low Irrig. AS/AS Low Irrig. U/AS CaN/CaN Low Irrig. Low Irrig. U+Gyp/U+Gyp * See Table 2. SPECIFIC GRAVITY 1.088 1.088 1.088 1.090 1.089 1.087 1.088 1.087 1.090 1.088 1.086 1.088 1.088 1.089 1.090 1.087 1.088 TABLE 5. STREPTOMYCES SOIL POPULATIONS N FORM TREATMENT STREPTOMYCES POPULATIONS 7STREPTOMYCES POPULATIONS * June 4 *May U/U High Irrig. U/U Low Irrig. AS/AS High Irrig. AS/AS Low Irrig. 404,000 374,200 401,000 465,800 204,000 238,000 352,500 366,000 LSD=73,000 * per gram of dry soil. TABLE 6. SEED PIECE TREATMENTS TREATMENT a RATE (lb/cwt) % STAND VIGOR b CGA 449 + Fir Bark 0.5 1.0 CGA 449 + Fir Bark 2.0 CGA 449 + Fir Bark 0.5 CGA 449 1.0 CGA 449 2.0 CGA 449 1.0 Tops 2.5 Tops 1.5 + Rovrall 1.0 1.0 Tops 1.5 + Rovrall 2.0 1.0 Tops 1.5 + Rizolex 1.0 1.0 Tops 1.5 + Vitavax 1.0 1.0 --- Check 61.9 ± 6.9 50.3 ± 9.5 54.8 ± 3.4 84.3 ± 4.3 75.3 ± 6.8 57.0 ± 6.7 93.3 ± 3.7 93.3 ± 1.9 88.8 ± 2.0 97.8 ± 1.9 93.3 ± 3.7 84.3 ± 5.8 poor poor poor good fair poor good good good good good good a Four replications per treatment. b Vigor: poor = plants less than 4" tall on average fair = plants 4 to 8" tall good = plants over 8" tall Funding: MPIC MANAGEMENT OF COLORADO POTATO BEETLE E. Grafius, L. Connington, and D. Herrington Department of Entomology Michigan State University Summary Evaluation of the relative costs and benefits of treatment at planting with Temik or Thimet in comparison with weekly foliar treatment or scouting and treatment as needed was conducted at the Montcalm Potato Research Farm. Temik treatment resulted in slightly increased yields over other treatments, even though insect populations and damage were similar. "As-needed" treatment produced lowest marginal return because of low levels of control when treatment was applied, demonstrating the need for resistance monitoring and careful selection of insecticide. Field insecticide trials indicated that Temik and Thimet applied at planting or side-dressed (Temik 2 lb ai/A) gave season-long control in Superior variety potatoes at this location. Di-Syston was ineffective and Furadan gave larval control up to July 7. Early-season adult numbers were relatively low due to the change in plot location between 1985 and 1986 and most materials would be less effective against adults. Furadan 4F was the only standard foliar material that gave reliable control. Experimental materials tested included combinations of soil treatments for insect+nematode control, exotoxin from Bacillus thuringiensis (BT) a new pyrethroid (Baythroid), and 2 materials from FMC (F 5951 and f 4922). The new FMC materials seem especially promising, providing excellent control of potato beetle adults and larvae for up to 2 weeks after treatment and reported to have little or no cross resistance problems with other materials. Studies of insecticide resistance in the Colorado potato beetle (not reported here) are continuing, with funding from a USDA pest management grant. 1. Economics of Soil Insecticide Use for Control of Colorado Potato Beetle The objective of this study was to compare the economics of soil insecticide use (Temik and Thimet) with foliar treatments weekly or as-needed (based on scouting). The date will be useful in evaluation of the importance of Temik registration and as preliminary information on alternatives, if Temik is removed from the market. Methods Russet Burbank potatoes were planted at the Montcalm Potato Research Farm on May 8. Treatments were arranged in a randomized complete block design with 4 replications per treatment. Plots were 4 rows wide and 40 ft long, with the western row left untreated as a consistent source of infestation for each plot. Plots were separated from adjacent plots by 3 ft on each end and 6 ft (one blank row) on each side. Weekly insect counts were made on 2 randomly-selected plants from each plot and damage ratings were made on July 17 and 29. alternating between Imidan 50 WP (1 lb ai/A = 2 Ib/A) and Furadan 4F (1 lb ai/A = 2 pt/A). Treatment decisions in the "as-needed" plots were made based on the observed insect counts and treatment were applied within 2 days after sampling, if needed. Treatments were applied when numbers exceeded 2 adults and/or large larvae per plant. Imidan was applied on June 25 and July 31 and Furadan 4F on July 2, at the above rates. All plots were treated with Cygon for control of potato leafhoppers on July 10. "Weekly foliar" plots were sprayed weekly from June 25 through August 12, Time required to sample the "as-needed" plots was recorded weekly and used to estimate scouting costs. Yield data were taken from the center row of the three treated rows. Cost analyses were calculated for the respective treatments and marginal returns estimated. (Marginal return is the increase in profits from a particular treatment minus the costs of the respective treatment - scouting, spraying, etc.). Results In untreated plots, potato beetle numbers were extremely high and most plants were defoliated by early August. This is similar to what would occur in many non-rotated fields in Michigan without treatment and is less severe than what occurs in treated fields in the northeastern U.S. Numbers of large larvae reached a peak of 47 per plant on July 1 and numbers of adults reached 16 per plant on July 29 (Figure 1, Tables 1 and 2). Adult numbers would have been higher, except that plants were defoliated by early August and many adults moved to other plots. August 5, when untreated ptants had begun to die. This indicates that no attraction or il unt repellence occurred between plots and that the data from small plots may be valid for large fields, at least up until early August. Numbers of small larvae were extremely high in the foliar sprayed and untreated plots, since egg hatch often occurred between spraying and when scouting was done. Numbers of egg masses per plant did not differ significantly between treatments Figure 1. Seasonal dynamics of Colorado potato beetle eggs, larvae, and adults in untreated plot. Large larvae and adults do nearly all of the feeding and numbers of these stages determine the extent of defoliation and indicate the effectiveness of control. Numbers of large larvae reached very high levels in "weekly foliar" and "as-needed" plots on July 1, as the result of high numbers of small larvae on June 24 and incomplete control with Imidan (Figure 2, Table 1). Imidan was effective in 1985 at this location but not in 1986 (see insecticide trial data, part 2 of this report). Increased Imidan tolerance is the probable reason for this difference, emphasizing the need for routine testing for resistance levels before treatment and immediate field checking after treatment. Adult control with Imidan was also inadequate and adults in the "as-needed" plots reached a level of 13 per plant on July 29 and were still a 9 per plant on August 5, after Imidan treatment (Figure 2, Table 2). Some of the adults present on August 5 had probably emerged from pupation after the July 29 spray and were not affected by the residual levels of Imidan. As the result of these two cases of incomplete control, potato beetle levels were far above the target threshold in the "as-needed" plots on several occasions during the season. Table 1 Mean Number of Large Larvae/plant * 7-22 7-29 7-29 8-12 b 8-19 b 8-29 b 0.0 a 0.0 a 0.0 a 0.0 a 1.0 b 0.1 0.0 0.0 0.0 0.0 n.s. 0.0 0.0 0.0 0.0 0.0 Treatment 6-17 6-24 Temik 20 lb/A Thimet 15 lb/A Weekly foliar Foliar as needed 0.0 0.0 0.0 0.0 0.0 0.0 2.8 2.1 7-1 0.0 a 4.0 a 7-7 a 0.0 a 1.5 b 19.6 ab 1.2 b 21.8ab 0.6 ab 7-14 0.5 a 1.4 a 0.0a 3.9 a 0.2 1.0 0.0 1.6 0.0 0.0 0.0 0.1 0.6 0.0 0.0 3.8 Control 0.0 n.s 5.1 n.s. 34.2 b 46.6 c 12.8 b 1.5 n.s. 0.1 n.s. 0.5 n.s. * Means followed by the same letter are not significantly different (SNK test, P > 0.05). a SNK test based on square-root transformed data. b Some plants dead. Table 2 Mean Number of Adults/plant * Treatment Temik 20 lb/A Thimet 15 lb/A Weekly foliar Foliar as needed 6-17 0.0 0.1 0.5 0.2 6-24 7-1 0.2 0.1 0.2 0.1 0.6 0.1 0.0 0.5 7-7 7-14 7-22 a 7-29 8-5 8-12 b 8-19b 8-29 b 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.1 0.4 a 0.6 a 0.1 a 1.1 a 1.8 a 1.9 4.2 ab 3.4 4.1 ab 3.0 12.6 ab 8.9 0.5 0.4 0.1 0.6 0.4 0.5 0.4 0.9 0.0 0.5 0.0 0.0 Control 0.1 n.s.. 0.2 n.s. 0.0 n.s. 0.0 n.s. 0.0 n.s. 10.6 b 16.4 b 3.5 n.s. 1.0 n.s. 0.4 n.s. 0.0 n.s. * Means followed by the same letter are not significantly different (SNK test, P > 0.05). a SNK test based on square root transformed data. b Some plants dead. Figure 2. Numbers of large larvae and adult Colorado potato beetles in "weekly foliar' and "as-needed" plots. Damage ratings made on July 17 and 29, indicated that some defoliation had occurred in all plots and all treated plots showed similar levels of injury (Table 3). Yields were nearly identical for Temik, Thimet, and "weekly foliar" treatments and were slightly reduced in the "as-needed" treatment (not statistically significant, perhaps the result of the control problems discussed above). The slightly increased yield in the Temik treatment may have been the result of decreased nematode or early-dying injury. Yields in the untreated plots were severely reduced. Economic analysis of grade A's indicates that Temik provides the highest marginal return on investment (Table 4). Treatment "as-needed" provided the lowest marginal return, due to the decreased yield discussed above. Scouting costs were not included in Temik, Thimet, or weekly foliar treatment analyses, but would be a normal part of costs on most farms. Results will differ from farm to farm, depending on pest pressure, treatment and scouting costs, etc. Table 3 Damage Ratings and Yield Data Treatment Mean Damage Rating a Mean Damage Rating a Yield b (lb/40 ft) Yield b (lb/40 ft) 7-17 7-29 Grade A Yield b (lb/40 ft) Grade B Yield b (lb/40 ft) Oversize Knobby Total Yield b (lb/40 ft) Temik 20 Ib/A Thimet 15 Ib/A Weekly foliar Foliar as needed Control 1.2 2.0 2.0 2.0 3.0 2.0 2.0 2.0 2.2 3.8 53.4 a 50.6 a 51.2 a 45.6 a 14.9 b 18.5 17.5 13.9 16.0 18.5 n.s. 3.1 2.9 8.1 1.8 0.0 0.8 0.8 0.3 0.3 n.s. 1.0 n.s. 75.0 a 71.8 a 74.0 a 63.6 a 34.6 b a Damage ratings based on a scale of 1 to 5, where 1 = no damage, 2 = 1-5% defoliation, 3 = 6-25% defoliation, 4 = 26-50% defoliation, 5 = 51-100% defoliation. b Means followed by the same letter are not significantly different (SNK test, P>0.05). Table 4 Economic Analysis of Treatments empty table cell Scouting a Costs ($/A) Costs ($/A) Chem's b Appl. C Temik $52.00 $0 Thimet 24.00 0 Weekly foliar 0 48.00 Foliar as needed17.31 19.50 $0 0 35 15 Yield difference Treatment-Control (cwt/A grade A) Price Price Difference Price Difference @$4/cwt @ $8/Cwt Difference @ $6/cwt 148.0 137.2 139.5 118.0 $592 $888 $1184 1097 549 558 1116 472 944 823 837 708 Marginal Return Marginal Return $6 $4 $2 Marginal Return $540 $836 $1132 1073 525 475 1033 438 909 799 754 674 a For a 20 A field, 50 plants sampled per field @ $10/hr, based on sampling time for "as needed" plots. b Furadan 4 F @ $60/gal, Imidan 50 WP @ $3/lb. c Based on $5/A cost. 2. Field Insecticide Evaluations Potatoes (cv. Superior) were planted May 7 '86 at the MSU Montcalm Potato Research Farm. Plots were 3 rows wide (34 inch spacing) by 40 ft, with 3 ft of buffer zone before the next plot. Two untreated rows were left between adjacent plots. Treatments were arranged in a randomized complete block design with 4 blocks per treatment. Treatments were applied at planting, as a sidedress with fertilizer at hilling (May 28), or as weekly foliar treatments from June 25 to August 6. Foliar treatments were applied with a sprayer mounted boom at 3C gal/acre, 40 psi with a cluster of 3 nozzles over each of the three rows. One nozzle was pointed down directly over the top, with the other two directed at the sides of the plants. Weekly insect counts (June 17 to August 5) were made from two randomly selected plants ir the center row of each plot. On July 10, Cygon was sprayed on all plots to control potato leafhoppers. On July 17 and 30 the plots were rated for Colorado potato beetle damage. Yields were taken from center row of each plot on August 26 and 27. Colorado potato beetle larvae first appeared on June 17 in untreated plots and larval numbers peaked during mid-July (Fig. 3). Summer adults in the untreated plots peaked during the last week of July. Very few second generation larvae were present in the untreated plots due to the extensive defoliation and natural plant senescence that had occurred by the end of July. A comparison of the effects of soil systemic treatments indicated large differences between treatments (Fig. 4, Tables 5 and 6). Both Temik and Thimet appeared to give nearly season-long control of adults and larvae. Furadan 15G was less effective and larval control apparently nad broken down by July 7. DiSyston gave little apparent Colorado potato beetle control, although flea beetles and potato leafhopper numbers were reduced. Among the foliar treatments, Furadan 4F gave excellent control of larvae and adults. Imidan, the other standard, was not as effective as in previous years. Baythroid, the only pyrethroid evaluated, also gave only moderate control of larvae and no apparent adult control. This result was not surprising, since high levels of pyrethroid resistance are present in the beetle population. The ABG materials, B.t. exotoxins, gave good to very good control of larvae, although the effects were not rapid enough to affect the number of small larvae. F5951 and F4922 gave extremely effective control of larvae, especially considering that treatments were applied only every 2 weeks. Both materials also gave control of adults and numerous deformed undersized pupae were observed on the soil surface. Seasonal totals of egg masses and small larvae were generally highest in plots treated with materials effective against larvae (therefore reducing defoliation) but not effective against adults. Defoliation and yield data follow the same general patterns as large larvae and adult numbers. However, there were no significant differences in total yield or yield of grade A potatoes. The maximum difference in yield was 32% (Temik 3 lb ai/A versus untreated). Much of the defoliation occurred after tuber bulking was well along ('Superior' is a mid-season variety), limiting yield losses. Peak larval numbers occurred on July 14 and adult numbers peaked on July 22 in the untreated plots. material that are registered and remain effective at this location. New types of materials look good to very good, but may be more effective against larvae than adults. Overall, data indicate that there are 2 systemic materials and at least 1 foliar Figure 3. Seasonal dynamics of Colorado potato beetle in untreated plots. Figure 4. Large larvae numbers in plots treated with soil systemic materials compared to numbers in untreated plots. Table 5 Seasonal Mean Densities (number per 2 plants) Soil Treatments Egg masses a Small larvae a, b Large larvae a Adults a, c Temik 15G, 3 lb ai/A in furrow Temik 15G, 2 lb ai/A side-dress at hilling Mocap 15G, 3 lb ai/A band pre-plant + DiSyston 15G, 3 lb ai/A band pre-plant Mocap 15G, 3 lb ai/A band pre-plant + Thimet 20G, 3 lb ai/A band pre-plant UAP 101,25 lb form/A band pre-plant UAP 101,20.75 lb form/A band pre-plant Furadan 15G, 3 lb ai/A in furrow Thimet 20G, 3 lb ai/A in furrow Thimet 20G, 2 lb ai/A in furrow Foliar Treatments ABG 6162, 40 g form/A 0.5 a 0.6 a 0.8 abc 0.6 a 2.3 b 10.6 b 0.3 a 1.5 a 11.1 ab 1.0 abc 4.2 b 4.9 ab 1.4 abc 1.5 abc 1.1 abc 0.7 ab 0.6 a 13.2 b 14.8 b 11.4 b 3.1b 7.7 b 10.8 ab 9.5 ab 6.3 ab 1.1 a 2.4 a 0.8 1.5 2.9 2.9 2.9 4.6 2.2 1.9 1.4 Foliar TreatmentsFoliar Treatments Foliar TreatmentsFoliar Treatments 1.4 abc 16.2 b 3.9a 3.6 ABG6162, 80g form/A ABG 6211 40 g form/A ABG 6211, 80 g form/A (bi-weekly) Baythroid 4E, 0.5 lb ai/A F 5951 0.78 EC, 0.05 lb ai/A (bi-weekly) F5951 0.78 EC, 0.10 lb ai/A (bi-weekly) F5951 0.78 EC. 0.20 lb ai/A (bi-weekly) F4922 0.78 EC, 0.05 lb ai/A (bi-weekly) F4922 0.78 EC, 0.10 lb ai/A (bi-weekly) F4922 0.78 EC, 0.20 lb ai/A (bi-weekly) lmidan 50WP,1.0 lb ai/A Furadan 4F, 1.0 lb ai/A Untreated 1.6 abc 1.7 abc 0.9 abc 1.6 abc 1.6 abc 0.8 abc 1.6 abc 20 c 2.1 c 1.0 abc 1.9 bc 1.4 abc 0.6 ab 20.3 b 20.5 b 18.4 b 10.5 b 13.0 b 10.1 b 13.0 b 11.1 b 14.8 b 4.6 b 21.1 b 6.3 b 7.7 b 1.9 a 4.3 a 10.3 ab 4.9 ab 2.7 a 4.1 a 2.9 a 3.6 a 1.8 a 1.2 a 7.8 ab 1.2 a 14.6 b 1.9 3.9 3.5 6.2 3.6 1.9 2.3 3.2 1.7 1.9 4.8 0.6 5.3 a Means of samples from 4 replications per treatment, 2 plants per replication, over 8 sample dates. Means followed by the same letter are not significantly different (SNK test, p>0.05). b SNK test based on log-transformed data. c Excluding data for 8/5/86. Numerous plants in untreated plots and ineffective treatments were dead and significant adult movement to plots with more foliage had occurred by this date. Table6 Damage Ratings and Yield Data Soil Treatments Damage Rating a 7/17 Damage Rating a 7/30 Yield (lb/40 ft) b Grade A Yield (lb/40 ft) b Grade B Yield (lb/40 ft) b Oversize Yield (lb/40 ft) b Knobby Yield (lb/40 ft) b Total Temik 15G, 3 lb ai/A in furrow Temik 15G, 2 lb ai/A side-dress at hilling Mocap 15G, 3 lb ai/A band pre-plant + DiSyston 15G, 3 lb ai/A band pre-plant Mocap 15G, 3 lb ai/A band pre-plant + Thimet 20G, 3 lb ai/A band pre-plant UAP 101, 25 lb form/A band pre-plant UAP 101, 20.75 lb form/A band pre-plant Furadan 15G, 3 lb ai/A in furrow Thimet 20G, 3 lb ai/A in furrow Thimet 20G, 2 lb ai/A in furrow 2.0 1.8 3.0 2.0 2.3 3.0 79.3 71.6 9.5 abc 7.4 bc 68.8 6.8 bc 1.1 2.8 2.3 0.6 b 90.5 0.9 b 82.6 0.5 b 78.3 2.0 2.5 67.9 8.3 abc 0.9 1.3 b 78.3 2.5 3.3 2.5 2.0 2.0 3.5 3.5 2.8 2.3 2.5 58.9 9.6 abc 62.1 10.4 ab 65.6 11.5 a 67.5 64.3 9.0 abc 9.6 abc 0.5 0.1 1.6 3.8 1.5 0.8 b 69.8 0.5 b 73.1 1.3 b 80.0 1.0 b 81.3 0.5 b 75.9 Foliar Treatments Foliar Treatments Foliar Treatments Foliar Treatments Foliar Treatments Foliar Treatments Foliar Treatments 2.0 2.0 2.0 2.5 2.0 2.3 2.0 Foliar Treatments ABG 6162, 40 g form/A ABG 6162, 80 g form/A ABG 6211,40 g form/A ABG 6211, 80 g form/A (bi-weekly) Baythroid 4E, 0.5 lb ai/A F 5951 0.78 EC, 0.05 lb ai/A (bi-weekly) F5951 0.78 EC, 0.10 lb ai/A (bi-weekly) F5951 0.78 EC, 020 lb ai/A (bi-weekly) F 4922 0.78 EC, 0.05 lb ai/A (bi-weekly) F4922 0.78 EC, 0.10 lb ai/A (bi-weekly) F 4922 0.78 EC, 0.20 lb ai/A (bi-weekly) Imidan 50WP, 1.0 lb ai/A Furadan 4F, 1.0 lb ai/A Untreated 2.0 2.0 2.0 2.0 2.0 2.0 3.3 2.8 2.0 3.0 3.3 2.8 2.5 2.3 2.3 2.5 2.0 2.0 2.8 2.0 4.0 64.3 66.0 63.3 56.9 66.3 64.6 6.6 bc 6.4 bc 9.4 abc 6.9 bc 6.3 c 8.0 abc 67.0 7.5 bc 68.8 62.4 70.6 70.6 62.5 79.3 54.1 7.0 bc 6.9 bc 6.0 c 6.3 bc 6.8 bc 6.0 c 6.8 bc 1.4 0.5 1.5 0.8 1.9 0.7 1.0 2.6 3.6 3.0 2.4 2.4 4.6 0.1 0.4 b 72.6 0.6 b 73.5 74.9 0.8 b 65.4 0.9 b 0.6 b 0.9 b 75.0 74.1 1.5 b 77.0 0.6 b 79.0 0.9 b 77.3 0.9 b 80.5 1.3 ab 80.5 0.6 b 72.3 2.4 a 92.3 61.4 0.4 b a Damage ratings based on a scale of 1 to 5, where 1=no damage, 2=0-5% defoliation, 3=5-25% defoliation, 4=25-50% defoliation, and 5=50-100% defoliation. b Means followed by the same letter are not significantly different from each other (SNK, P>0.05). Funding: MPIC 1986 POTATO NEMATODE RESEARCH REPORT G.W. Bird Michigan State University POTATO EARLY-DIE CONTROL 1986 Russet Burbank research data from the Montcalm Potato Farm indicated a significant increase in tuber yield from potato early-die (PED) control with Temik 15G and Vorlex (Figure 1). This management practice resulted in a $675.00 increase in potential net profit per acre (Table 1). MONTCALM, MI. 1986 GROWTH DATA Figure 1. Table 1. Economics of Potato Early-Die Control Best Management Practice >10 oz 39 cwt $8.00/cwt $312.00 Best Management Practice 4-10 oz <4oz Best Management Practice Best Management Practice Ks Gross/A Best Management Practice Production Costs Best Management Practice Net/A Best Management Practice 278 cwt 31 cwt 63 cwt 411 cwt empty table cell empty table cell 6.00/cwt 1.50/cwt 3.00/cwt empty table cell empty table cell empty table cell 1,668.00 46.50 189.00 $2,215.50 1,150.00 $1,065.50 No PED Control >10 oz 30 cwt $8.00/cwt $240.00 4-10 oz No PED Control <4oz No PED Control No PED Control Ks No PED Control Gross/A Production Costs No PED Control Net/A No PED Control 158 cwt 33 cwt 51 cwt 272 cwt empty table cell empty table cell 6.00/cwt 1.50/cwt 3.00/cwt empty table cell empty table cell empty table cell 948.00 49.50 153.00 $1,390.50 1,000.00 $390.50 A nematicide evaluation trial with Superior at the Montcalm Potato Farm showed continued season-long control of the root-lesion nematode with Temik 15G, and similar nematode population reduction with Mocap 15G or Mocap + (Table 2). SN556 and SN61 provided nematode control similar to Vorlex, with the high rate of SN61 possibly being superior. This site had not been used for potato production for about 8 years, and the incidence of PED was very low. No yield benefits were observed in a nematicide trial in Rogers City (Table 3). Although the root-lesion nematode was present, no Verticillium dahliae was detected at planting, and the population density was very low during the growing season. PED symptoms were not observed. Table 2. 1986 Montcalm Potato Nematicide Trial. Treatment Yield (cwt/A) DiSyston Temik Vorlex & DiSyston SN556 & DiSyston (10) SN556 & DiSyston (15) SN61 & DiSyston (10) SN61 & DiSyston (15) Mocap & DiSyston (6) Mocap & DiSyston (12) Mocap + (6) Mocap + (12) 449 493 473 468 472 494 455 498 456 506 477 Pratylenchus penetans/100 cm3 soil & 1.0 g root tissue Pratylenchus penetans/100 cm3 soil & 1.0 g root tissue Pratylenchus penetans/100 cm3 soil & 1.0 g root tissue Pratylenchus penetans/100 cm3 soil & 1.0 g root tissue Pratylenchus penetans/100 cm3 soil & 1.0 g root tissue Pratylenchus penetans/100 cm3 soil & 1.0 g root tissue 4/28 58a 41a 33a 68a 76a 59a 72a 66a 55a 46a 40a 5/13 38ab 32ab 2a 1a 3a 6a 1a 52b 55b 27ab 37ab 6/23 42ab 7a 13a 8a 14a 10a 2a 7a 4a 5a 2a 7/28 8/28 182a 124b 17b 3a 72ab 24b 62ab 42b 38b 22a 26b 48a 5b 11a 13b 4a 0b 0a 5b 2a 2b 1a 9/8 126a 4a 29a 28a 38a 36a 3a 58a 5a 63a 71a Table 3. Rogers City 1986 Potato Nematicide Trial. Treatment Temik Temik &Telone II Temik & Vorlex Thimet Thimet &Telone II Thimet & Vorlex Yield (cwt/A) 404 350 397 380 403 456 Pratylenchus penetans/100 cm3 soil & 1.0 g root tissue Pratylenchus penetans/100 cm3 soil & 1.0 g root tissue Pratylenchus penetans/100 cm3 soil & 1.0 g root tissue Pratylenchus penetans/100 cm3 soil & 1.0 g root tissue 5/21 16 23 13 16 23 13 5/30 23 3 6 23 3 6 7/2 5 3 2 22 8 2 8/21 10 3 6 96 31 7 Pratylenchus penetans/100 cm3 soil & 1.0 g root tissue 9/10 26 3 5 21 20 7 Verticillium dahliae colonies/1.0 g soil = 0.04 (0.00-0.40, n = 10). POTATO EARLY-DIE DISEASE COMPLEX OBSERVATIONS Root-lesion nematodes penetrated potato feeder roots as soon as they were produced (Figure 2). High root population densities of this nematode were recovered as early as 14 days after planting. Root-lesion nematode population densities increased throughout the growing season, reaching a maximum of about 55,000 per plant. In a microplot experiment, root-lesion nematodes were recovered from potato feeder roots 15 days after planting (Table 4). V. dahliae was recovered from below ground stems 21 days after planting. The fungus was also recovered from the skin, eyes and center of seed pieces. Potato plant dry weight had been significantly impacted by PED as early as 33 days after planting (Figure 3). Root-lesion nematodes were recovered from both stolon tissue and tubers (Table 5). As with the 1985 research data, tuber yields were lower where potatoes were previously grown, compared to first-year potato land (Table 6). There also appeared to be a relationship with root-lesion nematodes. MONTCALM, MI. 1986 NEMATODE Figure 2. MONTCALM MI. 1986 GROWTH DATA Figure 3. Table 4. 1986 Microtile Experiment. Root-lesion Nematode 15 days after planting (15 P. penetrans) 18 days after planting (10 P. penetrans) 21 days after planting (38 P. penetrans) Verticillium dahliae 21 days after planting 1 BGS 1st 5 mm 1 BGS 1st 15 mm Superior seed Skin Eyes Center + V. + V. dahliae + V. dahliae dahliae Table 5. Root-Lesion Nematodes Recovered from Potato Stolon and Tuber Tissue. Stolons August 4,1986 88 P. penetrans/1.0 g stolon fresh weight (n = 10 plants) September 1, 1986 40 P. penetrans/1.0 g stolon fresh weight (n = 6 plants) Tubers September 1, 1986 0.5 P. penetrans/ 1.0 g tuber fresh weight (n = 6plants) Table 6. 1986 Potato Production Observations. Antrim County No Potato Early-Die Control 1st year 1st year 1st year 20 Yrs Pasture 83 Potatoes 425 cwt 521 cwt 489 cwt 421 cwt 380 cwt 0 PP/RK 0 PP/RK 0 PP/RK 5 PP/RK 97 PP/RK CHEMIGATION In most cases, 40 gal/A of metham was adequate for optimum tuber yields and root-lesion nematode control (Table 7). No differences were observed among Vapam, Busan 1020 and Nemasol. Spring chemigation was satisfactory in 1986. A positive response was obtained from a spring soil spray application of metham followed by discing. V. dahliav control was not obtained with 27 gal Vapam/A. Control of this fungus with 103 gal of Vapam/A was superior than 53 gal/A of Vapam (Table 8). Table 7. Influence of Metham on Potato Yield and Nematode Control. Treatment Yield Root-lesion Nematode 0 gal Busan 1020 f 25 gal Busan 1020 f 50 gal Busan 1020 f 100 gal Busan 1020 f 40 gal Vapam f 50 gal Vapam f 50 gal Vapam f 50 gal Vapam s 40 gal Nemasol f 50 gal Nemasol f 50 gal Vapam s 0 gal Vapam s 300 417 490 485 487 488 498 467 436 488 281 159 0% control 99% control 100% control 100% control 100% control 99% control 100% control 100% control 100% control 100% control (dry corner disc) (dry corner disc) Table 8. Verticillium dahliae Colonies/1.0 g Soil Treatment 5/2 6/27 7/24 9/4 10/4 Antrim County 0 gal Vapam 27 gal Vapam Antrim County 53 gal Vapam Antrim County 103 gal Vapam Antrim County Montcalm County 50 gal Vapam Loam Check Montcalm County Sand Check Montcalm County 3.5 4.4 0.4 0.0 4.7 4.6 0.8 0.0 empty table cellempty table cell empty table empty cell table cell empty table empty cell table cell 31.0 22.4 11.4 0.0 27.9 20.9 13.7 0.2 empty table cell 0.4 (0.0-1.2) 1.3 (0.5-2.4) empty table 6.6 (10.1-4.2)empty cell table cell 7.8 5.4 6.2 0.1 empty table cell empty table empty cell table cell VERTICILLIUM DAHLIAE ASSAY OBSERVATIONS Population densities of V. dahliae increased throughout the growing season (Table 8). Population densities were variable both within individual potato fields, and between fields and farms (Table 9). The population densities ranged from non­ detectable (0.00 cotomes per 1.0 g soil) to very high (56.0 colonies per 1.0 g soil). Population densities of V. dahliae were greater in sandy soils than in sandy loams. Table 9. Verticillium dahliae Colonies/1.0 g Soil Montcalm County Farm No. 1 Field No. 1 Montcalm County Farm No. 1 Field No. 2 Montcalm County Farm No. 1 Field No. 3 Farm No. 2 Montcalm County Field No. 1 Antrim County Farm No. 1 Field No. 1 1 Field No. 2 Antrim County Farm No. Antrim County Farm No. 1 Field No. 3 4.9 (0.0-20.4) 2.0 (0.0-7.2) 1.8 (0.0-5.2) 2.8 (0.0-6.0) 3.9 (0.0-19.0) 0.7 (0.0-6.0) 32.7 (16.8-56.0) POTATO MODEL VALIDATION Four computer simulations of potato growth and development and associated pests are being evaluated in a joint integrated pest management research project at Michigan State University, University of Minnesota, North Dakota State University and the University of Wisconsin (Table 10). Figure 4 is an example of a POTATOPEST computer simulation of dry weight of the below ground parts of the potato plant compared to actual Russet Burbank data collected at the Montcalm Potato Farm during 1986. All components of the potato plant are being studied in detail (Figures 5-7). Table 10. Potato Growth Models Used in the MI/MN/ND/WI Potato Model Validation Project. Model POTATOPEST POTATO SPUDGRO POTATO CERES Date 1974 1982 1984 1985 Authors Institution G.W. Bird Loomis/Ng Adams/Rouse P. Teng J. Ritchie MSU ID/UC-Davis Univ.WI Univ. MN MSU MONTCALM MI. 1986 GROWTH DATA FIgure 4. MONTCALM MI. 1986 GROWTH DATA Figure 5. MONTCALM MI. 1986 GROWTH DATA Figure 6. MONTCALM, MI. 1986 NEMATODE Figure 7. Funding: MPIC PROGRESS REPORT TO THE MICHIGAN POTATO IMPROVEMENT COMMITTEE EFFECT OF SPRAY SCHEDULE AND POTATO CULTIVAR ON DEVELOPMENT OF EARLY BLIGHT AND EFFECT OF EARLY BLIGHT ON YIELDS M. L. LACY Department of Botany and Plant Pathology Michigan State University Objectives: To determine the effect of three fungicide spray schedules (every 7 days, every 14 days, and unsprayed) on development of early blight and on yield in six potato cultivars. 1986 Procedures: Six potato cultivars (Onaway, Atlantic, Superior, Shepody, Russet Burbank, and Rosa) were planted in plots at the MSU Botany and Plant Pathology Farm on May 1. Approximately 800 pounds per acre of 12-12-12 fertilizer was applied prior to planting. No nitrogen side-dress was applied to encourage early blight development. Insects (mostly Colorado potato beetle) were controlled with three applications of Sevin 80W (1.25 lbs per acre) and one application of Imidan 50W (2 lbs per acre). Weeds were controlled with a pre-emergence application of Lorox 50W and one application of Fusilade 4E (6.8 oz. per acre) plus cultivation. Plots were sprayed with a conventional boom sprayer delivering 50 gallons per acre at 100 PSI. Each row was sprayed with two D2-25 nozzles, one on each side of the row, from a 45 degree angle. Plots were set up on a split plot design with each cultivar replicated 4 times and each fungicide treatment replicated 4 times on each cultivar. Guard rows were inoculated with spores of the early blight fungus on 7/25 and all plots were inoculated on 8/5/86. Dithane M-45 80W (1.8 lbs per acre = 1.45 lbs active) was applied every 7 days, every 14 days, or not at all beginning on July 3 and ending on August 26 (8 applications on the 7 day schedule and 4 applications on the 14 day schedule). Visual disease ratings estimating % of diseased foliage were made on August 18, vines were killed with paraquat on September 3, and tubers were harvested on October 8 (harvest was delayed due to heavy rains the latter part of September). Results: Cultivar was clearly an important factor in both disease rating and in yields (Table 1). Shepody had the lowest disease ratings of any cultivar for any given treatment, and it outyielded all other cultivars, regardless of treatment, including the unsprayed. Cultivars could be ranked in order of decreasing yields regardless of fungicide treatment in most cases, in the order Shepody (highest, Atlantic, Rosa, Russet Burbank, Superior, and Onaway. In no case did fungicide treatment significantly increase yields, which was a great surprise to me. However, fungicides did have a significant impact on disease ratings in most cases. In examining the recent literature, I found that other researchers have had similar experiences. Rowe in Ohio and Stevenson in Wisconsin both found that differences in disease severity due to fungicide application were not reflected in yield differences in some of their experiments. In Washington, Eaton and Nagle found that application of Bravo through center pivot irrigation significantly reduced lesion numbers but did not reduce yields. On the other hand, Teng and Bissonnette at Minnesota found that both spray schedule and cultivar were significant determinants of yield; however, they only used two cultivars, Norland and Russet Burbank. It appears from this experiment and the experience of others that cultivar is probably the most important determinant of early blight's effect on yield, although not necessarily on development of foliar lesions. This may not be too surprising if we extrapolate from the results of Baker and Wilcox, who examined the effects of removing different amounts of leaf tissue at different times on onion yields.They found that leaf area reduction had the largest effect on yields when it occurred at the time of bulb initiation about 5 weeks prior to harvest. Defoliation prior to or subsequent to this time had decreasing effects on yields as the timing moved further away from this critical period. They also found that it took about 50% Defoliation or greater to have a significant effect on yields so it may be that plants have a "safety margin" of leaf tissue that can be lost before yields are materially affected. It may be that severe early blight developed too late in this experiment to significantly affect yields. We had our only dry period of the summer during July and early August which were probably the critical times for tuber formation, and we inoculated our plots on July 25 and August 5. Early blight did not really become severe until late August. I believe that next year we should inoculate earlier; however, the early period when nitrogen fertilizer levels are still high and potato tissue still vigorous may not be very conductive to disease development. Table 1. Disease Ratings and Yields of Potato Varieties Infected with Early Blight, Sprayed with Di thane M-45 or Left Unsprayed, 1986. Variety Shepody Shepody Shepody Atlantic Atlantic Atlantic Rosa Rosa Rosa R. Burbank R. Burbank Superior Superior R. Burbank Onaway Onaway Superior Onaway Spray Schedule * 7 Day 14 Day Unsprayed 14 Day 7 Day Unsprayed 14 Day Unsprayed 7 Day 14 Day 7 Day Unsprayed 14 Day Unsprayed 7 Day Unsprayed 7 Day 14 Day FGH FGH DEF Disease Rating ** 1.0 A 1.5 ABC DE 2.5 DEF 2.8 2.3 BCD 3.5 3.0 3.8 2.5 CDE 2.8 DEF 2.0 BCD 5.0 4.8 3.5 1.3 AB 2.8 4.0 2.0 BCD DE FGH GH Yield (CWT/A) 410.77 A 407.79 A 377.30 AB 342.82 ABC 320.17 BCD 306.95 BCDE 298.60 BCDEF 277.11 CDEF 275.66 CDEFG 261.72 CDEFG 253.74 CDEFG DEFG 251.70 DEFG 237.04 DEFG 236.17 226.73 EFG 222.01 EFG 211.77 FG 184.40 G J IJ Percent Rot *** 2 0 0 10 10 24 0 0 4 0 2 10 8 4 4 6 0 0 * Plots were sprayed with 1.8 lbs. of Dithane M-45 80% WP. ** Based on a visual rating scale of 1 to 5, where 1=0-2%, 2=3-10%, 3=11-25%, and 5=>50% of tissue diseased. Disease ratings were made on 8/18/86. *** Total amount of tuber rot after 11 weeks in storage at 45 F. Means followed by the same letter are not significantly different (Duncan's Multiple Range Test, P=.O5). Harvested 10/8/86. Table 2. Comparison of Fungicide Sprays on Yields of Six Potato Varieties with Yield Data Pooled, 1986. Spray Schedule * Every 7 Days Every 14 Days Unsprayed Yield (CWT/Acre) 288.95 A 283.14 A 278.78 A * Sprayed with 1.8 lbs per acre Dithane M-45 80% WP. Means followed by the same letter are not significantly different (Duncan's Multiple Range Test, P=.O5) Table 3. Yields of Six Potato Varieties with Data from Spray Treatments Pooled, 1986. Variety * Shepody Atlantic Rosa R. Burbank Superior Onaway Yield (CWT/Acre) 398.57 A 323.07 B 283.87 BC 250.47 CD 233.77 D 211.27 D * Varieties were sprayed every 7 or 14 days or left unsprayed. Means followed by the same letter are not significantly different (Duncan's Multiple Range Test, P=.O5) Funding : Federal Grant Title: Influence of Environmental Factors on Wound Healing of Potato Tubers in Relation to Storage Disorders Investigators: R. Hammerschmidt and A. Cameron Justification: Wounding of potato tubers commonly occurs during harvesting and handling. It is well established that physical and chemical barriers formed during the early stages (1-2 weeks) of wound healing can reduce subsequent shrinkage (water loss) and pathogen-mediated decay during storage. Additionally, the rate and extent of wound healing is influenced by environmental factors such as temperature, humidity, oxygen and carbon dioxide. However, knowledge of optimal conditions is incomplete, particularly under commercial storage conditions. Research is needed to provide information which then can be used to aid in design of potato storage facilities which will provide conditions that minimize losses due to shrinkage and disease. Objectives: A. Develop and refine refine screening methods for parameters of wound healing most closely linked to resistance to shrinkage and pathogen-mediated decay. Specifically, this includes resistance to water loss, production of lignin and wax, and resistance to pathogen inoculation and tissue maceration. B. Utilize screening methods to test effects of environmental factors and of extended storage duration. Ultimately, the objective is to establish upper and lower limits for factors such as temperature, humidity, O2 and CO2 which can be used for design of potato storage facilities. C. Screen selected varieties for wound healing using methods developed in Part A. In addition, determine varietal varietal to environmental factors. D. Screen selected varieties for resistance to Fusarium and Erwinia tuber rots. Procedures: A. Screening methods. 1. Resistance to water loss: A standard method has been developed utilizing potato discs of 2.1 cm diameter and 1 cm thick. Potato tubers are surface sterilized prior to slicing. Discs are placed at 20°C in chambers through which humified air (90-95% RH) is passed at a constant flow rate. Generally, discs are sampled for water loss at 0, 2, 4, 6, 8 and 10 days after wounding. Each disc is placed separately on a balance (accurate at 0.1 mg) which measures the rate of weight loss at 5 sec intervals and transfers the data to a computer. A separate computer programs was written to analyze and display the data for visual confirmation of the results. The resistance to water loss was calculated using the rate of water loss and the ambient temperature and RH measured within the balance chamber. 2. Lignin production: Lignin is a major structural component of suberin, therefore monitoring production of this polymer can be used as a measure of suberization. Generally, the top mm of discs (prepared as above) were sampled at intervals after wounding. Each set of slices from the discs are thoroughly extracted with methanol and thee chloroform. The insoluble residue is analyzed by the thioglycolic acid procedure for lignin content. Slices were also evaluated for lignin by histochemical techniques. The methanol and chloroform soluble materials are saved for analysis of waxes and wound-induced antibiotic compounds. 3. Resistance to maceration: Both Erwinia and Fusarium attack tuber tissue using enzymes that macerate or degrade the tissue. Solvent extracted slices (see above) are incubated with a preparation of tissue degrading enzymes. Coherency of tissue after 24 h in the enzyme solution is a measure of wound induced resistance to these factors. 4. Wound induced antibiotic substances and waxes: The methanol soluble fraction can be assayed for antibiotic (antifungal and antibacterial) phenols by applying small amounts of the extracts onto filter paper. After drying of the solvent, the filter papers are sprayed with a suspension of the pathogen in a nutrient solution. Antibiotic materials appear as clear zones on a background of fungal growth. Total phenol was determined spectrophotometrically. Wax analyses methods are still under development. 5. Resistance to pathogen inoculation: At intervals (0, 2, 4, 6 days) after wounding, the discs were challenged with a suspension of Fusarium sambucinum macroconidia (the dry rot pathogen). One week later, discs were visually assessed for dry rot infection and rated as infected or not-infected. B. Environmental factors and storage duration. 1. Storage duration: Russet Burbank tubers were stored at 5°C (41°F) and sampled several times during storage up to 8 months. 2. Effect of CO2: CO2 was blended into air stream to yield final concentrated of 8% during wound healing period. Discs were sampled for resistance to water loss as outlined above. C. Varietal screening. 1. During fall of 1986, 14 varieties of potato tubers were harvested and tested for development of barriers to water loss and pathogen infection and timing of resistance development. Methods were comparable to those described above. 2. Whole tubers were evaluated for genetically based resistance to Fusarium dry rot and Erwinia soft rot. Whole tubers were injected with 10 ul of F. sanbucinum or 50 ul of E. carotovora. Fusarium inoculated tubers were incubated at 20°C for 3 weeks prior to disease assessment while Erwinia inoculated tubers evaluated at 96 h. Amount of disease was determined by measuring lesion size after bisecting the tuber through the lesion. Results: A. Screening method. 1. It was found that the resistance to water loss could be consistently calculated using data from 2 minutes of weight loss data. In almost every case, resistance to water loss begins to increase 3 days after wounding with a very large increase on day 4. Resistance to water loss continues to develop but at a slower rate through day 10. 2. Use of the thioglycolic acid method indicated this part of wound healing began between 1 and 2 days after wounding. Largest increases occurred between 2 and 5 days after wounding. Microscopic observations using histochemical techniques confirmed these results. 3. Maceration tests indicated that the coherency of the suberized layer was complete by 3-5 days after wounding. 4. Analysis of the methanol soluble materials revealed that accumulation of wound induced antibiotic materials (mostly phenols) started within 24 h of cutting. These reached apparent antibiotic levels within 2-3 days. B. Environmental factors and storage duration. 1. Storage duration: There was no significant difference in the rate and pattern of water loss during wound healing noted for tubers sampled through 8 months of storage. 2. Effect of C02: Carbon dioxide exposure during wound healing marked decreased rate of water loss barrier formation. The initiation of resistance to water loss did not begin until 6 days after wounding and exposure to 8% CO2 compared to only 3 days when in air. However, 10 days after wounding, there was little difference between air and carbon dioxide treated discs. 3. Air flow: It was discovered that when discs were held in closed containers rather than in constant air, there was consistently a higher rate of mold development on the cut surfaces. In all cases, molds were associated with lowered resistance to water loss. C. Varietal screening. 1. Preliminary data indicate that shortly after harvest, all 14 varieties exhibit very similar rates and patterns of development of resistance to water loss during wound healing. 2. Some variation among varieties was noted in the whole tuber susceptibility to Fusarium and Erwinia, wound induced resistance to Fusarium and wound induced phenol and lignin accumulation. Conclusions: 1. Screening methods for measurement of resistance to water loss and structural and chemical barrier formation during wound healing were developed to yield consistent results. 2. Wounded potato tubers initiate barriers to water loss 3 days after wounding with the greatest increase at 4 days. Structural barriers are initially evident within 2 days and increases greatest between 2 and 5 days. Barriers continue to develop for at least 10 days after wounding. 3. There appears to be no loss in ability to generate barriers to water loss during wound healing for at least 8 months of storage at 5°C (41OF), however, resistance to Fusarium in these tubers did decline. 4. Eight percent CO2 retards development of barriers by 3 days during a period which is critical for pathogen interactions. 5. Lack of air movement during wound healing is very conducive to mold development which is associated with loss of ability to resist water loss. 6. No differences were noted in ability to develop water barriers during wound healing for 14 varieties of freshly harvested potato tubers. Some differences (1-2 days) in wound related lignin synthesis, phenol accumulation and resistance to Fusarium were detected. The first 3 days appear critical. 7. No resistance to Fusarium nor Erwinia was detected in whole tubers. However, there was variation in the amount of susceptibility from variety to variety. Double inoculations with both pathogens resulted in more disease than with either separately. 8. Resistance to pathogen attack may be due to a mixture of wound repair and constitutive factors in the tubers. Funding: Federal Grant SIMULATED POTATO STORAGE RESEARCH: 1985-1986 INVESTIGATORS: Burt Cargill, Todd Forbush GOAL AND OBJECTIVES: The overall goal of the 1985-86 Simulated Potato Storage research was to determine the practicality of an operational potato storage research facility which will accurately simulate the storage environment encountered in a typical commercial bulk potato storage. The specific objectives include: 1. Comparison of the out of storage quality of potatoes from the storage research facility and from a companion commercial bulk storage 2. Evaluation of equipment for monitoring and controlling the environment of a bulk potato storage JUSTIFICATION: In the past potato storage research has been conducted at two levels: using commercial potato storage bins (10,000 cwt and larger) and using small samples (25 lb.) stored in environment controlled cubicles. The commercial bins are grower owned and operated, making controlled research difficult. The small samples are good for developing base line data regarding the response of potatoes to different environmental conditions. However they lack the effect of storage conditions encountered in bulk potato storages such as pile depths, bin pressures, and variations in air flow. There is a need for potato storage research facility that can make the transition from small sample research to commercial bulk potato storage conditions. The research facility must be able to accurately simulate bulk storage conditions, yet be small enough to allow for replications using equivalent potatoes and environments within the same season. METHODS AND PROCEDURES: A storage research bin measuring 8’X 8'X 16’ (see Fig. 1 and 2) was constructed and placed within a commercially stored potato pile at Sandyland Farms in Howard City, MI. This bin was filled with approximately one acre of potatoes (300 cwt.) Identical to those in the pile surrounding it. The air handling system of the "Simulated Storage" was designed to deliver 3.0 cfm/cwt, twice the current recommendations for bulk potato storage in Michigan. The commercial storage was ventilated at the industry standard of 1.5 cfm/cwt. The intake air of the Simulated Storage was removed from above the commercial storage. Even air distribution within the Simulated Storage was obtained through the use of an under floor plenum (see Fig 1). The fans used for ventilation of both storages were under the control of a commercially available Paragon time clock set by Michigan State University for the Simulated Storage bin and by Sandyland Farms for the commercial bin. Both fans were run continuously during the period of suberization. Fan times were then decreased at the discretion of the management of the respective storage Small samples (25 lb potatoes) were placed at three levels (6,10, and 12 foot above floor level) within both the commercial storage and the Simulated Storage. Upon removal from storage these samples were evaluated for market quality using the procedure outlined by Cargill, et al. (1985). Four large samples (80 lb. each) were randomly selected from the Simulated Storage during unloading. Two samples were chosen at the same time from the commercial storage. The samples were taken to the Frito-Lay plant in Allen Park, MI for evaluation of chip color and percent solids. Throughout the storage season, different types of environmental monitoring systems were installed on the Simulated Storage and evaluated on their performance in monitoring the environment of the storage and on their ability to control the storage environment. Parameters of interest included the temperature and relative humidity of the environment surrounding the potato, as measured from within the potato pile. The instrumentation systems were tested included: 1. A Digi-Strip data logger by Kaye Instruments, 2. A CR21 weather logger by Campbell Scientific, 3. A 21X weather station consol by Campbell Scientific RESULTS: FAN TIME - The fan time of both the commercial storage and the Simulated Storage were recorded on a weekly basis. The fan time for both storages are presented in Table 1. The total fan time the Simulated Storage during the 122 day storage season was approximately 531 hours, compared to approximately 1392 hours for the commercial bin. The reduction in the fan time could reduce the energy required for ventilating the potatoes by 24%. POTATO QUALITY - The market quality of the potatoes as determined from the examination of the individual potatoes is listed in Table 2. A market quality of the potato samples from the Simulated Storage averaged 85.0%, with an observed vertical gradient of 10%. The market quality of the potato samples from the commercial storage averaged 78.7% with an observed gradient of 25%. The potatoes higher quality were those stored near the air inlet into the potato pile (the 6 foot level) in both cases while the potatoes furthest from the air inlet (the 12 foot level) were lower quality. CHIP COLOR - The results of the chip color analysis carried out by Frito-Lay are presented in Table 3. All potato samples received a number 2 color designation (55-64 Agtron). The samples tested showed no significant difference in chip color. PERCENT SOLIDS - An evaluation of the large samples for percent solids, performed during the chip color evaluation and presented in Table 3. The evaluation gives some indication the amount of water lost during the storage season. The value of 12.6% obtained for the Simulated Storage is 1.1% less than the value obtained in the commercial storage. This lower value for percent solids Indicates that the potatoes within the Simulated Storage retained more of their original fluid content than did the commercially stored potatoes. Cargill, BF, et al. 1985. Influence of prestorage chemical treatments on out- of-storage market quality of potatoes. ASAE Paper 85-4028. WEIGHT LOSS - The weight loss from the small samples in both storages are presented in Table 4. The data indicates that, on the average, the Simulated Storage lost more weight (water) due to ventilation than did the commercial storage. The validity of this data is questionable since different scales were used for determining initial and final weights. ENVIRONMENTAL CONTROL - The Digi-Strip data logger did not record the data well on impact paper due at the high humidity in the storage. The CR21 by Campbell Scientific performed well in the harsh environment, but was not completely compatible with the temperature sensors (copper-constantan thermocouples). The best performance was obtained from the 21X weather station controller. The data output was in a desirable form and easily recoverable, using a cassette tape for data storage and a reader for placing data on disk file. The 21X was used to monitor the inlet air temperature and the temperature within the Simulated Storage at the 6 ft and 10 ft levels (see Fig. 3 and 4). A temperature gradient was observed indicating that the fan operation period was not long enough to allow the temperature front to move through the pile. Thus, the temperature gradient within the Simulated Storage, as indicated in Figure 3, increased with time up to 1.0F. CONCLUSIONS: The results of this pilot study indicate that the storage research facility can accurately simulate the out of storage quality of stored potatoes when compared to a companion commercial bulk storage. In addition, the data from this years study indicates that there may be some advantages in the use of high volume, low fan time air flow in the extended storage of potatoes. The potatoes subjected to this type of air flow maintained a higher marketable percent solids and a chip color equivalent to potatoes subjected to normal ventilation airflow. The instrumentation systems tested were successful in recording the temperature within the potato storage. However, they were deficient in the number of control ports and the conditions of control port activation. Further investigation into the field of instrumentation is required to obtain an environmental controller. capable of handling the complex task of controlling a potato storage environment. TABLE 1 Fan time for MSU Simulated Storage and for companion commercial bulk storage. Fan Operation Dates 10/02/85 - 10/07/85 10/08/85 - 10/14/85 10/15/85 - 10/24/85 10/25/85 - 11/21/85 11/22/85 - 12/05/85 12/06/85 - 01/31/86 TOTAL Elapsed Days Fan Hours per Day 1 MSU Fan Hours per Day 1 Bulk Fan Hours Total Fan Hours Total Bulk MSU 6 7 10 28 14 57 122 24 7 7 4 3 2 -- 24 24 12 12 12 8 -- 144 49 70 112 42 114 144 168 120 336 168 456 531 1392 1 Fan time was divided into equal increments within each 12 hour period of the day. TABLE 2 Market quality (% by number) of potatoes stored in MSU Simulated Storage and companion commercial bulk storage. Sampling Position (feet above floor) 6 10 12 AVERAGE MSU 89.6% 85.6% 79.8% 85.0% Bulk 92.6% 76.1% 67.3% 78.7% TABLE 3 Clip color and percent solids for MSU Simulated Storage and companion commercial bulk storage. Chip Color (Agtron scale) Chip Color (Agtron scale) MSU Bulk Percent Solids MSU Percent Solids Bulk 61 62 63 60 64 60 -- -- 62.0 Average 61.5 12.8 12.7 12.0 12.9 12.6 13.6 13.8 -- -- 13.7 TABLE 4 Weight data for MSU Simulated Storage and companion commercial bulk storage. Sampling Position (feet above floor) Weight Loss % 1 MSU Weight Loss % 1 Bulk 6 10 12 AVERAGE 6.8 9.7 4.6 7.0 4.3 6.0 6.5 5.6 1 Due to error in weighing techniques and the use of different scales for determining beginning and ending weights, the weight loss data recorded in this table has questionable validity. Figure 1. Perspective of Simulated Storage Figure 2. Top View of Simulated Storage Figure 3. One Increment Equals 75 Minutes Figure 4. One Increment Equals 75 Minutes Funding: MPIC A PILOT STUDY INVESTIGATING SPROUT INHIBITING AND VINE KILLING METHODS 1985-86 SEASON B.F. Cargill, Agricultural Engineering Department T.D. Forbush, Agricultural Engineering Department R.L. Ledebuhr, Agricultural Engineering Department G. R. VanEe, Agricultural Engineering Department H. S. Potter, Botany and Plant Pathology Michigan State University East Lansing, MI 48824-1323 ABSTRACT During the 1985 growing season, field trials were conducted on Atlantic variety potatoes to determine the effectiveness of various chemical solutions and application methods for sprout inhibiting and vine killing in potatoes. The studies compared straight stream air assisted rotary atomization (MSU Air Curtain) to conventional nozzles. In the sprout inhibitor tests, two different active ingredient rates were applied on two spray dates at the MSU Montcalm Research Farm, Entrican, MI. Samples were stored in environmentally controlled cubicles at MSU and in a commercial storage at Sackett Ranch, Stanton, MI. The data from the 1985-1986 sprout inhibitor study indicated that the early spray date, 89 days after planting, was more effective in the limiting of sprout growth in extended storage than was the late spray date, 99 days after planting. In the vine kill study, four treatments with varying chemical solutions were performed at V&G Farms, Stanton, MI. The data from the 1985-1986 vine kill studies indicates that the use of the Air Cur-tain sprayer increases the rate of potato vine "kill down" over the conventional hydraulic nozzle equipment. Application Methods PROCEDURE In both the sprout inhibitor and the vine kill tests the spray systems used remained the same. They were: 1. Conventional brush type boom sprayer with hollow cone D4-25 nozzles applying 50 GPA carrier at 50 psi. 2. MSU Air Curtain sprayer with Micronair AU7000 applying 5 GPA carrier. Chemical Treatments All chemical treatments included standard herbicide and insecticide materials applied at label rates as needed before and after planting. A commercially available form of MH-30, Super Sprout Stop, was the chemical used for the sprout inhibitor study. Active ingredient rates of 1-1/3 GPA (labeled rate) and 2/3 GPA were applied using the application methods listed above. Application dates were July 30 (89 days after planting) and August 9 (99 days after planting). These dates will be referred to as early and late spray dates respectively. The treatments and methods of application are listed in Table 1. All vine kill treatments were applied September 19, approximately one week prior to harvest. The treatments and methods of application are listed in Table 3. Experimental Designs In the sprout inhibitor study, all sprayer plots were 0.0122 acre each, while the check plot was 0.0245 acre. After harvest, the treated potatoes were divided into samples of 20-25 lbs. These samples were then placed in con­ trolled environment cubicle storage on the MSU campus and in the center of a 14,000 cwt balanced air flow storage at the Sackett Ranch, Stanton, MI. The bulk potatoes surrounding the research potatoes in this commercial bin had been treated with MH-30 using conventional application methods. The potatoes in the cubicles were suberized for two weeks, one week at 60F and 95% r.h. and one week at 55F and 95% r.h. After suberization the air temperature in the cubicle was lowered to 50F. The potatoes were held at this temperature for the remainder of the approximately 6 month storage season. Samples stored in the commercial storage were suberized at 55-60F with continuous ventilation for approximately 30 days. The air temperature was then gradually lowered to the storage temperature of 50F. In the vine kill study, sprayer plots were 0.206 ace. Four sampling areas were chosen within these plots. Evaluation Method Evaluation of the sprout inhibitor experiment was performed upon removal of samples from the commercial storage. This evaluation involved removal of the respective bag from storage, emptying the bag and, examining the tuber for the degree sprouting that had occurred over the approximately 230 day storage season. Tuber sprouting was classified as follows: A. No sprout B. Peeper sprout (This included any potato with a button sprout less than 3/8" in length. C. 3/8 - 3" sprout 3 - 6" sprouts D. E. Sprouts over 6" Categories C - E were divided once more on the basis of sprout vigor. Sprouts less than 3/16" in diameter were classified as "spindly" sprouts, while sprouts with diameters larger than 3/16" were classified as "hardy" sprouts. For example, a potato with a 2.5" sprout 1/4" in diameter would be placed into category C, hardy, indicating a sprout less than 3" in length and over 3/16" diameter. Data in the vine kill study was compiled by means of subjective panel evalua­ tions. The desiccation index was based on a scale from 1 to 10, 10 being complete vine kill. Evaluations were performed every two days for eight days after spraying. The evaluations represent an average of 10 readings taken in each replication. Complete desiccation by chemical treatments after eight days was the basis for discontinuing evaluation. Effectiveness of Sprout Inhibitor, MSU Stored Potatoes RESULTS AND DISCUSSION Table 2 shows the percent potatoes (by number) that exhibited retarded sprout growth after 230 days of storage at 50F. Retarded sprout growth is defined as potatoes having sprouts less than 3" in length and not larger than 3/16" in diameter. A statistical analysis performed on data showed the following statistically significant differences: 1. A difference of 10% between treatments one and two, labeled rate vs. half labeled rate applied with boom sprayer, at the 99.5% level of significance 2. Differences of 13 to 28% between early and late spray dates at the 90% level of significance 3. Differences of 38 to 77% between the treated samples vs. the check samples at the 99.5% level of significance. The percent of potatoes that exhibited retarded sprout growth suggests a very significant decrease in the number of potatoes that develop vigorous sprouts when treated with sprout inhibitor. The data also suggests that the early spray date (89 days after planting) demonstrated a greater decrease in the vigor of the sprouts than did the late spray date (99 days after planting). A slight increase in percent of potatoes with retarded sprout growth was demonstrated by the early treatments with the Air Curtain. However, no statistical difference was observed. Effectiveness of Sprout Inhibitor, Commercially Stored Potatoes Table 2 shows the percent potatoes (by number) that exhibited retarded sprout growth. A statistical analysis on the data showed the following statistical significant differences: 1. A difference of 2% between the labeled rate and one-half labeled rate applications with the boom sprayer at the 95% level of significance. 2. 3. A difference of 15% between the early and late applications of one- half labeled rate by the boom sprayer at the 99.5% level of significance. A difference of 20% between the early and late applications of labeled rate by the Air Curtain sprayer at the 99.5% level of significance. 4. Differences of 7 to 12% between the labeled boom and Air Curtain applications vs. the check treatment on the early spray date. Similar to the MSU stored potatoes, the commercially stored samples indicated a reduction in the effectiveness of sprout inhibitor applied at the late spray date, 99 days after planting. A slight increase in the effectiveness the sprout inhibitor sprayed on the early date with the MSU Air Curtain sprayer vs. the boom sprayer at the labeled application rate was indicated. However, no statistical difference was observed. The effectiveness of the sprout inhibitor may have been reduced in both studies by the occurrence of rainfall after the application was made. The manufacturer of Super Sprout Stop (Uniroyal Chemical) suggests that for optimum spray effectiveness, there should be no irrigation or rainfall 24 hours before or after application. There was no rain 24 hours before applica­ tion, but a trace rain fell on both application dates within 24 hours of application. Effectiveness of Vine Kill Table 4 shows the desiccation index for the vine kill studies. applications by the Air Curtain sprayer consistently increased vine desiccation (0.1 to 1.0) over the conventional boom sprayer. Treatments which included Diquat as part of the spray solution demonstrated more effective vine kill both by the desiccation index and the rate of vine desiccation. Figure 1 shows the data in Table 4 in graphical form. The data also suggests a slight increase in the vine desiccation with the use of drift retardant, as shown in Figures 2 and 3. However, no statistical difference was observed. Al treatments effectively eliminated potato vines over the eight-day evaluation period. CONCLUSIONS The data from the 1985-1986 sprout inhibitor study indicated that the early spray date, 89 days after planting, was more effective in the limiting of sprout growth in extended storage than was the late spray date, 99 days after planting. The data from the 1985-1986 vine kill studies indicates that the use of the Air Curtain sprayer increases the rate of potato vine "kill down" over the conventional hydraulic nozzle equipment. Table 1. Sprout Inhibitor Chemical Treatment Treatment No. Spray Date Chemical Applied 1 2 3 4 5 6 7 8 9 July 30, 1985 1 July 30, 1985 July 30, 1985 July 30, 1985 August 9, 1985 2 August 9, 1985 August 9, 1985 August 9, 1985 empty table cell Boom sprayer, 1-1/3 GPA MH-30 Boom sprayer, 2/3 GPA MH-30 Air curtain sprayer, 1-1/3 GPA MH-30 Air curtain sprayer, 2/3 GPA MH-30 Boom sprayer, 1-1/3 GPA MH-30 Boom sprayer, 2/3 GPA MH-30 Air curtain sprayer, 1-1/3 GPA MH-30 Air curtain sprayer, 2/3 GPA MH-30 Check 1 89 days after planting 2 99 days after planting Table 2. Percent Potatoes (by Number) Exhibiting Retarded Sprout Growth, MSU Stored and Commercially Stored. Treatment No. 1 Retarded growth, % MSU Storage Retarded growth, % Commercial Storage 1 (early) 2 3 4 5 (early) 6 7 8 9 (check) 91 81 92 95 78 53 65 76 15 3 92 90 97 87 -- 2 85 77 75 85 4 1 Treatments listed in Table 1 2 Data lost 3 Sample untreated with sprout inhibitor 4 Sample untreated, but stored with potatoes field treated with MH-30 Table 3. Chemical Treatments in the Vine Kill Study. Treatment No 1 Chemical applied 1 2 3 4 5 solution 5 lbs/a Diquat, 1 pt/a; X-77 spreader, 4 oz/a Diquat, 1 pt/a; X-77 spreader, 4 oz/a; STAYPUT, 0.64 oz/gal Diquat, 1 pt/a; X-77 spreader, 4 oz/a; copper sulfate CuSO4 Copper sulfate CuSO4, 5 lbs/a; X-77, spreader 4 oz/a Check 1 All treatments applied with air curtain and boom sprayers, only carrier volume was varied due to CDA nozzles in air curtain Table 4. Desiccation Index for the Vine Kill Study. Treatment No. 1 Desiccation Index 2 days Desiccation Index 4 days Desiccation Index 6 days Desiccation Index 8 days 1 (air curt.) 2 3 4 5 (boom spray) 6 7 8 9 (check) 1.9 2.7 2.3 3.0 2.2 2.9 0.8 0.8 0.2 5.6 7.2 6.2 8.2 5.6 7.2 2.8 4.2 0.4 8.6 9.6 8.7 9.5 8.5 9.3 6.4 6.8 2.1 9.6 9.9 9.5 9.8 9.7 9.8 9.2 9.3 2.4 2 1 Treatments listed in Table 3 2 Kill down due mostly to early blight FIG. 1 DESICCATION INDEX FIG.2 AC WITH AND WITHOUT DRIFT RETARDANT FIG.3 BOOM WITH AND WITHOUT DRIFT RETARDANT Funding: MPIC THE EFFECTS OF PRESTORAGE CHEMICAL TREATMENTS ON THE MARKET QUALITY OF 1985 ATLANTIC POTATOES 1985-1986 B.F. Cargill, Agricultural Engineering Department T.D. Forbush, Agricultural Engineering Department R.L. Ledebuhr, Agricultural Engineering Department G. R. VanEe, Agricultural Engineering Department H. S. Potter, Botany and Plant Pathology Michigan State University East Lansing, MI 48824-1323 INTRODUCTION While the current potato harvesting and handling equipment has greatly reduced the time required for fall harvest, it also has one large disadvantage— excessive tuber damage. This report is part of continuing research on the influence of prestorage mechanical handling and chemical treatments on the market quality of potatoes out of extended storage. Various prestorage chemical treatments have demonstrated the ability to increase the out storage quality of potatoes. The application technology developed in the Agricultural Engineering research facilitates at Michigan State University has allowed the full advantage of these chemical treatments to be realized. Through the use of low volume application, the problem of excessive water in the pile that was apparent with previous application systems has been eliminated, while maintaining the increased market quality exhibited by the chemical treatments. Potato Samples PROCEDURE The MSU Atlantic potatoes were grown it the Michigan State University potato research farm at Entrican, MI. These potatoes were harvested using the MSU one-row plot harvester. The potatoes for the commercial phase of this project were grown and harvested by Sandyland Farms, Howard City, MI. During the 1985-1986 growing season, the nine potato growers collaborated in the market quality research on the effectiveness of prestorage chemical treatment. This phase of the research included several varieties potatoes. Chemical Solution/Treatments All of the potatoes were treated with the MSU developed air curtain sprayer, currently marketed under the trade name CURTEC by BEI, Inc., South Haven, MI., mounted on the bin piler. The chemical solution used in the MSU Atlantic storage project consisted of a fungicide, a bactericide, and a chemical carrier. In all the chemical treatments, the chemicals used remained constant. They were 0.42 oz/ton of Mertect 340F (Merck & Cd., Rahway, NJ), with a carrier solution which contained 4 oz of either water or soybean oil with 5% Rohm Hass food grade emulsifier. Purigene (BIO-CIDE Chemical Co., Inc., Norman, OK) was added to the total solution to provide 200 ppm of chlorine dioxide. The Mertect is used to help control dry rot, while the chlorine dioxide helps reduce the occurrence of bacterial soft rot. Along with chemical treatments, the effect of various degrees of bruising was also investigated. Non-bruised potatoes were subjected to a slight level of bruising (MSU plot harvester and piler only) while bruised samples were artificially bruised using a one-row potato windrower after the potatoes had been harvested. A complete list of treatments is presented in Table 1. Storage Environment Immediately after treatment, 25 lb samples were bagged and placed in controlled environment cubicle storage on the MSU campus and in the center of a commercial balanced air flow potato storage at Sandyland Farms, Inc., Howard City, MI. The potatoes in the cubicles were suberized for two weeks; one week at 60f and 95% r.h. and one week at 55F and 95% r.h. After suberization there potatoes wen lowered 5F/week until the desired storage temperatures of 40F, 45F, and 50F were obtained. Samples stored in commercial storage received 24 hr ventilation and were lowered in storage temperature approximately 1F every 2 days until the desired storage temperature Of 50F was reached. The management of the storage for the collaborating commercial growers was left to the discretion of the respective grower. Residue Analysis EVALUATION METHODS Ten pounds of randomly selected tubers from the MSU Atlantic potatoes and from the potatoes grown by the collaborating growers were removed from selected treatments and air shipped to New Jersey for evaluation of TBZ residue. The results Of the analysis are presented in Table 2 for the MSU Atlantic potatoes and in Table 3 for the potatoes grown by the collaborating growers. The potato assay for thiabendazole was performed from opposite quarters of each tuber by the Ag Chem Division of Merck Chemical Co., Rahway, NJ. Bruise Analysis Various lots of 80 lb samples of potatoes were collected: 1) after harvesting with the MSU plot harvester and 2) at the end of the bin piler just prior to placement in the storage bin. These samples were delivered to Ore-Ida Foods, Greenville, MI., when they were held at room temperature for 48 hours before evaluation for bruising (including both shatter bruise and black spot bruise). The bruise-free percent for the MSU Atlantic potatoes is presented in Table 4. Market Quality Market quality evaluations (Cargill, et al., 1985) were done on the samples of the MSU Atlantic potatoes in commercial storage after 124 days. MSU Atlantic potatoes in the MSU cubicles were evaluated after 70 and 165 days of storage. Market quality reported is presented as percent by number tubers. Weight Loss The samples stored in the MSU cubicle were weighed after two weeks of suberization and at the market quality evaluation dates. Samples stored commercially were weighed upon removal from storage. Shatter Bruise All samples removed from the storages of the collaborating commercial growers were examined for shatter bruise. The tubers were classified as either table or non-marketable. The marketable tubers were those affected less marke than 5% by weight. The results the analysis are presented as percent acceptable (marketable) by number. The reason for the use of this category is to more efficiently describe the effects of the fungicide treatment. A potato that has no shatter bruise will not be affected by the fungicide treatment since there is no avenue for the fungus to enter the tuber. This classification deals only with those potatoes that had suffered a shatter bruise, indicating whether the bruise was allowed to consume the tuber, or if the bruise was restrained by the treatment to a level which is considered acceptable. Black Spot Bruise All samples removed from the storages of the collaborating commercial growers were examined for the occurrence of black spot. A black spot bruise occurs when a potato is impacted in the handling process. However, the skin was not broken as in the case of the shatter bruise. The evaluation included peeling the marketable potatoes with a Toledo laboratory model of an abrasive vegetable peeler for approximately 10 seconds to expose the black spot bruise. Each tuber was then examined for degree of black spot. The tubers were classified into the following categories: 1. no black spot 2. slight black spot (less than 3/16” deep) 3. severe black spot The results are reported as percent by number of the tubers in both class 1 and 2. Cargill, BF, et al. 1985. Influence of prestorage chemical treatments on out-of-storage market quality of potatoes. ASAE Paper 85-4028. Harvest RESULTS AND DISCUSSION Due to excessive soil moisture and rainfall on and around the date of harvest (the Stanton weather station received 10 inches of rain through the months of August and September, about 3 inches above normal with 2.3 inches falling in the last ten days of September) the amount of quality, harvestable potatoes was reduced by approximately one-half. This reduction in potato quality caused the MSU Atlantic project to be reduced in scale. All treatments were carried out. However, the amount of potatoes in each treatment was reduced. The reduced treatment size had an effect on the statistical significance that was observed. In most cases the treatments did exhibit sizable mean separations that are worth noting. Market Quality Table 5 shows the market quality for the MSU grown 1985 Atlantic project stored at MSU and Sandyland Farms. The data suggests the following mean separations: 1. Differences of 3.8 to 4% between treatment 3 (bruised check) and treatment 4 (Mertect and chlorine dioxide with water carrier) stored at 40F and 45F for 70 days at MSU. 2. Differences of 6.1 and 5.2% between treatment 3 (bruised check) and treatment 6 (Mertect and chlorine dioxide with water carrier) stored at 40F and 45f for 70 days at MSU (see Figures 1 and 3). 3. A difference of 3.3% between treatment 3 (bruised check) and treatment 4 (Mertect and chlorine dioxide with water carrier) stored at 50F for 124 days at Sandyland Farms. 4. A difference of 4.1% between treatment 3 (bruised check) and treatment 6 (Mertect and chlorine dioxide with Oil carrier) stored at 50F for 124 days at Sandyland Farms. 5. Differences of 7.0 and 7.1% between treatment 3 (bruised check) and treatment 4 (Mertect and chlorine dioxide with water carrier) stored at 40F and 45F for 165 days at MSU (see Figures 2 and 4). 6. A difference of 5.7 between treatment 3 (bruised check) and treatment 6 (Mertect and chlorine dioxide with oil carrier) stored at 40F for 165 days at MSU. The above differences indicate that; the treatments used in this experiment have the greatest effect on potatoes with market quality less than 85% (see Table 4, treatment 3). The chemicals used in this study are primarily designed to act as protection to cover a wounded tuber. Potatoes with bruise free ratings higher than 85% had few wounds. These potatoes show less response to chemical treatments. The data does suggest slight increases in the quality of the non-bruised treatments. However, no statistical difference was observed. Table 6 shows the market quality for the potatoes grown by Sandyland Farms. These potatoes showed only slight changes between treated and check potatoes. However, these potatoes were all of high quality, thus the treatments were less effective. Table 7 presents the weight loss data for the 1985 Atlantic Project. This data was inconclusive due to the relatively small mean separations. Table 8 presents the market quality, shatter braise and black spot data for the potatoes grown by the collaborating growers. Notice again that high quality tubers (low percentage of shatter braise or black spot) generally exhibited only a slight response to the fungicide treatment. Table 1. Treatments Performed in the MSU Atlantic Potato Storage Research Project. Treatment No. 1 2 3 4 5 6 7 Mechanical handling MSU plot harvester MSU plot harvester and bin piler MSU plot harvester, bin piler and artificial bruising devices (windrower) MSU plot harvester, bin piler and artificial bruising devices (windrower) Plot harvester and bin piler MSU plot harvester, bin piler and artificial bruising devices (windrower) Plot harvester and bin piler Chemical applied -- -- -- 0.42 fl oz Mertect 340F, 4.2 oz water with 200 ppm chlorine dioxide 0.42 fl oz Mertect 340F, 4.2 oz water with 200 ppm chlorine dioxide 0.42 fl oz Mertect 340F, 4.2 oz soybean oil with 5% Rohn Hass food grade emulsifier 0.42 fl oz Mertect 340F, 4.2 oz soybean oil with 5% Rohn Hass food grade emulsifier Table 2. Chemical Residue for MSU Atlantic Potatoes. TBZ (ppm) Treatment 1 Check samples Water carrier 1 Oil carrier 2 -- 2.92 4.93 1 Chemical solution equal to treatments 4 and 5 in Table 1. 2 Chemical solution equal to treatments 6 and 7 in Table 1. Table 3. Production and Residue Data for the Nine Growers Participating in the Prestorage Chemical Application Study Grower Number 1 2 3 4 5 6 7 8 9 Variety Atlantic Atlantic Frito-Lay 945 Monona Monona Superior Monona Shepody Monona Date Treated 9-14-85 9-14-85 10-29-85 10-30-85 10-10-85 10-21-85 10-03-85 9-30-85 10-29-85 Days in Storage 128 128 179 251 190 186 190 244 235 MSU Storage Temperature 50F 50F 45F 45F 45F 45F 45F - 45F TBZ Residue (PPM) — — 1.56 - 2.90 1.48 - 2.46 0.58 - 0.67 6.70 - 8.90 1.65 - 1.96 1.75 - 2.30 1.36 - 2.19 Table 4. Bruise Free Percent Evaluated by Ore-Ida Foods, Greenville, MI. Mechanical handling Bruise free rating (%) MSU plot harvester MSU plot harvester and bin piler MSU plot harvester, bin piler and artificial bruising 80 75 62 Table 5. Market Quality (% Marketable by Number) for the 1985 MSU Grown Treatment 1 Potatoes Stored at MSU and in commercial storage. 70 days 40F 124 days 2 50F 165 days 40F 165 days 45F 70 days 45F 70 days 50F 1 2 3 4 5 6 7 96.4 91.9 75.4 79.2 94.0 82.1 94.1 97.8 88.8 79.7 83.7 89.1 84.9 91.8 92.3 91.9 78.1 76.0 94.6 77.4 92.0 92.1 89.4 74.6 77.9 87.0 78.7 85.3 1 Treatments listed in Table 1 2 Stored in commercial storage at 50F 97.9 90.5 82.8 89.8 95.6 88.5 94.2 97.7 93.1 86.0 93.1 94.8 88.9 95.7 165 days 50F 94.6 95.6 88.4 87.5 96.5 83.8 93.3 Table 6. Market Quality (% Marketable by Number) for the 1985 Sandyland Farms Atlantic Potatoes Stored at MSU and in commercial storage. Treatment 40F 70 days 70 days 45F — Check truck Check piler 90.2 Water 86.5 carrier 2 Oil Carrier 3 Oil only 4 88.8 - — 88.7 87.9 89.5 - 50F 70 days -- 87.9 84.7 89.0 - 124 days 1 50F 86.2 89.5 87.3 84.3 87.3 165 days 165 days 45F - 88.9 89.9 91.6 - 40F -- 90.3 86.8 89.1 - 165 days 50F — 89.4 90.8 90.5 - 1 Stored at Sandyland Farms, Inc., Howard City, MI, at 50F 2 Chemical treatment; equal to treatments 4 and 5 in Table 3 3 Chemical treatment; equal to treatments 6 and 7 in Table 3 4 Treated with emulsified oil only Table 7. Weight Loss Percentages for the MSU Atlantic Potatoes Stored at MSU and in commercial storage. Treatment 70 days 45F 70 days 50F 124 days 50F 70 days 40F 165 days 45F 165 days40F 1 2 3 4 5 6 7 3.90 5.23 4.88 4.79 4.05 4.31 4.16 Commercial Storage check truck Commercial Storage check 5.31 piler 6.51 Commercial Storage H2O/ Mertect 5.63 oil/ Commercial Storage Mertect - Commercial Storage oil - 2.79 3.53 3.74 3.47 4.35 3.89 3.06 — 3.99 5.03 3.59 — 3.52 3.04 2.78 3.54 3.27 3.32 2.97 — 4.49 5.21 3.77 — 4.50 4.50 3.90 3.60 4.20 4.20 5.20 5.49 6.08 5.99 5.35 5.70 11.20 7.15 7.73 8.09 10.21 8.69 5.84 — 8.42 8.63 9.93 — 5.8 4.75 5.14 5.33 5.70 5.64 5.08 — 5.16 7.25 6.44 — 165 days50F 6.77 3.92 5.28 6.73 8.28 6.66 5.62 — 7.42 7.29 5.97 — Table 8. Market Quality, Acceptable Shatter Bruise and Black Spot Bruise (% by number) for Potatoes Grown by Collaborating Growers. Grower Number Market Quality MSU Market Quality Grower Shatter Bruise MSU Shatter Bruise Grower Black Spot Bruise MSU Black Spot Bruise Grower 1 - Treated 1 Check 2 - Treated 2 Check 3 - Treated 3 Check 4 - Treated 4 Check 5 - Treated 5 Check 6 - Treated 6 Check 91.2 93.6 93.7 88.1 96.6 96.5 98.2 99.4 97.3 97.7 96.4 90.7 91.8 78.8 85.1 82.6 95.4 95.1 88.1 90.2 96.0 93.9 94.1 95.1 79.2 80.5 66.7 79.5 76.5 67.0 63.3 67.2 92.2 85.3 81.3 89.0 92.9 92.5 60.3 75.3 82.8 89.1 81.2 71.8 81.8 84.4 72.1 85.8 83.0 84.8 82.5 78.0 92.0 94.3 96.5 99.1 95.3 95.7 92.6 87.0 79.3 64.6 63.5 63.8 89.9 88.8 76.6 87.5 91.4 89.8 89.5 90.7 7 - No data due to poor harvest conditions empty table cellempty table cell 8 - Treated 8 Check 9 - Treated 9 Check — — 95.2 90.7 91.6 92.2 90.8 95.9 79.8 — 74.7 — — 89.1 90.8 empty table cell empty table cellempty table cell empty table cell — 85.9 82.7 78.4 90.7 89.8 86.8 83.2 92.8 FIG. 1 PERCENT MARKETABLE INCREASE OVER CHECK FIG. 2 PERCENT MARKETABLE INCREASE OVER CHECK FIG. 3 MARKETABLE POTATOES (%) AFTER 70 DAYS FIG. 4 MARKETABLE POTATOES (%) AFTER 165 DAYS Funding: Federal Grant TITLE: Potato Processing and Utilization for Improved Marketing INVESTIGATORS: Jerry N. Cash and Ron Morgan Food Science and Human Nutrition Department, and Roger Griffin-School of Packaging, Michigan State University OBJECTIVE: Improve utilization of the total potato crop by developing processed products which can use small, extra large and off-grade potatoes. JUSTIFICATION: In any given year, a portion of the potato crop will be graded into small, extra large or off-grade classes. Some of these tubers may find acceptance in certain types of processed products but this is usually minimal. Since this segment of the crop represents significant quantities of raw product, economics dictate that these potatoes be utilized in some manner, however, without processing alternatives a majority find their way into fresh market channels. This results in lowering the consumer's perception of Michigan potato quality, with attendant losses in sales and revenue. It is imperative that new processed products be developed which can utilize that portion of the potato crop which is not suited for use in presently established processed products. PROCEDURES: Efforts will be divided into short and long term projects but both will be carried out simultaneously, at the outset. The short term effort will concern a technology update and feasibility study of the potential for retort pouch processing. The long term effort will be aimed at developing new products. These proposed projects are described separately and with two distinctly different budgets. I. Retort Pouch Feasibility Study: It is envisioned that this project would be funded on a one time basis and for approximately on calender year. A previous venture by a Michigan firm into the area of retort pouch processing of potatoes met with a degree of success during the early phases of their effort. The problems which left to the eventual demise of the company were both technical and managerial nature. Since that time, a number of technological advances have been made in retort pouch operations. This proposed study will investigate preferred packaging materials and methods for obtaining will be done on a pilot plant scale but will utilize concepts which can be expanded to a full scale production operation with minimal effort. All products will be subjected to sensory evaluations to determine consumer acceptance and will undergo storeage stability and shelf-life studies to assess the usable market life of the product. Although all initial efforts will involve potatoes, it is logical to assume that information and techniques developed in this work may be applicable to other low acid products (i.e. peas, carrots, etc.) and any processing operations deceloped can eventually expand to include processing of other crops. Also, work will be carried out in the long term product development studies to devise new products, such as soup bases and convenience foods for processing in pouches. Market pouch products will also be carried out. II. New Product Development: Long term and continued for several years. The primary thrust of this effort will be the development and evaluation of one or more convient, ready-to-serve potato products. One such item for initial investigation is development of a precooked, formed potato which could be used as a baked potato substitute in restaurants and other establishments where potatoes with a uniform size and shape are sought after. For this application, potatoes wil be cooked in various ways (i.e. boiling, steam injection, dry heat) to determine the best preparation method. Peels wil be removed after cooking and the potatoes wil be mashed. The mash wil be shaped by extrusion and the shaped pieces wil be exposed to combinations of air, hot air and/or hot air plus steam, in an effort to cause case hardening, which wil form a crust and simulate the potato skin. This critical step of forming a crust may provide a product which can be frozen without further treatment and subsequently heated for use as a baked potato. However, it may be necessary or more desirable to further treat the formed potato by applying a coating preparation such as a starch batter, wheat flour-cornstarch batter or an amylase coating material which can then be breaded to give better texture and add flavor to the product. Many variations and/or combinations of these preparations are likely to be tried before a suitable blend is formulated. If a precooked, formed product can be developed it wil have not only the obvious advantages of using any size potato, but it would also reduce losses caused by peeling, cut down on waste disposal problems and yield a product with higher solids, i.e. more nutritive value, than conventional types of potato products. Also, it may be possible to use potatoes coming out of cold storage without developing poorly colored end products. A number of other areas wil also be explored, however, the very nature of product development, where one or more raw materials (in this case potatoes) provide the basis for the effort and are then built on from many different directions, makes it impossible to predict exactly what wil be done or what the final outcome wil be. This is the reason R&D work is time consuming and costly. In addition, there is never any guarantee that new products wil be successfully developed. RESULTS: Retort Pouch: New products being formulated include: german potato salad, potato soup bases and combinations of potatoes and other vegetables. These items will utilize potatoes but will fall into the category of convenience items, which will give the value added incentive for consumers to purchase them. Processing parameters for each of these items are being devised and further efforts in conjunction with Agricultural Economics are being undertaken to determine processing plant design and processing costs. These efforts include: specification of plant operations, operating conditions, determinations of requirements for equipment, budding facilities, labor and calculations of annual costs of processing. Remanufactured Potato Product: The first step in this effort has been development of a computer model, using many variations of the wide variety of parameters which must be incorporated into the study. A number of models were tried and discarded but the final model developed from these efforts depends or temperature and times required for starch gelatinization. Studies were carried out at temperatures of 80°C, 90°C and 97°C with cooking times of 0, 3, 6, 8, 10, 12, 15 and 25 minutes at each temperature For these studies, cylindrical samples 1 inch in length and 0.39 inches in diameter were taken from potatoes of the Superior variety. These cylindrical samples were plac in tubes, covered with distilled water and cooked in a circulating water bath at the previously indicated times and temperatures. The cooked samples were cooled and measured for viscosity, using a back extrusion method in the Instron pressure testing machine. Curves reflecting the relation between time and puncture force were drawn and these data were further used in the following equation to develop information about the activation energy (time/temperature) required for processing. MI = Viscosity Vp = Plunger Velocity Fp = Puncture Force Lp = Length of Wet Plunger K = Radius of Plunger Radius of Sample Tube α = 1 - K2________ 1 + K2 The effort thus far represents approximately one third of the total project and has allowed us to begin actual processing procedures in the pilot plant with comercial extrusion equipment. Funding: MPIC and PPC Application of Potato Carbohydrate Analysis and CIPC Interaction in a Commercial Growing and Storage Operation J.N. Cash, Food Science and Human Nutrition R. Chase, Crop and Soil Sciences A. Cameron, Horticulture Michigan State University Procedure: Atlantic and Russet Burbank potatoes were commercially harvested on the Wayne J. Leonard and Sons farm in Monroe County. Thirty six, 30 pound samples of Atlantics and twenty seven, 30 pound samples of Russet Burbanks were placed in double mesh bags and buried in a commercial storage bin with 15,000 hundred weights of Atlantic potatoes. The samples were arranged in the bin to give four replications, with nine bags per rep, of Atlantics and three replications, with nine bags per rep of Russet Burbanks. One additional sample of Atlantics and Russet Burbanks containing specifically sized (small, medium and large) tubers was placed in each rep for PPG Industries, Inc. to use in their analysis of CIPC residues 48 hours after application of the sprout inhibitor. At the same time, the bags were being placed in the bin, plastic tubing was run from a point within each rep and at one point somewhat removed from the samples, for collecting gas for CO2 analysis. The samples were placed in storage on September 5th and subsamples were taken for analysis. One set of samples (i.e. one bag of each cultivar from each rep) was removed for analysis after one week of storage and a second set was removed immediately before CIPC application on September 22nd. Subsequent samples were taken at 48 hours, 10 days, 20 days, 40 days and 80 days after CIPC application. The last samples will be removed at 120 and 160 days. At each sample time, gas samples were taken for CO2 analysis and tubers were analyzed for specific gravity, sucrose, glucose, fructose, CIPC residue, chip color and sprout inhibition. Results : Tables 1 and 2 show that specific gravity did not change appreciably throughout the sampling period. CO2 and O2 remained relatively constant during the first three months storage although the respiration rate seemed to rise early in October (Table 3). It was anticipated that CO2 levels might increase shortly after CIPC application and it is possible that the higher levels seen in early October constituted a delayed response to sprout inhibitor presence but this is uncertain. The CIPC analysis of tubers sent to PPG Industries, Inc. showed that the sprout inhibitor dissipation followed the expected pattern (Figures 1 and 2). Two days after CIPC application, residues on both cultivars ranged from 12-15 ppm. Within ten days, those levels had dropped to approximately 3-5 ppm and have remained in this area throughout the sampling period. Visual examination of tubers show that the CIPC is effectively retarding sprouting, although some Atlantics show the initiation of primary sprouts which seem to have been inhibited after rudimentary growth. The sucrose (Figure 3), glucose (Figure 4) and fructose (Figure 5) content of the Russet Burbanks increased during storage, thus contribution to an increase in the total sugar content for this cultivar (Figure 6). Not unexpectedly, the color of chips made from these potatoes reflected the increases in the reducing sugars (fructose and glucose) and became darker as the storage time increased. The sucrose (Figure 3), glucose (Figure 4) and fructose (Figure 7) content of the Atlantic samples decreased slightly during storage, however, the fructose content showed a slight overall increase about 70 days in storage and this reflected in the color of chips made from these tubers. The fluctuations in total sugars (Figure 8) are due almost entirely to changes in fructose during the storage period. At the December sampling time, which was approximately 100 days after harvest, the commercial bin of potatoes in this study seemed to be in good chipping condition and the analytical analysis do not indicate any problem areas. However, changes may occur rapidly in the latter stages of storage and if adverse conditions repeat, it is anticipated that they can be detected early by one or more of the analytical procedures being employed. Table 1. Specific Gravity of Atlantic Potatoes in Storage, Leonard Farm, 1986. Date 9/9 9/12 9/22 9/24 10/3 10/13 Rep 1 Rep 2 Rep 3 Rep 4 Average 1.088 * 1.083 1.084 1.084 1.083 1.083 - 1.084 1.086 1.084 1.082 1.081 - 1.083 1.086 1.086 1.083 1.084 - 1.084 1.084 1.083 1.083 1.084 empty table cell 1.084 1.085 1.084 1.083 1.083 * All measurements are averages of 3 samples from each rep. Table 2. Specific Gravity of Russet Burbank Potatoes in Storage, Lennard Farm, 1986. Date 9/9 9/12 9/22 9/24 10/3 10/13 Rep 1 1.078 * 1.075 1.078 1.078 1.075 1.076 Rep 2 - 1.077 1.075 1.077 1.076 1.073 Rep 3 - 1.077 1.074 1.078 1.075 1.072 Rep 4 Average - - - - - - empty table cell 1.076 1.076 1.078 1.075 1.074 * All measurements are averages of 3 samples from each rep. Table 3. CO2 and O2 Content of Atlantic Potatoes in Storage, Lennard Farm, 1986. Sampling Date Rep 0 1/ CO2 % 2/ Rep 0 1/ O2% Rep 1 CO2 % Rep 1 O2 % Rep 2 CO2 % Rep 2 O2 % Rep 3 CO2 % Rep 3 O2 % Rep 4 CO2 % Rep 4 O2 % 9/9 9/24 3/ 10/3 10/13 11/14 .22 .31 1.57 .20 .22 21.20 19.25 19.05 20.00 23.5 .23 .24 1.17 .20 .22 21.02 19.00 23.45 20.00 23.80 .21 .24 1.08 .20 .21 20.76 18.75 24.4 20.00 23.70 .39 .20 .98 .20 .23 21.28 20.95 24.6 20.00 24.35 .34 .24 1.18 .20 .28 20.37 17.70 19.00 20.00 23.30 1 Rep 0 located at a point near the fan. 2 All measurements are averages of two samples from each rep. 3 Sample taken 48 hours after CIPC application. Figure 1. Dissipation of CIPC from Russet Burbanks, Lennard Farm, 1986. Data supplied by PPG Industries, Inc. Figure 2. Dissipation of CIPC from Atlantics, Lennard Farm, 1986. Figure 3. Sucrose Content of Atlantic and Russet Burbank Potatoes in Storage, Lennard Farm 1986. Figure 4. Glucose Connent of Atlantic and Russet Burbank Potatoes in Storage, Lennard Farm 1986. Figure 5. Fructose Content of Burbank Potatoes in Storage, Lennard Farm 1986. Figure 6. Total Sugar Content of Russet Burbank Potatoes in Storage, Lennard Farm 1986. Figure 7. Fructose Content of Atlantic Potatoes in Storage, Lennard Farm 1986. Figure 8. Total Sugar Content of Atlantic Potatoes in Storage, Lennard Farm 1986. Funding: Federal Gra POTATO RESEARCH PROJECT REPORT Title Market and Economic Feasibility of Precooked (Retort Pouch) Potato Products. Investigators Thomas R. Pierson and Donald Hinman, Department of Agricultural Economics, Michigan State University. Objectives Earlier research (A Comparative Analysis of Potato Packing Costs: Assorted versus Specific Size Packs: Thomas R. Pierson, Department of Agricultural Economics, Investigator) was designed to determine costs per consumer package of round white potatoes in small, medium, and large sizes packed in both small and large packing plants. This proposal will build on that research to determine the following: • Conduct a preliminary survey of institutional market interest in Michigan for retort potato products. • Determine order of magnitude investment required for retort pouch potato processing plants which could utilize undersized and oversized potatoes resulting from a uniform size packing program. General recommendations will be made regarding plant sizes and an appropriate complement of manufacturing equip­ ment. • Estimate the potential number of jobs created by such processing facilities. Justification Each year a significant portion of the Michigan potato crop consists of small, extra large and otherwise off-grade product classes. Most growers believe that economic considerations mandate the sale of these potatoes. Without viable processing markets, the majority of these potatoes are sold in fresh market channels. This practice in turn has highly negative effects on Michigan's fresh market quality. The present and long-term impact of the Michigan industry's poor quality reputa­ tion among wholesaler buyers and shoppers is very negative. Today's fresh produce business, including potatoes, is characterized by rising quality standards, thus, the long­ term viability of the Michigan fresh potato industry is importantly influenced by the ability to market a quality fresh pack. One approach for improving fresh pack quality is to identify and help develop a viable processing market outlet for small, extra large and otherwise off-grade potatoes. Precooked potatoes are a relatively new type of processed produce in need of economic and market evaluation. Procedure There are two major components to this research as indicated in the objectives section above. Research procedures are associated with each of the objectives: • Preliminary analysis of institutional market distributor and user interest in retort potato product concepts. A participant interactive survey of Michigan institutional wholesalers and selected food service retailers will be undertaken to estimate potential demand and determine likely market acceptance for various product attributes. • Determination and analysis of economic costs and job creation associated with the operation of a commercial scale retort processing facility. Budgeting techniques will be used to develop key fixed and variable operating costs for a retort pouch potato product processing plant. Knowledge of such cost estimates on a per unit of volume basis will permit preliminary cost and price comparisons with completing products in the marketplace. Cost information will be gathered from secondary sources as are available, however, it is likely that much information will be gathered from primary industry sources. Results The status of work on this project is as follows: • Preliminary survey work to determine likely market interest in retort pouch potato products has been conducted. Additional survey work remains to be done. • Procedures are complete for the processing plant cost analysis and work with university and industry sources to obtain needed cost information is well underway. Funding: Federal Gran POTATO RESEARCH PROJECT REPORT Title A Comparative Analysis of Potato Packing Costs: Assorted Versus Closely Sized Packs. Investigators Thomas R. Pierson and Lisa Allison, Department of Agricultural Economics, Michigan State University. Objectives The general objective is to help improve marketing methods of Michigan tablestock producers by providing cost information on potato packing plants and sizing operations. Specific objectives are to determine costs per consumer package of round white potatoes: assorted sizes packed in small packing plants 1) assorted size packed in large packing plants 2) small, medium and large sizes packed in small packing plants 3) 4) small, medium and large sizes packed in large packing plants Justification Potato production and marketing activities comprise an important and dynamic industry in Michigan and the midwest. Current and projected production and utilization trends support the importance of this Michigan industry, particularly if it is responsive to the critical problems and opportunities that exist. Michigan potato industry leaders have identified the need to improve the fresh market quality and image of Michigan potatoes as the top priority concern that the industry must address in the immediate future. The dramatic changes that have been occurring in food consumption patterns because of changing lifestyles and nutritional concerns are having great impact on the kind and variety of food products demanded. Expanding the demand for Michigan's fresh potatoes will necessitate that growers and marketers become market oriented rather than commodity oriented. Producers must recognize the importance of upgrading the appearance, uniformity, quality, variety and versatility of the products that are offered as well as the services they provide to cap­ ture a part of the expanding "fresh" demand. Michigan's fresh industry must drastically alter its commodity orientation to the production and marketing of fresh potatoes. Failure to adjust to a strong market orientation will limit the economic potential for this industry regardless of current or projected production and, utilization trends. Procedures Information and data for this research was collected from two primary sources; a literature search and personal on-site interviews. To meet the cost analysis objectives four packing plant layouts were considered; 1) a representative small plant, packing 10 lb. bags of assorted size potatoes; 2) a representative small plant, packing 10 lb. bags of small, medium and large sized potatoes; 3) a representative large plant, packing 10 lb. bags of assorted size potatoes; 4) a representative large plant, packing 10 lb. bags of small, medium and large sized potatoes. The plants are "representative" in that they reflect the usual machinery and building layouts of packing plants operating throughout Michigan. The records, knowledge and experience of four main groups of people were relied on for the necessary data: 1) packing plant owners and managers of small and large packing plants throughout Michigan and in central Wisconsin; 2) potato packing equip­ ment and building manufacturer sales representatives; 3) Michigan State farm manage­ ment specialists and; 4) agricultural engineers. Results A thesis for a Master of Science Degree in Agricultural Economics is complete. Two industry oriented bulletins are in progress. The major findings are as follows: Michigan round white potato packers face a declining share of the fresh tablestock market and an overall low quality image. The study shows that the Michigan packing industry is characterized mainly by many small independent packers packing only assorted sized packs over a relatively short packing season and exhibiting high costs. Results also indicate that increasing plant size from small to large and plant utilization from Michigan's relatively low average to full utilization while packing closely sized packs may improve pack quality and reduce costs by up to thirty percent. MICHIGAN POTATO INDUSTRY COMMISSION 13109 Schavey Road, Suite 7 DeWitt, Michigan 48820 Bulk Rate U.S. Postage PAID Permit No. 979 Lansing, Mich.