1989 MICHIGAN POTATO RESEARCH REPORT Volume 21 Michigan State University Agricultural Experiment Station In Cooperation With The Michigan Potato Industry Commission THE MICHIGAN POTATO INDUSTRY COMMISSION March 20, 1990 To All Michigan Potato Growers and Shippers The Michigan Potato Industry Commission, MSU's Agricultural Experiment Station and Cooperative Extension Service are happy to provide you with a copy of the results of 1989 potato research projects. This years report includes research projects funded by the MPIC as well as projects funded through the USDA. Providing research funding and direction to principal investigators at MSU is a function of the MPIC Research Committee, on behalf of the Michigan Potato Industry Commission and potato growers of Michigan. Best wishes for a prosperous year, The Michigan Potato Industry Commission THE MICHIGAN POTATO INDUSTRY COMMISSION • 13109 SCHAVEY RD., STE. 7 • DEWITT, Ml 48820 • (517)669-8377 TABLE OF CONTENTS Page INTRODUCTION AND ACKNOWLEDGEMENTS, WEATHER AND GENERAL MANAGEMENT...................... 1 1989 POTATO VARIETY EVALUATIONS R.W. Chase, G.H. Silva, D.S. Douches and R.B. Kitchen.............................................. 4 THE RESPONSE OF SPARTAN PEARL AND NORCHIP TO THE RATES AND SOURCE OF POTASSIUM FERTILIZER G.H. Silva, R.W. Chase and R.B. Kitchen................................................................................ 26 MANAGEMENT PROFILES OF RUSSET NORKOTAH, SNOWDEN (W855) AND SAGINAW GOLD G.H. Silva, R.W. Chase and R.B. Kitchen................................................................................ 32 IRRIGATION, NITROGEN AND SUPPLEMENTARY CALCIUM IN RELATION TO SPECIFIC GRAVITY, TUBER YIELD AND INTERNAL DEFECTS OF ATLANTIC AND RUSSET BURBANK G.H. Silva, R.W. Chase and R.B. Kitchen................................................................................ 46 MICHIGAN STATE UNIVERSITY POTATO BREEDING PROGRAM D.S. Douches, R.W. Chase, R. Hammerschmidt, G.H. Silva and J.N. Cash.......... 54 POTATO SCAB RESEARCH R. Hammerschmidt, D.S. Douches, M.L. Lacy, K. Ludlam, C. Wallace, L. Hanson and F. Spooner.................................................................................................................... 57 CONTROL OF INTERNAL BROWN SPOT (IBS) IN ATLANTIC R. Hammerschmidt, R.W. Chase, Paul Marks and G.H. Silva.......... .............................. 66 NITROGEN MANAGEMENT STRATEGIES TO MAXIMIZE PROFIT AND MINIMIZE NITRATE LEACHING: 1989 RESULTS J.T. Ritchie, B.S. Johnson and P.R. Grace........................................... 68 NITROGEN MANAGEMENT STRATEGIES FOR RUSSET BURBANK POTATOES B.C. Joern and M.L. Vitosh............................................................................................................... 75 Page NITROGEN MANAGEMENT STUDIES ON POTATOES - SANDYLAND FARMS M.L. Vitosh, D.B. Campbell, D.A. Hyde and B.P. Darling............................................ 81 NITROGEN MANAGEMENT STUDIES ON POTATOES - ANDERSON BROS. M.L. Vitosh, D.B. Campbell, D.A. Hyde and B.P. Darling............................................ 86 1989 NEMATOLOGY PROGRESS REPORT G.W. Bird......................................................................................... 91 CONTROL OF INSECTICIDE-RESISTANT COLORADO POTATO BEETLES IN MICHIGAN E. Grafius, B.A. Bishop, P. Ioannidis and P. Henry..................................................... 96 INFLUENCE OF ENVIRONMENTAL FACTORS ON WOUND HEALING IN RELATION TO STORAGE DISORDERS R. Hammerschmidt and A.C. Cameron............................................................................................... 109 DETERMINATION OF BISULFITE RESIDUES IN POTATO PRODUCTS J.N. Cash.........................................................................................................................................................114 PACKAGING ALTERNATIVES FOR LIGHT USERS OF TABLESTOCK (FRESH) POTATOES...A SYNTHESIS OF TWO FOCUS GROUPS M.D. Zehner.................................................................................................................................................... 116 1989 POTATO RESEARCH REPORT R.W. Chase, Coordinator INTRODUCTION AND ACKNOWLEDGEMENTS The 1989 Potato Research Report includes reports of potato research projects conducted by MSU potato researchers at several different locations. This volume includes research projects funded by the Special Federal Grants (USDA 85-CRSR-2-2562 and 88-34141-3372), the Michigan Potato Industry Commission and other sources. The principal source of funding for each project has been noted at the beginning of each report. We wish to acknowledge the excellent cooperation of the Michigan potato industry and the MPIC for their continued support of the MSU potato research program. We also want to acknowledge the significant impact that the funds from the Special Federal Grant have had on the scope and magnitude of several research areas. Many other contributions to MSU potato research have been made in the form of fertilizers, pesticides, seed, supplies and monetary grants. We gratefully acknowledge all of these supporters. It is this type of support and cooperation that makes for a productive research program. We also want to acknowledge the professionalism of the MPIC Research Committee. The Michigan potato industry should be proud of the dedication of this committee and the keen interest they take in the needs and directions of Michigan potato research. A special thanks to Dick Kitchen for his excellent coordination of the production management and the day-to-day operations of the Montcalm Research Farm. A special thanks also to Dr. George Silva who has played a significant role in the Special Federal Grant program, the computerized weather station at the Montcalm Research Farm and the preparation of this report. Also a special thanks to Jodie Schonfelder for the typing and preparation of this report. WEATHER The 1989 weather data for the Montcalm Research Station as compared to the average of the 15 previous years are presented in Tables 1 and 2. The weather conditions during the growing season were somewhat normal except for the drought conditions in July and excess rainfall in August. The dry September allowed most of the harvesting to be completed by the end of the month. SOIL TESTS Soil test results for the general plot area were: lbs/a pH 5.6 P lbs/a K 480 185 lbs/a Ca 533 lbs/a Mg 62 % Organic Matter 1.5 Cation Exchange Capacity 5 me/100g FERTILIZERS USED The previous crops in most of the plot areas were dry beans plowdown in fall 1988 and rye plowdown in spring 1989. Except in fertilizer trials, where the amounts of fertilizers used are specified in the project report, the following fertilizers were used in the potato trials. Banded at planting Plowdown Sidedress with irrigation 28% Liquid N (twice) - 90 lbs N/a 500 lbs/a 100 lbs/a - - 15-10-15 + 4% Mg 0-0-60 HERBICIDES AND HILLING Most of the hilling was completed by the end of May, when the soil started to crack. The potatoes were hilled, building a wide and flattened hill and placing a thin layer of soil over the top of the ridge. Immediately after hilling, a tank mix of metolachlor (Dual) 2 lbs/a plus metribuzin (Lexon 4L) 1/2 lb/a were applied on May 25. No further tillage was done until harvest. Several hand weedings were done during the season. Potato vines were killed with Diquat + X77 on September 10. IRRIGATION During the growing season, the potato crop received 7 inches of irrigation water in 10 separate irrigations. Irrigation scheduling was done according to the Michigan State University irrigation scheduling program. The minimum soil profile moisture level maintained throughout the growing season was 50-60%. The amount of water applied ranged from 0.5 to 1.0 inch per application. Nitrogen at 28% was incorporated into irrigation water twice during the season. The heavy rains in late May and early June combined with those in early August did deplete soil N for tuber sizing of several late maturing long type varieties. The drier than normal soil conditions during September harvests did increase the incidence of blackspot. Hollow heart was much more prevalent in 1989. INSECTS AND DISEASE CONTROL Aldicarb (Temik 15G) was applied at planting at 20 lbs/a. The foliar fungicide application was initiated on June 28 and 11 separate applications were made during the season. Fungicides used were Dithane M45 (seven applications) and Bravo 720 (four applications). Fungicides were generally used alternatively and were sprayed at 7-10 day intervals. Canopy temperature and humidity levels were monitored and used with the blight forecaster as a guide to commence funigicide spraying for early blight. Foliar insecticides used were Imidan + PBO (six applications) and Cygon (two applications). Although no serious insect problems were encountered during the season, early blight appeared to be high in August and contributed to foliage loss, particularly in early varieties. Table 1. The 15 year summary of average maximum and minimum temperatures during the growing season at the Montcalm Research Farm. April April Year Max Min Max May May Min June June Max Min July Max July Min August August Min Max September Max September Min 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 15-YR. AVG. 48 58 62 50 50 49 56 53 47 54 58 60 61 52 56 54 28 35 37 31 33 31 35 28 28 34 38 36 36 31 32 34 73 63 80 67 66 69 64 72 60 60 70 70 77 74 72 69 48 41 47 45 44 42 39 46 38 39 44 46 46 46 34 42 75 79 76 78 74 73 73 70 76 77 71 77 80 82 81 75 56 57 50 50 55 50 50 44 49 54 46 50 56 53 53 52 80 81 85 81 82 81 77 80 85 78 81 82 86 88 83 82 57 58 61 56 57 58 51 53 57 53 55 59 63 60 59 56 79 80 77 82 77 81 78 76 82 83 75 77 77 84 79 79 58 53 52 57 55 58 53 48 57 55 54 51 58 61 55 55 65 70 70 75 76 70 67 66 70 69 70 72 72 71 71 70 44 46 53 52 47 49 47 44 46 45 50 50 52 49 44 49 6-Month Average Max 6-Month Average Min 70 71 75 72 71 71 69 70 70 70 71 73 76 75 74 72 49 48 50 49 49 48 46 44 46 47 48 49 52 50 46 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 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 15-YR. AVG. 1.81 3.27 1.65 2.34 2.58 3.53 4.19 1.43 3.47 2.78 3.63 2.24 1.82 1.82 2.43 2.68 2.05 4.03 0.46 1.35 1.68 1.65 3.52 3.53 4.46 5.14 1.94 4.22 1.94 0.52 2.68 2.60 June 4.98 4.22 1.66 2.55 3.77 4.37 3.44 5.69 1.19 2.93 2.78 3.20 0.84 0.56 4.85 3.10 July August September Total 2.71 1.50 2.39 1.89 1.09 2.64 1.23 5.53 2.44 3.76 2.58 2.36 1.85 2.44 0.82 2.34 11.25 1.44 2.61 5.90 3.69 3.21 3.48 1.96 2.21 1.97 4.72 2.10 9.78 3.44 5.52 4.22 3.07 1.40 8.62 2.77 0.04 6.59 3.82 3.24 5.34 3.90 3.30 18.60 3.32 5.36 1.33 4.69 25.87 15.86 17.39 16.80 12.85 21.99 19.68 21.38 19.11 20.48 18.95 32.72 19.55 14.14 17.62 19.63 Funding Federal Grant 1989 POTATO VARIETY EVALUATIONS R.W. Chase, G.H. Silva, D.S. Douches and R.B. Kitchen The objective of the potato variety evaluation and management program at Michigan State University is to identify improved cultivars for Michigan’s fresh market and processing industry. Round whites, russets, reds and yellow fleshed varieties were tested in separate trials for their adaptability potential for specific markets. Round whites and russets were harvested at two dates to evaluate their marketable and physiological maturity. Varieties selected for their exceptional qualities were then subjected to more intensive tests to determine their strengths and weaknesses. Management profiles were established with some selected varieties that optimized production inputs for improved quality and marketability. Special emphasis was given to tuber quality parameters of all new varieties. The focus was on overall appearance, external and internal defects, specific gravity, chip color, storability and culinary properties. Of significant interest to Michigan is resistance to common scab and bruising. For chip color and storability studies, potential chipping varieties were stored at two temperatures (45° and 52°F). Blackspot bruising was evaluated with tubers stored at 40°F. A. DATES OF HARVEST TRIAL FOR ROUND VARIETIES Eight named and four advanced selections were tested at two harvest dates (98 and 138 days). Onaway, Atlantic and Norchip were included as check varieties. Four replications of a randomized complete block design were harvested at each harvest date. Plots were 23 ft. x 34 inches and plants were spaced 12 inches. The trials were planted in the first week of May. Trials were located at the Montcalm Research Farm in Entrican. The previous crop was dry beans plowdown in fall 1988 and rye plowdown in spring 1989. Basal fertilizer and aldicarb (Temik 15G) were applied as described in the previous chapter. The hilling and herbicide application was completed by May 25. The crop was irrigated 10 times based on Michigan State University potato irrigation schedule. The amount of water applied ranged from 0.5 to 1.0 inch per irrigation, totalling to 7 inches for the season. An early and late blight forecasting program from Wisconsin was used as a guide to commence fungicide spraying. Relative humidity and temperature at canopy levels were monitored for this purpose. Fungicide spraying started on June 28 and sprayed every 7-10 day intervals. Fungicides Dithane M45 and Bravo 720 were alternated for early blight control. Weather data at the Montcalm Research Farm was collected using a Campbell’s CR10 micrologger. In the culinary tests, chip color was measured for chips made from 20 tubers. A single slice was taken from each tuber. Frying temperature was 350-360°F. An Agtron E-10 colorimeter was used for color measurements. Chip defects such as stem end and vascular discolorations, off colors and bruises were also noted. Samples were stored at 45° and 50°F for chipping out of storage. For after cooking darkening, peeled halves of three tubers were steam cooked and evaluated at 0 and 1 hour after cooking. Blackspot bruising was evaluated for both check and artificially bruised potatoes. Artificial bruising was carried out by taking samples out of 40°F storage. Twenty tubers were placed in a wooden drum and manually turned 10 revolutions at a moderate speed. These tubers were kept for 48 hours at room temperature prior to peeling. In the check treatments, no artificial bruising was done, so any blackspot observed occurred during harvest and handling. A Hobart peeler was used for peeling the tubers. Both the number of tubers with blackspot and the number of blackspots per tuber were recorded for each sample. Results The data for the round varieties at the two harvest dates are presented in Tables 1 and 2. At 98 days, Onaway and Eramosa were the earliest in maturity. Eramosa matured in about 80 days and produced smooth oblong tubers with good general appearance. Although it produced only average yields, Eramosa has potential for early tablestock market. Most of the medium to medium-late maturing varieties performed well in 1989. Kanona, Spartan Pearl, Somerset, Snowden, Saginaw Gold and AF875-16 produced a high percent of U.S. No. 1 tubers, minimal internal defects and excellent chip color. The tuber yield was above average in Kanona and Spartan Pearl. MS716-15 and AF875-16 had higher specific gravities than Atlantic. Kanona, Spartan Pearl and Saginaw Gold had lower specific gravities compared to Atlantic. Snowden appears to have an excellent potential for chip processing in Michigan. Somerset has slightly lower solids compared to Snowden and the tubers are cylindrical in shape. It also has a good potential in Michigan for processing and fresh market. Among the late maturing varieties, Steuben, Allegany, MS700-70 and Norwis (FL657) produced very high yields and excellent chip color. There was a high percent of oversized tubers in Steuben and Allegany. MS700-70 had higher solids than Steuben and Allegany. Norwis (FL657) had excellent chip color but its specific gravity was lower than desired for processing. MS716-15 produced average yields but its specific gravity and chip color were excellent. In the boiling tests (Table 11), undesirable levels of after cooking darkening were observed in Steuben, Allegany and Spartan Pearl. Some sloughing was observed in Kanona, MS716-15, W855 and Atlantic. MS700-70 and Norwis (FL657) had excellent flesh appearance after cooking. In the blackspot evaluations (Table 11), varieties that showed greater than 25% blackspot in the check treatments were Allegany, Kanona, Atlantic and AF875-16. Most varieties showed a higher incidence of blackspot when they were artificially bruised. Varieties with greater than 75% blackspot were Allegany, Kanona, W855, Atlantic and AF875-16. The drier than normal soil conditions during the 1989 harvest may have contributed to the increased incidence of blackspot compared to previous years. Variety Characteristics Spartan Pearl (MS700-83) - To be named and released in 1990 from Michigan State University. Mid-season maturity and above average yields with medium gravity. Good size distribution and skin appearance. Excellent potential for fresh market and chipping. Susceptible to scab, some susceptibility to growth cracks, air checks and after cooking darkening. It has minimal internal defects. MS716-15 - Medium-late maturity, tubers well shaped and smooth general appearance. It has average yields, high gravity, excellent chip color and no internal defects. It is susceptible to scab. MS700-70 - Late season maturity with prolific yields. It has high gravity and excellent chip color out of field. Tubers are somewhat rough in appearance with medium deep eyes. Tends to produce a high percent of oversized tubers at 12 inch spacing. Saginaw Gold - Round to oblong tubers with light yellow flesh and mid-season maturity. It has an excellent chip color but the specific gravity is medium. Good appearance after cooking. Susceptible to early blight in the field and storage. It is susceptible to scab. Steuben (NY81) - Very late maturity with above average yields and medium gravity. Tends to produce a high percent of oversized tubers at 12 inch spacing. Some hollow heart in 1989. Chip color is excellent. Kanona (NY71) - Medium to medium-late maturity with above average yields. Excellent chip color but the gravity was average. It is susceptible to scab and has minimal internal defects. Allegany (NY72) - Very late maturity, above average yields with medium gravity. Tendency to produce oversized tubers at wider spacings but has minimal internal defects. Chip color out of field is excellent. Somerset - Medium to late maturity, with average yields. Tubers are oblong in shape with medium gravity. Chip color is excellent. Susceptible to greening in the field, scab, hollow heart and growth cracks. Chip color out of cold storage (45°F) was acceptable. Snowden (W855) - Late maturity with average yields. It has high specific gravity and excellent chip color. Sets heavy and tends to produce undersized tubers if spaced too close. Some reports of increased Colorado beetle attack to its foliage. Has excellent potential for chipping in Michigan. Has minimal internal defects. Chip color out of cold storage (45°F) was excellent. With rough handling, blackspot can be a problem. Higher response to nitrogen than Atlantic. Norwis (FL657) - A variety to be named and released from Frito-Lay, Inc. Late maturing with high yields. It has light yellow flesh and a rough appearance on the larger tubers. It has excellent chip color but the gravity is too low for processing. Internal defects were minimal. AF875-16 - Excellent gravity and chip color but yields were below average. Minimal internal defects. Tubers are somewhat small in size. Eramosa - Very early maturity (80 days) with smooth, round to oblong and slightly flattened tubers with good general appearance. It had no internal defects. Tuber yield and gravity lower than Onaway. Has potential for first-early market. Susceptible to scab. Atlantic - Major chipping variety in Michigan. Mid- to late-season maturity. High gravity, excellent chip color. It is susceptible to internal brown spot, hollow heart, scab and white knot. Does not store well. Norchip - Mid-season maturity with below average yields. It has medium gravity but excellent chip color. Tubers vary in size and shape and the appearance is rough. Not widely used in Michigan at present due to poor yields. Onaway - Early maturity with above average yields. Tubers are round to oblong. Minimal internal defects but vascular discoloration can be a problem. It has a tendency to produce oversized tubers with a rough appearance. It is susceptible to growth cracks and early blight. Does not store well. B. dates OF HARVEST TRIAL FOR RUSSET AND LONG VARIETIES Fourteen varieties were tested for the. count-pack and processing potential at two harvest dates, 112 and 142 days (Tables 3 and 4). The production practices used in this trial were similar to those described for the round varieties. Russet Burbank was used as the check variety. Poor sizing was a general problem in this trial and is due in part to heavy rains in early June and early August which apparently depleted the available nitrogen for sizing. Early to medium maturing varieties were Russet Norkotah, HiLite Russet, ND671-4R and Cal-Ore. They were characterized by lower specific gravities compared to Russet Burbank. All four varieties had smooth external appearance. ND671-4R and Cal-Ore performed poorly in tuber yield with poor sizing. Based on external appearance and freedom from internal defects, Russet Norkotah and HiLite Russet had excellent potential for the count-pack market. Most of the other varieties in the trial were late to very late maturing. Those with high gravity and potential for processing were A7411-2, Frontier Russet (A74114-4) and A78242-5. A78242-5 is a blocky russet and although the solids were not very high, its shape and appearance were ideal for the French fry market. B7592-1 is a medium-long white with high yields, but the tuber shape appeared to be variable from oblong to long. It had good solids and minimal internal defects. A76147-2 produced high yields with medium gravity and its use may only be for fresh market. A79341-3 and A79357-17 were deleted from future tests due to their susceptibility to hollow heart. MN10874 is a russet with a smooth external appearance and minimal internal defects. It requires further testing. Russet Nugget was very late maturing and produced a very low yield. It had high solids, but was susceptible to hollow heart, blackspot and after cooking darkening. In artificially bruised tests, varieties having greater than 75% blackspot were B7592-1, A76147-2, A74114-4, A7411-2, Russet Nugget and Russet Burbank. A74114-4, A7411-2 and Russet Nugget showed some sloughing after boiling. Varieties with good to excellent appearance after cooking were A79341-3, B7592-1, A76147-2, A78242-5, Russet Burbank, ND671-4R and Cal-Ore. Variety Characteristics A76147-2 - Long, very light russet, late maturity with high yields and medium It has good external appearance and minimal internal gravity. defects. Has potential for fresh market. Sometimes susceptible to heat sprouting. Does not perform well in dry conditions. A78242-5 - Good early growth and vigor. Blocky russet, maturity is late with above average yields. Has excellent shape and external appearance. Although gravity is not very high, it has potential for French fry industry. A79341-3 - Late maturing russet, with high yields and solids. Good external appearance and quality. It will be deleted from future trials because of high hollow heart. A79357-17 - Good early growth and vigor. Produced above average yields and high gravity. Maturity is considered very late. Russet with good external appearance but deleted from future trials because of high hollow heart. Frontier Russet (A74114-4) - Late season maturity with above average yields and high gravity. Russet with good cooking qualities. Has excellent external appearance, quality and potential for processing and count-pack market. Internal defects are minimal. Rough handling produced blackspot. A7411-2 - Mid- to late-maturity, average yields with very high gravity. Tubers have good external appearance. Excellent potential for processing with few internal defects. Should be handled carefully because of potential for blackspot. Poor sizing can be a problem. B7592-1 - Medium to late maturity with high yields. Oblong to long white tubers but shape can be variable. Has a tendency to oversize. Minimal internal defects. Medium to high specific gravity but has potential for processing. MN10874 - Russet with average yields and specific gravity. Medium to late maturity. Good external appearance for count-pack market. Poor sizing can be a problem. HiLite Russet - A patented variety, mid-season maturity with below average yields and low gravity, somewhat similar to Russet Norkotah. Has good cooking qualities and moderate resistance to blackspot. Has good external quality, appearance and potential for count-pack market. Minimal internal defects. Poor sizing can be a problem. Russet Nugget - Very late maturing russet with very low U.S. No. 1 yields. Poor sizing was a major problem. High solids. Susceptible to hollow heart, blackspot and after cooking darkening. Cal-Ore - Mid-season maturing russet introduced by Plant Genetics, Inc. Produced very low tuber yields. Poor sizing was a major problem. Low gravity but good external appearance. Moderate resistance to blackspot and good appearance after boiling. ND671-4R - Mid-season maturity. Russet with smooth external appearance but below average yields and gravity. Produced a high percent of undersized tubers. Minimal internal defects with moderate resistance to blackspot. Good appearance after boiling. Russet Norkotah - Oblong to long russet, early to mid-season maturity. Tubers have a smooth external appearance. Specific gravity lower than Russet Burbank or Shepody. Produced average yields but poor sizing can be a problem. Very susceptible to Verticillium wilt. Excellent potential for fresh market with moderate resistance to blackspot. Some tubers had pink eye at harvest. Some darkening after boiling. Russet Burbank - Used as a check variety. Late maturity with below average yields. Good specific gravity for processing but produced a high percent of undersized tubers and pick outs. Moderate resistance to blackspot. Excellent appearance after boiling. C. RED SKINNED VARIETY TRIAL Red skinned varieties have generated an ongoing interest among Michigan growers. The emphasis was on fresh market potential with uniform size, shape and color retention during storage. In 1989, 11 varieties were tested in a randomized block design with four replications. The trial was harvested after 118 days. The varieties that performed well and showed the best appearance and color at harvest were ND2224-5R, NDT9-1068-11R and Dark Red Norland. NDT9-1068-11R had the highest tuber yield but its use appears to be limited because of susceptibility to skinning, air checks and soft rot during storage. W949-R, W948-R and Red LaSoda showed severe skinning during harvest. Dark Red Norland and Norland were very similar in growth and maturity but the skin color was darker in Dark Red Norland. All varieties, except Reddale, had minimal internal defects. Reddale was susceptible to hollow heart. There was a high percent of undersized tubers in Red Gold. In cooking tests, varieties that showed after cooking darkening were Reddale, W949-R, ND2224-5R and Red Gold. Variety Characteristics Red LaSoda - Late maturity with high yields. Low specific gravity. Severe skinning at harvest, color not appealing, deep eyes and difficult to peel mechanically. W949-R - Late maturity with average yields. Some tendency for after cooking darkening. Shape is not uniform. NDT9-1068-11R - Late maturity with excellent yields. Good appearance and red color at harvest. Has a tendency to oversize. Susceptible to air checks, skinning and soft rot. Poor storability. Minimal internal defects. Sangre - Mid-season maturing with average yields. Has harvest. Very slow early establishment and pre-cutting of seed recommended. Looks good after peeling and cooking. excellent color at is W948-R - Late maturing with below average yields. Showed a higher percent of Severe skinning at blackspot in artificially bruised treatments. harvest and tubers have deep eyes. Red Gold - Mid-season maturing with below average yields. Has a pink skin and yellow flesh. Had a tendency for poor sizing and after cooking darkening. Reddale - Late maturity with above average yields. Susceptible to growth cracks and skinning. Has a tendency to oversize and susceptible to hollow heart. ND2224-5R - Early to medium maturity with average yields. Excellent color and appearance at harvest. Some tendency for after cooking darkening. Retains red color and stores well. Poor sizing can be a problem. Viking - Medium to late maturity with excellent yields. Good external appearance. Minimal internal defects. Good appearance after boiling. Norland - Used as a check variety. Below average yields. Light red skin color at harvest. Poor color retention after harvest and tendency to sprout early in storage. Dark Red Norland - A mutant selected from Norland. Below average yields. Plants very similar to Norland in growth and maturity. Skin color darker than Norland but variable and streaky. Tubers somewhat smaller than Norland with a high percent of undersized tubers. D. 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 locations prior to a release decision. One MSU line, MS700-70 was included in the 1989 trial. Sixteen varieties (seven round whites, four russets and five reds). MN13420 is a purple fleshed variety tested for fresh market. The results are presented in Tables 6 and 7. On a general merit rating based on external appearance and overall worth as a variety, the five top varieties selected were W1005, MS700-70, W855, ND1538-lRuss and ND2224-5R. W1005 is a light russet with medium size and high solids. ND1538-lRuss is a moderate russet with variable shape. It is reported to be resistant to hollow heart. W855 had high solids and excellent chip color. MS700-70 produced very high yields and several other participating states have consistently given it high merit ratings. ND2224-5R had excellent red skin and shape. In culinary tests, after cooking darkening was undesirable in W1005 and ND2224-5R. Chip color was excellent in MN13451, MN13545, NEA219.70-3 and W855. Poor sizing was a problem in many varieties and consequently the percent of U.S. No. 1 tubers was low. A summary of general notes, percent external and internal defects are found in Tables 6 and 7. E. MSU SEEDLING TRIAL Six new MSU lines were tested at two harvest dates, 96 and 130 days. At each harvest date, four replications of a randomized complete block design were harvested. The lines included four from the 401 series (Atlantic x Yukon Gold) and two from the 402 series (Atlantic and Onaway). Three lines from the 401 series (401-1, 401-2 and 401-8) were yellow fleshed. The results are summarized in Tables 8 and 9. Cultivars Onaway, Atlantic, Michigold and Yukon Gold were included as checks. Varieties having excellent potential for chip processing with high specific gravity and Agtron chip color were MS401-2, MS401-7 and MS401-1. These varieties have performed consistently well at Montcalm during four years of testing. The two varieties tested for the fresh market, 402-7 and 402-8, had smooth external appearance and a high percent of U.S. No. 1 tubers. Onaway had the highest yield with minimal internal defects. Atlantic was susceptible to hollow heart. Michigold produced a high percent of undersized tubers. Yukon Gold produced below average tuber yield. MS401-8 will be dropped because of susceptibility to internal brown spot. All MSU lines showed no after cooking darkening but MS401-2 and MS401-7 showed some sloughing. F. ADVANCED ADAPTATION TRIAL Entries into this trial consisted of advanced lines released from other states with potential for chipping in Michigan. Nine varieties were tested in a randomized complete block with four replications at one harvest date. Three cultivars, Onaway, Atlantic and Norchip were included as checks. The results are summarized in Table 10. Trent had high yields and specific gravity. The varieties having excellent Agtron chip color were Trent, B9792-157, B9792-158, Conestoga, CS7232-4 and B9792-61. Trent and B9792-157 were susceptible to hollow heart. CS7232-4 is reported to have an ability to chip out of cold storage. However, its below average yields and gravity are limitations. In post harvest evaluations, all varieties except Trent, had moderate resistance to blackspot. In boiling tests, only B9792-158 had an undesirable level of after cooking darkening. Some of the promising varieties from this trial will be tested more intensively in 1990, depending on the availability of seed. Table 1. First Date of Harvest Yield Data - Round White Varieties August 8, 1989 (98 days) Variety Yield cwt/a US#1 Yield cwt/a Total Percent Size Distribution #1 Percent Size Distribution <2 Percent Size Distribution Percent Size Distribution 2-3 >3 1/4 Percent Size Distribution Agtron Chip Color Sp.Gr. PO * Defects HH Defects * VD * Defects IN 0 0 0 0 0 0 0 0 0 1 5 0 1 0 0 12 0/34 0/3 0 0/8 4 0 0/11 7 0/40 2/27 0 0/9 1 1 0/10 0 0/3 0/12 0 2/27 1 0 0/5 0 1/13 0/8 2 0 0/5 30 71 66 63 61 65 62 33 63 60 61 69 54 58 64 empty table cell empty table cell empty table cell empty table cell Onaway 413 Saginaw Gold 368 366 Kanona Spartan Pearl 357 Steuben 351 Norwis (FL657) 340 AF875-16 318 316 Eramosa 315 MS716-15 MS700-70 308 306 Atlantic 301 Somerset 281 Allegany 273 Norchip Snowden(W855) 253 465 448 409 429 381 376 372 367 379 355 349 334 313 352 344 Average 324 378 1 76 12 89 82 15 81 1 90 10 88 2 83 16 80 3 7 73 19 92 9 81 9 90 85 14 82 3 86 13 85 1 1 83 16 83 87 12 83 4 88 11 76 12 2 9 88 90 90 10 85 5 78 17 75 3 74 26 72 2 1 3 0 1 1 1 1 1 1 1 1 1 0 5 0 empty table cell empty table cell empty table empty table cell cell 86 1.066 1.076 1.075 1.076 1.073 1.067 1.086 1.065 1.084 1.082 1.083 1.076 1.074 1.075 1.081 1.076 * Internal defects/Number of oversized (>3 1/4") tubers cut Table 2. Second Date of Harvest Yield Data - Round White Varieties September 18, 1989 (138 days) Variety Yield cwt/a US#1 Yield cwt/a Total Percent Size Distribution Percent Size Distribution Percent Size Distribution 2-3 <2 #1 Agtron Percent Size Distribution Chip Color >3 1/4 Percent Size Distribution Sp.Gr. PO 579 Steuben Allegany 512 485 Kanona 483 MS700-70 Norwis (FL657) 470 466 Onaway Spartan Pearl 439 419 MS716-15 407 Somerset Snowden (W855) 385 Atlantic 379 370 Saginaw Gold 325 AF875-16 Eramosa 324 Norchip 262 601 540 518 529 522 518 513 474 469 464 434 428 370 383 359 4 60 95 95 4 70 5 86 94 7 79 91 4 82 90 89 6 75 86 12 82 88 11 82 87 12 73 84 15 81 7 69 87 86 11 83 88 10 85 85 13 84 73 15 71 35 25 8 12 8 14 4 6 14 3 18 3 3 1 2 0 1 0 1 6 4 2 0 2 1 5 3 2 2 12 1.077 1.078 1.076 1.083 1.065 1.064 1.075 1.088 1.079 1.084 1.085 1.076 1.088 1.062 1.073 65 67 69 60 71 27 63 66 68 76 70 73 71 35 61 Matu- rity * Defects HH Defects * VD Defects * IN 4.5 6 5.0 1 1 3.5 5.0 3 4.0 0 2.5 0 1 4.0 5.0 0 4.0 3 4.0 1 4.0 7 3.0 0 0 3.5 1.5 0 3.5 0 0 /40 9 0 /40 1 0 /33 4 7 /37 2 2 /38 0 0 /32 2 1 /16 3 0 /11 0 1 /38 3 0 /9 3 11 9 /38 0 /14 3 1 /13 0 0 /5 2 0 /7 3 Average 420 475 88 empty table cell empty table cell empty table empty table cell cell 1.077 empty table cell empty table cell empty table cell empty table cell empty table cell * Internal defects per number of oversized (>3 1/4 ") tubers cut Maturity: 1 = early; 5 = late maturity Planting Date 5.2.89 Harvest Date 9.18.89 Observations: Eramosa had smooth skin at harvest. MS700-83 and Somerset had some shatter bruise. Somerset, Allegany and Steuben showed some greening. Allegany had some stolons still attached to tubers after harvest. Table 3. First Date of Harvest Yield Data - Count Pack Varieties August 23, 1989 (112 days) Variety Yield cwt/a US#1 Yield cwt/a Total Percent Size Distribution #1 Percent Size Percent Size Distribution Distribution <4 4-12 Percent Size Distribution >12 Percent Size Distribution Sp.Gr. PO Int. Defects HH Int. Defects VD Int. Defects IN A76147-2 461 A79341-3 447 401 B7592-1 371 A79357-17 A78242-5 283 277 MN10874 R. Norkotah 271 251 A7411-2 H. Russet 248 Frontier Rus. 242 191 R. Burbank ND671-4R 170 Cal-Ore 87 R. Nugget 74 597 533 506 530 424 406 385 404 382 402 371 387 246 219 77 19 68 9 84 13 64 20 79 17 57 22 70 23 55 15 67 27 57 10 68 30 62 6 70 27 61 9 62 32 57 5 65 33 56 9 3 60 33 57 51 38 51 0 44 55 43 1 35 60 35 0 34 63 34 0 3 3 4 7 6 2 2 6 2 7 11 1 4 3 Average 259 413 63 empty table cell empty table cell empty table cell empty table cell 1.076 1.085 1.077 1.078 1.075 1.070 1.068 1.088 1.064 1.085 1.079 1.061 1.070 1.087 1.075 8 29 3 11 2 2 1 1 0 0 - 0 1 - empty table cell 0/35 0/40 0/40 0/39 0/30 0/23 0/25 0/13 0/24 0/11 - 0/1 0/1 0 0 0 0 0 0 2 0 0 0 - 0 0 - - empty table cell empty table cell * Internal defects/Number of oversized (>10oz) tubers cut Table 4. Second Date of Harvest Data- Count Pack Varieties Montcalm Research Farm 1989 (142 days) Variety Yield (cwt/a) US#1 Yield (cwt/a) Total % Size Distribution #1 % Size Distribution <4 % Size Distribution 4-10 % Size Distribution >10oz % Size Distribution P.O. SP. GR. Matu- rity Int. Defects HH Int. Defects VD Int. Defects IBS/cut A79341-3 501 B7592-1 482 A76147-2 478 A79357-17 416 A78242-5 332 Frontier Russet 313 304 A7411-2 265 MN10874 Russet Norkotah 264 Russet Burbank 221 Hilite Russet 198 ND671-4R 180 Russet Nugget 122 Cal-Ore 93 594 608 597 562 477 446 428 404 377 420 339 390 260 239 Average 298 438 84 80 81 75 70 70 71 65 70 53 58 47 48 39 68 12 14 15 18 26 19 24 30 36 35 38 52 51 59 empty table cell 70 61 69 57 60 56 61 63 61 49 55 45 46 39 empty table cell 14 19 12 18 10 14 10 2 9 4 3 2 2 0 empty table cell 4 7 4 7 3 10 5 5 3 12 4 1 1 2 empty table cell 1.077 1.083 4.5 4.0 1.078 1.075 5.0 1.081 5.0 1.075 4.5 1.088 4.5 1.090 4.5 1.074 4.0 1.068 3.0 1.080 5.0 1.064 3.5 3.5 1.063 1.089 5.0 1.071 3.5 empty table cell 26 0 7 20 3 6 2 0 1 5 1 0 2 - empty table cell 0 2 0 0 0 0 0 0 1 0 0 0 0 — 0/40 0/40 0/39 0/40 0/31 0/36 0/33 0/9 0/21 0/16 0/10 0/3 0/4 — empty table cell empty table cell Internal defects / # oversized (>10oz) tubers cut Planting Date 5.2.89 Harvest Date 9.22.89 Maturity: 1 = early; 5 = late maturity. Observations: Russet Norkotah and ND671-4R had some pink eye at harvest A79341-3 and A79357-17 had severe hollow heart 37592-1 variable tuber shape Table 5. Yield of Red Potato Varieties 1989 Montcalm Research Farm - August 29, 1989 (118 days) Variety Yield cwt/a Yield cwt/a US#1 Total #1 Percent Size Percent Size Distribution Distribution <4 Percent Size Distribution 4-12 PO Percent Size Distribution >12 Percent Size Distribution Matu­ rity Int. Defects* HH Sp.Gr. Int. Defects* IN Int. Defects* VD NDT9-1068-11R 598 570 Viking 475 Red Lasoda 467 Reddale 457 Sangre 452 W948-R 402 W949-R 372 ND2224-5R 341 Norland D.Red Norland 306 283 Red Gold 634 640 537 503 504 518 440 452 420 377 419 Average 429 495 5 68 25 6 74 15 8 9 80 5 66 27 8 77 14 7 8 81 10 3 1 0 1 93 89 88 93 91 87 13 80 91 82 19 79 82 18 81 80 20 80 68 32 67 empty table cell empty table cell 86 empty table cell 2 5 3 2 1 0 1 0 0 1 0 empty table cell 4.5 4.0 4.5 4.5 4.0 5.0 5.0 3.5 3.0 3.0 3.5 empty table cell 1.060 1.066 1.057 1.056 1.060 1.072 1.063 1.056 1.063 1.062 1.070 1.063 0 0 3 8 3 0 0 0 1 — 0 empty table cell 0 0 0 0 0 3 1 2 0 — 0 empty table cell 0/4 0/4 0/3 0/4 0/3 0/3 0/3 0/8 0/2 — 0/2 empty table cell * Internal defects/Number of oversized (3 1/4") tubers cut Notes: ND2224-5R, NDT9-1068-11R and Dark Red Norland had good skin color and appearance W949-R late variety, shape not uniform W948-R deep eye and skinning Red Lasoda Skinning 1989 NORTH CENTRAL REGIONAL POTATO TRIALS Location Montcalm Research Farm Michigan State University__________ Soil Type Sandy Loam - McBride__________ Fertilizer Treatment Stated below_________ Date Planted May 3, 1989_______________ Date Harvested September 19, 1989___________ Size of Plots 25'_______________________ Spacing - Between Hills 12"_______________ Spacing - Between Rows 34"__________ Replications______________23___________________ Number of Replications 4_______________ Environmental Factors (rainfall, temperature, irrigations, etc.): Month May June July August September October Total RF 2.68 4.85 0.82 5.52 1.33 0.68 Max. T°(c) Average Min. T (c) Average Radiation (cal/cm2) Average 22.2 26.9 28.4 25.9 21.6 17.3 0.6 11.5 15.2 13.0 6.5 3.0 NA 398.6 502.8 442.0 354.8 216.8 Crop received 6.0" of irrigation water in 9 separate irrigations. Sprays Applied: HERBICIDES: Dual + Lexone FUNGICIDES: Dithane M45 - - - INSECTICIDES: Imidan + PBO - - Bravo 720 Cygon 1 application (5/25) 7 applications (6/28, 7/6, 8/3, 8/13,8 /16, 8/29, 9/8) 3 applications 6 applications (6/28,7/6,7/13,8/3,8/16,9/8) 2 applications (7/25,8/10,8/23) (8/10,8/16) Other Data (vine killing, specific gravity determinations, etc.): Vine killing date 9/8/89 (Diquat + X77) Specific gravity measured by weight in air and weight in water method. BN9826-1 seed was not received and therefore not tested in the trial. Fertilizers: 500 lbs/A 15-10-15 + 4% Mg at planting 100 lbs/A 0-0-60 plowdown 90 lbs/A N applied as 28% liquid through irrigation (2 - 45 lb/A applications) Previous crop: soybeans plowdown in fall 1988 and rye plowdown in spring 1989. Table 6. North Central Regional Trial - 1989. SUMMARY SHEET Aver. (1) Mat. EARLY TO MEDIUM MATURITY Most (2) Representive Scab Area-Type (A-T) EARLY TO MEDIUM MATURITY CWT/A Yield US #1 cwt/a Gen (4) Aver. Merit Yield Rating EARLY TO MEDIUM EARLY TO MEDIUM EARLY TO MEDIUM EARLY TO MEDIUM MATURITY MATURITY MATURITY MATURITY Aver. (3) % Total Solids Aver. Percent US #1 Chip (5) Color Early (6) Blight Reading EARLY TO MEDIUM EARLY TO MEDIUM MATURITY MATURITY EARLY TO MEDIUM MATURITY Comments and General Notes 1.5 2.5 3.0 3.0 0 0 0 0 348 352 390 384 287 222 295 286 82 63 75 74 15.4 16.7 19.0 15.8 MEDIUM LATE TO LATE MATURITY empty table cell 55 empty table cell 33 empty table cell 59 empty table cell 53 MEDIUM LATE TO LATE MATURITY EARLY TO MEDIUM MATURITY skinning, rough. Good red color, growth crack, Medium russet, high % undersized tubers. Poor overall shape, medium deep eye. Considerable skinning, small size,good red color. 2.5 3.5 3.5 3.0 MEDIUM LATE TO LATE MATURITY MEDIUM LATE TO LATE MATURITY MEDIUM LATE TO LATE MATURITY MEDIUM LATE TO LATE MATURITY MEDIUM LATE TO LATE MATURITY MEDIUM LATE TO LATE MATURITY MEDIUM LATE TO LATE MATURITY MEDIUM LATE TO LATE MATURITY 3.5 3.5 3.5 4.5 3.5 4.0 - 3.5 3.5 4.0 4.0 4.5 5.0 3.6 0 0 0 0 0 0 - 0 0 T-l 0 0 0 empty table cell 409 361 324 559 425 483 - 389 420 423 461 598 520 405 262 232 195 497 364 443 - 318 304 349 351 541 312 329 64 64 60 89 86 92 - 82 72 82 76 90 60 82 2 15.0 16.9 17.1 21.6 18.2 17.3 - 15.4 17.3 20.7 20.3 16.0 19.9 empty table cell 56 empty table cell 61 empty table cell 64 56 empty table cell 60 empty table cell 38 empty table cell - 55 55 63 54 empty table cell 37 empty table cell 57 empty table cellempty table cell 54 5 4 3 1 High % below 2" diameter, pigmented stem, purple flesh, skinning, shallow eyes. Virus in foliage, poor type, deep eyes, oval shape. Smooth shallow eyes, high % below 2" diameter. Medium deep eye, some scurf. Deep eyes, small size, bright skin, some scurf. Bright skin. Seed not received. Good red color, some skinning. Moderate russet, variable shape. Indented stem end, variable size. Light russet, moderate size. Deep eyes, growth cracks, size variable. Small size, medium russet. empty table cell 2.5 2.5 3.0 4.0 3.0 4.0 - 3.5 3.0 4.0 4.5 4.0 4.5 3.5 Selection Number or Variety EARLY TO MEDIUM MATURITY Norland Norgold Russet Norchip ND1196-2R MEDIUM LATE TO LATE MATURITY MN13420 MN13451 MN13545 MS700-70 NEA219.70-3 NEA22.75-1 BN9826-1 ND2224-5R ND1538-1Russ W855 W1005 Red Pontiac Russet Burbank AVERAGE* * Please Average 1) 1-Very Early - Norland maturity; 2-Early - Irish Cobbler maturity; 3-Medium - Red Pontiac maturity; 4-Late - Katahdin maturity; 5-Very Late - Kennebec or Russet Burbank maturity. 2) AREA: T-less than 1%; 1 - 10-20%; 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) Percent total solids, not total solids/acre 4) Place top five among all entries including cheek varieties; disregard maturity classification. (Rate first, second, third fourth and fifth (in order) for overall worth as a variety). 5) Chip Color - PCII Color Chart or Agtron. Indicate what Agtron you are using. Model E10 calibrated at factory. EARLY TO MEDIUM MATURITY Norland Norgold Russet Norchip ND1196-2R MEDIUM LATE TO LATE MATURITY MN13420 MN13451 MN13545 MS700-70 NEA219.70-3 NEA22.75-1 BN9826-1 ND2224-5R ND1538-1Russ W855 W1005 Red Pontiac Russet Burbank AVERAGE* 0 0 0 0 0 0 0 0 0 0 - 0 0 4 0 0 0 empty table cell 2 4 2 0 0 4 0 0 0 0 - 0 0 0 0 4 2 8 6 2 0 2 0 0 0 0 4 - 0 2 0 0 0 2 2 2 0 0 2 2 0 4 0 0 - 0 0 2 0 0 0 0 0 0 2 0 0 - 0 0 2 0 0 0 96 98 100 94 100 96 - 100 98 92 100 96 96 0 0 0 8 4 0 - 2 0 0 0 8 4 0 0 0 12 0 0 - 0 0 0 2 0 0 empty table cell 0 0 0 4 2 8 - 4 0 100 100 100 76 94 92 - 94 100 80 0 98 4 88 0 96 20 (slight) Table 7. North Central Regional Trial - 1989. SUMMARY OF GRADE DEFECTS Selection Number or Variety Scab (2) Percent External Defects(1) Growth Cracks Percent External Defects(1) Percent External Defects(1) Off Shape Percent External Defects(1) and Second Growth Sun Green Total (3) Tubers Free of External Tuber Percent External Defects(1) Rot Defects EARLY TO MEDIUM MATURITY EARLY TO MEDIUM EARLY TO MEDIUM EARLY TO MEDIUM EARLY TO MEDIUM EARLY TO MEDIUM MATURITY MATURITY MATURITY MATURITY MATURITY Percent Internal Defects (1) Percent Internal Defects (1) Percent Internal Defects (1) Hollow Heart Vascular Percent Internal Defects (1) Internal Discolor- Necrosis ation EARLY TO MEDIUM EARLY TO MEDIUM MATURITY MATURITY EARLY TO MEDIUM MATURITY EARLY TO MEDIUM MATURITY Normal Tubers (4) MEDIUM LATE TO LATE MATURITY MEDIUM LATE TO LATE MATURITY MEDIUM LATE TO LATE MATURITY MEDIUM LATE TO LATE MATURITY MEDIUM LATE TO LATE MATURITY MEDIUM LATE TO LATE MATURITY MEDIUM LATE TO LATE MATURITY MEDIUM LATE TO LATE MATURITY MEDIUM LATE TO LATE MATURITY 0 0 0 0 88 88 96 100 MEDIUM LATE TO LATE MATURITY 12 0 0 0 2 0 0 0 10 (slight) 2 4 0 84 90 96 100 empty table cellempty table cellempty table cellempty table cellempty table cell empty table cellempty table cell empty table cell *Please average (1) Based on four 25 tuber sanples (one from each replication). Percentage based on number of tubers. (2) Includes all tubers with scab lesions whether merely surface, pitted or otherwise and regardless of area. Be sure to count tubers with any amount of scab in this category. (3) This total - tubers free from any external defect of any sort. (4) Percentage normal tubers are those showing no internal defects. Some individual tubers will have more than one type of internal defect. Table 8. First Date of Harvest Yield Data - MSU lines August 8, 1989 (96 days) Percent Size Distribution Percent Size Percent Size Distribution Distribution <2 2-3 #1 Percent Size Distribution >3 1/4 Percent Size Distribution Agtron Chip Color Sp.Gr. PO Variety Onaway MS401-7 MS401-2(y) MS401-l (y) MS401-8(y) Atlantic MS402-7 MS402-8 Yukon Gold Michigold Yield cwt/a Total Yield cwt/a #1 402 367 345 318 298 295 281 276 265 247 470 412 382 379 335 336 320 294 295 346 3 9 83 86 1 7 88 89 8 82 90 8 84 15 82 2 89 8 8 81 9 80 8 88 9 72 16 88 5 85 9 94 9 85 90 5 71 29 71 0 5 4 2 1 3 3 3 1 1 0 * Defects * Defects HH VD * Defects IN 0 0 1 3 6 5 5 1 5 0 0 0/12 0/8 0 1 0/27 1/7 0 0 10/20 1 1/19 0 3/30 1/20 1 0 0/12 0 0 32 65 60 64 53 60 55 58 57 55 1.067 1.086 1.084 1.082 1.083 1.084 1.069 1.066 1.078 1.083 1.078 Average 309 356 87 empty table cell empty table cell empty table empty table cell cell empty table cell empty table cell empty table cell empty table cell *Internal defects/Number of oversized (3 1/4") tubers cut Table 9. Second Date of Harvest - MSU lines 1989 Montcalm Research Farm, MSU (130 days) Yield cwt/a No.1 Yield cwt/a Total % Size Distribution #1 % Size Distribution <2 % Size Distribution 2-3 1/4 % Size Distribution >3 1/4 % Size Distribution PO Sp.Gr. Agtron Chip Color * Int. Defects HH Int. Defects * VD Int. * Defects IBS 466 411 392 386 342 333 328 326 315 295 551 440 449 438 380 421 370 347 398 335 359 413 85 93 87 88 90 79 89 94 79 88 87 8 6 8 8 6 21 8 5 19 9 80 88 87 78 77 78 79 79 77 85 5 5 0 10 13 1 10 15 2 3 7 1 5 4 4 0 3 1 2 3 1.065 1.085 1.087 1.088 1.070 1.083 1.081 1.068 1.081 1.077 27 64 66 65 - 58 59 - 69 49 0 0 - 9 4 1 3 3 4 3 0 0 - 0 0 0 0 0 0 0 0/19 2/19 - 4/29 1/28 0/4 7/20 0/30 0/6 0/7 empty table cell empty table cell empty table cell empty table cell 1.079 empty table cell empty table cell empty table cell empty table cell Variety Onaway MS401-2 MS401-7 Atlantic MS402-7 Michigold MS401-8 MS402-8 MS401-1 Yukon Gold empty table cell *Internal defects per number of oversized (3 1/4”) tubers cut Table 10. Yield of Potential Chipping Varieties in the Advanced Adaptation Trial. Montcalm Research Farm, MSU (128 days) Variety Onaway Trent ND1859-34 F72004 B9792-157 Atlantic B9792-158 Conestoga AF330-1 Norchip CS7232-4 B9792-61 empty table cell Yield cwt/a No. 1 Yield cwt/a Total % Size Distribution #1 % Size Distribution <2 % Size Distribution 2-3 1/4 % Size Distribution >3 1/4 % Size Distribution PO Sp.Gr. Agtron Chip Color * Int. Defects HH Int. Defects * VD * Int. Defects IBS 503 463 449 435 417 392 359 346 330 326 315 312 580 507 499 471 468 441 432 407 380 453 349 363 387 446 87 91 90 92 89 89 83 85 87 72 90 86 87 5 4 10 6 9 27 13 12 11 23 9 12 75 79 82 83 80 74 81 81 82 72 87 83 12 12 8 9 9 15 2 4 5 0 3 3 8 5 0 2 2 4 4 3 2 5 1 2 1.060 1.091 1.077 1.075 1.073 1.083 1.079 1.074 1.077 1.074 1.072 1.077 27 63 56 50 65 67 61 60 - 60 68 63 0 13 3 0 10 11 2 2 1 0 2 2 0 0 0 0 0 0 0 0 0 0 0 0 2/33 4/39 1/15 0/32 2/30 6/36 0/11 0/15 0/13 0/4 0/9 0/14 empty table cell empty table cell empty table cellempty table cell empty table cell empty table cell empty table cell empty table cell 1.076 * Internal defects per number of oversized (>3 1/4") tubers cut Table 11. Post Harvest Quality Evaluations of Potato Varieties Tested in 1989. Percent Blackspot Percent Blackspot After Cooking Darkening After Cooking Darkening Variety Check Bruised 0 1 Hour Remarks Round Varieties - Dates-of-Harvest Round Varieties - Dates-of-Harvest Round Varieties - Dates-of-Harvest Round Varieties - Dates-of-HarvestRound Varieties - Dates-of-HarvestRound Varieties - Dates-of-Harvest Steuben Allegany 60 100 20 30 2.5 2 all 3 dark ends all 3 have slightly dark ends some sloughing excellent appearance excellent appearance 1 1 1 1.5 empty table cell 2 all 3 dark ends but not 35 10 10 0 0 95 60 25 25 45 35 70 95 75 40 85 10 10 15 30 10 40 10 15 Advanced Adaptation severe some sloughing 1 dark end some sloughing some sloughing 1 slightly dark 1 1.5 1 1 1.5 1.5 empty table cell 1.5 2 slightly dark empty table cellempty table cell Advanced Adaptation Advanced Adaptation 35 35 Advanced Adaptation 1 empty table cell Advanced Adaptation 0 20 10 5 25 75 25 15 1 1 1 1 1.5 empty table cell 1 1.5 all 3 sloughed yellow flesh but slightly dark 1.5 empty table cell 5 15 10 0 0 0 0 0 20 40 50 15 10 25 20 15 all 3 slightly dark good 1 1.5 empty table cell 2 1.5 empty table cell 1 empty table cell empty table cell 1 1.5 1.5 1 slightly dark 1 slightly dark MSU LinesMSU Lines MSU LinesMSU Lines MSU Lines 10 0 10 5 5 10 - 0 0 10 45 35 70 55 70 40 - 45 15 40 1 1 1 1 1 1 - 1 1 1 2 1 1 all 3 discolored some sloughing excellent appearance, some sloughed some sloughing empty table cell 1 1 1.5 - empty table cell 1.5 empty table cell 1.5 1 empty table cell deep eyes for peeling all 3 mildly discolored 2 1 1 1 1 1 1 1 1.5 1 1 1 1 1 1 1.5 1 1 1 1 1 Kanona MS700-70 Norwis (FL657) Onaway Spartan Pearl (MS700-83) MS716-15 Somerset Snowden (W855) Atlantic Saginaw Gold AF875-16 Eramosa Norchip Advanced Adaptation Onaway Trent ND1859-34 F12004 Coastal Chip (B9792-157) Atlantic B9792-158 Conestoga AF330-1 Norchip CS7232-1 B9792-61 MSU Lines Onaway MS401-2 MS401-7 Atlantic MS402-7 Michigold MS401-8 MS402-8 MS401-1 Yukon Gold Table 11. (continued) Percent Blackspot Percent Blackspot Variety Check Bruised After Cooking Darkening After Cooking Darkening 1 Hour 0 Remarks North CentralNorth Central North CentralNorth Central North Central North Central MN13420 MN13451 MN13545 NEA219.70-3 NEA22.75-1 Long Types A79341-3 B7592-1 A76147-2 A79357-17 A78242-5 Frontier Russet (A74114-4) A7411-2 MN10874 Russet Norkotah Russet Burbank HiLite Russet ND671-4R Russet Nugget Cal-Ore ND1538-lRuss W1005 Norgold Russet Reds NDT1068-11R Viking Red LaSoda Reddale Sangre W948-R W949-R ND2224-5R Norland Dark Red Norland Red Gold ND1196-2R Red Pontiac 0 20 0 15 0 30 55 10 60 45 - - 1 - 1 - - 1 - 1.5 empty table cell empty table cell excellent empty table cell empty table cell Long TypesLong Types Long TypesLong Types Long Types 5 25 35 5 15 20 20 25 15 10 0 0 20 5 0 25 0 Reds 0 10 0 5 0 15 0 10 0 5 0 0 0 100 Reds 30 85 85 70 45 85 75 35 40 55 25 95 15 30 60 55 45 45 10 45 20 80 30 40 0 5 80 30 10 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1.5 - Reds 1 1 1 1.5 1 1 1 1.5 1.5 1.5 1 - - 1 1 1 1 1 1 2 2 2 1 1.5 1.5 2 1.5 1.5 2 - Reds 1.5 1.5 1.5 3 1.5 1 2 2 1.5 1.5 2 - - excellent appearance good excellent appearance empty table cell good some sloughing severe sloughing 2 dark ends 2 dark ends excellent empty table cell good 2 dark ends, some sloughing good all 3 slightly dark empty table cell empty table cell Reds 1 dark good deep eyes, difficult to peel 3 dark ends good good 2 dark ends empty table cell empty table cell good appearance 2 dark ends empty table cell empty table cell Funding Federal Grant THE RESPONSE OF SPARTAN PEARL AND NORCHIP TO THE RATES AND SOURCE OF POTASSIUM FERTILIZER G.H. Silva, R.W. Chase and R.B. Kitchen Introduction Spartan Pearl (MS700-83) and Norchip are possible chipping varieties for Michigan but their marginal specific gravities are frequently a major limitation for processing. The objective of this study was to determine if the specific gravity could be increased by manipulating the potassium rate or source without adversely effecting other desirable quality characteristics. Potassium (K) is required by plants for translocation of sugars and synthesis of starch. Since potato tubers are high in starch, potatoes have a high requirement for K. It is estimated that 500 hundredweight (cwt) of potatoes will remove approximately 300 lbs of K2O per acre. In Michigan, most potatoes are grown on sandy soils that do not hold large amounts of K. Therefore a great deal of attention must be given to K fertilization. Previous research has demonstrated that high rates of K fertilizers will lower specific gravity (percent dry matter). It has also been speculated that it is the increased chloride levels, rather than the K, that is most detrimental in lowering the dry matter content of tubers. Procedure In 1989, the effects of two sources (muriate of potash and potassium sulphate) and four levels (0, 100, 200 and 300 lbs K2O/a) were tested in a randomized complete block design with four replications. All K was applied broadcast with a gandy applicator before planting. The initial soil test showed 303 lbs/a K and a soil pH of 5.5. For a yield goal of 550 cwt/a (for Spartan Pearl) the Michigan recommendation calls for an additional 150 lbs K2O/a. For Norchip, yield goal of 450 cwt/a, the addition of 100 lbs K2O/a is recommended. Both varieties received at planting 175 lbs N and 50 lbs P205. The trial was planted on May 5 and harvested on September 12. Petioles for nutrient analysis were taken on August 6. Following harvest, freeze dried tuber samples were taken for cation and anion analysis. Results The results are summarized in Tables 1 and 2. In Spartan Pearl, the highest specific gravity (1.082) was obtained where no K was applied whereas in Norchip the highest specific gravity (1.079) was at 100 lbs K2O as sulphate. In both varieties, specific gravity decreased with increasing rates of K, but the decrease with muriate source was more profound compared to the sulphate source. It is apparent therefore that the chloride component is a major contributing factor for lowering the specific gravity. The lowest specific gravity in Spartan Pearl (1.072) and Norchip (1.071) was produced in the 300 lbs K2O/a as muriate treatment. No significant increases in U.S. No. 1 yields resulted from higher K rates. There was an increased uptake of K in the petioles in the K treated plots compared to the untreated. Post harvest evaluations indicated that the Agtron chip color of Spartan Pearl was slightly lower with the sulphate compared to the chloride source (Table 1). This was not true in Norchip. Potassium rate or source produced no substantial differences in the after cooking darkening (Tables 3 and 4). However, there was a tendency for an increased susceptibility to blackspot at lower K levels. This increased susceptibility was more evident in the potatoes that were artificially bruised following storage at 40°F, compared to the check treatment where bruising occurred during harvest and handling. This study indicated that the dry matter content of potatoes could be influenced by manipulating the K source and rate. It appears that by using reduced K levels and preferably sulphate source, an opportunity exists to optimize the desired dry matter levels of varieties such as Spartan Pearl and Norchip. With 303 lbs K in the soil before the test, further increments of K only resulted in decreased specific gravity with no response in tuber yield. Increased susceptibility to blackspot at low K levels must also be considered in the decision regarding potash needs. The drier than normal soil conditions during the 1989 harvest contributed to the increased amount of blackspot. Potatoes for chip processing are usually stored at about 50°F and not at 40°F as in this blackspot evaluation. Therefore blackspot incidence can be expected to be lower than those shown for the artificially bruised samples. The use of the sulphate source will incur an increased cost that must be considered. To apply 150 lbs K20/a, it would cost approximately $20.00 more per acre with the sulphate source compared to the muriate. It should be emphasized that soil testing is the key to potassium fertilizer use for potatoes. In Michigan, the common source of K fertilizer is muriate of potash. Using more than the recommended rate of this source is therefore detrimental to specific gravity of Spartan Pearl and Norchip. Table 1. Effects of Potassium Rate and Source on Spartan Pearl Montcalm Research Farm 1989 (134 days) Percent size distribution Percent size distribution <2 Percent size distribution 2-3 1/4 Percent size distribution >3 1/4 Percent size distribution PO SP.GR. Chip Color % % Petiole Petiole K N Source/K20 (lbs) Check KCl/100 KCL/200 KCL/300 K2S04/100 K2S04/200 K2S04/300 Yield (cwt/A) US#1 Yield (cwt/A) Total 457 442 480 492 473 499 502 539ab 506 b 562a 562a 540ab 589a 576a Average 478 553 #1 86 87 85 88 88 85 87 87 13 12 14 11 12 13 10 80 82 75 77 79 78 78 6 6 10 11 9 7 9 1 0 0 1 0 2 3 1.082a 1.080ab 1.075bc 1.072c 1.081a 1.080ab 1.078ab 66 66 64 67 62 63 60 3.20a 6.56b 7.84ab 3.08ab 7.79ab 2.67ab 2.55b 9.97a 7.60ab 3.16ab 7.65ab 3.06ab 8.48ab 3.06ab empty table cell 13 empty table cell 80 empty table cell 6 empty table cell 1 1.078 1.082a empty table cell 66 empty table cell 6.59b empty table cell 3.20 6 6 9 9 8 8 9 10 1 1 1 0 2 0 1 2 1.078b 64 1.082a 1.076b 1.080ab 1.082a 1.081ab 1.078bc 1.075c 66 66 65 62 64 64 64 8.22a 6.59b 2.93 3.20 2.76 8.54a 7.91ab 3.09 6.59b 3.20 7.71ab 3.12 7.72ab 2.86 2.81 9.22a 78 78 81 76 78 Check vs K Check +K Check vs K Check vs K source Check 457 KC1 Check vs K source K2SO4 Check vs K source 457 Check vs K amount Check 457 539 86 481 556 87 12 78 539 86 13 80 471 491 543 568 87 87 12 12 539 86 13 80 K (100) Check vs K amount K (200) Check vs K amount K (300) Check vs K amount 458 490 496 523 576 569 88 85 88 12 14 10 Previous crop: Rye Initial soil test K: 303 lbs/a All K applied broadcast before planting Planting date: 5.5.89 Harvest date: 9.12.89 Table 2. Effects of Potassium Rate and Source on Norchip Montcalm Research Farm 1989 (134 days) Source/K20 (lbs) Check KC1/100 KCL/200 KCL/300 K2S04/100 K2S04/200 K2S04/300 Yield (cwt/a) US#1 Yield (cwt/a) Total 283 258 271 271 285 268 280 355 340 364 351 377 357 379 Average 274 360 Check vs K Check 283 355 +K Check vs K Check vs K source Check 272 361 355 283 80 80 #1 80 76 74 77 76 75 74 76 Percent size distribution Percent size distribution <2 Percent size distribution 2-3 1/4 Percent size distribution >3 1/4 Percent size distribution PO SP.GR. Chip Color % % Petiole Petiole K N 11 16 14 14 15 15 16 77 74 68 74 73 72 72 3 2 6 3 3 3 2 9 8 12 9 9 9 10 1.078a 1.078ab 1.072bc 1.071c 1.079a 1.078a 1.075ab empty table cell 11 empty table cell 77 empty table cell 3 empty table cell 9 1.076 1.078a 65 60 63 62 64 63 66 63 62 65 65 5.61b 3.49a 8.08a 3.40a 8.94a 2.70b 8.87a 2.70b 9.09a 3.64a 8.70a 3.13ab 8.61a 3.43a 8.26 5.61b empty table cell 3.49 8.70a 5.61b 3.17 3.49 75 15 11 77 1.074b 1.078a KCl Check vs K source K2SO4 Check vs K source 283 Check vs K amount Check 267 278 352 371 75 75 15 15 355 80 11 77 K (100) Check vs K amount K (200) Check vs K amount K (300) Check vs K amount 272 270 275 359 360 365 76 75 75 16 14 15 72 72 72 74 70 72 3 3 3 4 3 5 5 3 10 9 10 10 9 9 11 10 1.074b 62 1.077ab 64 1.078ab 65 8.60a 8.80a 5.61c 2.93 3.40 3.49 1.079a 1.075bc 1.073c 62 63 64 8.60ab 3.52 8.82a 2.92 8.69ab 3.07 Previous crop: Rye Initial soil test K: 303 lbs/a All K applied broadcast before planting Planting date: 5.5.89 Harvest date: 9.12.89 Table 3. Post Harvest Evaluations - Spartan Pearl. After Cookingy Darkening After Cookingy Darkening Source/K2O (lbs) 11/28/89 12/4/89 Remarks Blackspot Percent Percent Blackspot Check Bruisedz Check Kcl/100 Kcl/200 Kcl/300 K2SO4 /100 K2SO4 /200 K2S04/300 1.3 2.1 1.7 1.8 1.8 1.4 1.4 1.5 1.5 2.0 1.5 1.8 1.3 1.8 sloughed on boiling some sloughing no sloughing no sloughing some sloughing good good 20 15 0 0 10 10 5 85 65 50 40 70 65 55 y Rating based on a scale of 1-5; 1 = no color, 5 = severe darkening (black overall) one hour after boiling. z Tubers removed from 40°F storage and bruised artificially in a manually driven wooden drum and peeled after 48 hours. Table 4. Post Harvest Evaluations - Norchip. Source/K2O (lbs) After Cookingy Darkening Percent Blackspot Blackspot Percent Check Bruisedz Check Kcl/100 Kcl/200 Kcl/300 K2SO4 /100 K2SO4 /200 K2SO4 /300 1.0 1.0 1.0 1.3 1.0 1.2 1.2 15 10 15 5 5 0 0 95 70 45 45 75 45 50 y Rating based on a scale of 1-5; 1 = no color, 5 = severe darkening (black overall) one hour after boiling. z Tubers removed from 40°F storage and bruised artificially in a manually driven wooden drum and peeled after 48 hours. MANAGEMENT PROFILES OF RUSSET NORKOTAH, SNOWDEN (W855) AND SAGINAW GOLD G.H. Silva, R.W. Chase and R.B. Kitchen Funding Federal Grant Introduction In 1989, three promising varieties for Michigan, Russet Norkotah, Snowden (W855) and Saginaw Gold were selected to study the optimum nitrogen and spacing requirements for optimum yield and quality. Russet Norkotah has excellent potential for the count-pack market because of its smooth appearance. In some years, under standard cultural practices, it has a tendency for poor sizing resulting in a higher percent of tubers less than 4 oz. Snowden (W855) and Saginaw Gold have exceptional chipping qualities and a potential for expansion in acreage in Michigan. Snowden possesses high solids, minimal internal defects and most importantly, the capacity to chip out of 45°F storage. In Michigan, it has experienced problems of small sizing and below average yields. Saginaw Gold is a yellow fleshed potato with exceptional chip color and good tuber yield, however, its marginal processing dry matter could restrict its chip marketability in a year of excess potato production. The management practices currently used for new releases are generally based on standard practices adapted for more traditional cultivars. Procedure In 1989, three levels of nitrogen (100, 150 and 200 lbs/a) and three within row spacings (6, 9 and 12 inches for Russet Norkotah and Saginaw Gold; 9, 12 and 15 inches for Snowden) were investigated. Rows were spaced 34 inches apart. The treatments were studied in a split-plot design with four replications. A cost/revenue analysis for each treatment combination was used to further establish the optimum nitrogen and spacing requirements in relation to tuber yield and quality. The trials were planted on May 8. The previous crops were dry beans plowdown in fall 1988 and rye plowdown in spring 1989. The fertilizer application with the planter was 500 lbs/a 15-10-15 + 4% Mg. A sidedressing of urea providing 25 lbs N/a (for treatments receiving 100 lbs N) and 75 lbs N/a (for treatments receiving 150 and 200 lbs N) were applied on June 18. Another sidedressing of urea providing 50 lbs N was applied on July 5 to the treatment receiving 200 lbs N. Petioles for nitrogen analysis were taken on August 7. Saginaw Gold was harvested on August 30, Russet Norkotah September 11 and Snowden September 15. Results Russet Norkotah: The results are summarized in Tables 1, 2, 3 and 4. Nitrogen effects were significant for U.S. No. 1 yield and spacing effects were significant for total yield (Table 1). The highest U.S. No. 1 tuber yield was obtained at 200 lbs N and 9 inch spacing. The highest total yield was obtained at 200 lbs N and 6 inch spacing. Size distribution of potatoes indicated that the highest percent of tubers under 4 oz. was produced at 100 lbs N and 6 inch spacing. The percent of tubers over 10 oz. tended to increase with increments of spacing and nitrogen. Although not significantly different, specific gravity was higher at lower nitrogen and closer spacings. Petiole N content was significantly higher at higher nitrogen levels. The U.S. No. 1 yields for the nine treatment combinations (Figure 1) clearly illustrated that in 1989 Russet Norkotah performed well at intermediate to high nitrogen levels and at intermediate spacings. The total number of tubers set per plant (Table 2) was not influenced by the level of nitrogen but were influenced by spacing. Average total tuber weight increased with increments of nitrogen and spacing, but the range was higher among spacing treatments. Post harvest evaluations indicated that nitrogen and spacing treatments had no significant effects on after cooking darkening and blackspot incidence (Table 3). Nitrogen and seed costs/revenue analysis (Table 4) showed that the highest average net revenues were obtained at 150 lbs N and 9 inch spacings. Snowden (W855): The data from Snowden is summarized in Tables 5, 6, 7 and 8. Both nitrogen and spacing effects were significant for U.S. No. 1 yield (Table 5). Only nitrogen effects were significant for total yield. The highest U.S. No. 1 tuber yield was obtained at 200 lbs N and 15 inch spacing. Size distribution of potatoes indicated that the highest percent of tubers below 2 inch diameter was produced at 100 lbs N and 9 inch spacing. The percent of tubers over 3 1/4 inch diameter increased from 100 to 150 lbs N and from 9 to 12 inch spacing, but the increment from 150 to 200 lbs N and 12 to 15 inch spacing was small. Specific gravity was significantly higher at 12 and 15 inches compared to 9 inches. These results indicate that Snowden has a favorable response to higher N levels than the variety Atlantic. As expected, petiole N content was significantly higher at higher N levels. The U.S. No. 1 yields for the nine treatment combinations (Figure 2) clearly illustrated the preference of Snowden for higher nitrogen and spacing levels. The total number of tubers set per plant and the average tuber weight (Table 6) indicated Snowden to be a heavy setter (about 12 tubers per plant). Under these conditions, adequate nitrogen and space between plants should be provided for proper sizing of tubers. Post harvest evaluations indicated that nitrogen and spacing treatments produced no substantial differences in chip color, after cooking darkening and blackspot. The percent blackspot in the artificially bruised tubers was high compared to Russet Norkotah. Nitrogen and seed costs/revenue analysis (Table 8) showed that the highest average net revenues were derived from 200 lbs N and 15 inch spacings. The tubers from this experiment are being stored at 45° and 50°F for further chip evaluations. Saginaw Gold: Significant differences in U.S. No. 1 yield were obtained for both nitrogen and spacing effects (Table 9). Size distribution of potatoes indicated that the highest percent of tubers under 2 inch diameter was produced at 100 lb N and 6 inch spacing. The percent of tubers over 3 1/4 inches was low in all treatments. Specific gravity was highest at the lowest N and spacing, but not significantly different from other treatments. The U.S. No. 1 yields (Figure 3) produced by the treatment combinations indicated that Saginaw Gold performed well at intermediate to high nitrogen and at intermediate spacing levels. The total number of tubers set per plant (Table 10) was not influenced by the level of nitrogen but was affected by the spacing. The average set was lower than Snowden but higher than Russet Norkotah. Average tuber weight increased with increments of nitrogen and spacing. Nitrogen and seed costs/revenue analysis (Table 11) showed that the highest average net revenues were obtained at 200 lbs N and 9 inch spacing. Table 1. RUSSET NORKOTAH : Management Profile Montcalm Research Farm, Michigan State University 1989 (134 days) rogen Spacing s/a) rogen Spacing (inches) Yield(cwt/a) Yield(cwt/a US#1 )Total 00 .50 .50 00 .50 00 .00 .00 .00 9 9 12 6 6 12 12 9 6 380a 475ab 492a 375ab 46labc 365ab 505a 364ab 345abc 495a 341abc 418 c 339abc 432 bc 459abc 326bc 466abc 313c 467 345 Average empty table cell rogen effects - Significant for US #1 Yield 00 50 00 rogen effects - Significant for US #1 Yieldrogen effects - Significant for US #1 Yieldrogen effects - Significant for US #1 Yieldrogen effects - Significant for US #1 Yield empty table cell 326 b 72 empty table cell 362a 75 empty table cell 361a 78 452 482 466 #1 80 76 79 72 70 82 78 71 67 75 16 22 20 27 30 16 20 27 32 66 61 60 63 62 59 65 63 62 empty table cell rogen effects - Significant for US #1 Yield 26 24 19 empty table cell rogen effects - Significant for US #1 Yield 63 61 63 cing effects - Significant for total yields cing effects - Significant for total yields empty table cell6 empty table cell9 empty table cell12 cing effects - Significant for total yields cing effects - Significant for total yields 341 361 348 488a 475a 437 b cing effects - Significant for total yields cing effects - Significant for total yields cing effects - Significant for total yields cing effects - Significant for total yields 69 76 80 30 22 18 63 63 61 Percent size distribution Percent size distribution Percent size distribution <4 Percent size distribution 4-10 Percent size distribution PO SP.GR. Petiole N % 2 1 1 1 0 1 2 1 1 1.068 1.067 1.068 1.068 1.070 1.067 1.069 1.070 1.071 3.68a 2.80 bc 2.73 bc 3.67 a 2.92 b 3.67a 2.35 cd 2.37 cd 2.16 d >10 14 15 19 9 8 23 13 8 5 empty table cell rogen effects - Significant for US #1 Yield empty table cell rogen effects - Significant for US #1 Yield 1.069 2.93 rogen effects - Significant for US #1 Yield rogen effects - Significant for US #1 Yield 9 14 15 7 13 19 1 0 1 1.070 1.068 1.067 2.29 c 2.82 b 3.65a cing effects - Significant for total yields cing effects - Significant for total yields cing effects - Significant for total yields 0 1 1 1.070 1.069 1.067 2.89 2.95 2.92 Table 2. RUSSET NORKOTAH : MANAGEMENT PROFILE 1989 Tuber Number and Size Treatment Marketable Marketable Total Total # tubers/plant Av.Tuber Weight (gm) # tubers/plant Av.Tuber weight (gm) Nitrogen (lbs/a) 100 150 Nitrogen (lbs/a) 200 Nitrogen (lbs/a) Spacing (inches) 6 9 Spacing (inches) 12 Spacing (inches) 4.0 3.0 4.0 4.0 4.5 5.3 176 172 181 193 188 191 7.5 6.3 7.6 6.8 7.8 8.3 133 119 131 147 144 151 Table 3. Post Harvest Evaluations - Russet Norkotah Nitrogen Spacing After Cookingy Darkening Percent Blackspot Percent Check Blackspot Bruisedz 100 100 100 150 150 150 200 200 200 6 9 12 6 9 12 6 9 12 1.0 1.0 1.5 1.0 1.0 1.5 1.0 1.0 1.5 10 5 15 10 5 5 10 15 10 25 15 20 55 25 55 45 55 40 y Rating based on a scale of 1-5; 1 = no color, 5 = severe darkening (black overall) one hour after boiling.z Tubers removed from 40°F storage and bruised artificially in a manually driven wooden drum and peeled after 48 hours. Table 4. Management Profile : RUSSET NORKOTAH 1989 Nitrogen and Spacing Costs/Acre N Applied (lbs/ac) N +Appl'na cost ($) Spacing (inches) Seedb Cost ($) N + Seed Cost ($) Yield (cwt/ac) A 52 38 38 52 38 52 24 24 24 200 150 150 200 150 200 100 100 100 B 174 174 131 261 261 131 131 174 261 A+B 226 212 169 313 299 183 155 198 285 9 9 12 6 6 12 12 9 6 Revenuec ($) c Net ($) C- (A+B) 380 375 365 364 345 341 339 326 313 2510 2484 2430 2392 2265 2276 2238 2140 2041 2284 2272 2261 2079 1966 2093 2083 1942 1756 Nitrogen 100, 150, and 200 lbs applied in 2,3 and 4 applications. aNitrogen cost = $ 0.20/lb. Cost per application = $ 3.00/ac. bSeed cost = $7.00/cwt cRevenue on the basis of $ 6.50/cwt (4-10 oz) and $ 7.00/cwt (>10 oz) Table 5. SNOWDEN (W855) : Management Profile Montcalm Research Farm, Michigan State University 1989 (140 days) itrogen Spacing lbs/a) itrogen Spacing (inches) 200 200 200 150 150 150 100 100 100 15 12 9 15 12 9 15 12 9 Yield (cwt/a) Yield (cwt/a) US #1 Total 445a 428ab 425ab 425ab 388bc 360cb 343cb 323de 295e 493ab 480abc 501a 460bcd 441d 446cd 396e 402e 403e empty table cellAverage 381 447 #1 91 89 85 92 88 81 87 80 73 85 Percent size distribution Percent size distribution <2 Percent size distribution 2-3 1/4 Percent size distribution >3 1/4 Percent size distribution PO SP.GR. Petiole N % 6 10 13 8 12 18 11 19 25 79 78 82 84 81 76 80 77 73 12 10 4 8 7 5 7 3 0 2 2 2 0 0 1 2 0 1 1.083abd 3.4 a 3.3 a 1.086ab 1.086a 3.4 a 2.6 b 1.085ab 2.3 bc 1.085ab 2.3 bc 1.085ab 1.083abc 2.0 d 1.083 bc 2.1 cd 1.082 c 2.0 d empty table cell empty table cellempty table cellempty table cell 1.084 2.6 itrogen effects- Significant for US #1 and Total Yield itrogen effects- Significant for US #1 and Total Yielditrogen effects- Significant for US #1 and Total Yield itrogen effects- Significant for US #1 and Total Yield itrogen effects- Significant for US #1 and Total Yield 80 100 87 150 88 200 empty table cell 320c empty table cell 392b empty table cell 432 a 400c 449b 491 a itrogen effects- Significant for US #1 and Total Yield 18 13 10 pacing effects- Significant for US #1 Yieldpacing effects- Significant for US #1 Yield empty table cell9 empty table cell12 empty table cell15 pacing effects- Significant for US #1 Yieldpacing effects- Significant for US #1 Yield pacing effects- Significant for US #1 Yield 79 360b 86 379ab 90 406a 450 442 453 pacing effects- Significant for US #1 Yield 19 14 8 pacing effects- Significant for US #1 Yield 77 78 81 3 8 9 1 1 2 1.084 1.085 1.084 2.6 2.5 2.6 itrogen effects- Significant for US #1 and Total Yielditrogen effects- Significant for US #1 and Total Yielditrogen effects- Significant for US #1 and Total Yield itrogen effects- Significant for US #1 and Total Yield itrogen effects- Significant for US #1 and Total Yield 77 80 79 3 7 9 1.082b 1.085 a 1.085 a 1 0 2 pacing effects- Significant for US #1 Yield 2.0c 2.4b 3.4 a pacing effects- Significant for US #1 Yield pacing effects- Significant for US #1 Yield pacing effects- Significant for US #1 Yield Table 6. SNOWDEN : MANAGEMENT PROFILE 1989 Tuber Number and Size Treatment Marketable Marketable Total Total # tubers/plant Av. Tuber Weight (gm) # tubers/plant Nitrogen (lbs/a) 100 150 Nitrogen (lbs/a) 200 Nitrogen (lbs/a) Spacing (inches) 9 6.6 6.9 12 Spacing (inches) 15 Spacing (inches) 8.3 10.5 8.6 10.8 120 117 130 138 130 145 11.6 11.1 11.3 12.9 11.5 13.9 Av. Tuber weight (gm) 89 91 111 121 112 123 Table 7. Post Harvest Evaluations - Snowden (W855). Nitrogen Spacing After Cookingy Darkening Percent Blackspot Percent Blackspot Check Bruisedz 100 100 100 150 150 150 200 200 200 9 12 15 9 12 15 9 12 15 1.0 1.0 1.5 1.0 1.5 1.5 1.0 1.5 1.5 5 15 5 20 5 10 5 10 10 45 80 70 55 80 55 75 60 65 y Rating based on a scale of 1-5; 1 = no color, 5 = severe darkening (black overall) one hour after boiling. z Tubers removed from 40°F storage and bruised artificially in a manually driven wooden drum and peeled after 48 hours. Table 8. Management Profile : SNOWDEN(W855) Nitrogen and Spacing Costs/Acre N Applied (lbs/ac) N +Appl'na cost ($) Spacing (inches) Seedb Cost ($) N + Seed Cost ($) Yield (cwt/ac) A 52 52 52 38 38 38 24 24 24 200 200 200 150 150 150 100 100 100 B 104 131 174 104 131 174 104 131 174 A+B 156 183 226 142 169 212 128 155 198 15 12 9 15 12 9 15 12 9 Revenuec ($) C Net ($) C-(A+B) 445 428 425 425 388 360 343 323 295 2927 2810 2773 2776 2539 2352 2238 2106 1917 2771 2627 2547 2634 2370 2140 2110 1951 1719 Nitrogen 100, 150, and 200 lbs applied in 2, 3 and 4 applications. aNitrogen cost = $ 0.20 /lb. Cost per application = $ 3.00/ac. bSeed cost = $7.00/cwt cRevenue on the basis of $ 6.50/cwt (2-31/4") and $ 7.00/cwt (>31/4") Table 9. SAGINAW GOLD : Management Profile Montcalm Research Farm, Michigan State University 1989 (130 days) trogen Spacing bs/a) trogen Spacing (inches) Percent size Distribution Percent size Distribution <2 Percent size Distribution 2-31/4 Percent size Distribution >31/4 Percent size Distribution PO SP.GR. Petiole N % 200 150 200 150 150 200 100 100 100 empty table cell (cwt/a) Yield Yield (cwt/a) US#1 Total 361a 357ab 352ab 343ab 340ab 330ab 329ab 322bc 289c 446a 443a 415bc 416bc 392c 391c 397bc 423a 361d 6 6 9 9 12 12 9 6 12 Average 335 409 trogen effects- Significant for US #1 Yield trogen effects- Significant for US #1 Yieldtrogen effects- Significant for US #1 Yield trogen effects- Significant for US #1 Yield empty 100 table 150 empty cell 200 empty table table cell cell Spacing- Significant for Yield effects 313 b 347a 348a 393 417 417 Spacing- Significant for Yield effects empty table empty cell empty table table cell cell 6 9 12 Spacing- Significant for Yield effectsSpacing- Significant for Yield effects 347a 437a 341a 409 b 320 b 381 c #1 81 81 85 83 87 84 83 76 80 82 17 17 13 13 9 13 13 23 16 80 81 85 82 83 79 83 76 79 empty table cell empty table cell trogen effects- Significant for US #1 Yield trogen effects- Significant for US #1 Yield 17 13 13 80 84 83 trogen effects- Significant for US #1 Yield 79 82 81 Spacing- Significant for Yield effects 79 84 84 Spacing- Significant for Yield effectsSpacing- Significant for Yield effects 19 13 12 79 83 80 1 0 0 1 4 6 0 0 2 2 3 2 4 5 1 4 2 4 1.077 1.077 1.076 1.076 1.075 1.075 1.079 1.079 1.076 2.60bc 2.20d 2.87a 2.55c 2.45c 2.83ab 1.86 e 1.87 e 1.86 e empty table cell trogen effects- Significant for US #1 Yield empty table cell trogen effects- Significant for US #1 Yield 1.077 2.34 trogen effects- Significant for US #1 Yield trogen effects- Significant for US #1 Yield 0 2 3 3 4 2 1.078 1.076 1.076 1.86 c 2.40 b 2.77a Spacing- Significant for Yield effects Spacing- Significant for Yield effects Spacing- Significant for Yield effects Spacing- Significant for Yield effects 0 1 4 2 3 4 1.078 1.077 1.076 2.22 b 2.43a 2.38a Table 10. SAGINAW GOLD : MANAGEMENT PROFILE 1989 Tuber Number and Size Treatment Marketable ble Marketa Total Total # tubers/plant Nitrogen (lbs/a) 100 150 Nitrogen (lbs/a) 200 Nitrogen (lbs/a) Spacing (inches) 6 9 Spacing (inches) 12 Spacing (inches) 5.9 6.0 6.1 4.8 7.2 7.0 Av. Tuber Weight (gm) 120 121 129 136 122 140 # tubers/plant 8.2 7.3 8.2 8.5 9.4 9.6 Av. Tuber weight (gm) 102 96 111 116 109 121 Table 11. Management Profile : Saginaw Gold 1989 Nitrogen and Spacing Costs/Acre Applied lbs/ac) N +Appl'na cost ($) Spacing (inches) Seedb Cost ($) N + Seed Cost ($) Yield (cwt/ac) A 52 38 52 38 38 52 24 24 24 200 150 200 150 150 200 100 100 100 B 261 261 174 174 131 131 174 261 131 A+B 313 357 352 343 340 330 329 322 289 6 6 9 9 12 12 9 6 12 361 357 352 343 340 330 329 322 289 Revenuec ($) C Net ($) C-(A+B) 2349 2321 2288 2252 2216 2240 2139 2093 1881 2033 2022 2062 2040 2047 2057 1941 1832 1624 Nitrogen 100, 150, and 200 lbs applied in 2,3 and 4 applications. aNitrogen cost = $ 0.20 /lb. Cost per application = $ 3.00/ac. bSeed cost = $7.00/cwt cRevenue on the basis of $ 6.50/cwt (2-31/4") and $ 7.00/cwt (>31/4") Figure 1. Russet Norkotah - Management Profile 1989. Figure 2. Snowden (W855) - Management Profile 1989. Figure 3. Saginaw Gold - Management Profile 1989. Funding Federal Grant IRRIGATION, NITROGEN AND SUPPLEMENTARY CALCIUM IN RELATION TO SPECIFIC GRAVITY, TUBER YIELD AND INTERNAL DEFECTS OF ATLANTIC AND RUSSET BURBANK G.H. Silva, R.W. Chase and R.B. Kitchen Introduction Quality parameters such as specific gravity and internal defects are of crucial importance particularly to processing potatoes. A study initiated in 1987 was continued in 1989 to investigate the role of irrigation and nitrogen management and supplementary calcium on specific gravity and internal defects of Atlantic and Russet Burbank. Procedure A split-plot design with four replications was used to evaluate three irrigation levels and four calcium treatments in Atlantic, and three irrigation levels and two nitrogen levels in Russet Burbank. Irrigation was used as the main plot treatment and was applied through a drip irrigation system. The three irrigation treatments included (a) irrigation scheduling, based on Michigan State University potato irrigation scheduling program, (b) over-irrigation, where the plots received an excess of 5 inches of water more than the irrigation schedule, applied in five separate irrigations during the month prior to harvest and (c) irrigation water was withheld after August 1. In 1989 the irrigation schedule recommended the application of 8.5 inches of water throughout the growing season. The total rainfall during the season was 14.5 inches. Supplementary calcium tested for only Atlantic was specifically directed towards controlling internal brown spot (IBS). Treatments included 750 lbs gypsum/a applied (a) at planting, (b) at hilling, (c) split at planting and hilling and (d) untreated. Most of the literature suggests that localized calcium deficiency in the tubers as the primary cause of this disorder, with environmental factors modifying the expression of the disease. In light of the relative immobility of calcium within the plant, the intention was to place the gypsum in close proximity to the stolons and developing tubers. It has been reported that only very little calcium absorbed by the root system is able to reach the developing tubers. For Russet Burbank, in a separate experiment, the two levels of nitrogen tested were 150 and 225 lbs/a. The trials were planted on May 8 and the previous crops were rye and dry beans. Initial soil tests showed a pH of 5.4 and a calcium level of 480 lbs/a. The fertilizers applied were 500 lbs/a of 15-10-15 + 4% Mg with the planter and a sidedressing of 75 lbs N/a on June 15. A second sidedressing of 75 lbs N/a was applied to Russet Burbank on July 6. Petiole samples for nutrient analysis were taken on August 5 and the trial was harvested on September 22. Following harvest, 100 tubers (25 from each replication) were cut to determine the frequency of IBS and hollow heart in Atlantic. Tuber peel samples were sent to MSU Soil Testing Laboratory for calcium analysis. Results The results obtained with Atlantic and Russet Burbank are summarized in Tables 1 and 2, respectively. In both varieties, over-irrigation resulted in a significant decrease in specific gravity. Although over-irrigation produced slightly higher tuber yields, it was also associated with the highest frequency of hollow heart. In Atlantic, gypsum treated plots showed a slight decrease in the frequency of IBS from 7.8% for untreated to an average of 4.4% for the three gypsum treatments. The gypsum treatments produced no significant effects on tuber yield, specific gravity and hollow heart. In Russet Burbank, 225 lbs N/a produced significantly higher U.S. No. 1 tuber yield compared with 150 lbs N. However, higher nitrogen levels were associated with a decrease in specific gravity, and an increased hollow heart. Petiole nitrogen content was significantly higher at 225 lbs/a N. It is evident that gypsum application was only partially effective in reducing the incidence of IBS. Based on studies at the Montcalm Research Farm, gypsum has not eliminated the problem of IBS nor has it consistently reduced IBS to an acceptable level. Petiole and peel calcium levels in the gypsum treated plants showed only slight increases in the uptake of calcium compared to the untreated (Table 1). This may account for the lack of a significant response to applied gypsum in controlling IBS. Soil samples collected from the tuber zone in the row following harvest indicated that the gypsum application had no influence on the soil pH. Soil calcium levels were higher in the gypsum treated plots compared to the untreated. Post harvest quality evaluations showed that irrigation, calcium and nitrogen levels tested in the trial had no significant effects on after cooking darkening and blackspot susceptibility (Tables 3 and 4). The results from irrigation treatments substantiate the importance of irrigation management as a tool to increase specific gravity of Atlantic and Russet Burbank. Traditionally, Michigan receives excessive amounts of rainfall late in the growing season and it is not uncommon for this rain to occur when the crop was irrigated on the same or previous day. It appears that reducing irrigation, particularly during the month prior to harvest, would lead to optimizing dry matter and reduced hollow heart. Any increased tuber yields achieved by an over supply of water at this stage appears to be insignificant. Harvest management, which avoids long delays after the crop has matured and the vines have senescenced is desired, particularly if the soils are wet. In view of the fact that gypsum has failed to produce the desired results, particularly for the control of IBS and that only slight increases in the uptake of Ca was achieved by the gypsum treated plants, a preliminary trial was conducted using alternate calcium sources to evaluate their effectiveness for controlling IBS. In addition to Atlantic, MS401-6 seedling was used in this trial because of its high susceptibility to IBS. Gypsum was applied at two rates, 750 and 1500 lbs/a. All calcium treatments were applied to the furrow at planting, except for the wet emulsion treatment which was used as a seed piece treatment. Results indicated that none of the calcium sources produced acceptable IBS control in the susceptible seedling MS401-6 (Table 5). Although anhydrous CaSO4 produced the lowest level of IBS in Atlantic, the results did not establish any one superior calcium source for IBS control. None of the calcium sources applied at planting produced adverse effects on plant stands. The chloride source resulted in the lowest specific gravity with both varieties. Table 1. Dry Matter and Internal Defects : Atlantic Montcalm Research Farm 1989 (138 days) Treatment Tuber Yield (cwt/a) Tuber Yield (cwt/a) Total US#1 SpGr Pet- iole Ca Chip Color Peel Ca % (g/kg) HH % IBS % Soi Soil pH l CA (lb/a) Zero-Irrigation Irrigation Schedulin Over-irrigation Gypsum: 418 b 463 b 441a 484a 496a 447a 480 432 (1)0 438 478 : (2) 750(P) Gypsum : (3) 375P+375H 435 483 Gypsum 483 440 : (4) 750(H) Gypsum 1.088a 1.086a 1.083 b 1.086 1.086 1.087 1.085 60 1.06 7.6 7.8 64 1.05 62 0.99 7.5 61 0.94 b 7.5 62 1.07a 7.9 63 1.10a 7.8 64 1.04a 7.6 15 18 24 21 17 20 19 5.0 57 4.4 5.0 58 6.1 5.1 57 5.3 5.0 53 7.8 4.1 5.1 59 5.0 57 3.6 5.0 61 5.4 Planting date: May 8, 1989 Harvest date: Sep 22, 1989 Previous crop: Rye Initial soil test Ca: 480 lbs/a Table 2. Dry Matter and Internal Defects : Russet Burbank Montcalm Research Farm 1989 (136 days) reatment Tuber Yield Tuber Yield (cwt/a) (cwt/a) US#1 Total % US #1 ero-Irrigation rrigation Scheduling ver-irrigation itrogen: 150 lbs 225 " itrogen: 465 302 477 324 331 493 303a 469 338 b 488 65 68 68 64 70 Sp. Gr. 1.082a 1.082a 1.078 b 1.082a 1.079 b * HH % Petiole N % 15 23 30 21 26 3.0 3.3 2.7 2.7 b 3.3a Hollow heart in oversized (l0oz) tubers Planting date: May 8, 1989 Harvest date: Sep 22, 1989 Previous crop: rye First top dressing: 6/15/89 urea (75 lbs N/a) Second top dressing: 7/6/89 urea (75 lbs N/a) Table 3. Post Harvest Quality Evaluation - Atlantic. Treatment Zero irrigation Irrigation Scheduling Over irrigation Gypsum (1) 0 (2) 750 (P) Gypsum (3) 375 (P) + 375 (H) Gypsum (4) 750 (H) Gypsum After Cookingy Darkening Percent Blackspot Blackspot Percent Check Bruisedz 1.1 1.1 1.3 1.0 1.2 1.2 1.3 23 18 15 20 13 18 20 38 41 39 43 45 35 33 yRating based on a scale of 1-5; 1 = no color, 5 = severe darkening (black overall). zTubers removed from 40°F storage and bruised artificially in a manually driven wooden drum for 10 revolutions and peeled after 48 hours. Table 4. Post Harvest Quality Evaluation - Russet Burbank. Treatment Zero irrigation Irrigation scheduling Over irrigation Nitrogen 150 lbs 225 lbs Nitrogen After Cookingy Darkening Percent Blackspot Percent Blackspot Check Bruisedz 1 1 1.5 1 1.5 20 13 18 19 13 62 65 65 65 63 y Rating based on a scale of 1-5; 1 = no color, 5 = severe darkening (black overall). z Tubers removed from 40°F storage and bruised artificially in a manually driven wooden drum for 10 revolutions and peeled after 48 hours. Table 5. EFFECTS OF CALCIUM SOURCE ON YIELD AND INTERNAL QUALITY OF ATLANTIC AND MS401-6 MONTCALM RESEARCH FARM MICHIGAN STATE UNIVERSITY 1989 Source Cultivar Dose (lbs/a) Plant Stand (%) * US#1 Total (cwt/a) (cwt/a) % #1 * IBS (%) SPGR pH CA 750 750 750 1500 1500 750 Atlantic MS401-6 Atlantic MS401-6 Atlantic MS401-6 Atlantic MS401-6 US GYPSUM US GYPSUM US GYPSUM US GYPSUM AGRICO CaS04 AGRICO CaS04 Anhydrous CaS04 750 Anhydrous CaS04 Wet Emulsion(US Gypsum) empty table cell Atlantic Wet Emulsion(US Gypsum)empty table cellMS401-6 Calcium Chloride 750 Atlantic MS401-6 Calcium Chloride Control Atlantic MS401-6 Control 750 750 0 0 93 90 90 93 90 97 93 97 93 90 93 97 97 97 314 231 311 246 341 257 307 266 320 239 358 289 326 224 389 276 369 276 368 277 352 282 360 259 401 302 371 258 81 84 84 89 93 92 87 94 88 92 89 95 88 87 6 13 5 8 6 10 3 14 8 13 4 11 10 15 1.090 5.4 800 1.076 5.6 800 1.087 5.4 838 1.080 5.3 824 1.089 5.4 762 1.075 5.3 686 1.090 5.6 800 1.079 5.4 762 1.090 5.5 724 1.078 5.5 762 1.080 5.6 762 1.073 5.5 724 1.087 5.4 648 1.076 5.4 648 * LSD (0.05) for US#l yield = 12.8 LSD (0.05) for IBS = 5.4 Wet emulsion from US Gypsum was applied as a seed piece treatment Variety MS401-6 was used because of its high susceptibility to IBS in previous trials. However, during the 1989 season the overall IBS observed in both Atlantic and MS401-6 was much lower than in 1988. For this reason, the test did not establish any one superior CA source for IBS control. None of the CA sources adversely affected the plant stand. Funding Federal Grant MICHIGAN STATE UNIVERSITY POTATO BREEDING PROGRAM David S. Douches Department of Crop and Soil Sciences Cooperators: R.W. Chase, R. Hammerschmidt, G. Silva, J. Cash I. Varietal Development In 1989, 20,000 single hills were evaluated at the Clarksville Horticultural Experiment Station (CHES). These plants represented 150 different crosses between advanced lines and/or varieties. Thirty-five of the crosses were between russet/long white types, 114 crosses were between round white/yellow flesh types, and 1 cross for red types. Visual selection for tuber set, internal quality, external appearance was made. Approximately 300 single hills (1.5% selection rate) were selected and advanced for further testing in 1990. In the subsequent years, advancement of these seedlings will be based upon scab resistance, specific gravity, cold chipping, storability, internal/external quality and yield. II. Advanced Selections 35 advanced selections from USDA Idaho (3), Maine (5), USDA In 1989, Beltsville (12), Wisconsin (4), New York (1), Minnesota (7) and North Dakota (3) were grown and evaluated at the Montcalm Potato Research Farm. Each line was planted in two replications (23 hills/replication) except F100-1 and A80559-2 (1 replication each). Atlantic and Russet Norkotah were used as standards in the trial. The field was planted May 18 and harvested September 12 (127 days). The plots were mechanically harvested then graded for size distribution, internal defects, external defects, specific gravity. Table 1 summarizes the data from all the lines tested. Tables 2 and 3 list the best 10 lines for US#1 yield and specific gravity, respectively. In November, most of the round types were chipped and fried. This data are reported in Agtron values (model E-10) in Table 1. Additional tubers of these lines were placed in 45°F and 50°F long-term storage (120 days) for further evaluation. These advanced selection were also placed in the replicated scab trial at the Soils Farm, East Lansing (see Potato Scab Research Report). Thirty tubers of each line were classified into 5 categories for percent scab coverage (0, 1, 5, 10, and 25%) and then averaged. Lines with less than 2% scab coverage were considered resistant in the trial. TABLE 1. ADVANCED SELECTION TRIAL 1989. Clone Total %US#1 %A's %>3.25" %<2" 327.7 A79141-3 269.6 AF465-2 348-1 AF845-11 363.4 AF875-15 374.6 AF875-17 288.6 AF879-3 347.1 ATD63-2 363.8 Atlantic B0034-10 208.7 511.3 B0172-15 314.1 b0178-16 B0178034 352.9 336.6 B0202-4 B0234-4 392.3 293.4 B0257-3 B9792-2B 298.1 B9922-11 247.1 B9955-11 335.5 242.4 B9955-33 B9972-2B 294.1 D43 376.7 457.9 J8 MN12823 377.0 MN12828 291.0 294.4 MN12966 303.6 MN13540 277.4 MN13653 MN13740 331.8 284.9 MN9632 NDA2031-2 309.0 NDA2126-6 415.4 216.5 R. Nork 312.4 S465 306 TND22-2 259.7 W231 344.8 F100-1 374 A80559-2 63 45 88 88 81 84 73 87 68 92 80 90 84 82 69 84 67 88 91 78 79 72 84 67 80 64 70 82 69 58 88 56 84 84 66 86 91 63 45 81 87 79 84 73 75 68 77 72 74 84 81 69 75 57 74 76 75 79 68 76 67 79 64 70 80 69 57 75 56 84 84 66 82 73 0 0 06 01 01 0 0 11 0 15 08 15 0 00 0 09 09 13 15 02 00 04 08 0 00 0 0 01 0 00 12 0 0 0 .0 4 17 35 54 07 09 16 14 24 09 28 03 14 08 14 13 29 11 28 05 05 18 18 16 10 21 15 32 29 16 30 40 08 43 12 14 33 12 7 PO 01 00 04 01 02 00 01 02 03 03 04 01 01 03 00 03 03 05 02 02 02 10 05 10 04 02 00 00 0 00 03 0 02 01 0 2 3 HH 2 IBS 2 VD 2 SPGR 3 SCAB 4 AGTRON % Coverage 6 0 1 0 0 0 10 7 0 2 3 7 1 10 0 2 4 1 0 2 1 0 3 0 0 0 0 2 0 1 0 0 0 0 0 2 2 0 0 1 0 0 0 0 0 7 0 7 3 0 0 1 0 1 0 0 0 0 0 2 0 0 3 0 0 0 1 0 0 0 0 0 2 0 0 0 7 1 1 2 0 1 3 0 1 1 0 0 3 8 1 2 1 2 3 0 1 0 0 2 0 4 1 0 6 0 0 2 0 0 0 1.080 1.071 1.067 1.080 1.080 1.082 1.086 1.081 1.077 1.078 1.083 1.081 1.080 1.074 1.086 1.083 1.075 1.078 1.076 1.081 1.064 1.062 1.071 1.070 1.064 1.067 1.063 1.070 1.069 1.069 1.065 1.062 1.075 1.074 1.076 1.080 1.079 - - - 63 65 73 46 61 77 68 73 67 56 65 58 62 - 61 63 63 48 59 65 60 - 62 64 69 62 63 57 - 70 63 64 - 70 2.2 3.0 7.3 11 5.1 12 0.9 3.6 6.5 13 7.5 2.8 5.6 5.0 4.2 6.4 0.5 9.6 20 7.5 1.9 6.4 3.2 10 - - 0.4 7.1 6.5 10 - 4.1 2.2 5.0 5.7 4.6 9.3 1 - cwt/acre 2 - 20 tuber sample 3 - average of 2-3 Kg samples 4 - range of scab coverage: 0.4 (resistant) - 20 (susceptible) ADVANCED SELECTION TRIAL 1989 MONTCALM RESEARCH FARM TEN BEST FOR US #1 YIELD US #1 Yield Total Yield Spec Grav HH IBS VD Type 475 366 333 322 322 319 319 318 308 307 511 415 458 392 363 363 353 364 348 375 1.079 1.065 1.062 1.075 1.080 1.072 1.081 1.082 1.068 1.080 2 0 2 6 0 1 4 1 1 0 0 0 0 0 0 2 3 0 1 0 0 6 0 0 1 1 1 1 7 1 TABLE 2. Family B0172-15 NDA2126-6 J8 B0234-4 AF875-15 MN12823 B0178-34 ATLANTIC AF845-11 AF875-17 TABLE 3. RND RND RND RND RND RND RND RND RND RND Type RND RND RND RND RND RND RND RND RND RUSS Family Spec Grav Total Yield US #1 Yield HH IBS VD TEN BEST FOR SPECIFIC GRAVITY B0257-3 ATD63-2 B9792-2B B0178-16 AF879-3 ATLANTIC B9972-2B B0178-34 AF875-17 A79141-3 1.087 1.086 1.083 1.083 1.082 1.082 1.082 1.081 1.081 1.081 293 347 298 314 288 364 294 353 339 328 205 256 253 253 244 318 231 319 268 208 2 9 2 5 7 1 2 4 0 6 1 0 0 7 0 0 0 3 0 0 3 0 8 1 2 1 2 1 2 0 Funding Federal Grant POTATO SCAB RESEARCH R. Hammerschmidt, D. Douches, M.L. Lacy, K.. Ludlam, C. Wallace, L. Hanson and F. Spooner Research has been carried out with the following objectives: 1. Evaluation of varieties and advanced selections for resistance to scab. 2. Identification of the factors responsible for scab resistance and characterization of the heritability of scab resistance. 3. Evaluation of selected cover crops for influence on scab expression and examination of soils for presence of antagonists. 4. Further characterization of the mode of pathogenicity by the scab pathogen. Disease Resistance Research During the Summer of 1989, named varieties and advanced selections were screened for scab resistance at the MSU soils farm. All seed pieces were inoculated with a Streptomyces scabies spore suspension prior to planting and each hill was amended with S. scabies infected vermiculite. Several lines were shown to have some resistance. We also evaluated several 2x and 4x populations that were segragating for scab resistance. Several of these families exhibited resistance. The results of these evaluations are presented in Tables 1-3. A green house screen for both advanced selections and for seedlings was used to enhance the breeding efforts. Pot tests, using plants grown from seed pieces, were used to augment field evaluations. Based on these results, we have been able to categorize the varieties and selections into resistant or susceptible (Tables 4). We have also used this test to examine the interaction of several varieties with different isolates of S. scabies (Table 5). This work is being carried out to determine tha variability of plant response to different isolates of S. scabies that we have collected in Michigan. Table 6 lists the diploids and tetrapioids that will be investigated by this method. A seedling screen was also developed in order to facilitate determining the resistance of individual progeny. In brief, individual seedlings were transplanted to seedling trays containing soil infested with S. scabies. The results of this evaluation is shown in Table 7. This type of evaluation will be very useful in characterizing resistance as well as providing for an early evaluation step in variety development. We have also continued to look at biochemical factors that are possibly involved in scab resistance. Although we have found that there is a rough correlation between chlorogenic acid levels in the young periderms of 4x varieties (Table 8), we have not seen this relationship in the 2n populations. We have incorporated into our work an evaluation of another plant compound that appears to be in the resistant, but at very low levels (if present at all) in susceptibles. We are currently characterizing this material. The young periderm tissue is also being analyzed for the presence of any unique suberization-related peroxidases. Thus far, resistant varieties that have been examined have an additional acidic isozyme that is not in the susceptibles. This isozyme could prove useful in determining how periderm formation is regulated in resistant varieties as well as provide a new isozyme marker for reisistance. Influence of selected cover crops on scab expression Last year we reported that certain cover crops strongly influenced the expression of scab in the Atlantic variety. We have repeated this work this past Summer. In brief, green manure crops were planted 4 May (the field was in potatoes the previous year and left fallow overwinter). The cover crops were rototilled in on 7 June. Atlantic potatoes were planted on 12 June. Evaluation of the potatoes for scab is presented in Table 9. There were no significant differences between the fallow treatment and any of the cover crops. However, corn, soybean and red clover prior to potatoes resulted in the highest amount of scab. Oriental mustard had the greatest effect in reducing scab. None of the treatments, however, resulted in reduction of disease to 100% marketable level. Soil samples were collected from the red clover and oriental mustard plots to determine if the differences in disease between these two cover crops could be the result of soil borne antogonists of S. scabies. On two dates, antagonists were identified by ability to inhibit growth of the pathogen (Table 10). Two actinomycetes and one bacillus, that still were antagonistic to S. scabies following isolation are being further tested for disease suppression and for characterization of possible antibiotics produced by the antagonists. Pathogenicity characteristics of S. scabies Further study of the ability of S. scabies to produce extracellular enzymes that may be of importance in pathogenesis was cerried out. The pathogen appears to be very good at producing certain types of pectin degrading enzymes. Pathogenic variability does appear to correlate with production of these enzymes. However, the sole importance of these enzymes in infection is doubtful since at least one saprophyte is a more competent enzyme producer. The ability of these organisms (including pathogenic types) to survive as saprophytes may be related to the production of the enzymes. TABLE 1 1989 SCAB TRIAL: RUSSETS Soils Farm East Lansing, Michigan Michigan State University VARIETY RUSSET NUGGET B9922-11 HILITE RUSSET A79239-8 A79141-3 LEMHI RUSSET AF465-2 RED LASODA A74114-4 REDDALE ATLANTIC RUSSET NORKOTAH B7592-1 RIDEAU SUPERIOR A78242-5 A79357-17 MS700-83 ONAWAY A76147-2 A7411-2 B9955-33 % Scab Coverage 0.5 0.5 0.6 1.2 2.2 2.8 3.0 3.3 3.6 3.6 3.6 4.1 4.2 4.4 5.7 7.5 7.8 8.1 8.3 10. 12. 20. Scab rating is based upon a 30 tuber average TABLE 2 1989 SCAB TRIAL: ROUND & RED TYPES Michigan State University VARIETY % Scab Coverage ND791-5R B0178-34 LEMHI RUSSET ND2224-5R MN12823 RED LASODA REDDALE ATLANTIC NDA2126-6 B0257-3 RIDEAU W949-R NTD9-1068-11R F100-1 W948-R TND22-2 B0234-4 AF875-17 ROSE GOLD LA01-38 B0202-4 SUPERIOR W231 B9792-2B B0034-10 MN13740 MS402-7 AF845-11 B9972-2B B0178-16 STUEBEN KANONA MN10874 MS700-83 ONAWAY ND860-2 SOMERSET A80559-2 MN13540 ERAMOSA B9955-11 MN12828 AF875-15 MS401-2 MS402-8 SAG GOLD AF879-3 B0172-15 MS401-1 B9955-33 0.3 2.8 2.8 3.1 3.2 3.3 3.6 3.6 4.0 4.2 4.4 4.5 4.5 4.6 4.7 5.0 5.0 5.1 5.3 5.5 5.6 5.7 5.7 6.4 6.5 7.1 7.2 7.3 7.5 7.5 7.7 8.0 8.0 8.1 8.3 8.3 8.3 9.3 9.5 9.5 9.6 10. 11. 11. 11. 11. 12. 13. 19. 20. TABLE 3 1989 SCAB TRIAL SOILS FARM, EAST LANSING, MI PROGENY DISTRIBUTIONS Overall Scab Rating Overall Scab Rating Overall Scab Rating 2 3 4 Progeny 5 Overall Scab Rating Tested Parents 4 10 10 1 9 8 10 22 8 9 11 6 1 7 4 15 18 3 10 2 1 10 12 6 5 11 5 5 3 6 3 10 0 1 1 4 6 12 9 2 5 7 9 5 2 7 7 12 3 8 8 16 25 19 17 7 9 7 8 2 0 4 0 0 2 4 1 0 0 0 0 1 2 3 4 0 4 2 3 5 2 5 6 17 7 2 11 2 1 13 6 9 3 1 4 1 0 0 0 0 0 0 0 0 0 0 0 0 1 1 3 0 2 2 1 2 2 3 5 4 0 1 2 0 1 2 0 2 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 35 29 5 22 21 28 38 15 27 29 39 11 18 25 34 48 37 37 23 14 20 24 14 21 22 11 13 12 10 12 10 4 2 3 5 Onaway selfed Superior selfed Atlantic selfed ND860-2 selfed 700-83 selfed Lemhi R selfed Sag Gold X Superior Y245.7 X 84SD22 Atlantic X Onaway ND860-2 X Lemhi R Atlantic X 700-83 Onaway X ND860-2 Superior X Onaway Atlantic X ND860-2 ND860-2 X 700-83 Sag Gold X Lemhi R Superior X Lemhi R Sag Gold X Onaway Onaway X Lemhi R Sag Gold X Atlantic 700-83 X. Onaway Superior X 700-83 Superior X 700-83 P100-2 X 84S10 84S11 X 84S10 P100-2 x 84SD20 84SD20 X 106-2-1 84S10 X 84S11 P100 X P168-1 85SD56 X 84S11 106-2-1 X W5337.3 85SD55 X P100-2 106-2-1 X 84S11 106-2-1 X 84SD22 106-2-1 X 84S10 P133-5 X 106-2-1 Family A120 A073 A048 A109 A102 A063 A060 SD19 A115 A067 A054 A119 A112 A055 A104 A057 A065 A114 A117 A049 A113 A050 A099 A191 A192 A156 A162 A187 A193 A169 A155 A185 A153 A146 A152 A149 Overall Scab Rating 1 2 9 3 2 2 2 5 4 1 3 0 0 0 0 0 1 3 0 4 3 0 2 0 5 16 7 6 8 7 0 8 0 4 1 2 0 based upon 5-10 tubers/seedling 1989 GREENHOUSE SCAB TEST - SUMMER/FALL TABLE 4 CLONE NOOKSACK BURBANK LEMHI RUSSET SUPERIOR 133-72 84S10 ONTARIO 133-128 133-9 W5295.2 133-124 133-67 133-197 R. BURBANK 84SD22 ATLANTIC 133-151 133-26 133-208 ONAWAY 133-16 133-227 133-158 133-47 DM56-4 133-293 133-250 MS716-15 133-30 85SD55 MONONA MICHIGOLD KATAHDIN SAGINAW GOLD PIOO-2 MS700-83 NDD277-2 133-87 Y245.7 133-273 ND860-2 * RATING 1 1 1 1.1 1.3 1.3 1.5 1.5 1.6 2 2 2 2 2 2 2.3 2.3 2.3 2.5 2.5 2.6 2.6 2.6 2.6 3 3 3 3 3 3 3.1 3.1 3.3 3.3 3.5 3.8 4 4 4 4 4.5 * Based on three replications TABLE 5 Strains DP (Z) Onaway 9/25 830103 F945 RP RP(F) Onaway Atlantic R. Burbank deep common common common deep common deep common common deep deep, comm. common common --- --- common --- --- TABLE 6 Variety x strain analysis Varieties 4x Varieties 2x Superior Lemhi Russet Onaway Atlantic Saginaw Gold MS700-83 ND860-2 84S10 84SD22 W5295.7(I) DM56.4 W5337.3 P100-2 empty table cell TABLE 7 GREENHOUSE SEEDLING SCAB TEST 1989 Progeny Distribution Progeny Distribution Progeny Distribution Progeny Distribution Progeny Distribution FAMILY FEMALE MALE 246 245 247 248 244 251 250 360 249 254 253 364 366 363 357 358 356 362 Lemhi R Superior ND860-2 Monona Superior ND860-2 Superior NDD277-2 Lemhi R 84SD22 84SD22 84S11 31-75 31-75 NDD277-2 NDD277-2 NDD277-2 NDD277-2 Lemhi R Superior ND860-2 Monona Lemhi R Lemhi R Monona Lemhi R Monona 84S10 84S11 84S10 84SD22 84S10 84S10 84SD22 31-75 84S11 1 18 17 0 33 78 5 16 80 0 58 7 71 80 74 24 58 33 9 2 18 22 15 22 17 19 6 11 0 35 23 19 8 18 36 20 18 11 3 55 22 23 45 5 33 44 4.5 27 7 30 7 8 8 10 8 20 17 4 9 29 54 0 0 38 28 4.5 36 0 30 3 4 0 20 13 24 28 1=0% scab coverage; 5 = > 25% scab coverage 5 PROGENY TESTED 0 11 8 0 0 5 6 0 36 0 10 0 0 0 10 2 5 35 11 18 13 27 18 21 32 44 11 31 30 42 25 40 42 48 45 46 TABLE 8 Mean levels of chlorogenic acid Resistant CGA Susceptible CGA Hindenburg Onaway Nooksack Superior Lemhi R. empty table cell 1.863 1.654 1.508 1.428 0.972 empty table cell Saginaw Gold Michigold MS700-83 NDD277-2 Atlantic ND860-2 0.556 0.584 0.608 0.637 1.155 1.654 TABLE 9 Effect of pre-planted green manure/soil ammendment crops on scab incidence in field-grown Atlantic potatoes, summer, 1989 Cover crop1 Scab rating2 Marketable Yield (CWT/A)3 alfalfa (7 lbs/A) corn (7 lbs/A) fallow control oat (20 lbs/A) oriental mustard4 (20 lbs/A) red clover (7 lbs/A) rye (20 lbs/A) soybean (20 lbs/A) 10.5 BC5 14.5 A 11.9 ABC 10.6 BC 12.7 AB 10.2 BC 12.4 AB 9.5 C 102 ABC 53 C 118 AB 109 ABC 140 A 73 BC 141 A 87 ABC 1 all plots had been left fallow through the winter 2 based on a rating scale where 0= no scab, 1=1-4% scab, 5=5-9% scab, 10= 10-20% scab, and 25=20-25% or more scab 3 estimated weight per acre of marketable potatoes with less than 5% scab 4 Brassica juncea 5 numbers with different letters indicate are significantly different by Duncan's Multiple Range test at =0.05 Antagonists from soil amendment field trials. TABLE 10 date (avg. number of plaques) red clover of plaques) (avg. number mustard 4 on 10-4 , 1 on 10-5 1 on 10-4 1 on 10-4 0 0 0 6/16 6/30 0 0 2 on 10-4 7/14 7/28 8/11 8/25 2 did not show antagonism when isolated 3 2 of these (both Actinomycetes) showed antagonism to 5 pathogenic Streptomyces when isolated 4 1of these (a Bacillus) showed antagonism to 5 pathogenic Streptomyces when isolated 0 0 0 CONTROL OF INTERNAL BROWN SPOT (IBS) IN ATLANTIC R. Hammerschmidt, R.W. Chase, Paul Marks, and G. Silva Funding MPIC Heat necrosis/internal brown spot has been reported as a significant concern in the Atlantic variety in many areas throughout the U.S. It has occurred in various potato regions of Michigan but has had the greatest frequency in Southeastern Michigan. In 1988 a field study was initiated at the W.J. Lennard Farm in Monroe County to evaluate the effect of banded applications of 750 lbs/A of agricultural gypsum to the soil at planting, at hilling and as a split application of 375 lbs/A at planting and at hilling. The use of an anti-transpirant (Vaporgard) was applied as the main plot treatment. The experiment was duplicated with two planting dates of April 15 and May 15. Application of gypsum did significantly reduce the amount of IBS but not to an acceptable level. There was no effect from the anti-transpirant. Procedure: In 1989 a similar plot was established at the Lennard Farm with a single planting on May 3, 1989. Individual plots were 4 rows x 25’ and the 2 center rows were harvested for yields and quality evaluations. The gypsum applications of 750 lbs/A and the split application of 375 lbs/A were applied to the soil surface (1 ft. x 25 ft.) just prior to planting. The mechanical action of the planter shoe and covering disc thoroughly incorporated the gypsum. Prior to hilling, the gypsum was applied in a similar matter. The experimental design was a randomized complete block with four replications. A main plot treatment of maleic hydrazide at 2 gal/A in 23 gpa of water was applied to one-half of the area on July 28. The plots were harvested on October 19. Results: There were no emergence or plant growth effects observed as a result of the gypsum treatments. Following the application of the maleic hydrazide, there was a light yellowing of the foliage. Table 1 summarizes the yields, specific gravity and internal defects of the harvested tubers. There was no significant effect on yields and specific gravity from any of the treatments. Tuber samples were also evaluated for the incidence of common scab with no treatment differences. There was a significant reduction in the incidence of IBS on the plot treated with MH30 regardless of the gypsum treatment. There was a reduction in the incidence of IBS where gypsum was applied, however it was not at an acceptable level, similar to the 1988 results. There was an increase in the incidence of vascular discoloration resulting from the MH30. Interaction effects between gypsum and maleic hydrazide were not significant. Following harvest, soil samples were collected from the untreated and the gypsum treated plots and were analyzed. Table 2 shows that there were no increased levels of calcium resulting from the addition of gypsum. The magnesium levels on the check plots were lower than where gypsum was applied. A pre-plant soil test showed phosphorus at 627, potassium at 96, calcium at 436 and magnesium at 50 lbs/A, respectively. The pH was 5.3. TABLE 1. YIELDS, SPECIFIC GRAVITY AND INTERNAL DEFECTS OF ATLANTIC POTATOES TREATED WITH MALEIC HYDRAZIDE AND GYPSUM (LENNARD FARM, MONROE COUNTY, 1989). Treatment No. 1 2 3 4 5 6 7 8 MH - - - - + + + + Gypsum (lbs/A) 0 750 P 750 H 750 (P+H) 0 750 P 750 H 750 (P+H) Significance emptytable cell Level empty table cell Yields Yields (cwt/a) (cwt/A) U.S. No. 1 Total Specific Gravity % No. 1 187 175 191 204 176 197 188 180 247 237 251 261 231 248 236 226 1.084 1.082 1.083 1.084 1.082 1.082 1.082 1.080 ns ns ns 76 74 76 78 76 79 80 80 empty table cell % HH* 5 0 11 9 8 8 4 3 ns *Data from cutting 25 tubers/plot. TABLE 2. SOIL TEST RESULTS OF POST-HARVEST SAMPLES. empty table cell 750 lbs/A Gypsum A 750 lbs/A Gypsum B 750 lbs/A Gypsum C 750 lbs/A Gypsum D 750 lbs/A Gypsum Ave. Zero Gypsum A Zero Gypsum B Zero Gypsum C Zero Gypsum D Zero Gypsum Ave. 5.5 5.3 pH 5.3 5.3 5.4 5.3 5.3 5.3 5.3 5.3 644 593 Pounds/Acre P 610 576 606 681 610 627 610 632 Pounds/Acre Pounds/Acre Ca K 112 112 96 88 102 88 96 96 89 92 509 436 436 436 454 1%; 436 364 436 436 418 % IBS* 58 45 40 37 11 9 7 11 * 5% 192 110 % VD* 1 7 3 0 4 8 16 17 * 10% Pounds/Acre Mg 80 70 113 60 50 50 60 55 Funding MPIC Nitrogen Management Strategies to Maximize Profit and Minimize Nitrate Leaching: 1989 Results J.T. Ritchie, B.S. Johnson, and P.R. Grace This study represents a continuing effort to evaluate the impact of contrasting nitrogen management strategies on crop yields and nitrate leaching. In 1988 we demonstrated that the nitrogen (N) application rate could be reduced without affecting yield and quality of Russet Burbank potatoes. Leaching loss of nitrate-N, as measured in permanently installed drainage lysimeters, was about 15 lb/A lower by the end of October where the N rate was reduced. Two important questions were left unanswered by our 1988 results. First, due to the drought in 1988, we were unable to evaluate the impact of a large rain on nitrate leaching when the concentration of soil N is high (e.g., after application of fertilizer N) . Second, it was impossible to determine whether nitrate appearing in the drainage water originated from fertilizer additions or from other sources such as mineralization of soil organic matter. The experiment conducted at the lysimeter site in 1989 was modified as follows to address these issues: (1) Tracer techniques were used to determine the fate of the fertilizer N applied to the lysimeter areas; and (2) The plots were irrigated excessively at midseason to simulate the occurrence of a large rain. The latter objective was in response to the MPIC Research Committee's request to study how much N is lost during a summer storm through leaching. This report contains the 1989 results and a summary of the soil water drainage and nitrate leaching data collected from the drainage lysimeters during the last two years. Methods It was necessary to plant the lysimeter site to corn in 1989 due to problems with Potato Early Die Complex during the previous year. Two plots, 16 rows X 50 ft in length, were planted to corn hybrid Pioneer 3585 on May 24. The row spacing and seed spacing within the row were 23 inches and 9 inches, respectively giving a population of 30,300 plants/A. A treatment consisting of conventional nitrogen management (CON) was applied to one plot and a "Better Management System" (BMS), involving reduced input of fertilizer N, was applied to the second. Permanently installed drainage lysimeters, one in each plot, were used to monitor soil water drainage and nitrate leaching. The lysimeters (48" X 68" X 6 ft deep) consist of steel boxes that are open at the top and closed at the bottom except for an opening used to collect water that drains through the lysimeter profile. The lysimeters intercept water at the 7 1/2 ft soil depth, the sum of the distance from the soil surface to the top of each lysimeter (l 1/2 ft) and their depth (6 ft). The 68" dimension accommodates three rows of corn, each containing 5 plants over the 48" length for a total of 15 plants over each lysimeter. Drainage depths and nitrate leaching were determined by measuring the volume of water collected and sampling it each time for nitrate concentrations using traditional autoanalyzer techniques. Sampling frequency was dictated by drainage rates during the season. Each plot received N as ammonium sulfate at a rate of 13 lb/A at planting and one additional application of ammonium sulfate on June 21. The second application involved an N rate of 187 lb/A (200 lb/A total) for the CON treatment and 116 lb/A (130 lb/A total) for BMS. The ammonium sulfate applied to each lysimeter area on June 21 was labeled with the stable isotope 15N. Four microplots (46” X 29”) were established adjacent to the lysimeters in each treatment to provide replication of the soil and plant 15N measurements. They also received the 15N labeled ammonium sulfate at the prescribed rates (187 lb/A for CON and 116 lb/A for BMS) on June 21. The 46” dimension of each microplot was chosen as an exact multiple of the 23 inch row spacing. Each row, 29 inches in length, accommodated 3 plants for a total of 6 plants in each microplot. Soil samples for NH4 and NO3 measurements were collected prior to planting, at midseason, and after fall harvest. Samples were collected in 4 inch increments to a depth of 1 ft on each occasion. Samples collected after application of the labeled material will be analyzed for 15N concentrations. Plant leaf disks for 15N analysis were collected during the season and whole plant samples were collected at harvest for 15N uptake measurements. Drainage water samples collected after the June 21 application of the labeled fertilizer were also analyzed for 15N concentrations. Results of the soil, plant, and lysimeter 15N measurements will enable us to calculate the total N balance in terms of the amount of fertilizer N taken up by plants (corn in 1989, potato in 1990), the amount of fertilizer N remaining in the soil at the end of each season, and the leaching loss of N from the lysimeter profiles. Results of these measurements will be included in a future report except for preliminary findings from the drainage water 15N concentrations. Both plots were irrigated as needed during the season using similar irrigation schedules for each treatment. The simulated "storm" consisted of irrigating 3.9 inches over a 3-day period, 2.4 inches on July 24 and 1.3 inches on June 26. Constraints of the irrigation system existing at the lysimeter site precluded the possibility of applying this quantity of water during a shorter time period (e.g., 4 hours). 1989 Results Yields and yield components for the contrasting N management strategies are given in Table 1. Plant growth was similar for both treatments as grain yield for CON exceeded the yield for BMS by only 8.0 Bu/A. Total above ground biomass production for the CON treatment was 7.66 tons/A compared to 7.53 tons/A for BMS, a difference of 0.15 tons/A (300 lb/A). The dry weight of grain produced was about 45 % of the biomass for both treatments. The plant responses reported in Table 1 are consistent with the premise that N rates applied to many crops can be reduced without diminishing yields appreciably. This should result in lower residual N in the soil at the end of each season and therefore a lower potential for nitrate leaching. Figures 1 to 3 illustrate the extent to which BMS reduced nitrate leaching. The time scale in each Figure represents a 8 month period from May 15, 1989 through January 5, 1990. A significant "pulse" of soil water drainage is evident shortly after the simulated storm as drainage amounts increased sharply from 5 inches to about 11 inches over a two-week period (Fig.1). Very little drainage occurred during the remainder of the season totalling 12.1 inches for the BMS compared to 10.8 inches for the CON treatment. A large natural rainfall of 3.5 inches on August 4 added to the observed response. Nitrate concentration in the drainage water was consistently greater where the CON treatment existed than where the BMS was applied (Fig. 2). For both treatments, nitrate concentrations decreased from about 80 ppm at planting to 30 ppm by the beginning of September. Cumulative nitrate loss from each lysimeter is illustrated in Fig. 3. As expected, most of the nitrate leaching occurred prior to September when the drainage rates and nitrate concentrations in the drainage water were greatest. The total amount of nitrate lost from the profile during the 8-month period was 121 lb/A for the CON treatment and 107 lb/A for BMS. The results given in Fig. 3 show that treatment differences are small compared to the difference between fertilizer N rates for CON and BMS (70 lb/A). Because the fertilizer applied to each lysimeter was labeled with 15N, the nitrogen (mostly nitrate) appearing in the drainage water should eventually exhibit this label. As of the last measurement date (January 5, 1990), less than 1 percent of the 15N applied to each lysimeter as ammonium sulfate was recovered in the drainage water. This result suggests that there is a substantial time lag between the application of fertilizer N and its appearance in drainage water intercepted at the 7 1/2 ft depth. Most of the 15N not taken up by the 1989 crop remained in the soil by the end of 1989, some of which will be used by the subsequent crop. However, continued movement of water through the lysimeter profile will gradually transport some of the residual 15N to greater depths until it exits the lysimeter into the collection device. 1988 and 1989 Combined Results The 1988 report considered the April to October time period. The measurement period for data included in Fig. 1 to 3 begins at May 15, 1990 leaving a 6-month "gap" in data obtained from the lysimeters. Fig. 4 to 6 summarize the results of our lysimeter measurements from June 1, 1988 through January 5, 1990. Soil water drainage was negligible prior to fall harvest in 1988 due to the drought that year. Above normal rainfall during October and November caused a substantial amount of drainage during the last part of 1988. Cumulative soil water drainage totalled about 10.0 inches for both treatments over the 6-month post harvest period. Drainage after planting in 1989 equalled drainage that occurred during the previous 6-month period. Drainage for the entire 19-month period totalled 20.3 inches for the CON treatment and 20.9 inches for the BMS. Fig. 5 shows the seasonal changes in nitrate concentrations of the drainage water. Three distinct patterns are evident corresponding to time periods when crops were variously present or absent. Nitrate concentrations increased gradually prior to harvest in 1988, they were relatively constant after harvest, and decreased with time after planting in 1989. Fig. 6 shows the combined effects of the dynamically changing drainage rates and nitrate concentrations on nitrate leaching. Though nitrate concentrations in the drainage water were high during the 1988 growing season, nitrate leaching was negligible due to insignificant drainage amounts during the same time period. By the time of planting in 1989 however, nitrate leaching totalled 177 lb/A for CON compared to 163 lb/A for BMS. The final nitrate leaching values of 272 lb/A for CON and 245 lb/A for BMS are obtained by "adding" the cumulative curves in Fig. 3. Plans for the 1990 Experiment The lysimeter site will be planted to potatoes and treatments similar to those existing in 1989 will be established. This will allow us to build a long term record of the impact of reduced N application rates on crop yields and nitrate leaching. All fertilizer inputs will be unlabeled (i.e., no 15N) in 1990 so that the following objectives can be addressed: (1) Determine how much of the 15N remaining in the soil from 1989 is taken up by the subsequent crop; and (2) Determine how much of the labeled N appears in the drainage water. The second objective is particularly important because it will finally allow us to determine the contribution of fertilizer N (applied the previous year in this case) to nitrate leaching. Table 1. Corn grain yield and yield components for the Conventional nitrogen management treatment (CON) and the Better Management System (BMS) during 1989. Treatment CON BMS Grain Yield1 (Bu/A) 149 141 Yield Components2Grain lb/A Yield Components2Coblb/A Yield Components2Stover lb/A Yield Components2 Biomass 7047 6669 1255 1189 7009 7211 tons/A 7.66 7.53 1 Reported at a grain moisture content of 15.5 percent. 2 All yield components are reported on a dry weight basis. Figure 1. Cumulative soil water drainage during 1989. Figure 2. Nitrate concentration of drainage water collected during 1989. Figure 3. Cumulative nitrate leaching during 1989. Figure 4. Cumulative soil water drainage from June 1, 1988 through January 5, 1990. Figure 5. Nitrate concentration of drainage water collected during 1988 and 1989. Figure 6. Cumulative nitrate leaching during the June 1, 1988 to January 5,1990 period. Funding MPIC NITROGEN MANAGEMENT STRATEGIES FOR RUSSET BURBANK POTATOES B.C. Joern and M.L. Vitosh Introduction Nitrate contamination of groundwater from non-point sources has developed into a serious and well publicized environmental issue. The present potato production system is quite susceptible to nitrate leaching because potatoes are a shallow rooted crop grown mainly on coarse-textured soils under irrigation. The relatively high economic value of the crop has historically led to an excessive use of fertilizer nitrogen (N) and irrigation water, which further contributes to the nitrate leaching potential of the potato production system. There is a need to develop N management strategies for potatoes that will improve their N use efficiency and reduce their nitrate leaching potential. With groundwater protection acts already legislated in several states, public support is building for comprehensive federal groundwater legislation. It is imperative that good local research data is available to demonstrate the high efficiency and minimal groundwater contamination risk of improved N management strategies for the potato production system. Procedure The 1989 potato studies were conducted at the Montcalm Research farm on a Montcalm-McBride sandy loam soil (location 1) and at the Michigan State University soils farm located on Hagadorn road on a Spinks-Riddles sandy loam soil (location 2) . The experimental design selected for this study was a randomized complete block with four replications. Six N management practices (combinations of N rates and application times) were used as treatments for this investigation. Russet Burbank was the potato cultivar used and ammonium sulfate, (NH4)2SO4, was the fertilizer N source applied to the crop. 15N depleted ammonium sulfate was applied to each plot for fertilizer N uptake and N use efficiency determinations. Soil samples were taken to a depth of four feet four times during the growing season in the potato experiment. These soil samples will be analyzed for nitrate and ammonium to monitor N movement through the profile during the growing season. The major objectives of this investigation were to evaluate the selected N management strategies for their ability to: 1. maximize tuber yield and quality 2. maximize fertilizer N uptake 3. minimize residual N in profile after harvest. 1989 Results The potato yield data for locations 1 and 2 are shown in Tables 1 and 2, respectively. Tuber yields at location 1 were significantly influenced by the N management treatments. Both U.S. number 1 yields and total yields were maximized at 120 to 180 pounds N per acre as long as the N was applied by the onset of flowering. Nitrogen applied after flowering (treatment 6) did not appear to increase yields. A slight increase in large tuber yields (greater than 10 ounces) was detected at the highest fertilizer N rate (180 pounds per acre). Tuber yields at location 2 also indicated that yields were maximized at N application rates of 120 to 180 pounds per acre. At this location, the 180 pound N per acre treatment had a significant yield response of both the U.S. number 1 and total yield compared to 120 pounds of N per acre applied at planting. No significant yield increases were detected between the 180 pound N per acre treatment and the 120 pound N per acre treatment when the N applications were split. From the results of the 1989 experiments, it appears that 120-180 pounds of N applied by the end of tuber set (late June to early July) was sufficient for maximum tuber yields. The effects of splitting the N applications on tuber yields was mixed in 1989. Potato tuber quality, as indicated by specific gravity, was not significantly affected by the N treatments at either location. Fertilizer N uptake by the tubers at harvest for the 1988 (Year 1) and 1989 (Year 2) growing season is presented in Table 3. From the data, it appears that the percent recovery of the fertilizer N by the tubers was maximized at the 120 pounds N per acre rate, but these results are based on preliminary data and are highly variable. Data for percent N in petiole samples taken throughout the growing season are presented in Tables 4 and 5 for locations 1 and 2, respectively. The petiole samples were taken just prior to each fertilizer sidedress application so that each petiole sample collected would reflect the previous fertilizer application. The percent N in the petioles generally reflected the most recent fertilizer application prior to petiole sample collection dates at both locations. The percent N in the petioles was generally maximized in the treatment which received the highest sidedress N application prior to sample collection. To determine if the increase in percent N in the petioles was due directly to the fertilizer N, the fertilizer N in the petioles was also evaluated. These results are presented in Tables 6 and 7 for locations 1 and 2, respectively. The percent N from fertilizer in the petioles was directly correlated to the total percent N in the petioles, indicating that total N in the petioles may be a good indicator of fertilizer N uptake. This does not mean that percent N in the petioles is necessarily a good indicator of yield potential, as it appears that N applied after the onset of flowering (late June to Early July) may be taken up by the crop, but not translocated to the tubers for increased yields. Conclusions From the results of the 1989 (and 1988) investigation, it appears that 120 to 180 pounds of N per acre applied by the onset of flowering was sufficient for obtaining maximum yields of Russet Burbank potatoes. The effects of splitting the N applications was variable although there is some indication that N uptake efficiency may be increased by splitting the N applications. For this reason and the flexibility of yield goal modifications due to other environmental factors, the use of split N applications (planting and hilling) is recommended. Table 1. The effect of N rate and application time on yield of Russet Burbank potatoes. Location 1. N fertilization rate N fertilization rate N fertilization rate N fertilization rate N fertilization rate N Application N Application date date 7-07 5-09lb N per acre lb N per acre N Application date 6-23 lb N per acre N Application date 7-2 0lb N per acre Total N lb N per acre Yield Tuber size distribution Off type cwt per acre Yield Tuber size distribution 4-10 oz. cwt per acre Yield Tuber size distribution Under 4 oz. cwt per acre Yield Tuber size distribution Over 10 oz. cwt per acre Yield Tuber size distribution U.S. no. 1 cwt per acre Yield Tuber size distribution Total yieldcwt per acre Specific gravity g/cc -- -- 60 -- 120 -- 60 60 30 -- -- -- -- -- -- 60 60 30 -- 60 30 -- -- 30 0 60 120 120 180 120 7a 77 bc 93 c 2 d 95 c 179 c 1.079a 11a 15a 19a 19a 16a 94a 150 b 1 d 151 b 256 b 77 bc 232a 7 cd 61 d 224a 14ab 68 cd 220a 18a 239a 238a 238a 331a 318a 325a 1.080a 1.081a 1.079a 1.077a 86ab 157 b 9 bc 166 b 268 b 1.079a Values followed by the same letter were not statistically different at the .05 level of probability. Table 2. The effect of N rate and application time on yield of Russet Burbank potatoes. Location 2. N fertilization N fertilization N fertilization rate N fertilization N fertilization rate Total N lb N per acre N Application date 7-03 lb N per acre -- rate N Application date 7-17 lb N per acre -- rateN Application date5-04lb N per acre rate N Application date 6-1 8lb N per acre -- -- 60 -- 120 -- 60 60 60 30 60 30 -- -- -- -- -- 60 30 -- -- 30 Yield Tuber size distribution Off type cwt per acre Yield Tuber size distribution Under 4 oz. cwt per acre Yield Tuber size distribution 4-10 oz. cwt per acre Yield Tuber size distribution Over 10 oz. cwt per acre Yield Tuber size distribution U.S. no. 1 cwt per acre Yield Tuber size distribution Total yield cwt per acre Specific gravity g/cc 0 60 120 120 180 120 21a 49a 39a 49a 51a 34a 34a 161 c 2 d 163 d 218 d 1.081a 41a 44a 40a 41a 32a 241 b 14 c 255 c 364 c 289ab 17 c 306 bc 389 bc 329a 332a 31 b 42a 360ab 374a 449ab 466a 1.083a 1.083a 1.084a 1.083a 287ab 24 bc 311 bc 377 bc 1.085a Values followed by the same letter were not statistically different at the .05 level of probability. Table 3. The effect of N rate and application time on the percentage of the applied fertilizer N found in potato tubers at harvest. Years 1 and 2. N fertilization rate N application date N fertilization rate N application N fertilization rate N application N fertilization rate N application date M.S. * lb N per acre -- -- PTGlb N per acre date F.F. lb N per acre -- date T.I. lb N per acre -- 60 -- 120 -- 60 60 60 30 60 30 -- -- -- -- -- 60 30 -- -- 30 N fertilization rate Total N lb N per acre 0 60 120 120 180 120 % Fertilizer N found in tubers Year 1 Location 1%N % Fertilizer N found in tubers Year Location 2 %N 1 % Fertilizer N found in tubers Year % Fertilizer N found in tubers Year 2 Location 2* 2 Location 1 %N * %N 0.0 b 0.0 c 0.0 c 0.0 35.0 a 29.8a 30.2a 25.6a 28.8a 42.7ab 51.5a 44.7ab 32.7 b 47.3ab 37.5 b 36.6 b 42.8a 40.5a 40.2a 40.0 47.3 40.6 35.6 36.1 * PTG = at planting, T.I. = tuber initiation, F.F. = first flower, M.S. = mid season. ** Estimated values, so no statistical analyses run. Values followed by the same letter were not statistically different at the .05 level of probability. Table 4. The effect of N rate and application time on petiole N concentration of Russet Burbank potatoes. Location 1. acre 3 % N sample -- date 8-03 % N Petiole date 7-07 % N Tissue N Concentration Petiole sample -- -- -- N fertilization rate Total N lb N per N fertilization rate N Application date 5-0 9lb N per acre Tissue N Concentration Petiole sample date 6-2 Tissue N Concentration Petiole N fertilization rate N Application date 7-07 lb N per acre N fertilization rate N Application date 7-20 lb N per acre Tissue N Concentration N fertilization rate N Application date 6-2 3 lb N per acre -- -- 60 -- 120 -- 60 60 30 Values followed by the same letter were not statistically different at the .05 level of probability. sample date 7-20 % N 3.43 d 3.07 4.02 c 4.21 c 5.23a 4.58 b 4.16 d 6.00 b 7.11a 6.37 b 6.34 b 5.29 C 2.89 b 2.57 C 2.90 b 2.89 b 4.06a 3.99a 3.57 c 3.21 c 4.37 b 4.86a 5.07a 4.25 b 0 60 120 120 180 120 -- -- -- 60 60 30 -- -- 60 30 30 e Table 5. The effect of N rate and application time on petiole N concentration of Russet Burbank potatoes. Location 2. acre 8-01 % N Petiole sample Tissue N Concentration Petiole sample date sample date 7-03 % N N fertilization rate Total N lb N per N fertilization rate N Application date 5-0 4lb N per acre Tissue N Concentration Tissue N Concentration Petiole Tissue N Concentration Petiole sample date 6-17 % N N fertilization rate N fertilization rate N Application N Application date 7-17 date 7-03 lb N per acre lb N per acre -- -- —— -- -- -- -- N fertilization rate N Application date 6-18 lb N per acre -- -- 60 -- 120 -- 60 60 30 Values followed by the same letter were not statistically different at the .05 level of probability. date 7-17 % N 2.38 e 2.68 de 3.24 bc 3.04 cd 4.40a 3.65 b 3.75 d 0 60 5.57 b 120 120 5.52 b 180 5.64 b 120 4.87 c 2.84 c 3.42 b 4.14a 3.95ab 4.14a 3.44 b 2.16 d 2.27 cd 2.61 bc 2.64 b 3.81a 3.65a 60 60 30 6.37a -- 30 60 30 -- Table 6. The effect of N rate and application time on percent N from fertilizer in petioles of Russet Burbank potatoes. Location 1. 6-23 % N % N from fertilizer Petiole sample date8-04% N 7 % N 0 60 sample % N from fertilizer Petiole sample date N fertilization rate N Application date 5-0 9lb N per acre % N from fertilizer Petiole sample date 7-0 % N from fertilizer Petiole date 7-20 % N e N fertilization rate N fertilization rate N fertilization rate N Application date Total N N Application 7-20 lb N per acre date 7-07 lb N per acre lb N per acre -- -- N fertilization rate N Application date 6-23 lb N per acre -- -- 60 -- 120 -- 60 60 30 Values followed by the same letter were not statistically different at the .05 level of probability. 0.0 13.5 24.2 d 31.2 c 49.1a 42.7 b 0.0 19.3 d 34.9 c 44.9 b 56.3a 42.8 b 0.0 d 34.9 c 47.7 b 59.7a 60.0a 44.9 b 0.0 d 60.3 b 67.9a 61.2 b 60.6 b 45.7 c -- -- -- -- -- -- 60 -- 30 60 60 30 120 120 180 120 f e 30 Table 7. The effect of N rate and application time on percent N from fertilizer in petioles of Russet Burbank potatoes. Location 2. N fertilization rate N Application date 5-0 4lb N per acre -- N fertilization rate N Application date 6-18 lb N per acre -- -- -- N fertilization rate N Application date 7-03 lb N per acre -- N fertilization rate N Application date 7-1 7 lb N per acre -- N fertilization rate Total N lb N per acre -- % N from fertilizer Petiole % N from fertilizer Petiole % N from fertilizer Petiole sample date6-17% N sample date 7-03 % N -- -- -- 60 120 60 60 30 Values followed by the same letter were not statistically different at the .05 level of probability. 60 60 30 -- 60 30 -- 30 -- 0.0 d 53.1 b 69.2a 56.5 b 58.2 b 45.0 c 0.0 c 45.2 b 61.7a 56.0ab 64.6a 50.7ab sample date 7-17 % N 0.0 d 37.1 c 51.1 b 51.4 b 70.0a 57.8 b % N from fertilizer Petiole sample date8-01% N 0.0 d 28.1 c 41.2 b 39.3 b 58.9a 60.0a 0 60 120 120 180 120 Funding Other Sources NITROGEN MANAGEMENT STUDIES ON POTATOES Sandyland Farms, Montcalm County M.L. Vitosh, D.B. Campbell, D.A. Hyde and B.P. Darling Objective: To evaluate the use of soil and plant N analysis during the growing season for determining the optimum N fertilizer rate on Atlantic potatoes. Soil Type: Mancelona loamy sand Initial soil nitrate level............... : 18 lb N/A-2ft. on May 30, 1989 Fertilizer Program : Planting time N..................................... : 90 lb/A Broadcast N June 1............................. : 46 lb/A Sidedress Treatments........................ : Applied June 13, 1989 #1........................................ 0 lbs N/A #2........................................ 60 lbs N/A #3........................................ 90 lbs N/A #4........................................ 120 lbs N/A INTRODUCTION: This study was conduced on small plots located at the end of the growers field. The plots were 3 row plots replicated 4 times. Nitrogen fertilizer was applied at planting time and again on June 1 by the grower for a total of 136 lbs of N per acre. The sidedress N treatments were applied on June 13th. No other N fertilizer was applied to the study area. RESULTS AND DISCUSSION : The soil nitrate and ammonium nitrogen data collected during the summer are shown in Table 1, Figures 1 and 2. On June 28, most of the nitrate and ammonium was uniformly distributed between both the surface and subsurface samples. Nitrate levels were generally related to the rate of N fertilizer applied. On July 10, soil nitrate and ammonium levels were considerably lower, however on July 17, both nitrate and ammonium levels were considerably higher. The reason for higher levels of soil nitrate and ammonium levels on July 17 are difficult to explain. We initially suspected that some N fertilizer was applied to the entire field between July 10th and 17th; however, the plant analysis data in Table 2 does not confirm this. We can only speculate that the increased N levels are due to increased soil mineralization during July or improper handling of the soil samples. Table 1. Soil nitrate and ammonium levels during the growing season as affected by four sidedress N fertilizer rates.1 Sidedress Rate lb N/A 0 60 90 120 Sidedress Rate lb N/A 0 60 90 120 Sidedress Rate lb N/A 0 60 90 120 Sidedress Rate lb N/A 6-28 lb NO3 -N/A 1st ft.2 7-10 7-25 7-17 lb NO3 -N/A 1st ft.2 lb NO3 -N/A 1st ft.2 8-24 lb NO3 -N/A 1st ft.2 9-19 lb NO3 -N/A 1st ft.2 lb NO3 -N/A 1st ft.2 16d 33b 28c 65a 9a lla 9a 23a lb NO3 -N/A 2nd ft. 43a 31a 35a 45a -- -- -- 16 -- -- -- 44 -- -- -- 30 lb NO3 -N/A 2nd ft. lb NO3 -N/A 2nd ft. lb NO3 -N/A 2nd ft. lb NO3 -N/A 2nd ft. lb NO3 -N/A 2nd ft. 17c 30b 29b 48a -- -- -- -- 22a 34a 33a 57a -- -- -- -- -- -- -- -- -- -- -- 22 lb NH4 -N/A 1st ft. lb NH4 -N/A 1st ft. lb NH4 -N/A 1st ft. lb NH4 -N/A 1st ft. lb NH4 -N/A 1st ft. lb NH4 -N/A 1st ft. 22b 21b 25ab 28a 7a 7a 7a 8a lb NH4 -N/A 2nd ft. 51a 56a 54a 36a -- -- -- 33 -- -- -- 50 -- -- -- 6 lb NH4 -N/A 2nd ft. lb NH4 -N/A 2nd ft. lb NH4 -N/A 2nd ft. lb NH4 -N/A 2nd ft. lb NH4 -N/A 2nd ft. 0 60 90 120 21b 21b 24ab 27a -- -- -- -- 36a 69a 40a 39a -- -- -- -- -- -- -- -- -- -- -- 6 1 Sidedress N applied June 13, 1989 2 Any means followed by the same letter were not statistically different at the .05 level of probability. Figure 1. Soil nitrate levels during the growing season as affected by four sidedress N fertilizer rates. Figure 2. Soil ammonium levels during the growing season as affected by four sidedress N fertilizer rates. Petiole nitrate levels for the season are shown in Table 2 and Figure 3. Nitrate levels declined throughout June and July. The amount of nitrate in the petioles on June 28 and July 17 were closely related to the rate of N fertilizer applied. However, petiole analysis on July 10 do not appear to be related to the N rates. Samples were not collected from the low N treatments on July 25th. According the MSU guidelines for nitrate levels in potato petioles (Extension Bulletin WQ09), the 90 and 120 lb N treatments exhibited adequate petiole nitrate N on June 28th. However, on July 10, 17 and 25 all levels were inadequate. The 120 lb N rate appeared to maintain between 5,000 and 6,000 ppm of nitrate throughout July. Anything above 6,000 ppm of nitrate this late in the season would be considered adequate. Table 2. Potato petiole nitrate levels during the growing season as affected by four sidedress N fertilizer rates1. Sidedress Rate Sampling date 6-28 lb/ NO 3 -N2 Sampling date Sampling date Sampling date 7-25 lb/ NO3 -N2 7-10 lb/ NO3 -N2 7-17 lb/ NO3 -N2 lb N/A 0 60 90 120 14,555a 17,917a 20,139a 21,111a 6,322a 7,574a 6,021a 5,078a 1 Sidedress N applied May 30, 1989 2 Any two means followed by the same letter are not statistically different at the .05 level of probability. 2,238b 3,060b 3,084b 5,390a -- -- -- 5,799 Figure 3. Potato petiole nitrate levels during the growing season as affected by four sidedress N fertilizer rates. Yields, tuber size distribution and specific gravity are shown in Table 3. Four check samples were collected adjacent to the experiment from the growers field where the growers N practices were slightly different. Yields from these plots, although not part of the randomized complete block experimental design, were analyzed statistically with the other N plots. Total yield and U.S. No. 1 yields were closely related to the rate of N fertilizer applied, although the difference between the 90 and the 120 lb N sidedress treatments are not statically different. The field check out yielded all N treatments, however, total and US No. yields were not statistically greater then the 120 lb N rate. Neither, off-type, small or large tubers, nor specific gravity were affected by any of the N treatments. Table 3. The effect sidedress nitrogen fertilizer rate on yield, tuber size and specific gravity of Atlantic potatoes.1 Sidedress nitrogen Yield Tuber size distribution off type cwt per acre Yield Tuber size distribution under 4 oz cwt per acre Yield Tuber size distribution 4-10 Yield Tuber size distribution over 10 oz Yield U.S. no. 1 cwt per acre Yield Total yield cwt per acre Specific gravity lbs/A oz cwt per acre cwt per acre g/cc 0 60 90 120 Field check 0a 0a 0a 0a 0a 52a 57a 54a 69a 69a 254b 306a 309a 312a 335a 16a 19a 25a 26a 34a 269c 325b 334ab 338ab 368a 329c 383b 386b 406ab 436a 1.092a 1.089a 1.092a 1.089a 1.085a 1 Any two means followed by the same letter are not statistically different at the .05 level of probability. We conclude from this study that plant analysis information is more reliable than soil analysis for determining N adequacy for potatoes during the growing season. Soil nitrate and ammonium levels were highly variable and appear to be greatly affected by environmental conditions (rainfall, irrigation and soil temperature). Funding Other Sources NITROGEN MANAGEMENT STUDIES ON POTATOES Anderson Bros., Montcalm County M.L. Vitosh, D.B. Campbell, D.A. Hyde and B.P. Darling Objective: To evaluate the use of soil and plant N analysis during the growing season for determining the optimum N fertilizer rate on Russet Burbank potatoes. Soil Types Mancelona loamy sand Initial Soil Nitrate Level: 50 lbs N/A-2ft. on May 31, 1989 Fertilizer Program : Planting time N................................. : 58 lbs N/A Sidedress Treatments..................: Applied May 30, 1989 #1........................................ 0 lbs N/A #2........................................ 60 lbs N/A #3........................................ 120 lbs N/A #4........................................ 180 lbs N/A INTRODUCTION: This study was conducted on small plots located at the end of the growers field. The plots were 3 row plots replicated 4 times. Fifty eight (58) lbs N fertilizer was applied at planting time by the grower. The sidedress N treatments were applied on May 31st. A heavy rain in excess of 2 inches occurred that evening. An additional application of N was considered due to anticipated loss but was not applied to the plots. The grower applied his N to the surrounding field after this heavy rain. RESULTS AND DISCUSSION : The soil nitrate and ammonium nitrogen data taken during June, July and September are shown in Table 1, Figures 1 and 2. On June 13, most of the nitrate and ammonium was found in the surface foot. Nitrate and ammonium levels were directly associated with the rate of N fertilizer applied. Significant amounts of nitrate were also present in the subsurface samples on June 13. A very heavy rain in excess of 2 inches occurred the evening the sidedress N treatments were applied and probably explains the relatively high levels of nitrate and ammonium in the subsoil on June 13. On June 21 the soil nitrate and ammonium levels were considerably lower and continued to decline until July 14. The reason for higher levels of nitrate and ammonium levels on July 14 can not be easily explained. We initially suspected that some N fertilizer was applied to the entire field between July 7th and 14th; however, we could not confirm this and the plant analysis data shown in Table 2 do not support this idea. We can only conclude that the higher level of nitrate and ammonium is due to increased mineralization of organic matter in July due to warm temperatures or improper handling of the soil samples. Table 1. Soil nitrate and ammonium levels during the growing season as affected by four sidedress nitrogen rates.1 6-13 lb NO3 -N/A 1st ft.2 6-21 lb NO3 -N/A 1st ft.2 6-30 lb NO3 -N/A 1st ft.2 7-7 lb NO3 -N/A 1st ft.2 7-14 lb NO3 -N/A 1st ft.2 9-19 lb NO3 -N/A 1st ft.2 lb NO3 -N/A 2nd ft. lb NO3 -N/A 2nd ft. lb NO3 -N/A 2nd ft. lb NH4 -N/A 2nd ft. lb NH4 -N/A 2nd ft. lb NH4 -N/A 2nd ft. lb NH4 -N/A 2nd ft. lb NH4 -N/A 2nd ft. 0 60 120 180 10 12 20 12 -- -- -- -- 22 17 21 26 -- -- -- -- -- 27 34 27 29 -- -- 9 1 Sidedress N applied May 30, 1989 2 Any means followed by the same letter or no letter are not significantly different (p=0.05). Sidedress Rate lb N/A 0 60 120 180 Sidedress Rate lb N/A 0 60 120 180 Sidedress Rate lb N/A 0 60 120 180 Sidedress Rate lb N/A 36c 12a 112b 36a 32a 180a 40a 204a lb NO3 -N/A 2nd ft. 40a 52a 76a 92a -- -- -- -- lb NH4 -N/A 1st ft. 20 60 68 63 19 20 20 22 lb NH4 -N/A 2nd ft. 14a 20a 17a 20a 16a 19a 18a 35a 12a 14a lla 16a 54a 64a 50a 73a -- -- -- 50 lb NO3 -N/A 2nd ft. lb NO3 -N/A 2nd ft. -- -- -- 36 lb NH4 -N/A 1st ft. 40a 62a 84a 93a -- -- -- -- 24 19 24 25 14 10 8 15 32 28 29 28 -- -- -- 8 lb NH4 -N/A 1st ft. lb NH4 -N/A 1st ft. lb NH4 -N/A 1st ft. lb NH4 -N/A 1st ft. Figure 1. Soil nitrate levels during the growing season as affected by four sidedress N fertilizer rates. Figure 2. Soil ammonium level during the growing season as affected by four sidedress N fertilizer rates. Petiole nitrate levels for the season are shown in Table 2 and Figure 3. Nitrate levels declined throughout June and July. The amount of nitrate in the petioles was directly related to the rate of N fertilizer applied. According the the MSU guidelines for nitrate levels in potato petioles (Extension Bulletin WQ09), only the 180 lb N treatment contained an adequate level of nitrate N on June 28, July 7 and July 14th. The level on July 14, however, was approaching the critical level. No samples were taken after this date. Table 2. Potato petiole nitrate content as affected by four sidedress N fertilizer rates1. Sidedress Rate lbs N/A 6-13 lb NO3-N2 6-21 lb NO3-N2 6-28 lb NO3-N2 7-7 lb NO3-N2 7-14 lb NO3-N2 0 60 120 180 20,737a 20,602a 26,045a 24,277a 22,210a 19,189a 20,613a 22,674a 3,275b 5,060b 10,719a 13,660a 980c 1,935bc 6,606ab 11,180a 1,476c 2,238bc 3,750b 6,484a 1 Sidedress N applied May 30, 1989 2 Any means followed by the same letter are not statistically different at the .05 level of probability. Figure 3. Potato petiole nitrate content during the growing season as affected by four sidedress N fertilizer rates. Yields, tuber size distribution and specific gravity are shown in Table 3. Four check samples were collected adjacent to the experiment from the growers field where the growers N practices were slightly different. Yields from these plots, although not part of the randomized complete block experimental design, were analyzed statistically with the other N plots. Total yield and U.S. No. 1 yields were directly related to the rate of N fertilizer applied, although the difference between the 120 and the 180 lb N sidedress treatments are not statically different. The field check significantly out yielded all N treatments. Neither, off-type, small or large tubers, nor specific gravity were affected by any of the N treatments. Table 3. The effect of nitrogen fertilizer rate on yield, tuber size and specific gravity of Russet Burbank potatoes. Sidedress Nitrogen YieldTuber size distribution off type cwt per acre Yield Tuber size distribution under 4 oz cwt per acre Yield Tuber size distribution 4-10 oz Yield Tuber size distribution over 10 oz Yield U.S. no. 1 cwt per acre cwt Yield Total Yield per acre Specific gravity Lbs/A cwt per acre cwt per acre 16a 13a 17a 22a Field check 20a 0 60 120 180 47a 49a 41a 42a 34a 257d 289c 328b 325b 365a la 10a 10a 7a 62a 258d 299c 338ab 331b 365a 320d 360c 394b 397b 480a g/cc 1.077a 1.080a 1.081a 1.078a 1.084a 1 Values followed by the same letter were not statistically different at the .05 level of probability. We conclude from this study that plant analysis information is more reliable than soil analysis for determining N adequacy for potatoes during the growing season. Soil nitrate and ammonium levels were highly variable and appear to be greatly affected by environmental conditions (rainfall, irrigation and soil temperature). Funding MPIC 1989 Nematology Progress Report G.W. Bird, Nematologist Department of Entomology MPIC funded a 1989 nematology project to develop and test computer software for the diagnosis, risk prediction and recommendations related to the root-lesion nematode in potato production. In addition to reporting the results of this project, the report contains the results of a nematicide trial, 1988 nematicide use survey, and crop rotation observations. NEMATICIDE EVALUATION Eleven nematicide treatments were evaluated in 1989 at the MSU Montcalm Potato Research Farm. All treatments provided excellent control of the root-lesion nematode (Table 1). The metham (Vapam or Busan 1020) treatment, however, resulted in the greatest tuber yield. 1988 NEMATICIDE USE SURVEY The results of the nematicide use survey indicated that 35,547 acres of potato land were treated with nematicides in 1988 (Table 3). Based on seventeen years of nematode research data, Michigan nematicide use resulted in an estimated profit increase of 13% of the crop value (Table 4). Chemigants and non-fumigant nematicides were used more widely than soil fumigants. Large potato farms used more nematicides than small or medium size farms. ROTATION CROP OBSERVATIONS As part of a Ph.D. dissertation by Mr. Tim Griffin, under the direction of Dr. Oran Hesterman, observations have been made on the impact of various rotation crops and management procedures on root-lesion nematodes, potato scab and black scurf (Table 5). A research project was initiated in 1989 at the MSU Montcalm Potato Farm to validate these observations. The test will be continued in 1990 and 1991, and the site will be available for observation by Michigan potato growers throughout the 1990 and 1991 growing seasons. NEMACAST-POTATOES NEMACAST-POTATOES is a computerized decision-support program designed to assist with diagnosis, predication and management of root-lesion nematodes and Verticillium in Michigan potato production. It is designed with an expert system component, which allows the user to quantify expert opinion. The resulting probabilities and management options can be used with a microcomputer or with a hand-held calculator. It is composed of three sections: Table 1. Influence of eleven nematicide treatments on Pratylenchus penetrans and potato foliage senescence in 1989. Treatment Mid-season nematodes 100 cm3 soil Mid-season nematodes 1.0 g root At harvest nematodes 100 cm3 soil PEDex (0-3) Control Telone II 10 gal/ A SN 109106 WP 18 lb/A SN 109106 WP 36 lb/A Telone II 15 gal/A Telone C-17 12.7 gal/A Telone C-17 19 gal/A Vorlex 12 gal/A Temik 15 G 20 lb/A Mocap 10G 90 lb/A Vydate 2L 2 gal/A Metham 75 gal/A 260 a 97 b 83 b 73b 50b 27 b 17b 10 b 10 b 7b 7b lb 151a 52 a 122 a 66a 473 a 18 a 5 a 18 a 21a 1 a 1 a la 267 a 104 a 87 a 80a 53 a 32 a 17 a 11a 13 a 17 a 12 a 2a Table 2. Influence of eleven nematicide treatments on tuber yields. Treatment Metham 75 gal/A Telone C-17 19 gal/A Vydate 2L 2 gal/A Telone II 15 gal/A Telone C-17 12.7 gal/A Vorlex 2L 12 gal/A Mocap 15 G 90 lb/A Temik 15 G Telone II 10 gal/A SN 109106 WP 18 lb/A SN 109106 WP 36 lb/A Control Tuber weight (cwt)a's 228 a 197 ab 195 ab 184 ab 183 ab 182 ab 180 ab 178 ab 174 ab 166 b 162 ab 151 b (cwt) b's 25a 29 a 26 a 29 a 28 a 27 a 21 a 32 a 31 a 30a 32 a 26 a Tuber weight Tuber weight (cwt) Tuber weight j's 15 a 11a 4a 11a 6a 8a 5a 6a 9a 9a 10 a 5a (cwt) k's 25a 18 ab 11 b 3b 10b 13 b 12 b 20 ab 11 b 13 b 11 b 11 b 2.5 a 1.8 ab 2.4 a 2.4 a 1.3 b 2.3 a 1.4 a 2.2 a 2.3 a 2.5 a 1.6 ab 1.1 b Total 290 a 250 ab 242 b 237 b 226 b 235 b 227 b 230 b 223 b 213 b 217 b 197 b • PROBLEM DIAGNOSIS: Use to assist growers in the within-season diagnosis of a plant growth or foliage senescence problems. • RISK PREDICTION: For use by growers to determine the potential risk of a nematode problem for a potato production site. Nematode and fungus sample population information required. • ECONOMICS OF NEMATODE MANAGEMENT: For use by growers to estimate the benefits of nematode management tactics. Information from "Risk Prediction" required. An example of the results of a NEMACAST-POTATOES Economics of Nematode Management analysis is provided in Table 6. The software indicates that under a specific set of grower-field conditions the potato crop would generate a revenue of $1,238 per acre without use of a nematicide for control of the root-lesion nematode population. Use of a non-fumigant nematicide would increase the projected revenue to $1,439 per acre, and chemigation with metham would further increase the projected revenue to $1,848 per acre. Nemacast-Potatoes is ready for grower testing. A computer disc containing the program can be obtained by calling (517) 353-8133. A hand calculator version of the program is also available for evaluation by Michigan potato growers. The software is designed to be user friendly, and should require very little instruction prior to use. Table 3. Nematicide use for three sizes of Michigan potato farms. Nematicide Chemigants Soil Fumigants Non-Fumigants 1 Total treated = 35,547 acres. 1 < 50 A Farms Acres Treated 0A 0A 225 A Acres Treated1 50-250 A Farms 54 A 569 A 2,846 A 1 >250 A Farms Acres Treated 11,554 A 5,777 A 14,522 A Table 4. Total net return increase from nematicide use in Michigan. Nematicide Chemigants Soil Fumigants Non-Fumigants Total 1 < 50 A Farms Acres Treated $0 $0 $47,700 $47,700 Acres Treated1 50-250 A Farms $14,526 $128,025 $572,046 $714,597 1 >250 A Farms Acres Treated $3,766,604 $1,178,508 $3,035,098 $7,980,210 1 Total = $8,742,507 or 13% of a $68,750,000 crop. Table 5. Potato crop rotation observations related to root-lesion nematodes, potato scab and black scurf.1 Management Rank2 Potato Production System Rotation Crop 3 Nematode Potato Production System Rotation Crop3Potato ScabPotato Production System Rotation Crop3 Potato Scurf Potato Production System Rotation C AGM RCH SC AGM BTH AGM BTGM AH • 1 2 3 • • 10 11 12 Potato Production System Rotation Crop3 N/PS AGM SC BTH Crop3 N/BS AGM AH QSC Potato Production System Rotation Crop3PS/BS AGM Potato Production System Rotation Crop3N/PS/BS AGM SC AH SC AH empty table cell empty table cell empty table cell empty table cell empty table cell empty table cell empty table cell empty table cell empty table cell empty table cell empty table cell empty table cell empty table cell empty table cell empty table cell empty table cell empty table cell empty table cell empty table cell empty table cell empty table cell AH BTGM HV BTGM C RCH HV RCGM RCH RCH BTGM HV RCGM BTH HV BTH RCGM RCH BTH RCGM RCH 1Observations from Mr. Tim Griffin's Ph.D. dissertation under the direction of Dr. Oran Hesterman and Dr. G.W. Bird. 21 = best for potato production, 12 = worst for potato production. 3N = nematode, PS = potato scab, BS - black scurf, C = corn, SC = sweet clover, AGM = alfalfa green manure, BTGM = birdsfoot treefoil green manure, AH = alfalfa hay, RCGM = red clover green manure, RCH = red clover hay, BTH = birdsfoot treefoil hay, HV = hairy vetch. Table 6. Example results of the Economics of Nematode Management section of Nemacast-Potatoes run for the following condition: Soil Texture Cultivar Yield Root-Lesion Nematode Population Verticillium Population Expected Yield: Selling Price: Sandy Loam Superior Low 10-24 4-9 350.00 6.00 empty table cell Revenue Cost of Application Yield gain Net revenue Net increase empty table cell Revenue Cost of Application Yield gain Net revenue Net Increase empty table cell Revenue Cost of Application Yield gain Net revenue Net increase No Application 1238.16 0.00 --- 1238.16 --- Nematicide Application 1439.40 50.00 33.54 1389.40 151.24 Chemigation Application 1848.90 200.00 101.79 1648.90 410.74 Insecticide Application 1338.66 25.00 16.75 1313.66 75.50 Soil Fumigant Application 1649.38 150.00 68.54 1499.38 261.22 empty table cell empty table cell empty table cell empty table cell empty table cell empty table cell Funding MPIC Control of Insecticide-Resistant Colorado Potato Beetles in Michigan 1989 Research Report E. Grafius, B. A. Bishop, P. Ioannidis, and P. Henry Department of Entomology Michigan State University Summary: Research on Colorado potato beetles (CPB) in 1989 included: Insecticide evaluations; development and distribution of an expanded test kit for monitoring insecticide resistance; research on inheritance and mechanisms of resistance and cross-resistance; and measurement of survival and development of resistant and susceptible CPB larvae on different host plants. Insecticide evaluation studies indicated that new insect growth regulators, cryolite, Asana, and Asana plus PBO synergist gave good to excelent control. Temik was less effective than in previous years, probably partly due to the very early planting date in relation to plant growth and CPB activity. The resistance test kit was expanded to include 4 insecticides and 1 insecticide/synergist combination. 296 kits were given to growers, county agents, and consultants and results were reported back from 84 sites. Laboratory and greenhouse studies were conducted to relate test kit results more precisely to insecticide performance under field conditions. At least six resistance mechanisms have been determined or Michigan CPB; three types of enzymes (two mixed-function oxidases and one esterase), knock-down resistance, penetration resistance, and altered nerve chemistry. Inheritance and cross resistance studies for Furadan and Guthion were completed. However, the Guthion data have not yet been completely analyzed at this time. Studies on Ambush/Pounce resistance and resistance to other pyrethroids are underway. Survival and development of resistant and susceptible CPB strains indicates that resistant strains are as vigorous or more so than susceptible strains. All larvae did poorly on tomato, but most did well on eggplant and Solanum chacoense (a wild potato species used in potato breeding). Data are being analyzed and will be reported later. Thanks to the Michigan Potato Industry Committee, Michigan Agricultural Experiment Station, and Michigan Energy Conservation Program for support of this research. Insecticide Evaluations Trials were conducted at the MSU Montcalm Potato Research Farm in Entrican, MI. Potatoes were planted on April 28, 1989. Plots were 40 ft long and 3 rows wide (34 in row spacing) and were arranged in a randomized complete block design with 4 replications (=blocks) per treatment. Granular systemic treatments applied at planting were sprinkled in the furrow directly over the seed piece. The Temik sidedressed treatment was applied on May 24,1989 by placing the insecticide over the row just prior to hilling. Foliar treatments were applied using a tractor-mounted boom sprayer at 30 gpa, 40 psi, with 3 nozzles per row. Foliar sprays were applied at approximately weekly intervals from June 23 to July 28. Insecticide effectiveness was evaluated by counting the number of insects on entire plants randomly selected from the middle row of each plot (2 plants per plot) 1 to 5 days after foliar application. The middle row of each plot was harvested on September 26. Tubers were separated by size and weighed. Most insecticide treatments (Table 1) effectively controlled Colorado potato beetle adults and larvae (Figure 1). The seasonal totals (sum of the number of beetles per plant on six different sampling dates) for adults and large larvae were significantly higher in untreated plots than in any of the treated plots. In generally, the Bacillus thuringeinsis treatments (M-One, Diterra, Trident) gave the poorest control, although the experimental Bt product MYX 1806 resulted in good control. The combination of Temik (at the 1#/A rate) with Asana resulted in season-long control of adults and larvae that was better than Temik alone at the 3#/A rate. Kryocide 96WP (registered in Michigan for the second year under section 18 emergency registration) was found to give excellent control of both adults and larvae Table 1. Insecticide treatments and rates included in insecticide evaluation studies at MSU Montcalm Potato Research Farm in 1989. Treatment No. Treatment Treatment No. Treatment 1 2 3 4 5 6 7 8 9 10 11 12 13 Dowco 473 10SC 0.5 oz ai/A Dowco 473 10SC 1.0 oz ai/A Dowco 473 10SC(0.5 oz ai/A) & Lorsban 50WP (1# ai/A) Dowco 473 (10SC)(1.0#ai/A) & Lorsban 50WP (l#ai/A) Lorsban 50WP (l#ai/A) Trident 4SC 4 Qt/A Trident II4SC 2 Qt/A Kryocide 96WP 12#ai/A Mycogen M-l 2Qt/A MYX 1806 3Qt/A Sevin XLR+ l#ai/A Sevin XLR+ (l#ai/A) & Cygon 4EC (0.25#ai/A) Sevin XLR+ (l#ai/A) & Asana XL 0.66EC (0.025#ai/A) 14 15 16 17 18 19 20 21 22 23 24 25 26 EXP 60145A 0.012#ai/A EXP 60145A 0.025#ai/A EXP 60145A 0.05#ai/A PP-0321 10WP 0.02#ai/A Karate 1EC 0.02# Ai/A AsanaXL 0.66EC (9.6oz/A) Asana XL 0.66EC (9.6oz/A) & Butacide 8E (0.25#ai/A) Temik 15G (l#ai/A IF@Plant) & Asana XL 0.66EC (9.6oz/A) Temik 15G (l#ai/A Side @ Hill) & Asana XL 0.66EC (9.6oz/A) Temik 15G (3#ai/A IF @Plant) Diterra (l#ai/A) Diterra (2#ai/A) Untreated Figure 1. Mean no. Colorado potato beetle adults and large larvae per plant. Seasonal totals for each treatment. Harvest Weights (total weight of tubers harvested from 40' of the middle row) were significantly lower in untreated plots (36.8 lb) than in any of the treated plots (Figure 2). Harvest weights in treated plots ranged from 57.5 to 89.3 lbs and, in general, did not differ significantly, although the 2 highest harvest weights (treatments 16 and 22) were signigicantly higher than the two lowest weights (treatments 4 and 9). Figure 2. Mean weight (lb) of tubers harvested from 40 ft of the center row of each plot for each treatment Development, Distribution and Evaluation of an Insecticide Resistance Test Kit The on-farm petri dish test kit for detecting insecticide resistance in Colorado potato beetles that was first introduced in 1988 was furthur refined. The test for evaluating resistance to Imidan was improved and a test for detecting resistance to Thiodan was added. Demand for these test kits was very high early in the season. A total of 296 kits was distributed in 1989. Most were distributed to growers, extension agents and pest control consultants in Michigan, although requests from kits were received from and honored from other places, specifically, Ohio and Quebec, Canada. A total of 84 copies of test results were sent in. In addition, many field-collected populations were tested in our lab. Results are still being analyzed, although preliminary analysis seems to indicate that, compared with 1988 results, the proportion of resistant populations was higher for all insecticides in the test kit. Demonstrations designed to show the relationship between petri dish resistance test results and field efficacy of an insecticide were conducted during the 1989 growing season. In June, 3 demonstrations were conducted in the Gun Marsh area and in August a demonstration was conducted on the Stan Leep Farm in the Gun Marsh area. Demonstrations consisted of collecting beetles from the field, testing them with the resistance test kit, applying insecticides (those in the test kit) to small plots in the field, doing a pre-application and post-application counts of Colorado potato beetle in the field, and evaluating how well the test kit results predict the effectiveness of the insecticide when applied in the field. Unfortunately, in all cases the beetle populations in the field were very low, and little difference in beetle numbers between small plots in the field could be detected. Consequently, simulated field applications of 3 insecticides (Furadan 4F, Imidan 50WP, and Thiodan 3EC) were made to 5 beetle populations collected from fields throughout Michigan. Results of the field application (% mortality) were compared to resistance test results (% mortality) and to results of topical application bioassays (LD50 and resistance ratios). Beetles were collected from field populations during late August and early September. Four different beetle strains were tested with each insecticide. Each strain was tested with the resistance test, topicial application bioassay, and field application simulation for that insecticide. Resistance tests were performed by placing 10 to 20 beetles in a resistance test plate and counting mortality 24 hours later. Topical applications were made by applying 2 ul of one of four different concentrations of technical insecticide diluted in acetone to the first abdomenal sternite of a beetle. Mortality at each concentration was evaluated 3 days later. Using probit analysis, LD50 values and resistance ratios were calculated. Field application was simulated by applying commercial grade insecticides at recommended field rate in the greenhouse. Insecticide was applied using a hand-held CO2 sprayer with a single nozzle at 20 gpa and 40 psi. Both potato foliage (potted potato plants) and beetles contained in screen-covered petri plates were sprayed. Beetles that were sprayed were subsequently fed untreated potato foliage for 3 days. A second group of beetles (unsprayed) were fed sprayed foliage for 3 days. Mortality was evaluated in both groups after 3 days. Results of the petri dish resistance test for carbofuran (Furadan 4F) showed that 3 of the 4 strains tested were resistant (less than 30% mortality) (Figure 3). The Montcalm strain was found to be a mixed population. The trends revealed by the resistance ratios (= LD50 of the strain in question / LD50 of a susceptible strain) corresponded well to the resistance test results. Mortality both in beetles that had been sprayed with Furadan 4F and those that had been fed Furadan-treated foliage was significantly correlated with mortality resulting from the petri dish resistance test kit. Figure 3. Results of testing 4 strains of Colorado potato beetle with 3 different tests of carbofuran resistance (petri dish resistance test [percent mortality], topical application bioassay [resistance ratio], and a simulated field application of Furadan 4F [percent mortality]). Mortality from simulated field application was evaluated by spraying beetles with Furadan 4F (sprayed group) and by feeding beetles potato foliage that had been sprayed with Furadan 4F (Fed/Contact group). Results with Imidan (phosmet) were similar, although somewhat more variable (Figure 4). Again, 3 of the 4 beetle strains evaluated with the petri dish resistance test were found to be resistant with the remaining Montcalm strain classed as mixed. Resistance ratios of these four strains confirmed these classifications. Mortality in beetles sprayed with Imidan 50WP was significantly correlated with mortality resulting from the petri dish resistance test. In general, mortality resulting from beetles consuming Imidan-treated foliage was also similar, although in one strain (B.T.) mortality was much greater. This particular strain was 4 generations removed from the field and was undergoing selection for resistance to Bacillus thuringeinsis, so it is possible that this may explain the inconsistency. Figure 4. Results of testing 4 strains of Colorado potato beetle with 3 different tests of phosmet resistance (petri dish resistance test [percent mortality], topical application bioassay [resistance ratio], and a simulated field application of Imidan 50WP [percent mortality]). Mortality from simulated field application was evaluated by spraying beetles with Imidan 50WP (sprayed group) and by feeding beetles potato foliage that had been sprayed with Imidan 50WP (Fed/Contact group). Results with Thiodan (endosulfan) were also similar (Figure 5). Once again, 3 of the 4 strains tested were classified by the petri dish resistance test as resistant. The resistance ratios obtained by topical application bioassay agreed with this classification. Mortality in beetles sprayed with Thiodan 3EC was significantly correlated with petri dish resistance test mortality. Again, mortality in beetles fed Thiodan-treated foliage was somewhat more variable than the other tests, being higher than predicted, in some beetle strains. Figure 5. Results of testing 4 strains of Colorado potato beetle with 3 different tests of endosulfan resistance (petri dish resistance test [percent mortality], topical application bioassay [resistance ratio], and a simulated field application of Thiodan 3EC [percent mortality]). Mortality from simulated field application was evaluated by spraying beetles with Thiodan 3EC (sprayed group) and by feeding beetles potato foliage that had been sprayed with Thiodan 3EC (Fed/Contact group). In general, then, these test results indicate that the petri dish insecticide resistance test for Colorado potato beetle is able to detect the presence of resistance in field populations, and predict when , due to resistance, control achieved by insecticide application will be less than adequate. Carbofuran Resistance Carbofuran resistance is rapidly becoming wide-spread in Michigan. A better understanding of the mechanism and inheritance may allow growers to avoid problems with Furadan, if it is still effective. Also, this knowledge may help in managing similar resistance if it occurs to other insecticides. The objectives were to: 1. Select for carbofuran resistance, beginning with large-scale field selection; 2. Characterize resistance in terms of dose-mortality relationships, possible mechanism, and inheritance (number of genes, degree of dominance, sex linkage, etc.); and 3) Compare the selected strain with other resistant populations. CPB populations. The initial field selection for carbofuran resistance was conducted in 1986 at the Michigan State University Montcalm County Potato Research Farm (Entrican MI). CPB at the research farm were susceptible to carbofuran (LD50 = 0.63 μg/beetle) and organophosphate insecticides (e.g. LD50 for Guthion = 1.43 ug/beetle ) and moderately resistant to pyrethroids (e.g. LD50 for permethrin = 6.86 ug/beetle)(unpublished data). Beetles at this site had been exposed to a range of commercial and experimental insecticides in previous years, particularly endosulfan (a chlorinated hydrocarbon), methamidophos (an organophosphate), and the carbamates, carbaryl and aldicarb. To the best of our knowledge, no carbofuran had been sprayed on the research farm prior to the study. Small plot studies of carbofuran as a soil insecticide had been conducted previously, but these never involved more than 0.3% of the potato acreage. The laboratory culture was started with ca. 300 individuals collected from unsprayed volunteer potatoes next to a commercial farm near Vestaberg MI (Montcalm Co.) in the summer of 1987 and kept in continuous laboratory culture. This was the most susceptible population to carbofuran of 29 field populations tested (unpublished data). The LD50 for Vestaberg to carbofuran was 0.18 ug/beetle and 1.24 ug/beetle to Guthion, with a homozygous response to both compounds. These values are in a agreement with those for susceptible strains reported by Forgash (1985) and Johnson and Sandevol (1986). The Vestaberg strain has been regularly tested to ensure continued susceptibility to carbofuran and shows no loss of vigor due to inbreeding. Laboratory techniques. Technical grade carbofuran (98% purity, courtesy of FMC Corporation) in acetone was used for all laboratory selections and assays. Adults were immobilized using a 3.3 mm diam. vacuum hose and 2 μl of solution was placed on the underside of the abdomen of each adult. Mortality was assessed 72 h post-treatment. Fresh potato leaves from greenhouse plants were provided to the beetles daily during the testing. For LD50 determinations, at least 4 doses of carbofuran with 16 beetles per dose 2 replications of 8 each), plus an untreated group (acetone only), were used. Results were corrected for mortality in the controls (acetone alone - usually less than 10% mortality) using Abbott's (1925) formula and standard log-probit analyses were performed. All laboratory rearing and experiments were conducted at 25°C±2°C, 16 h light: 8 h dark photophase. Adults were tested ca. 1 week after emergence from pupation. Field selection. Selection for carbofuran resistance was initiated in the field on 25 July 1987. Carbofuran was applied to a 16 row x 168 m plot of potatoes at 0.55 kg active ingredient per hectare using a commercial ground insecticide sprayer. CPB was in the first generation larval stage at the time of treatment and the pre-treatment density was estimated as 37 ± 10 (mean ± SE) larvae per plant based on data from adjacent untreated plots (unpublished data). The total number of CPB larvae treated in the field was approximately 488,400 (37 x 13,200 plants estimated in the plot). 24 h post-treatment, the plot was searched visually for surviving larvae. All surviving larvae were collected and returned to the laboratory. Laboratory selection. A sample of the field-collected larvae was tested for carbofuran resistance using a dose of 5 ug/beetle. (All survived.) The rest of the larvae were fed untreated potato foliage and reared to adults in the laboratory. These adults were tested for LD50 for Furadan as described above. The adults that survived the two highest doses (5 and 2.5 μg/beetle) were kept in culture. Progeny were reared to the adult stage and a sample was again tested for LD50 to Furadan. The untested adults were selected with Furadan to cause ca. 80% mortality. This process was repeated on the next 2 generations. These beetles were designated as the "Montcalm-C" strain and maintained in culture and subjected to a dose of 100 ug Furadan/beetle every generation to assure maintenance of resistance. Resistance mechanism studies. The synergists piperonyl butoxide (PBO) and s,s,s,tributylphosphorothionate (DEF) were used as indicators of possible resistance mechanisms. PBO is a specific inhibitor of mixed-function oxidase enzymes (MFO's). DEF inhibits esterases and MFO's. Synergists were applied at 100 ug/beetle for the Montcalm-C strain and 50 ug for the susceptible strain, 2 h prior to insecticide treatment of the beetles. The 100 ug dose caused no mortality to the Montcalm-C beetles but more than 20% mortality to Vestaberg beetles (hence the use of 50ug). Resistance ratios with and without synergist were calculated from LD50 values for resistant and susceptible strains. Susceptibility of the Montcalm-C strain to Guthion was also estimated using the standard LD50 method and results were compared to LD50 values for the unselected (field-collected) Montcalm farm population. Inheritance studies. Adults from the Montcalm-C and the Vestaberg strains were sexed within 48 h after emerging from pupation. Male/female reciprocal crosses were conducted. Pairs were kept together until they began mating (to insure that no male/female errors had been made) and then grouped with other pairs of the same cross in cages and fed potato foliage. Adult offspring (F1 adults) from the crosses were tested with a discriminating dose (3.12 ug/beetle) for Furadan resistance, and the numbers dead and alive were recorded after 72 h, as described above. A subsample of the F1 adults were treated with the descriminating dose. The survivors (resistant heterozygotes) were back-crossed to the Vestaberg strain and adult progeny tested with the descriminating dose, as before. This process was continued for 3 generations. F2 adults (progeny of F1 x F1 crosses) were also tested for susceptibility to Furadan. Results Initial field selection resulted in survival of ca. 80 larvae (>99.98% mortality). Survivors occurred in groups of 5 to 10 larvae on a plant, rather than individual larvae as might have been expected due to random effects of factors such as spray coverage. Analysis of adults developing from the surviving larvae indicated that they were approximately 52 times more resistant to Furadan than the initial population. Subsequent laboratory selection increased the resistance ratio to 175 fold, within 4 generations. Reports from commercial potato fields and on-farm resistance monitoring also support the rapid change from Furadan susceptible to highly resistant, often within one growing season. Inheritance studies indicated that F1 offspring of resistant x susceptible crosses were uniformly resistant. Resistance levels were nearly as high as parental levels and showed no significant difference between sexes, suggesting near complete dominance and autosomal inheritance (Fig. 6). F1 backcrosses to susceptible beetles and F1 x F1 crosses showed nearly perfect Mendelian segregation, indicating a single gene or closely linked genes (Table 2). Cross-resistance and synergist experiments showed a moderate cross-resistance to Guthion and almost no synergism for Furadan or Guthion with either PBO or DEF. Lack of synergism and the absence of low and intermediate levels of resistance in the Montcalm-C strain or other populations from commercial fields suggests target site insensitivity. Preliminary data from in vitro studies on the Montcalm-C strain and on another Michigan carbofuran-resistant population shows altered acetyl cholinesterase activity (Weirenga & Hollingworth, unpublished data). This mechanism is also suggested by cross-resistance to Guthion. The extremely rapid mortality of susceptible beetles in response to Furadan treatment (100% mortality in < 2 h) also suggests that detoxification enzymes would be of limited usefulness unless they were present at very high levels. In contrast to the Michigan populations studied, a population from Long Island NY, selected for Guthion resistance in our laboratory, shows significant synergism of Furadan by PBO and a lower level of resistance, probably indicating detoxification as the primary mechanism of resistance. In vitro studies with this train did not show any altered acetyl cholinesterase activity. Historically, Furadan was only used very late in the resistance history on Long Island, after failure of numerous organophosphates and carbamates. In Michigan, and specifically at the Montcalm site, Furadan resistance was selected much earlier in the resistance history. We hypothesize that this difference in resistance history explains the different mechanisms that involved. At the time of selection, detoxification enzymes in the Montcalm population were probably not near the very high levels required to detoxify the rapidly-acting Furadan, thus leading to selection for target-site insensitivity. Management of Furadan resistance in CPB appears to be a difficult proposition. The single gene dominant nature of the inheritance and high selection pressure exerted by Furadan treatment result in exceptionally rapid resistance occurrence. Resistant populations are, for all practical purposes, immune to Furadan treatment. The resistance factor appears to be present at very low frequencies in many or prehaps all Michigan populations, judging from the wide-spread and rapid build-up of resistance in the field. Limited use of Furadan (< once per CPB generation) and alternation of Furadan treatment with non-cross resistant materials (e.g. permethrin, where effective, or aldicarb), along with non-chemical management tactics, may increase the effective life of Furadan in the field. Table 2. CPB mortality from Furadan: Ratio expected if resistance is inherited by a single gene and observed mortality. Cross (# tested) Expected Ratio Observed Mortality RR : RS : SS (SS individuals) F1 F1 xF1 (150) B1 (191) B2 (323) B3 (36) 0:1:0 1:2:1 0:1:1 0:1:1 0:1:1 0 26.0% 49.7% 56.0% 52.8% Figure 6. Mortality (probit 5 = 50%, probit 4 = versus dose for Furadan-susceptible (Vestaberg) and resistant (Montcalm-C) strains and offspring of reciprocal male x female crosses. Funding Federal Grant INFLUENCE OF ENVIRONMENTAL FACTORS ON WOUND HEALING IN RELATION TO STORAGE DISORDERS INVESTIGATORS: R. HAMMERSCHMIDT AND A.C. CAMERON Improper and incomplete wound healing can lead to losses due to disease and water losses. The tuber, during the early stages of storage, is actively repairing wounds that occurred during the harveting and handling of the tubers. Since CO2 would be expected to accumulate in the storage environment as a result of the enhanced respiration during suberization,' we have further characterized the effects of CO2 on the wound repair process. In addition, we have examined the effects of non-pathogenic microorganisms on the wound response and have started to study the CO2/O2 levels in the tuber at two different temperatures. Evaluation of selected varieties for resistance to Fusarium dry rot was also initiated. PROCEDURES Suberization studies Suberization studies were carried out using 2.1 X 1.0 cm disks of tuber tissue. The discs were incubated at 20 C in humidified air or in air enriched with 4% CO2. Samples were taken at daily intervals to measure suberin deposition (via analysis of suberin lignin), chlorogenic acid content (in methanolic extracts of tissue), and the suberization enzymes phenylalanine ammonia lyase (PAL), coniferyl alcohol dehydrogenase (CAD) and peroxidase (PO) (in buffer extracts of tissue). Infection studies Tubers of selected varieties were inoculated with a 2mm mycelial plug of Fusarium sambucinum (FS) that was placed in a 3mm diameter wound in the tuber surface. The tubers were incubated at 18C and 95% relative hunidity for three weeks. Internal gas relations of the tuber Whole, unwounded tubers were analyzed for the internal content of CO2 and O2. Small cyclinders were affixed to the surface of tubers and the cylinders closed with a serum stopper. At intervals, the amounts of CO2 and O2 in the head space (a refelection of internal gas content) was evaluated by gas chromatography. RESULTS AND DISCUSSION Influence of elevated CO2 on biochemical factors involved in suberization Introduction of 4% CO2 into the incubation chambers decreased the time of induction and and total amounts of lignin (Fig. 1), chlorogenic acid (Fig. 2), and peroxidase (Fig. 3). PAL was also supressed (data not shown). Most striking were the consistent difference observed between Atlantic and Russet Burbank in relation to timing of induction of all parameters in air and the magnification of these differences in CO2. Isozyme analysis of the tissue demonstrated that the suberization specific peroxidase was induced at only a very low level in the tissue exposed to CO2. These results further demonstrate the wound repair suppressive effects of CO2 as well as the great differences that can be observed between cultivars. Wound induced peroxidase analysis of several cultivars further demonstrate the differences in wound healing induction rates that are found among varieties. Infection studies Inoculation of selected varieties with FS demonstrated no clear resistance among the varieties tested (Table 1). Tuber gas analysis We have carried out preliminary work to determine if we can monitor the internal gas composition of tubers without wounding. Oxygen and carbon dioxide were measured in Russet Burbank tubers over a 39 day period. The tubers were incubated at 20C for 22 days and then placed in 5C storage on day 23. Internal CO2 levels gradually declined over the first 22 days, possibly as a result of slowing respiration. Oxygen levels remained constant. When the tubers were placed at 5C, there was an immediate drop in CO2, and the level of CO2 remained low. We interpret this as a temperature- related drop in respiration. The transient increase in O2 at the same time was probably a direct reflection of the change in respiratory rate Figure 4). We plan to use this technique to further evaluate the effects of infection and tuber storage environments on the internal gas relations of the tuber. With infected tissues, we may also be able to determine specific metabolic profiles of the tuber under stress by observing changes in volatiles released during infection and disease development. TABLE 1 FUSARIUM DRY ROT DEVELOPMENT IN TUBER TISSUE VARIETY Atlantic Superior Saginaw Gold Onaway Lemhi ND 860-2 700-83 LESION DIMENSIONS * 10.9 X 6.0 13.0 X 5.4 16.0 X 9.1 15.8 X 5.8 12.6 X 6.2 12.9 X 5.6 13.9 X 6.5 * Diameter X depth, 10 tubers per variety Figure 1. Figure 2. Effect of CO2 on lignin portion of suberin Effect of CO2 on chlorogenic acid accumulation Figure 3. Effect of CO2 on peroxidase induction Figure 4. Meaurement of internal CO2 and O2 in whole tubers over time Funding MPIC Determination of Bisulfite Residues in Potato Products Jerry N. Cash Food Science and Human Nutrition INTRODUCTION In fresh, peeled potato products enzymatic browning occurs very rapidly after peeling so the use of an anti-browning agent is essential for obtaining any reasonable degree of shelf life. For many years bi sulfites (SO2) have been used to prevent discoloration and inhibit microbial growth in many plant tissues, including fresh, peeled potatoes. However, bisulfites have recently been implicated as the causative agent for adverse health reactions in certain sulfite-sensitive individuals and FDA has proposed banning sulfite usage in several products, including fresh, peeled potatoes. The potato industry has been requested to supply information regarding the minimum levels of sulfites required to achieve intended effects and the reductions in bisulfite levels during storage and preparation of potato products for consumption. The objective of this study was to assess the residue levels of bisulfites in potato products made from fresh, peeled potatoes. MATERIALS AND METHODS Medium size (7 to 9 oz) Russet Burbank potatoes, specific gravity 1.082 and approximately 20% dry matter were used throughout the study. After peeling, potatoes were sulfite treated as: 1) raw, whole tubers; 2) 3/8" french fry slices; or 3) 1/2" diced cuts. Whole potatoes went directly into the treatment tank after peeling. The whole potatoes to be cut into french fry slices and dice cuts were held briefly in a 1% salt (NACl) solution to retard browning before cutting. Based on previous work in our lab and information obtained from Michigan processors it was felt that a residual SO2 level of approximately 40-75 ppm immediately after dipping is required for 10- 12 days shelf life on whole tubers and french fries, while approximately 150- 200 ppm is required for the same shelf life on diced cuts because of the larger surface area of this product. Using data developed by Rodriguez and Zaritsky (1986) a 0.5% bisulfite solution was used with dip times of 60 seconds for the medium sized, whole tubers and 30 seconds for french fry and diced cuts. After bisulfite treatment, samples were packaged in plastic bags, refrigerated at 36°F and held for 0, 4, 8 and 12 days before cooking. At each sample time potatoes were removed from refrigeration and boiled in water for 25 minutes (whole and diced) or fried in vegetable oil at 370°F for 2-3 minutes until golden brown (french fries). Residual sulfite concentration was determined on triplicate raw and cooked samples by the AOAC Modified Monier- Williams method. RESULTS The changes in bisulfite concentration for all products throughout the study are shown in Table 1. A 12 day shelf life, based on product color, was obtained with all the samples in the study indicating that the sulfite concentrations and dip times chosen were adequate. Microbiological tests were not included in the study but the appearance, texture and overall quality of samples at the end of the storage time seemed to indicate that minimal microbiological deterioration had occurred. It is not known if smaller sulfite residue concentrations can achieve the same results. As expected, bisulfite levels did decrease greatly during storage and cooking because of the volatile nature of the compound. The rate of decline in the raw products over the 12 day storage period ranged from a 75% loss of SO2 in the french fries to 80% in the whole tubers and 86% in the diced samples. Cooking further reduced bisulfites in all products. In this study, boiling seemed to be slightly more effective than frying in terms of SO2 reduction but frying did lower SO2 levels dramatically. This study indicates that bisulfite residues in fresh, peeled potato products are reduced significantly during storage and preparation for consumption. The data from this work are in close agreement with the work of Finne (1987). REFERENCE 1. Rodriguez, N. and N.E. Zaritsky. 1986. Modeling of sulfur dioxide uptake in pre-peeled potatoes of different geometrical shapes. J. Food Sci. 51:618. 2. Finne, G. 1987. Effect of treatment conditions on the residual sulfite concentrations and shelf life of fresh raw peeled potatoes. Table 1. Bisulfite Residues in Raw and Cooked Potato Products Dipped in a 0.5% Bisulfite Solution. Residual SO2 (ppm) 1 Residual SO2 (ppm)1 Cooked3 Days of Storage @ 36°F Product SO2 Dip Time (sec) 0 4 8 12 0 0 4 4 8 8 12 12 Whole2 Diced French Fries Whole2 Diced French Fries Whole2 Diced French Fries Whole2 Diced French Fries 60 30 30 60 30 30 60 30 30 60 30 30 Raw 48 172 69 20 135 43 15 37 31 10 24 17 17 50 25 12 30 19 84 11 10 5-7 11 9 1 Average of 3 samples 2 Whole = Medium sized 7-9 oz. tubers. 3 Cooked = Whole and diced boiled 25 minutes; french fries fried in vegetable oil @ 370°F for 2-3 minutes. 4 SO2 analytical method loses sensitivity below 10 ppm. Funding Federal Grant PACKAGING ALTERNATIVES FOR LIGHT USERS OF TABLESTOCK (FRESH) POTATOES.. A Synthesis of Two Focus Groups Mary D. Zehner1 Focus group interviews were conducted with consumers of fresh potatoes in December, 1989 in Kalamazoo, Michigan. While the overall goal of the study was to suggest how the Michigan potato industry might recover its share of the fresh potato market (especially for round, white potatoes), specific objectives included: * To learn potato packaging preferences for light users of fresh potatoes (paper, plastic, mesh, from bulk display and unit of purchase). * To learn present use patterns and selection criteria for light users (potato size, quality, varieties, etc). * To examine levels of satisfaction/dissatisfaction with fresh potatoes in order to suggest ways in which producers can adjust to better meet the needs of the consumer. Methodology Two focus group interviews were held with light users of fresh potatoes. A light user was defined as someone who purchased one to ten pounds of fresh potatoes in an average month. Participants were recruited by random telephoning. Selected participants were adults most responsible for food purchase and preparation for their household. The groups were recruited to include a representation of age, employment patterns, household income and race. The sessions were conducted by Harrington Market Research of Kalamazoo, Michigan and were audiotaped. The sessions began at 5:45 p.m. and 8:00 p.m. and lasted one and one-half hours. Focus group interviewing consists of bringing together a small group of people, normally 8 to 10 at a time. Then let them talk about a topic, idea, product or concept. The unique advantage of focus group interviewing is the dialogue between participants. Members listen and react to each other. The focus group technique is qualitative, not quantitative in nature. Therefore findings cannot be statistically projected to the general population. This methodology provides the opportunity to gain insights into consumers’ decision-making process relative to fresh potatoes. It also offers direction for the follow-up mall intercept interviews with light potato users (a quantitative study) planned for March 1990. Summary The project was to determine the potato and potato packaging preferences of light users of potatoes. The focus was on the all-purpose Superior variety which accounts for the majority of round, white potatoes sold during the winter months from Michigan potato storages. The report summarizes the focus group interviews (part one of the two-part project). The participants were aware of a number of types of fresh potatoes; however, there was some confusion as to variety(ies) and sources of the potatoes (Idaho and Michigan). They were able 1 Department of Agricultural Economics, Michigan State University, East Lansing, MI 48824-1039. to describe 25 ways of preparing potatoes. Nearly everyone microwaved potatoes because of convenience and speed, but conventionally baked potatoes were preferred by the vast majority. Factors in the selection of fresh potatoes included price, size of potatoes, quantity per package, physical characteristics (firmness, number of eyes, taste, greening), brand or variety, and packaging. The decision to purchase potatoes was based on the interaction of these factors with the intended use of the potatoes--how and for whom they were to be prepared. Potatoes considered "best" for inclusion in a pot roast for the family might be quite different from those to be baked for a special dinner party. Everyone wanted inexpensive and uniformly high-quality potatoes. They also wanted the option of buying prepackaged potatoes or selecting individual potatoes from a bulk display. Because there consumers wanted prepackaged potatoes to be visible and well-ventilated, net bags were favored over plastic or paper. Sizing was also important to the participants. Uses for every size were described, but in addition to mixed size potatoes in a bag (but not very small potatoes in the same bag with large potatoes), these consumers wanted to be able to buy uniformly sized potatoes. A display box for bulk potatoes (50 lbs) designed to reduce greening from ultraviolet light was not enthusiastically received because the participants imagined having to dig through the box to select potatoes. No one in either group had identified the cause of greening as exposure to florescent light—if they had, the box might have been considered more useful. The people in the discussions were generally satisfied with the fresh potatoes they purchase. They view potatoes as a versatile, nutritious, economical, low-calorie and good tasting staple. The negative comments concerned packaging (paper and plastic bags) and the lack of quality (dirty, green, soft, nonuniformly sized and spoiled potatoes). Comparison of the "Idaho" potato to the "Michigan" potato revealed a sharp distinction in images. The Idahos were considered formal, elegant potatoes, suitable for guests, but lacked versatility. They were described as uniform and having a consistent quality that could always be counted on. In contrast, the Michigan were thought to be more like old friends that one is comfortable with on a day-to-day basis. They were thought to lack the consistent quality of Idaho; virtually all the complaints mentioned previously were directed at Michigan-grown potatoes. The participants also seemed to feel that Michigan growers lacked pride in their product. It must be emphasized that Michigan-grown potatoes were well-liked in terms of taste, texture and versatility. The majority of these participants would support the Michigan potato if quality control were improved. A number of ideas for promoting Michigan-grown potatoes emerged from the discussions including: - informational displays in the vegetable section of the supermarket - educational programs in schools - endorsement by restaurants - multi-media advertising - a guarantee of quality - emphasis on potatoes as a basic, "comfort" food The clearest message seemed to be that although a promotional campaign might be successful in getting the good word out about Michigan-grown potatoes, the money and the effort would be wasted unless, as several participants reported, the "Michigan potato industry first cleans up its act" by improving quality through better grading and sizing systems. It was felt that although advertising might encourage buyers to try Michigan potatoes once or twice; only a good product will retain those buyers. Direction For Mall Intercept Study The focus group findings suggest that there are market opportunities for Michigan potato products which better meet the needs and preferences of light users of fresh potatoes (i.e., ability to see the potatoes in the bags, smaller units of purchase, the option of selecting the number of potatoes needed and/or prebagged potatoes, improved quality, and more closely sized than U.S. No 1 potatoes). In response, the upcoming mall intercept interviews will address three areas: (1) Identifying the preferences (from a choice of six different displays) for buying fresh potatoes...and the reasons for the decision. Four of the six displays will represent packaging options not currently available in Michigan supermarkets. They include: bulk Superior potatoes 8 to 10 ounces, 3-pound bag sized Superior potatoes, 3-pound bag of Russet Norkotahs (strippers) and Russet Norkotahs in a tray with an overwrap. (2) If growers move in the direction of more closely sized potatoes, what specific size(s) of the variety(ies) of potatoes would best meet needs of light potato users? Three sizes of three different varieties will be displayed (Russet Burbank, Russet Norkotah and Superior potatoes). Participants will be asked to select their top choices and then indicate how they would likely prepare them. Price would not be a consideration in the decision. (3) Determine if greening of potatoes is an issue with consumers and how well participants understand what causes this greening to occur. Long a problem for growers and the main reason for packaging round, white potatoes in paper bags, the time has arrived to address the problem, if indeed, consumers are confused about and/or misinformed regarding greening of potatoes. Michigan Potato Industry Commission 13109 Schavey Rd. Suite #7 DeWitt, MI 48820 BULK RATE U.S. POSTAGE PAID Ithaca, Ml 48847 Permit No. 35