1975 Research Report MONTCALM EXPERIMENTAL FARM Michigan State University Agricultural Experiment Station ACKNOWLEDGEMENTS Research personnel working at the Montcalm Branch Experiment Station have received much assistance in various ways. A special thanks is due each of these individuals, private companies and government agencies who have made this research possible. Many valuable contributions in the way of fertilizers, chemicals, seed, equipment, technical assistance, personal services, and monetary grants were received and are hereby gratefully acknowledged. Special recognition is given to Mr. Theron Comden for his devoted cooperation and assistance in many of the day-to-day operations and personal services. TABLE OF CONTENTS Page. INTRODUCTION, WEATHER AND GENERAL MANAGEMENT ................................................ 1 New Variety Introductions R.W. Chase, N.R. Thompson, R.B. Kitchen & E. Meister-Clemons . ................................... 4 Russet Burbank Seed Performance R.W. Chase & R.B. Kitchen........................................................................................ 9 Soil Fertility Studies with Potatoes M.L. Vitosh, G. Raines & D. Hyde..................................................................... 12 Weed Control in Potatoes W.F. Meggitt, Robert Bond & R.W. Chase........................................................16 1975 Michigan Potato-Nematode Survey G.W. Bird..........................................................................................................................18 Integrated Nematode Population Management for Minimizing Losses in Potato Production G.W. Bird.......................................................................................................................... 22 1976 Nematicide Evaluations G.W. Bird..........................................................................................................................25 Ozone Injury to Potatoes - 1975 W.J. Hooker..................................................................................................................29 Potato Insect Research A.L. Wells............................................. 31 Bean Variety - Strains of Rhizobium Test M.W. Adams, A.W. Saettler, Jerry Taylor ........................................................... 39 Corn Hybrids, Plant Population and Irrigation E.C. Rossman & Bary Darling..................................................................................... 43 MONTCALM BRANCH EXPERIMENT STATION RESEARCH REPORT R.W. Chase and. M.H. Erdmann, Coordinators Department of Crop and Soil Sciences INTRODUCTION The Montcalm Branch Experiment Station was established in 1966 with the first experiments initiated in 1967. This report marks the completion of nine years of studies. The 40-acre facility is leased from Mr. Theron Comden and is located in west-central Michigan, one mile west of Entrican. The farm is used primarily for research on potatoes and is located in the heart of a major potato producing area. This report is designed to coordinate all of the research obtained at this facility during 1975. Much of the data herein reported represents projects in various stages of progress; so results and interpretations may not be final. RESULTS PRESENTED HERE SHOULD BE TREATED AS A PROGRESS REPORT ONLY as data from repeated trials are necessary before definite conclusions and recommendations can be made. WEATHER Tables 1 and 2 summarize the 8-year temperature and rainfall data. Average maximum and minimum temperatures for April and September of 1975 were lower than the 8-year average, whereas the average maximum and minimum temperatures in May of 1975 were higher than the 8-year average. Furthermore, the average minimum for April and the average maximum and minimum for September of 1975 were the lowest of any year for the 8-year period of 1968-1975. The average maximum and minimum temperatures for May of 1975 were the highest of any year for the 8-year period. The 1975 total rainfall of 25.87 inches for the 6-month period of April through September was the second highest for the 8 years for which records at the Farm are available. The 11.25 inches of rain in August was the highest for any year during the 8 years, and almost 4 inches more than the next highest year during this period. Rainfall in April and May was less than the 8-year average. Irrigation applications of approximately one inch each were made 7 times (July 2, 8, 16, 23, 29 and August 2, 19). SOIL TESTS For specific projects where more detailed analysis are needed the results are in the individual reports. Soil test results for the general plot area are: Pounds per Acre p 372 pH 6.3 Pounds per Acre K 276 Pounds per Acre Ca 908 Mg Pounds per Acre 188 Table 1. The 8-year summary of recorded maximum and minimum temperatures during the growing season at the Montcalm Branch Experiment Station. Year April Max April Min May Max May Min June Max June Min July Max July Min August Max August Min September September Min Max 6-month average Max 6-month average Min 1968 1969 1970 1971 1972 1973 1974 1975 8-year average 61 56 54 53 47 54 57 48 54 37 35 35 31 30 36 36 28 34 62 67 65 65 70 63 62 73 66 41 43 47 39 47 42 41 48 44 74 70 72 81 72 77 73 75 74 53 50 55 56 50 58 52 56 54 80 80 80 82 79 79 81 80 80 55 59 60 55 57 60 57 57 58 81 82 80 80 76 80 77 79 79 58 56 57 53 57 60 56 58 57 74 73 70 73 69 73 68 65 71 50 49 51 54 49 48 45 44 49 73 74 73 76 73 74 70 70 empty table cell 50 49 45 48 48 51 48 49 empty table cell Table 2. The 8-year summary of precipitation (inches per month) recorded during the growing season at the Montcalm Station. Year 1968 1969 1970 1971 1972 1973 1974 1975 8-year average April 2.84 3.33 2.42 1.59 1.35 3.25 4.07 1 .81 2.58 May 4.90 3.65 4.09 0.93 1.96 3.91 4.83 2.05 3.29 June 3.74 6.18 4.62 1.50 2.51 4.34 4.69 4.98 4.07 July 1.23 2.63 3.67 1.22 3.83 2.36 2.39 2.71 2.51 August September Total 1.31 1.79 6.54 2.67 7.28 3.94 6.18 11.25 3.30 0.58 7.18 4.00 2.60 1.33 1.81 3.07 17.32 18.16 28.52 11.91 19.53 19.13 23.97 25.87 5.12 2.98 20.55 FERTILIZERS USED Except for the specific fertility studies where the fertilizers are specified in the report, the following fertilizers were used on the potato plot area: Banded at planting - 16-8-8 - 600 lbs/A Sidedressed - 45-0-0 - 192 lbs/A Red clover plowed down. HERBICIDES Preemergence - Lorox at 1 lb/A + Lasso at 2 qts/A DISEASE AND INSECT CONTROL The systemic insecticide Temik was applied at planting at 3 pounds per acre. Foliar fungicide and insecticide sprays, applied with an air blast sprayer, were as follows: June 27 July 11 July 21 July 30 August 11 August 25 September 3 September 5 (Topkill) - Dinitro 2 qt/A + Crop Oil Concentrate 1 qt/A + Copper Bravo + Thiodan Bravo + Cygon Bravo + Monitor Bravo + Cygon Bravo + Monitor Bravo + Monitor + Copper Bravo + Copper NEW VARIETY INTRODUCTIONS R.W. Chase, N.R. Thompson, R.B. Kitchen & E. Meister-Clemons Dept. of Crop & Soil Sciences I. VARIETY CHARACTERISTICS A more detailed study of new variety characteristics was conducted in 1975 at the Montcalm Research Farm. Eighteen new variety releases, seedlings and standard varieties were compared in a study designed to evaluate variety perfor­ mance and marketable maturity. The 18 cultivars were planted on May 8 in three separate blocks with each designed for a different date of harvest. The first harvest was made August 8, the second September 3, and the third September 23. Yields, specific gravity, size distribution, chip quality and growth rate were determined for each entry. Table 1 summarizes the data for all of the varieties for each of the harvest dates. The ranking is according to the growth rate as determined on the September 3 harvest. The Superior and MSU seedling 1111-2 reached their maximum yield by the first harvest on August 8, after which there was no further increase. Those varieties still showing a substantial growth rate at the third harvest were con­ sidered as late varieties. Many of the varieties did not produce acceptable chips. Those showing favorable results were 1111-2, Superior, Bison, Snowchip, and Wischip. The growth rate factor allows one to determine what periods are the most active for yield increase. These data reveal that the most active period for growth in terms of yield increase gener­ ally is during August. Those still showing substantial increase during September were Bellisle, Katahdin and AL 37-5, and would be considered as the latest maturing of the total group. From these data, the following groupings as to marketable maturity were deter­ mined : early to mid season mid season to late late early MS 1111-2 Superior Onaway Snowchip Wischip MS 645-2 Bison MS 645-1 Al 3768-19 Bellisle Katahdin AL 37-5 MS 706-34 Table 2 ranks the varieties according to total yield for each of the harvest dates. Those varieties which appear highest on the list at the initial harvest (early market maturity) frequently end up on the lower end at the late harvest whereas those lower at the initial harvest end up near the top at the later harvest (a late market maturity). Table 3 summarizes the after cooking qualities of each of the several selections tested. Hudson A 6789-7 MS 711-8 MS 709 BLE 1 THE YIELD, SPECIFIC GRAVITY, CHIP QUALITY AMP GROWTH RATE OF SEVERAL VARIETIES ON 3 DIFFERENT HARVEST DATES. August 8, 1975 August 8, 1975 September 3, 1975 September 3, 1975 September 23, 1975 September 3, 1975 September 3, 1975 Growth1 Rate cwt/A/day September 23, 1975 September 23, 1975 Growth1 Rate cwt/A/day US No 1 cwt/A 222 226 340 353 351 349 407 402 349 482 378 454 418 460 382 498 392 — — 0.6 — — — — 1.7 — 1.0 — 4.4 1.1 2.6 — 0.9 — Chip2 September 23, 1975 Rate 3 3 3 3 2 5 8 4 7 4 5 4 7 7 6 5 8 September 23, 1975 S.G. 1.058 1.070 1.064 1.067 1.074 1.078 1.065 1.070 1.069 1.091 1.066 1.083 1.070 1.070 1.068 1.079 1.068 ariety S-1111-2 perior son owchip schip S 645-2 haway L 37-5 udson L 3768-19 S 709 ellisle S 706-34 atahdin S 711-8 S 645-1 6789-7 August 8, 1975 Total cwt/A 287 265 317 329 307 317 354 298 246 324 226 211 240 213 190 282 200 US No 1 cwt/A 257 248 271 298 279 279 337 239 218 296 206 193 209 201 176 257 161 S.G. 1.066 1.072 1.064 1.072 1.076 1.068 1.068 1.068 1.067 1.093 1.069 1.076 1.063 1.067 1.068 1.075 1.065 Chip2 August 8, 1975 Rate 3 3 2 5 3 7 9 7 8 6 3 7 8 8 7 9 7 September 3, 1975 Total US No 1 cwt/A cwt/A 276 248 239 268 329 353 381 410 374 407 374 399 437 450 368 398 381 410 462 490 384 393 367 406 396 413 401 421 382 399 481 516 396 427 — — 2.2 3.2 3.7 3.7 3.8 5.0 6.3 6.4 6.8 6.7 7.2 7.7 7.9 8.6 9.0 Chip2 Rate S.G. 4 1.065 1.072 3 1.068 2 1.074 3 1.077 2 1.080 6 1.070 7 1.071 6 1.074 6 1.100 4 1.069 4 1.082 6 1.068 7 1.074 6 1.073 4 1.081 4 1.075 5 Total cwt/A 237 259 388 378 395 385 429 462 410 515 407 510 448 486 410 546 437 Growth rate expressed as yield increase between harvests in terms of cwt. per acre per day. Chip ratings expressed on scale of 1 to 10. The smaller the number the lighter the chip color. TABLE 2 THE RANKING OF ALL VARIETIES FOR TOTAL YIELD & MARKETABLE YIELD FOR EACH OF THE HARVEST DATES. Variety August 8 Total August 8 No 1 Variety September 3 Total September 3 No 1 Variety September 23 Total September 23 No 1 Onaway Snowchip AL 3768-19 MS 645-2 Wischip Bison MS 1111-2 MS 645-1 Superior AL 37-5 Hudson MS 706-34 MS 709 Katahdin Bellisle MS-711-8 A 6789-7 Overall average 354 329 324 317 307 317 287 282 265 298 246 240 226 213 211 190 200 337 298 296 279 279 271 257 257 248 239 218 209 206 201 193 176 161 MS 645-1 AL 3768-19 Onaway Katahdin A 6789-7 MS 706-34 MS 709 MS 711-8 Hudson Snowchip Wischip MS 645-2 AL 37-5 Bellisle Bison MS 1111-2 Superior empty table cell 516 490 450 421 427 413 393 399 410 410 407 399 398 406 353 276 268 481 462 437 401 396 396 384 382 381 381 374 374 368 367 329 248 239 MS 645-1 AL 3768-19 Katahdin Bellisle MS 706-34 Onaway Al-37-5 A 6789-7 MS 711-8 MS 709 Snowchip Wischip Hudson MS 645-2 Bison Superior MS 1111-2 empty table cell 546 515 486 510 448 429 462 437 410 407 378 395 410 385 388 259 237 498 482 460 454 418 407 402 392 382 378 353 351 349 349 340 226 222 271 243 402 376 418 380 TABLE 3 THE RATING OF AFTER COOKING DARKENING OF SEVERAL VARIETIES AT 0, 1 AND 24 HOURS AFTER COOKING. Variety Rating of after cooking darkening1/ 0 hours Rating of after cooking darkening1/ 1 hours Rating of after cooking darkening1/ 24 hours2/ Bellisle Bison Hudson Katahdin Onaway Snowchip Superior Wischip MS 645-1 MS 645-2 MS 1111-2 MS 709 MS 706-34 MS 711-8 AL 37-5 AL 3768-19 A 6789-7 1/ Ratings based on relative degree of darkening after cooking, l=no darkening 1 2 1 2 2 2 1 2 2 1 1 1 1 1 1 2 1 1 2 1 2 2 4 2 2 2 2 1 1 2 1 1 2 1 2 4 2 2 4 4 3 3 2 4 2 2 3 2 1 3 1 and 5=considerable overall darkening. 2/ Rating at 24 hours is after sample was stored at normal refrigerator temperature VARIETY OBSERVATIONS Bellisle - a 1974 release from New Brunswick, Canada. A late maturing variety primarily for fresh pack with a high specific gravity. Has some resistance to common scab, late blight and Fusarium storage decay. It is susceptible to verticillim wilt and leaf rot. Appearance was generally good. Bison - released in 1974 from North Dakota. A red skin variety with very good skin color. Tubers are attractive with shallow eyes. Although it had a low specific gravity it produced very acceptable chips. The foliage has a very characteristic appearance being quite upright and dark colored early in its growth. Hudson - a later maturing release from New York. Very similar to Katahdin in most characteristics. Primarily a fresh pack variety. Snowchip - released in 1974 by Alaska and USDA as a desirable chipping potato. It was medium in specific gravity and did produce acceptable chips at the second and third harvests. It responded as an early to mid­ season variety. It is reported to have a short rest period similar to Ontario, one of its parents. Wischip - released in 1974 by Wisconsin and Frito Lay, Inc. Wischip has been in our trials two years. In 1974 it exhibited serious speckle leaf infection with a resulting very low yield whereas in 1975 the speckle leaf condition was not observed and the yield and quality response was very favorable. It has an attractive appearance, medium specific gravity and very acceptable chips. Continued studies will be made in 1976. MS 1111-2 - an early Michigan seedling. Specific gravity is low however it did produce acceptable chips. Emergence and initial growth are less vigorous than Onaway and Superior. It did yield comparable to Superior but less than Onaway and reached its maximum yield by early August. MS 645-1 - a late maturing seedling with high yield potential. Some irregularity in tuber shape and roughness in larger tubers. It has a deep eye and sets heavy. It was the highest yielder at the second and third harvests. MS 645-2 - performed as a late-mid season cultivar and similar to 645-1 in specific gravity and chipping, but lower in yield. It too has a heavy set and deep eye. MS 706-34 - performed as a late variety. It yielded well on both the second and third harvests. Specific gravity is low and it did not make acceptable chips. It did however have good tuber size and good general appearance as a fresh pack potato. MS 711-8 - a later maturing seedling with medium to low specific gravity and unacceptable as a chipper at each harvest. Alaska 37-5 - an unreleased red seedling which is late maturing. It is medium in specific gravity and does have good skin color. Alaska 3768-19 - ranked in the top 3 for yields at each harvest so appears to set and size tubers early, yet it continues to add tonnage and performs as a late maturing seedling. Exceptionally high specific gravity at each harvest in spite of the wet August and early September when most others were lower than normal. A-6789 - a seedling obtained from Idaho which performed very well in 1974 trials. It has good size, round white tubers, however, it did not yield as well in 1975 as in 1974. Specific gravity fluctuated between harvests but appears to be medium to low. II. Variety INTRODUCTION The seed introduction plots continued again at two locations; the Wayne Lennard Farm in Newberry and the MFSA at East Lansing. At East Lansing, 92 crossings were screened in 10 hill plots. These crosses were made in recent years and represent cultivars with both white and yellow flesh. Eleven of these were selected as the most outstanding and all the tubers were harvested. Tubers for tuber unit planting in 1976 will be selected out for developing a seed increase plot and the remainder will be evaluated in a performance trial at the Research Farm. Thirty six were completely discarded as being unacceptable as a potential variety. In most cases tuber shape and/or other defects were the major criteria for discard. The remaining 45 were considered worthy of a continued evaluation and from these 5 small whole tubers were selected for the 5 hill, planting at the MEF in 1976 and 10 tubers were selected for tuber unit planting in East Lansing. Considerable emphasis in 1975-76 is being placed on the tuber unit technique to permit more intensive screening, roguing and selection. At the Wayne Lennard Farm 8 seedlings and 2 named varieties in various stages of increase were grown. The numbered selections are 503, 1111-2, 623, 706-34, 711-8, 645-1, 645-2 and 003-69. From these seedlings 169 hill selections were made for the hill index program and clonal plantings in 1976. In addition 900 pounds of tubers for tuber unit screening were also selected. The balance, totalling 56 cwt will be used for clonal increase plantings in 1976. The named varieties included in the new introductions program are Wischip, Hudson, Bison and Jewel. Five commercial plantings of the seedling 1111-2 were also evaluated. It is an early maturing seedling however emergence, growth, general vigor, and yield were rated as poorer when compared to Onaway. It was comparable to Superior in yield but did not rate as well for chipping. The general appearance for the fresh pack was rated as better than Onaway. Appearance and shape are considered as its strong points. RUSSET BURBANK SEED PERFORMANCE R.W. Chase and R.B. Kitchen Department of Crop and Soil Sciences Foundation Russet Burbank seed was planted on three different dates and harvests made on four different dates in 1972, 1973 and 1974. The plantings were identified as early (May 2-9), intermediate (May 18-20) and late (May 31- June 4). The four harvests were 1. (Aug. 15-16), 2. (Sept. 1-3), 3. (Sept. 15-17) and 4. (Oct. 1-4). Table 1 summarizes the average number of days between planting and harvest for each treatment during the duration of the study. Table 1. The number of days between planting and harvest of potatoes collected for seed performance studies. Planting Time early intermediate late 1 Harvest time Harvest time 4 Harvest time 3 2 Harvest time (Days) 117 105 92 (Days) 133 121 107 (Days) 100 89 75 (Days) 149 137 123 Samples were collected from each combination of treatments (12 total) and stored for two weeks at approximately 65 F, to allow for suberization, and then stored at 40 F until planted the following year. Approximately one week before planting, the samples were removed from storage, warmed to 50-55 F, cut and hand planted. Planting dates (early May) and harvest dates (mid September) were the same for all samples when seed performance was evaluated. Determinations of emergence, vigor, visual virus leaf roll, yield, size distribution and specific gravity were made. RESULTS Data presented in Table 2 shows the yield for the combined 3 years. The yield from seed harvested at the third and fourth dates was less than from the earlier harvests. This response was consistent for each of the three years and was most dramatic in 1973. The overall average for harvest dates showed a continued yield decrease with harvests 3 and 4. A review of the overall yeild averages for the planting dates shows less effect with delayed planting, however the best yields were obtained with seed obtained from the earliest planting. Table 3 summarizes the yield results by harvest date for each of the 3 years. There were differences between years reflecting in part seasonal growing conditions. In 1973 yields from seed harvested at the latest date were reduced by 32% from that grown from seed harvested at the earliest date. In 1974 it was reduced by 11% and by 13% in 1975. Another contributing factor to the reduced yields with the later harvested seed was the increased incidence of visible virus leaf roll. The incidence of leaf roll based on visual sysptoms increased significantly with delayed harvests (Table 4), indicating that the hazard of late season virus leaf roll infection becomes a major concern as the season advances after mid August. The levels of virus leaf roll in this study were exceptionally high and this reflects the insect conditions of the area where the study was conducted. Studies to evaluate insect control programs which includes untreated areas were located nearby so the aphid pressure was very high, however the relative trend of increasing incidence of late season virus leaf roll infection with delayed harvest was readily apparent. Table 4 also shows that the risk of a late season virus leaf roll spread becomes greater with a late planting. Seed taken from plots planted late and harvested at the fourth interval contained more than twice the leaf roll than from seed planted at the early or intermediate stage. The data for the overall average for planting dates shows the incidence of leaf roll to be similar with the early and intermediate plantings but more than doubled with the late planting. The reasons for the greater leaf roll in the late planted seed may be: the plant has more green foliage and is more succulent (less mature) and is more attractive to aphids; the translocation mechanism in the less mature plant may be more produc­ tive and efficient and transfers the virus infection to the tubers more readily; more aphids at this time of the season are carriers of the virus and thereby potential transmitters; or the virus and foliar growth patterns are such that it is more difficult to obtain complete foliage coverage for aphid control. Ratings of emergence and early plant vigor are closely related to the sub­ sequent yields. Seed taken from the early harvested plots consistently had earlier and more uniform emergence, the greatest vigor and the highest yields. Seed taken from plots at the late harvest consistently had the lowest vigor ratings. The effect of planting date and harvest date had little effect on the pro­ duction of tubers smaller than 1-7/8 inch, off type or over 10 ounces. The effect on size distribution was noted in the 1-7/8" to 10 ounce potatoes with the greater production of tubers in this size range occurring from seed harvested early. There was no effect on specific gravity. Table 2. The total yield (cwt/A) of Russet Burbanks planted with seed from different planting and harvest dates the previous year. (Combined 3 year data) Planting * early intermediate late Harvest Date * 1 392 389 396 * Harvest Date Harvest Date * 3 364 348 345 2 392 370 392 Overall Average for Planting Dates Harvest Date *4 347 320 296 374 357 357 overall average for harvest dates * Planting and harvest date variables refer to management performed the previous year. 321 352 392 385 empty table cell Table 3. The total yield (cwt/A) of Russet Burbanks from seed harvested at 4 different dates for each of three years. Year 1973 1974 1975 Harvest Date 1 369 376 432 Harvest Date Harvest Date 3 311 347 401 2 366 383 405 Yearly Harvest Date Average 4 251 333 378 320 360 404 overall average for harvest dates 392 385 352 321 empty table cell Table 4. The incidence of virus leaf roll observed from seed planted and harvested at different dates the previous year. (Combined 3 year data) Planting early intermediate late overall average for harvest dates Overall Average for Planting datE Harvest Date Harvest Date 3 % 2 % 4 Harvest Date % 19.1 16.5 37.8 7.4 9.1 27.8 Harvest Date 1 % 0.4 7.4 0.9 7.8 1.2 9.6 8.3 8.6 8.6 19.1 0.9 14.8 24.4 empty table cell SOIL FERTILITY STUDIES WITH POTATOES Ml.L. Vitosh, G. Raines and D. Hyde Department of Crop and Soil Sciences Two soil fertility experiments were conducted in 1975. One was a liming study to evaluate the effect of lime on the incidence of scab disease, yield and quality of potatoes. This was the third year for this study. The second was a study to evaluate the application of nitrogen fertilizer through the irrigation water on yield and quality of potatoes. Nitrogen ferti­ lizer applied through the irrigation system during the growing season was compared with nitrogen applied at planting time. LIME STUDY This experiment was initiated in 1973 and included two rates of lime and two sources. In 1975 lime was again applied at a rate of 4 tons per acre to two previously limed areas bringing the total lime application for these two treatments to 6 and 8 tons per acre in a 3 year period. The lime was spring applied, disked and plowed prior to planting. The soil pH in 1973 was 6.1 not critically low for potato production but the interest here was primarily on the effect of lime on the occurrence of scab disease. The results of this study are shown in table 1. Yields for the Kennebec variety were not significantly affected by liming although there was some variation in yield. For the Katahdin variety there appears to be one treatment (4 tons of lime in 1973) which gave a significant yield increase. This kind of increase has not been consistent over the last three years and may be due to unusual variation in yield. Scab disease was not a problem in any of the plots. Only minor amounts of scab were observed as indicated by the ratings of "1." Size and specific gravity were also unaffected by the lime treatment. After 3 years of study we have not observed any increase in scab as it might be related to liming even though we have used varieties moderately susceptible to the disease. It is doubtful however that liming above pH 6.0 will increase potato yields. More efficient utilization of fertilizers may be one reason for liming above pH 6.0, especially if other crops are used in the rotation with potatoes. NITROGATION (NITROGEN-IRRIGATION) STUDY Efficient utilization of nitrogen fertilizer has been of much concern to potato growers because of the ease with which nitrogen can be lost from sandy soils. One method of increasing this efficiency is to add the nitrogen in small amounts at frequent intervals to meet the requirement of plant uptake and to keep the concentration of the nutrient in the soil at a high level at all times. In this study a planting time application of nitrogen fertilizer (96 lbs/acre) was compared with a weekly and biweekly application of nitrogen applied through the irrigation water. The biweekly treatment was limited to two 20 lb. Nitrogen applications. The weekly application was 20 lbs. N per acre for four weeks. Both treatments were started on July 9, 1975. The results of this study are shown in table 2. None of the measured properties were found to be significantly different from the treatment at planting time. In the three previous years, yields were improved by adding nitrogen through the irrigation system. The N application at planting time (96 lbs. N/acre) gave a better yield than expected in 1975. TABLE 1. EFFECT OF LIME ON YIELD, SIZE AND SPECIFIC GRAVITY OF IRRIGATED KENNEBEC AND KATAHDIN POTATOES Lime Treatmentsa Soil Kennebec pHc Total Kennebec Yield Over Kennebec 3 1/4"% Kennebec Kennebec Less than 1-7/8”% 1-7/8" to Kennebec Specific Gravity Scabb Kennebec Rating Katahdin Total Yield Over Katahdin 3 1/4" 1-7/8" to 3 1/4" Katahdin Katahdin Less than 1-7/8” Katahdin Specific Gravity Scab Katahdin Rating No lime 2 ton (1973) 4 ton (1975) 4 ton (1973) 4 ton (1975) 2 ton (1973) 4 ton (1973) 6.0 6.4 6.5 6.4 6.9 cwt 316 321 340 333 350 L.S.D. (.05) .3 NS 3 1/4" % 16 15 14 10 14 NS 75 75 75 77 76 NS 9 11 11 13 10 NS 1.070 1.068 1.070 1.070 1.068 1 1 1 1 1 NS NS 342 297 304 321 370 48 25 23 23 26 25 NS 70 70 71 69 69 NS 5 7 6 6 6 NS 1.069 1.069 1.069 1.069 1.072 NS 1 1 1 1 1 NS (a) Lime was applied on an equivalent basis using a neutralizing value of 100 for pure calcium carbonate. (b) Ratings on a scale at 10 with 1 being the lowest incidence of scab. (c) Spring 1975 before lime was reapplied. Planted: May 13, 1975 Row Spacing: 32 inches Basic Fertilizer: 600 lbs 16-8-8 Seed Spacing: 10 inches Irrigation: 7 inches Harvested: October 18, 1975 Harvest Area: 133 sq. ft. Soil Tests P = 299, K = 244, Ca = 1251, Mg = 221 TABLE 2. EFFECT OF NITROGEN FERTILIZER ON YIELD, SIZE AND SPECIFIC GRAVITY OF IRRIGATED KENNEBEC AND RUSSET BURBANK POTATOES. Nitrogena Applications (lbs N/A) 96 (planting time only) 136 (2-20 lb N Nitrogen) 176 (4-20 lb N Nitrogation) biweekly weekly Kennebec Total Yield cwt 326 348 323 L.S.D. (.05) NS Kennebec Kennebec 1-7/8" to 3 1/4" % Kennebec Over 3 1/4" % Less than 1-7/8” Kennebec Specific Gravity Russet Burbank Total Yield Russet Burbank Over 10 oz Russet Burbank Specific Russet Burbank Off Gravity Type Russet Burbank Russet Burbank 1-7/8" to 10 oz Less than 1-7/8” 14 12 13 NS 76 76 77 NS % 11 12 10 NS 1.073 1.072 1.072 NS 319 360 294 NS 8 6 9 NS 67 70 66 NS 17 16 18 NS 8 7 7 NS 1.083 1.083 1.081 empty table cell (a) Planting time nitrogen consisted of 600 lbs of 16-8-8. Nitrogation treatments were accomplished by injecting 28% N solution into the irrigation line. Planted: May 14, 1975 Row Spacing: 34 inches Basic Fertilizer: 600 lbs 16-8-8 Seed Spacing: 12 inches Irrigation: 7 inches Harvested: October 19, 1975 Harvest Area: 142 sq. ft. WEEP CONTROL IN POTATOES W.F. Meggitt, Robert Bond & R.W. Chase Department of Crop and Soil Sciences On May 28th 17 preemergence treatments were applied to Russet Burbank potatoes planted on May 15. None of the potatoes were emerged at this time. On June 7th, four postemergence treatments were applied; two in combination with preemergence treatments and two where no previous treatments had been made. The pigweed and barnyard grass infestations were light and all of the preemergence treatments gave 100% control of both of these weeds. RE17111 when applied postemergence gave something less than 100% control. There was considerable injury from RE17111 both pre and postemergence and there will be no further testing of it. FMC25213 also gave a fair amount of injury and probably will not be tested again. Lasso at 2 pounds per acre plus either Sencor/Lexone at 3/8 pound active ingredient or Lorox at 3/4 pound active ingredient has given excellent results over the past three years. Herbicides for Weed Control in Potatoes, Montcalm Research Farm, 1975. Planted: Hay 15, 1975 Treated: Pre: May 28, 1975 Post: June 7, 1975 July 10, 1975 Rated: Variety: Soil Type: Organic Matter: 2.0% Russet Burbank Loamy Sand Weeds Present: Pigweed, Barnyardgrass. Treatments Tmt. No. Rates lbs/A Injury Weed Control Ratings Weed Control Ratings PW BG 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 10.0 10.0 10.0 10.0 10.0 10.0 10.0 9.7 10.0 10.0 10.0 7.0 8.0 10.0 10.0 10.0 10.0 10.0 Pre Sencor/Lexone+Lasso Sencor/Lexone+Lasso Lorox+Lasso Lorox+Lasso Lorox Sencor/Lexone Premerge+Lasso RE 17111 RE 17111 RE 17111 1/2+2 3/8+2 3/4+2 1+2 1 1/2 1/2 4+2 1 2 3 Pre RE17111 + POST RE17111 RE17111 RE17111 1+1 1 2 Sencor/Lexone+Sencor/Lexone 1/2+1/4 Pre FMC 25213 FMC 25213+Sencor/Lexone 1.5+1/2 Hoe 23408+Sencor/Lexone 1.5+1/2 Hoe 23408+Premerge 1.5+4 2 0.0 0.0 0.0 0.0 0.0 0.0 0.7 0.7 4.0 5.3 6.3 5.7 8.0 0.0 2.3 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 9.7 10.0 10.0 10.0 0.3 0.0 0.0 0.0 10.0 10.0 10.0 10.0 Hoe 23408+Lorox NO TREATMENT 1.5+1 empty table cellempty table cellempty table cell empty table cell 10.0 0 = No control and no injury; 10 = complete control or kill. 1975 MICHIGAN POTATO-NEMATODE SURVEY G.W. Bird1 Department of Entomology and Department of Botany and Plant Pathology ABSTRACT Root-lesion nematodes (Pratylenchus penetrans, P. crenatus and P. neglectus) were recovered from 63.6% of 162 Michigan potato fields studied during the 1975 growing season (2% of state acreage). The root-lesion nematode was considered to be of potential economic significance in 56% of the total number of locations (Table 2). The northern root-knot nematode (Meloidogyne hapla) was found in 26.5% of the sites and believed to be an economic threat in 18% of fields surveyed. Half of the fields were treated with chemical nematicides in 1975 and nematode control was excellent (Table 1). Additional information about pesticide usage and efficacy, potato varieties, crop rotations, and the population density, frequency of occurrence and distribution of a number of plant parasitic nematodes was also obtained. A detailed report of this project was presented to the Michigan Potato Industry Commission on November 24, 1975. INTRODUCTION During the past four years the Michigan State University Nematology Research Program has studied the economics, pathology, biology and control of the root­ lesion nematode (Pratylenchus penetrans) associated with potato production. In 1975 the Michigan Potato Industry commission funded a project to determine the extent of the geographical distribution, frequence of occurrence and nature of the population density of root-lesion nematodes associated with Michigan potato production. Information from this survey, combined with data about the pathology, biology and control of root-lesion nematodes associated with potatoes will be used to provide a relatively accurate estimate of economic losses and their geographical distribution. This information will also be used by the Cooperative Extension Service and the potato industry in providing growers with the educational materials and specific recommendations necessary to minimize Michigan potato losses caused by the root-lesion nematode. As a by-product of this investigation, information was also collected about several other nematodes, usage of nematicides in the 1975 potato crop, and various other data pertaining to Michigan potato production. METHODS Approximately 2% of Michigan’s potato acreage was sampled for occurrence and population density of plant-parasitic nematodes. The state was divided into thirteen potato growing areas of three different acreage categories (Table 2). 1Sincere appreciation is expressed to Mr. Jack Bailey and Kathy Ries for conducting the survey and tabulating the data, respectively. A total of 162 potato sampling sites were selected in cooperation with local extension offices. Each site represented five acres and was sampled twice during the growing season (early-mid season and mid-late season). The number of sites selected in each region was based on an approximation of the percentage of the total state potato acreage. RESULTS Approximately 50% of the potato acreage surveyed was treated with a nematicide in 1975. This was a direct result of the registration of Temik 15 G, and probably about a 10-fold increase in potato acreage under chemical nematode control. In regards to the survey, this increase in nematicide application was unfortunate, and had to be taken into consideration in evaluation of the data. Both fumigant and granular nematicides were applied to mineral and organic soils. The usage of Temik 15 G and DiSyston varied greatly among geographical areas. The five potato varieties previously investigated at M.S.U. in regard to their susceptibility to root-lesion nematode damage, accounted for 46% of the sites surveyed. Norchip, Monona and Sebago were the most frequently encountered varieties for which root-lesion nematode susceptibility information is not avail­ able. Variety usage varied greatly with geographical area. While a majority of the sites studied were under some type of crop rotation, at lease 27% of the fields were planted with potatoes on a continuous basis. Small grains were by far the most frequent crops rotated with potatoes. Clover, which enhances populations of root-lesion nematodes was used in 12% of the rotations; whereas, sudax, which is detrimental to root-lesion nematode populations was used in 3% of the rotations. Root-lesion nematodes were recovered from 63.6% of the sites investigated. Pratylenchus penetrans was by far the most common species. P. crenatus and P. neglectus were also present, and frequently concomitantly with P. penetrans. The northern root-knot nematode (Meloidogyne hapla) and cyst nematodes (Heterodera (Heterodera) spp.) were found in 19.1 and 6.2% of the fields, respectively. No cysts resembling Heterodera (Globodera) spp. were recovered from any of the survey sites. Fields treated with nematicides generally had considerably lower populations of root-lesion, root-knot or cyst nematodes at early-mid season and mid-late season sampling dates than fields not treated with a nematicide (Table 1). The population density of these nematodes varied considerably between sites and among geographical areas. All three genera of nematodes were recovered from both mineral and organic soil. Taking into consideration nematode population density, frequency of occurrence, nematicide usage and nematode economic threshold level, it was estimated the root­ lesion nematode was a potential economic problem in 56% of the fields studied (Table 2). Potential root-lesion nematode problems existed in all fourteen geographical areas, having a range of 31-100% probable problem sites. The northern root-knot nematode was considered a potential economic threat in 18% of the fields investigated, and not found to be a potential problem in ten of the thirteen geographical areas. Table 1. Influence of nematicides on plant parasitic nematodes associated with Michigan potatoes.1 Nematode and treatment Root-lesion (Pratylenchus spp.) With nematicide .)No nematicide Root-lesion (Pratylenchus spp Northern root-knot (Meloidogyne hapla) With nematicide )No nematicide (Meloidogyne hapla Northern root-knot Cyst (Heterodera (Heterodera) spp.) With nematicide .)No nematicide Cyst ( Heterodera (Heterodera ) spp cm3 soil Nematodes per 100 per 100 cm3 soil Early-mid- Mid-late- season season Nematodes Nematodes per gram root Nematodes per gram root Mid-late- Early-mid- season season 3.6 7.8 8.0 164.1 0.6 3.1 6.5 35.4 28.4 36.8 0.0 1.0 -- -- 3.7 16.5 -- —- -- -- 3.5 74.8 —- —- 1Based on a 1975 survey of circa 2% of the state potato acreage. Table 2. Estimation of extent and distribution of plant parasitic nematode problems in Michigan potato production.1 Area and number of fields sampled Allegan (12) Antrim (10) Bay (36) Delta (6) Emmet (3) Houghton (10) Iron (10) Jackson (9) Manistee (3) Monroe (9) Montcalm (39) Presque Isle (10) Van Buren (5) Michigan (162) % of fields with probable nematode problem Root-lesion nematode % of fields with probable nematode problem Northern root-knot nematode 75 80 31 100 100 100 50 56 100 67 56 50 40 56 17 50 18 50 33 40 20 0 0 11 0 50 20 18 1Based on a 1975 survey of circa 2% of the Michigan potato acreage. INTEGRATED NEMATODE POPULATION MANAGEMENT FOR MINIMIZING LOSSES IN POTATO PRODUCTION1 G.W. Bird Department of Entomology and Department of Botany and Plant Pathology INTRODUCTION In recent years much has been learned about the economics, pathology, biology, and control of the root-lesion nematode (Pratylenchus penetrans) in relation to Michigan potato production. Specific aspects of soil fumigation, granular nematicide application, use of nematode-tolerant potato varieties and cultural alteration of nematode tolerance limits have been investigated. All of the information from these studies, however, has not yet been integrated into a grower-oriented nematode population management program designed to minimize losses in potato production. The objectives of this investigation were to develop and field evaluate an integrated nematode population management program designed to minimize losses in potato production. Information from the study will be used by the Cooperative Extension Service in the development of future nematode recommendations and educational programs. PROCEDURE Soil fumigation, granular nematicide application, use of nematode tolerant varieties, and alteration of the plant nematode tolerance limit was integrated and evaluated in field experiments at the Montcalm and Sodus Research Facilities during the 1974 and 1975 growing season. RESULTS In seven experiments conducted in 1974 and 1975 at two Michigan Research Farms, nematodes were responsible for mean yield losses of 22% for the root­ lesion tolerant variety Russet Burbank, and 39% for the root-lesion nematode- susceptible variety Superior (Table 1). On an annual basis, root-lesion nematode populations were temporarily reduced enough to prevent economic losses through the use of granule nematicides applied at-planting, in-row soil fumigants applied in the fall or spring and broadcast soil fumigants applied in the fall or spring. In general subsoiling beneath the planting row appeared to increase the tolerance of potato plants to root-lesion nematodes (Table 2). The 1974 data summarized above was presented to the Michigan Potato Industry Commission in the 1974 Nematology Report to the Commission. Much of it has since appeared in the American Phytopathological Society, Fungicide and Nematicide Tests: Results of 1974 (Volume 30). The 1975 data summarized above is presented in the last two sections of this report 1Sincere appreciation is expressed to Mrs. Natalie Knobloch and Mr. John Davenport for their assistance with this research and many extra hours of loyal dedication. Table 1. Influence of root-lesion nematodes on potato productivity in seven experiments conducted during 1974 and 1975. Potato variety, location year and experiment Yield with nematode control (ctw/A) Yield without nema­ tode control (ctw/A) Loss (%) Initial root-lesion nematode population density (no./100 cm3 soil) Russet Burbank Montcalm Potato Research Farm 1974 1975 Russet Burbank Montcalm Potato Research Farm Sodus Vegetable Research Farm Russet Burbank 1974 1975 Russet Burbank Sodus Vegetable Research Farm Mean of 4 experiments Superior Montcalm Potato Research Farm 1975 Experiment No. 1 1975 Experiment No. 2 Superior Montcalm Potato Research Farm Sodus Vegetable Research Farm Superior 1975 Mean of 3 experiments 471 399 348 261 370 171 415 101 229 380 278 272 222 288 95 241 70 135 16 29 22 15 22 44 42 31 39 4 20 10 5 10 20 34 5 20 Table 2. Influence of subsoiling beneath the planting row on potato production in four experiments conducted during 1974 and 1975. Location, potato variety and year Commercial land preparation Yield (ctw/A) Yield (ctw/A) Subsoiling beneath the planting row Montcalm Potato Research Farm Russet Burbank 1974 1975 Montcalm Potato Research Farm Russet Burbank Montcalm Potato Research Farm Superior 1975 1975 1975 Sodus Vegetable Research Farm Russet Burbank Superior Sodus Vegetable Research Farm 260a1 278a 95a 222a 70a 286b 314a 75a 281a 113a 1Row means followed by the same letter are not significantly different (P = 0.05). 1976 NEMATICIDE EVALUATIONS G.W. Bird Department of Entomology and Department of Botany and Plant Pathology Temik 15 G and Vorlex were evaluated separately and in combination for control of root-lesion nematodes associated with two cultivars of potatoes grown at the Michigan State University Montcalm and Sodus Experimental Farms. Vorlex was applied in-row on April 15, 1975 at Sodus and on May 8, 1975 at Montcalm. A single subsoil shank was used to apply half of the fumigant at 6 inches and half at a soil depth of 18 inches. Temik 15 G was applied in the seed piece furrow at planting (May 16, 1975, at Sodus and May 23, 1975, at Montcalm). In both locations, each treatment was replicated five times in a randomized block design. Each plot at Montcalm was 50 ft in length and contained eight rows, 34 inches apart. Four consecutive rows in each plot were planted with the root-lesion nematode-tolerant cultivar, Russet Burbank and four with the root-lesion nematode-susceptible cultivar, Superior. Each plot at Sodus was 50 ft in length and contained two rows, 36 inches apart. The south half of each row was planted with Russet Burbank and the north half with Superior. The plots were maintained under commercial irrigation, fertilizer, insect and disease control programs throughout the growing season. Soil samples were taken and analyzed for root-lesion nematodes be­ fore treatment (April 15, 1975, at Sodus and May 8, 1975, at Montcalm), mid-season (July 2, 1975, at Montcalm and July 24, 1975, at Sodus), and at harvest (September 9, 1975, at Sodus and August 21-22, 1975, and September 8-9, 1975, at Montcalm for the Superiors and Russet Burbanks, respectively). The center two rows of each cultivar in each plot at Montcalm were harvested, graded and analyzed for quality; whereas, at Sodus, all of the tubers were harvested and evaluated. At the Montcalm Experimental Farm, both Temik 15 G and Vorlex significantly reduced mid-season populations of root-lesion nematodes and resulted in signifi­ cant increases in the tuber yields of both Russet Burbank and Superior potatoes. Both chemicals enhanced the size of Superior, but not Russet Burbank tubers. No additional nematode control or yield increase resulted from the combined use of both materials. At this location, the mean preplant population density was 20 root-lesion nematodes per 100 cm3. The horizontal distribution of initial population was reasonably uniform (σ= 21.9), with no significant differences among the treatments. At the Sodus Experimental Farm, the preplant root-lesion nematode population density was 5 per 100 cm3 of soil. The horizontal distri­ bution was not uniform (σ= 81.6); however, there were no statistically significant differences among treatments. Neither of the pesticides or the combination resulted in a significant decrease in the root-lesion nematode population. Significant yield increases occurred only in plots treated with Vorlex. The Montcalm Experimental Farm was typical of a root-lesion nematode problem site, and responded as expected. The primary soil-borne problem at the Sodus Experimental Farm, however, was probably not of a nematological origin, and most likely fungal in nature. These results may partially explain why some growers must continue to use a broad spectrum soil fumigant in potato pro­ duction; while others can obtain adequate nematode control with a granular nematicide. Seven formulations of non-fumigant nematicides were evaluated for control of root-lesion nematodes associated with potato (cv Superior) at the Michigan State University Montcalm Experimental Farm. Each treatment was replicated four times in a randomized block design, with each plot consisting of four rows, 34-inches apart and 50 ft in length. All of the non-fumigant nematicides and the DiSyston 6 LC insecticide control were applied in the planting furrow, at planting on May 13-14, 1975. The potatoes were maintained under commercial fertilizer, irrigation, insect and disease control programs. Soil samples were taken for root-lesion nematode analysis before planting (May 13, 1975), at mid-season (July 2, 1975) and at harvest (August 20, 1975). The center two rows of each plot were harvested, graded and analyzed for quality. All of the non-fumigant nematicide and nematicide-insecticide combinations resulted in significantly lower mid-season root populations of root-lesion nematodes (Table 2). Temik 15 G, however, was the only chemical that maintained the root population low throughout the entire growing season. There were no statistically significant differences among the treatments for the soil populations at any of the three sampling dates. The mean preplant population density was 34 root-lesion nematodes per 100 cm3 of soil, and the horizontal distribution of the initial population relatively uniform (σ = 16.5), with no significant differences among the treatments. While the only statistically significant yield differences among the treatments were between Temik 15 G and the DiSyston control (174.1 ctw per acre increase), all of the yields were greater than those of the DiSyston control. Yield responses to the granular formulations of Nemacur appeared to be better than those associated with the liquid formulations. There were no significant differences among the treatments in the specific gravities of the tubers. Table 1. Influence of Temik and Vorlex on potato yields and root-lesion nematodes. Location, cultivar, treatment, method or application and rate per acre Montcalm Experimental Farm Russet Burbank Pratylenchus penetrans (7/22-24/75) 100g soil Montcalm Experimental Farm Russet Burbank Pratylenchus penetrans (7/22-24/75) g soil Montcalm Experimental Farm Russet Burbank Tuber yield (ctw/acre) Grade A Tuber yield (ctw/acre) Jumbo Tuber yield (ctw/acre) Montcalm Experimental Farm Russet Burbank Montcalm Experimental Farm Russet Burbank Total Montcalm Experimental Farm Russet Burbank Control (nontreated) Subsoil beneath planting row Temik 15 G (20.0 lb, in-row) Vorlex (6.0 gal, in-row) Temik 15 G (20.0 lb, in-row) plus Vorlex (6.0 gal, in-row) Superior Montcalm Experimental Farm Control (nontreated) Subsoil beneath planting row Temik 15 G (20.0 lb, in-row) Vorlex (6.0 gal, in-row) Temik 15 G (20.0 lb, in-row) plus Vorlex (6.0 gal, in-row) Sodus Experimental Farm Russet Burbank Control (nontreated) Subsoil beneath planting row Temik 15 G (20.0 lb, in-row) Vorlex (6.0 gal, in-row) Temik 15 G (20.0 lb, in-row) plus Vorlex (6.0 gal, in-row) Superior Sodus Experimental Farm Contro1 (nontreated) Subsoil beneath planting row Temik 15 G (20.0 lb, in-row) Vorlex (6.0 gal, in-row) Temik 15 G (20.0 lb, in-row) plus Vorlex (6.0 gal, in-row) 30a1 32a 15a 11a 17a 250a 165a 0b 18b 21b 232a 268ab 297bc 335c 315bc 18a 17a 21a 28a 27a 278a 314ab 371bc 390c 371bc Montcalm Experimental Farm Superior Montcalm Experimental Farm Superior Montcalm Experimental Farm Superior Montcalm Experimental Farm Superior Montcalm Experimental Farm Superior 83b 55b 33c 10c 16c 99c 188c 5e 80d 17de 75de 57d 138e 144e 133e 18b 15b 65c 61c 66c 95d 75d 207e 209e 171e Sodus Experimental Farm Russet Burbank Sodus Experimental Farm Russet Burbank Sodus Experimental Farm Russet Burbank Sodus Experimental Farm Russet Burbank Sodus Experimental Farm Russet Burbank l1d 17d 8d 0d 0d 44f 3f 3f 2f 0f 138f 194fg 162f 274g 212fg 0d 0d 0d 0d 0d 222f 281fg 261f 390h 351gh Sodus Experimental Farm Superior Sodus Experimental Farm Superior Sodus Experimental Farm Superior Sodus Experimental Farm Superior Sodus Experimental Farm Superior 17e 39e 6e 0e 0e 47g 88g 0g 2g Og 59h 102hi 90h 164i 160i 2e 2e 2e 8e le 70i 113ij 101ij 183j 173j 1Comparable column means followed by the same letter are not significantly different (P=0.05) according to the Student-Newman-Kuels Multiple Range Test. Experimental sites and cultivars were analyzed separately. Table 2. Influence of non-fumigant nematicides on potatoes and lesion nematodes. Treatment and rate per acre DiSyston 6 LC (0.5 gal) Nemacur 15 G (20.0 lb) Nemacur plus DiSyston 7.5 + 7.5 G (40.0 lb) Nemacur 3 S (1.0 gal) Nemacur 3S plus DiSyston 6 LC (1.0 gal + 0.5 gal) Furadan 10 G (30.0 lb) Vydate 10 G (40.0 lb) Temik 15 G (20.0 lb) Pratylenchu Pratylenchus s penetrans/ penetrans/g root tissue g root tissue 9/2/75 7/2/75 Tuber yield (ctw/acre) Grade B Tuber yield (ctw/acre) Grade A Tuber yield (ctw/acre) Total Tuber yield (ctw/acre) Jumbo 257.5a1 463.0a 8.8a 217.9a 14.0a 240.9a 12.5b 251.3ab 10.9a 322.2a 19.7a 353.0ab 63.5b 427.3a 11.4a 351.7a 21.7a 384.8ab 130.0b 271.5ab 6.4a 252.7a 11.7a 270.9ab 45.0b 172.8ab 8.6a 273.2a 15.4a 297.lab 30.5b 1523.5a 8.2a 269.2a 23.9a 301.3ab 5.0b 281.8a 14.2a 299.3a 16.5a 330.0ab 22.8b 21.8b 9.5 367.3a 38.2a 415.0b 1Column means followed by the same letter are not significantly different (P = 0.05) according to the Student-Newman-Kuels Multiple Range Test. OZONE INJURY TO POTATOES - 1975 Department of Botany & Plant Pathology W.J. Hooker Injury to potatoes from photochemical oxidants of which ozone is the most important in Michigan was not a problem in the commercial producing areas of Michigan in 1975. Injury, however, was severe in the potato breeding plots adjacent to the south edge of the Michigan State University campus by mid July. The air pollution monitoring station of the MSU Environmental Improvement Program was also situated on the south edge of the campus within 1.5 miles of the breeding plots. At this station, ozone levels were constantly recorded throughout the summer. Two major episodes of high ozone levels occurred; one in late June-early July, and another, less intense, in late July-early August. Injury of sensitive potato varieties and selections was severe within two weeks following the late June-early July exposure. During this episode, ozone levels exceeded 50 parts per billion (ppb) for over 6 hours on each of 7 days during the 8 day period between June 26 and July 3. Levels exceeded 80 ppb for 11 hours on July 2. On 3 days, 100 ppb was exceeded for at least a short time. Reactions of varieties and selections to this exposure were prompt and are shown in Table 1. Rows in the breeding plots were spaced approximately 6 ft apart which accounts to some extent for the severe response. Wischip and Snowchip were severely injured. In contrast, a new variety from Washington, Nooksack,was highly tolerant. Severe injury of some selections was in marked contrast to the tolerance exhibited by others. Advanced selections in the breeding program varied considerably in response. Although ozone injury is not regularly present in Michigan potato growing areas, tolerant varieties and selections should be identified for future use. Ozone injury was not confined to the field. In the greenhouses on the MSU campus both potato and bean plants being grown for transfer to the air pollution research facility in the field were severely injured during the late June-early July episode. Plant foliage acts as a sink to absorb or adsorb ozone and remove it from the air. Potatoes growing vigorously and closely crowded under normal field conditions protect each other because ozone is removed, at least in part, from the air by the heavy foliage mass. Injury when vines are dense and vigorous may be confined to the outside or topmost leaves of the plants. If exposure to high ozone levels occurs early in the season when plants have not yet closed the rows, injury should be much more severe than if exposure to high levels occurs later in the season after a heavy foliage mass has been established. Cultural practices which encourage early season vigor and early, abundant vine growth are helpful so that plants are able to withstand episodes of high ozone levels. Furthermore, potato varieties and selections differ widely in sensitivity or tolerance to ozone. Tolerant selections should be identified and tolerance incorporated into varieties suitable for production in Michigan. TABLE 1. AIR POLLUTION INJURY TO POTATOES 7/22/75 Observations of Plots South of Michigan Crop Improvement Buildings None to Slight Nooksack 103-59 106- 13 2 107- 132-55 303-2 303-4 305-25 Slight - Moderate R. Arenac 305-18 711-8 Moderate 107-3 235-2 302-1 305-24 307-1 307-6 Severe Wischip Snowchip 227-1 Very Severe 204-1 002-191 645-1 645-2 1111-2 002-408 004-16 002-152 002-215 002-302 004-165 503 002-378 003-22 004-341 231-1 235-3 307-5 004-198 POTATO INSECT RESEARCH Arthur L. Wells Department of Entomology Two potato insect research projects were conducted at the Montcalm Experimental Farm in 1975. One project was a continuation of a study initiated in 1974 to better understand the effects of different insect control programs and harvest management on quality of potato seed and the other was an evaluation of soil systemic insecticides on foliar insects. A. Evaluation of Insect Control Programs and Harvest Management on Seed Quality The insect populations on plots under the following insect control programs were monitored during the 1974 growing season: Single Systemics plus Foliars: Thimet 15 G applied at planting time (May 10) at 3 lb ai/Acre and a weekly commercial control program starting at hilling and continuing to harvest. Double Systemics: Thimet 15 G applied at planting time and Disyston 15 G sidedressed at 3 lb ai at the time of hilling (June 24). Double Systemics plus Foliars: The systemics applied as above with the additional foliar program. Untreated: Foliar fungicide treatments only. The plots using Foundation Russet Burbank and Premier Foundation Sebago seed were sample harvested at two week intervals starting August 19 and continuing until October 7. Adjacent rows were top killed at the same time and after wilting, half of the plots were sprayed with foliar insecticides to prevent aphid population build up during this period. After the harvest season 150 tuber samples of whole ”B" size seed from each plot was submitted to the Florida testing program for evaluation. Duplicate ”A” size tubers from each plot treatment were saved for replanting at the Montcalm Farm in 1975. One seed piece was cut from each of the seed and planted in four replica­ tions of 23 hills each on May 15 (Russet Burbank) and Sebago (May 19) to compare the viability of the seed and virus readings with the results from the Florida test. Temik 15 G was applied at planting time and a full com­ mercial foliar program was applied during the growing season. The virus readings on all of the plots were made by the Michigan Crop Improvement Association inspectors on July 23. The vines were top-killed in mid September and harvest was completed in October to determine yield, size distribution and specific gravity of the tubers. The results of the Florida test and the 1975 field data are summarized in Tables 1 and 2. Results The Florida data appeared to have followed the trend observed in other research plots since the earlier harvested material in both varieties had better stands and leaf roll readings than in the later harvested plots. Com­ parable trends were evident in the 1975 plots but they didn’t appear to affect Table 1. The effect of insect control programs, vine killing and harvest dates on quality of seed, total yield, size distribution and specific gravity (Russet Burbank) Insect Control Program (1974) Vines Killed Insect. Applied Harvest Fla Test Percent Stand Fla Test Percent L.R. MEF % L.R. Cwt/A % by Size Distribution B's % by Size Distribution A's % by Size Distribution % by Size Distribution Off Type 10 oz + Specific Gravity __ Untreated Sngl Syst + Fol — — Dbl Syst Dbl Syst + Fol — -- — — — Aug 20 — Untreated Sngl Syst + Fol Aug 20 — Aug 20 — Dbl Syst Aug 20 — Dbl Syst + Fol Untreated Aug 20 Aug 23 Sngl Syst + Fol Aug 20 Aug 23 Dbl Syst Aug 20 Aug 23 Dbl Syst + Fol Aug 20 Aug 23 __ Untreated Sngl Syst + Fol — — Dbl Syst Dbl Syst + Fol — -- — — — Untreated Sngl Syst + Fol Dbl Syst Dbl Syst + Fol Sep 5 Sep 5 — Sep 5 — Sep 5 — Aug 20 Aug 19 Aug 20 Aug 19 Oct 17 Oct 17 Oct 17 Oct 17 Oct 17 Oct 17 Oct 17 Oct 17 Sep 5 Sep 4 Sep 5 Sep 4 Oct 17 Oct 17 Oct 17 Oct 17 95 95 — 97 86 91 82 88 81 91 94 92 93 91 94 93 95 84 89 81 1 0 — 4 1 1 2 3 5 2 3 0 5 6 5 4 12 1 8 6 4 1 1 1 1 1 1 5 10 3 7 0 9 3 7 5 9 8 11 7 351 330 316 327 319 333 318 347 289 304 299 328 327 298 316 319 287 323 280 281 3 4 3 5 3 3 4 3 4 4 4 3 4 4 3 3 4 3 3 5 56 55 58 53 56 59 58 56 65 57 57 55 57 61 64 52 54 53 58 52 14 16 18 19 14 15 18 18 13 15 20 19 20 15 17 20 22 14 11 18 27 25 21 23 27 23 20 23 18 24 19 23 19 20 16 25 20 30 28 25 1.075 1.074 1.079 1.073 1.075 1.073 1.075 1.075 1.073 1.075 1.074 1.073 1.075 1.073 1.075 1.071 1.073 1.074 1.074 1.076 Sep 11 Sep 11 Sep 11 Sep 11 —- —- —- -- -- Sep 5 Untreated Sngl Syst + Fol Sep 5 Sep 5 Dbl Syst Sep 5 Dbl Syst + Fol —- Untreated Sngl Syst + Fol —- —- Dbl Syst Dbl Syst + Fol —- Untreated Sngl Syst + Fol Dbl Syst Dbl Syst + Fol Untreated Sngl Syst + Fol —- —- Dbl Syst Dbl Syst + Fol —- Sep 18 Sep 18 —- Sep 18 —- --- Sep 18 -- —- —- —- —- Oct 17 Oct 17 Oct 17 Oct 17 Sep 17 Sep 16 Sep 17 Sep 16 Oct 9 Oct 9 Oct 9 Oct 9 Oct 7 Oct 7 Oct 8 Oct 7 85 91 93 95 79 84 86 84 76 83 69 71 85 71 62 70 16 8 11 4 4 8 23 6 6 9 6 1 3 1 6 1 20 4 5 7 8 4 24 9 8 11 5 3 8 4 12 3 258 328 336 339 312 292 289 294 320 335 316 305 333 262 268 348 5 3 4 3 5 3 4 4 3 4 4 3 4 6 4 4 56 58 55 55 58 54 55 51 56 56 55 58 52 56 47 53 13 19 19 19 13 15 13 18 19 16 18 18 20 17 15 16 26 20 22 23 24 28 28 27 22 24 23 21 24 21 34 27 1.072 1.075 1.074 1.074 1.075 1.072 1.074 1.073 1.073 1.077 1.074 1.075 1.075 1.076 1.072 1.074 Table 2. The effect of insect control programs, vine killing and harvest dates on quality of seed, total yield, size distribution and specific gravity (Sebago) Vines Killed -- -- -- -- Insect Control Program (1974) Untreated Sngl Syst + Fol Dbl Syst Dbl Syst + Fol Aug 20 Untreated Aug 20 Sngl Syst + Fol Aug 20 Dbl Syst Aug 20 Dbl Syst + Fol Aug 20 Untreated Sngl Syst + Fol Aug 20 Dbl Syst Aug 20 Aug 20 Dbl Syst + Fol Untreated -- -- Sngl Syst + Fol Dbl Syst -- Dbl Syst + Fol -- Untreated Sngl Syst + Fol Dbl Syst Dbl Syst + Fol Sep 5 Sep 5 Sep 5 Sep 5 Insect. Applied -- -- -- -- -- -- -- -- Aug 23 Aug 23 Aug 23 Aug 23 -- -- -- -- -- -- -- -- Harvest Aug 20 Aug 19 Aug 20 Aug 19 Oct 17 Oct 17 Oct 17 Oct 17 Oct 17 Oct 17 Oct 17 Oct 17 Sep 5 Sep 4 Sep 5 Sep 4 Oct 17 Oct 17 Oct 17 Oct 17 Fla Test Percent Stand 98 97 93 98 85 76 85 91 87 83 89 81 100 91 89 98 90 88 83 75 Fla Test Percent L.R. 1 0 0 1 1 0 9 0 1 3 7 10 1 2 6 12 8 5 16 6 MEF % L.R. 7 3 3 9 2 2 12 5 3 2 18 8 5 5 10 3 3 11 9 4 Cwt /A 359 384 297 353 335 309 310 356 338 339 324 351 393 337 281 371 363 362 349 335 to 1 7/8" % by Size Distribution % by Size Distribution 1 7/8"-3 1/4" % by Size Distribution 3 1/4" + 3 3 3 3 3 3 3 3 3 3 3 3 3 4 4 3 3 2 3 3 73 74 71 64 71 63 63 72 67 67 78 66 71 68 68 63 67 62 68 70 24 23 26 33 26 34 34 25 30 30 19 31 26 28 28 34 30 36 29 27 Specific Gravity 1.065 1.068 1.063 1.065 1.065 1.065 1.063 1.066 1.066 1.066 1.063 1.068 1.065 1.064 1.063 1.064 1.060 1.067 1.066 1.065 Untreated Sngl Syst + Fol Dbl Syst Dbl Syst + Fol Untreated Sngl Syst + Fol Dbl Syst Dbl Syst + Fol Untreated Sngl Syst + Fol Dbl Syst Dbl Syst + Fol Untreated Sngl Syst + Fol Dbl Syst Dbl Syst + Fol Sep 5 Sep 5 Sep 5 Sep 5 -- -- -- -- Sep 11 Sep 11 Sep 11 Sep 11 -- -- -- -- Sep 18 Sep 18 Sep 18 Sep 18 -- -- -- -- -- -- -- -- -- -- -- -- Oct 17 Oct 17 Oct 17 Oct 17 Sep 17 Sep 16 Sep 17 Sep 16 Oct 9 Oct 9 Oct 9 Oct 9 Oct 7 Oct 7 Oct 8 Oct 7 85 87 85 83 85 92 89 73 84 88 85 91 79 70 81 61 5 10 22 9 1 9 10 8 3 0 6 12 9 11 16 10 7 10 5 4 3 15 9 5 4 7 11 5 7 7 13 11 338 303 297 337 334 342 309 347 370 396 315 323 313 317 323 287 2 3 3 3 3 3 3 3 3 2 4 3 3 3 3 3 62 55 71 72 74 69 60 67 71 67 67 62 63 72 69 63 36 42 26 25 23 28 37 30 26 31 29 35 34 25 28 34 1.066 1.065 1.063 1.065 1.064 1.064 1.065 1.064 1.066 1.066 1.064 1.064 1.066 1.066 1.065 1.065 the yields significantly. This could have been the response from the Temik treatment and the excellent growing season which minimized the differences between the plots. A statistical analysis of the data might show differences, however. B. Evaluation of Soil Applications of Systemic Insecticides Twelve treatments of granular formulations of six insecticides were evaluated for foliar insect control on Russet Burbank potatoes. The plots were established on May 19 in three replications of four 50 foot rows each. Eleven of the plots received in-row treatments at planting and two of these and one previously untreated plot received side dress applications at the time of hilling on June 23. The plots were checked for flea beetle damage prior to hilling but since damage was very slight no data were tabulated. The plots were rated for overall appearance and vigor on July 1 and foliar insect populations sampled on July 16, 30 and August 8 by taking ten sweeps with an insect net on the foliage of each plot. Leaf samples were taken on July 30 to compare aphid numbers with those determined by the sweep samples. The Insect data are shown in Table 3. The plots were top-killed in mid September and harvested in October for yield and size distribution evaluation (Table 4). Results The differences in plant response to certain treatments early in the season as shown by the plot ratings have been noted in previous research. It is probably due to protection from soil organisms when the plants were small. The major differences in insect control were seen in the late aphid population in the Furadan and CGA 30017 treatments when compared with the lower numbers in the other treatments including the untreated plots. The Colorado potato beetle population at the farm has been increasing the last two years and caused serious damage to certain treatments. This defolia­ tion was too severe in July to get meaningful aphid data from the leaf samples so they are not included in the table. The best season control was given by Thimet, Furadan, Temik and Dacamox while the other treatments would require foliar applications for adequate second generation beetle control. The ratio of larvae to adults in the samples indicate the second generation beginning in late July. The effects of early plant response and beetle protection is reflected in the yields since the highest yields were in the Furadan, Temik and Dacamox treatments although the tuber size is comparable in all of the plots. The additional side dress application of Disyston appeared to reduce the beetle population and increase the yield over the single application. The split application of Temik was comparable to the single application at planting or sidedressed. Table 3. Stand Ratings and Insect Populations on Insecticide Evaluation Plots Time of* Treatment Material and Formulation Thimet 15G Disyston 15G Disyston 15G Furadan 10G Temik 15G Temik 15G Temik 15G CGA 30017 5G CGA 30017 Dacamox 10G Dacamox 10G Dacamox 10G Untreated empty table cellempty table cell empty table cellempty table cell P P P+S P P+S P S P P P P P -- Lb Tox** per A. 3 lb 3 lb 3 + 3 lb 3 lb 3 lb 3 lb 2 lb 3 lb 2 lb 3 lb 6 lb -- 1 1/2+ 1 1/2 lb Stand *** Rating 4.0 2.0 3.0 2.0 1.0 1.0 2.3 3.0 2.3 1.0 1.0 2.7 3.2 Total Insects Collected**** Tarnish Pot Leaf Total Insects Collected**** Plnt Bug Hopper 17 38 36 20 12 11 13 28 33 10 2 4 13 Ast Leaf Hopper 16 28 30 13 11 8 13 34 17 9 13 7 9 empty table cell empty table cell Total Insects Collected**** Total Insects Collected**** Total Insects Collected**** Colorado Potato Beetle Colorado Potato Beetle Total Insects Collected**** Colorado Potato Beetle Jul/16 Aug/8 Jul/30 36 180 123 2 3 0 16 139 131 6 5 12 210 90% 10% Total Insects Collected**** Aphids 28 13 8 186 7 11 15 96 82 54 21 19 21 empty table cell% Larvae empty table cell empty table cell% Adults empty table cell 0 10 3 0 0 0 0 0 1 0 0 0 18 89% 11% 3 8 6 0 0 1 0 15 8 0 1 0 17 26% 74% 16 14 18 20 12 7 15 25 16 18 15 16 8 empty table cell empty table cell empty table cell empty table cell *Time of treatment: P = at planting; S = at sidedressing **Rates based on 34 in. rows ***Stand rating: 1-Excellent, even stand; — 4-Small and uneven ****Total insects collected 30 sweeps/plot on July 16, 30 and Aug 8 Table 4. Harvest Data from Insecticide Evaluation Plots Material and Formulation Thimet 15G Disyston 15G Disyston 15G Furadan 10G Temik 15G Temik 15G Temik 15G CGA 30017 5G CGA 30017 5G Dacamox 10G Dacamox 10G Dacamox 10G Untreated * Time of Treatment p p P+S p P+S p s p p p p p -- Lb Tox per A. 3 lb 3 lb 3 + 3 lb 3 lb 1 1/2+ 1 1/2 lb 3 lb 3 lb 2 lb 3 lb 2 lb 3 lb 6 lb -- Yield/A. Yield/A. Bu Cwt 186 310 300 180 194 323 228 380 396 238 374 224 388 233 185 309 177 295 226 377 239 399 358 215 174 290 *Mean of three untreated plots % Size Distribution to 1 7/8 % Size Distribution 1 7/8-10 oz % Size Distribution % Size Distribution Off 22 10 oz + 7 5 7 6 5 3 4 5 6 5 5 4 4 7 66 72 65 64 62 66 69 76 71 73 61 66 74 8 13 8 14 14 10 4 5 7 18 8 6 13 17 23 21 16 16 14 19 15 17 22 13 Specific Gravity 1.077 1.077 1.078 1.076 1.080 1.080 1.075 1.075 1.076 1.077 1.079 1.076 1.076 BEAN VARIETY - STRAINS OF RHIZOBIUM TEST M.W. Adams, A.W. Saettler, Jenny Taylor Department of Crop and Soil Sciences and Department of Botany and Plant Pathology During the winter of 1974-75, Dr. Joe Burton of the Nitragin Company of Milwaukee, Wisconsin, tested under greenhouse conditions 6 cultivars sent to him from Michigan State University against 6 strains of Rhizobia, the N-fixing bacterium. He found evidence of some specific variety X strain effects. We agreed to test these same varieties and strains in a field trial in 1975 to see if there showed up any practical advantage or difference in the field. The field experiment consisted of 7 bean strains and 6 strains of. Rhizobia, plus a Control, grown in a split-plot design with four replications. Individual plots consisted of 1 row, 20 feet long. No fertilizer was used. Herbicide (Eptam) at rate of 4 pints/acre was used. The experiment was planted on June 19. Irrigation by sprinkler was applied as necessary to main­ tain normal growth. The soil is a McBride sandy loam. A 1-year old stand of Red Clover was plowed down in May, before planting in June. The yield data from this experiment are presented in Table 1. Differences among varieties and among strains of inoculant were both highly significant, but we could detect no significant variety X strain interaction. There are several observations of interest: 1. In confirmation of results obtained in 1974 at the Bean and Beet Farm for 3 different commercial inoculants, the Seafarer yielded as well at the Control level as with the average of the 6 inoculame, although in 2 cases, Rhizobial strains KI 7 and K36, yields appeared to be significantly increased. Montcalm red kidney, as at the Bean and Beet Farm in 1974, responded to inoculation in 4 of the 6 strains, yielding on the average over all strains 1.8 bags of beans more when inoculated than when not. 2. The unreleased navy line, #0686, yielded poorly with no inoculation and responded significantly to inoculation in 4 of the 6 Rhizobial strains. It yielded significantly less than the control in 2 of the 6 cases, including the commercial ”D” strain. 3. Black Turtle Soup and Jamapa, also a black bean, yielded very well in the Control, but really yielded extra-ordinarily high, about 2.5 bags better, when inoculated. Strain K17 was particularly effective on these 2 varieties; they yielded about 4 bags better with strain K17. Other strains were no better than the Control. 4. For Pinto #114, the average of the inocula was no better than the Control, but individual strains gave both significantly higher and lower yields than the Control. 5. NEP-2, a white-seeded mutant of a tropical black bean and in other tests quite comparable to Black Turtle Soup in yield, was the only variety which yielded significantly better under no inoculation (Control) than when inoculated. There was a difference of 4 bags between Control and the average of the Rhizobial strains. General Comments: We do not know with assurance how far to extrapolate from these results. It appears that inoculation was favorable to yield increases in some varieties but not in all, and inoculation seemed to cause a decrease in one variety. Furthermore, not all strains are uniformly "good" over all varieties or uniformly ’’bad” over all varieties. There seem to be specific favorable effects and specific unfavorable effects in certain instances. It could be that these data would not be confirmed in another year. At no time could we see visually any difference in color or growth in the plots. We must recall, also, that we got good yields in most cases with no fertilizer used on any plot. The nursery was planted late, had no shortage of water at any time during the growing season, and was harvested late. The range in yield of the varieties greatly exceeded the range in yields as related to the different Rhizobial strains. The fact that a one-year old stand of Red Clover had been plowed down in May ahead of seeding this trial on June 19, surely implies a higher level of nitrogen in the soil than we would have preferred for this kind of experiment had we had a choice of sites. It may have elevated the yields on the Control plots and narrowed the difference between control and treated plots. Or it may only have raised the base level on both sites. We do not know to what extent our results have been affected by the plow down. Table 1. Average yield in pounds/acre, over 4 replications, of 7 varieties of beans inoculated with 6 different strains of Rhizobiam. 2056.7 ENTRY #0686 (navy) Seafarer (navy) Black Turtle Soup NEP-2 (white) Jamapa (black) Pinto #114 Montcalm (kidney) Mean over varieties 3216.9 2703.5 2675.3 2304.8 2199.6 1869.9 1866.7 2088.1 3130.6 2978.3 2196.4 1951.5 3088.2 3113.3 2191.7 1703.5 RHIZOBIUM STRAINS RHIZOBIUM STRAINS 127K12 127K36 127K14 RHIZOBIUM STRAINS RHIZOBIUM STRAINS RHIZOBIUM STRAINS RHIZOBIUM STRAINS RHIZOBIUM STRAINS Com."D" CONTROL 127K26 127K17 Means over treatments 1600.5 1876.2 1906.0 1570.0 1951.5 1667.3 * 1951.5 1789.0 (1809.3) ** 1996.6 (1986.6) 2986.6 (3038.5) 1966.1 (1909.6) 2912.1 2947.9 2921.1 (2916.0) 1675.4 (1701.1) 2321.0 (2329.9) 1758.4 2247.4 3105.5 2789.9 1705.0 2072.4 3114.9 2891.9 1813.4 1794.5 2703.5 2750.6 3237.3 2810.3 3103.9 3122.7 2449.9 2232.5 1763.1 1551.2 2471.4 2378.8 2943.8 2609.3 1880.9 1651.6 2697.3 2951.6 1521.3 2267.8 1526.0 2289.2 * A difference between variety-strain values in this table of 32.6 pounds is necessary for significance * A difference between variety-strain values in this table of 32.6 pounds is necessary for significance at the 5% level. **Numbers in parentheses are means not including the control. Test #5210 ENTRY 41497 41498 41499 Michicran CRANBERRY SELECTIONS YIELD IN LBS. CLEAN SEED/ACRE GMS/100 SEEDS 2436.6 2537.1 2705.1 2934.3 60.25 63.00 49.00 55.75 The purpose of this test was to compare for yield and seed size the selections of cranberry beans which remain from earlier screening experiments. The objective has been to find a cranberry bean of larger seed size than Michicran, and equal to it in yield, for certain European markets. It appears that we have acceptable seed size. However, though there was not a statistically significant difference among the lines, the Michicran appears to be a better yielder than the 2 larger seeded selections. Further testing is required to confirm this yield difference. Test #5211 RED KIDNEY SELECTIONS, STANDARD VARIETIES OF KIDNEYS, AND 2 PINTOS. ENTRY 41048 41050 41051 41056 41060 41070 41071 41072 41073 41080 Charlevoix DR Kidney Montcalm DR Kidney Mecosta LR Kidney Manitou LR Kidney Pinto 114 Ouray Pinto YIELD IN POUNDS CLEAN SEED/ACRE * 2640.74 2774.19 2709.82 2501.01 2756.92 2742.79 2791.46 2413.09 2741.22 2709.82 2494.73 2480.60 2504.15 2639.17 3056.79 2615.62 *Differences in yield were not significant. The selections were made at the Bean and Beet Farm in 1974 in an attempt to get some earlier maturing light reds than Manitou or Mecosta without sacrificing yield. There were no significant differences in yield, and the wet weather at the end of the growing season precluded getting good maturity data. Most of the lines yielded as good as Manitou and Mecosta, but we will have to have another years trial to get a more accurate fix on maturity. Some re-selections were made. CORN HYBRIDS, PLANT POPULATION AND IRRIGATION E.C. Rossman and Bary Darling Department of Crop and Soil Sciences Table 1 presents performance data for 75 commercial corn hybrids evalu­ ated in 1975 with irrigation and without irrigation. A total of nine inches of water were applied in seven applications on July 2, 8, 16, 23, 29, August 11 and 19. Bouyoucous soil moisture blocks were placed at 6, 12, 18 and 24- inch depths in both irrigated and unirrigated plot areas. Irrigated yields averaged 29.3 bushels per acre more than unirrigated — 153.9 vs. 124.6. Hybrids ranged from 106.3 to 206.5 irrigated and 80.4 to 157.2 without irrigation. Hybrids significantly better than the average yield (arranged in order of increasing grain moisture content at harvest) are listed below. Fifteen of the 17 hybrids were in the highest yielding group for both irrigated and unirrigated plots. Two hybrids yielded above 200 bushels per acre. The correlation of irrigated with unirrigated yields was highly sign­ ificant, .932, indicating a close relationship between relative yields of hybrids in both situations. Irrigated Northrup King PX32 (2X) Michigan 4122 (2X) Michigan 407-2X (2X) Funk 26516 (3X) Blaney B606 (2X) Asgrow RX53 (2X) Wolverine W166 (2X) Funk G-4321 (2X) Security SS105 (2X) Michigan 5802 (2X) Migro M-1130 (2X) Pioneer 3716 (3X) P-A-G SX69 (2X) Acco UC3301 (2X) Pioneer 3535 (2X) Unirrigated Northrup King PX32 (2X) Michigan 4122 (2X) Michigan 407-2X (2X) Funk 26516 (3X) Blaney B606 (2X) Asgrow RX53 (2X) Northrup King PX529 (3X) Wolverine W166 (2X) Funk G-4321 (2X) Super Crost S27 (2X) Security SS105 (2X) Michigan 5802 (2X) Migro M-1130 (2X) Pioneer 3716 (3X) P-A-G SX69 (2X) Acco UC3301 (2X) Pioneer 3535 (2X) Table 1 NORTH CENTRAL MICHIGAN Montcalm County Trial - Irrigated, vs. Not Irrigated One, Two, Three Year Averages - 1975, 1974, 1973 Zone 3 Bushels per Acre 3 years Irrig Hybrid (Brand - Variety) % Moisture % Moisture % Moisture 2 1975 yrs. 3 yrs. Michigan 275-2X (2X) DeKalb XL311 (3X) Michigan 280 (4X) Michigan 2853 (3X) Funk G-4195 (3X) Michigan 2833 (3X) DeKalb XL12 (2X) Migro M-1020 (2X) Wolverine W128 (2X) Migro M-0101 (2X) Super Croat 1692 (2X) Michigan 333-3X (3X.) Super Crost 1610 (2X) Asgrow 2222 (2X) Northrup King PX20 (2X) Blaney B302 (2X) Pioneer 3955 (3X) Michigan 3093 (3X) Blaney B401 (2X) Pioneer 3965 (3X) Funk G-4141 (2X) Funk G-4252 (3X) Pioneer 3958 (2X) Asgrow RX42 (2X) DeKalb XL15A (2X) 21.8 21.8 21.8 21.9 22.0 22.1 22.3 22.5 22.7 22.7 22.8 22.9 23.1 23.2 23.2 23.2 23.3 -- 23.5 23.5 23.5 23.6 23.7 23.9 24.0 24.1 25 26 25 25 -- 28 25 29 28 -- 25 26 27 26 25 -- -- -- 26 27 -- -- -- 25 -- -- 29 28 28 30 24 24 24 26 24 28 25 -- 26 25 -- -- -- -- -- 28 27 26 28 Irrig Bushels per Acre 2 years Bushels 1975 Bushels per Acre Irrig per Acre 1975 Not Irrig 101.0 80.4 91.5 100.4 109.1 100.7 102.8 113.5 100.6 109.6 104.2 114.3 107.6 106.9 111.4 114.7 124.6 125.7 130.3 115.3 114.5 -- 113.1 127.5 130.5 105.2 122 104 119 126 122 110 120 123 114 126 125 134 122 -- 122 131 -- -- -- 121 132 136 131 117 133.8 106.3 122.8 129.0 133.2 123.4 124.2 139.8 122.2 140.7 130.7 144.5 136.0 129.4 135.3 142.1 147.1 158.0 157.1 137.0 156.0 143.5 160.0 142.9 130.3 Bushels per Acre 2 years Not Irrig 104 83 97 104 108 102 104 108 100 104 108 115 106 -- 106 113 -- -- -- 108 -- 108 113 118 103 -- -- -- 116 104 113 -- 115 116 115 111 -- 119 128 -- -- -- -- -- -- -- 117 123 127 112 Bushels per Acre 3 years Not Irrig 101 85 97 -- 101 102 101 95 -- -- 102 112 -- -- -- -- -- -- -- -- -- 100 106 114 100 % Stall: lodging % Stall: lodging 1975 Irrig 1975 Not Irrig 10.6 2.3 9.8 6.8 3.8 5.7 3.9 0.0 3.5 4.7 8.1 0.8 1.6 4.4 3.1 0.0 1.5 2.2 0.8 0.0 2.1 3.1 0.0 13.7 10.4 5.2 10.2 5.8 7.2 8.8 16.8 18.7 0 2.3 4.7 4.6 2.4 2.3 2.9 0.8 7.6 0.7 4.7 3.1 5.8 1.5 1.6 5.6 0.7 0.0 12.0 -- -- -- -- -- % Stall: % Stall: lodging 2 years Irrig lodging 2 years Not Irrig % Stall: lodging 3 years Irrig % Stall: lodging 3 years Not Irrig 6 6 2 3 6 5 -- -- 3 4 4 5 7 7 -- -- 2 3 -- 2 3 -- -- -- -- 3 1 1 5 -- -- -- -- 3 3 -- -- -- -- -- 2 2 1 5 6 3 6 4 4 5 1 5 2 1 2 1 4 0 1 3 0 0 6 5 1 7 4 2 3 9 3 2 3 3 4 1 2 3 0 -- 1 2 0 7 -- -- -- -- -- -- -- -- -- -- Table 1 Continued Michigan 3102 (2X) Acco UC 2301 (2X) Blaney B442 (3X) Michigan 396-3X (3X) Funk G-4343 (2X) Blaney 7305 (2X) Cowbell 7300 (2X) Michigan 410-2X (2X) 1,2 Northrup King PX32 (2X) Pioneer 3785 (2X) Blaney B443 (3X) 1, 2 Michigan 4122 (2X) Acco DC231 (4X) Cowbell 102 (2X) Pride R290 (2X) Funk G-L2334 (Sp.) 1, 2 Michigan 407-2X (2X) Migro M-1212 (2X) Funk G-4288 (3X) 1, 2 Funk 26516 (3X) Michigan 572-3X (3X) 1, 2 Blaney B606 (2X) Acco U 334 (3X) Michigan 5443 (3X) Pride 4404 (2X) 1, 2 Asgrow -RX53 (2X) 2 Northrup King PX529 (3X) 1, 2 Wolverine W166 (2X) Cowbell 4100 (2X) 1, 2 Funk G-4321 (2X) 24.3 29 24.6 29 24.7 -- -- 25.2 25.3 30 31 -- -- -- 25.3 30 25.6 31 31 25.9 26.1 30 26.2 32 -- 26.3 26.3 -- 26.3 32 -- 26.3 26.5 32 -- 26.5 26.6 31 26.7 33 26.7 32 26.8 -- 26.8 33 26.8 33 27.0 -- 27.1 -- 27.1 -- 27.2 30 33 27.3 27.3 -- 27.6 33 27.7 33 -- 28 28 29 30 29 -- -- -- 30 -- 30 29 31 30 -- 31 -- -- -- -- 28 -- -- -- 31 157.3 131.1 158.7 132.7 128.4 113.3 -- 160.6 128.3 164.2 135.1 156.5 133.2 144.8 122.3 157.6 132.9 168.2 135.6 146.0 123.7 155.1 121.4 179.3 140.4 139.7 113.7 129.0 107.2 133.7 157.4 140.9 112.4 168.6 137.5 153.7 127.7 132.5 155.4 168.5 136.3 -- -- 128.1 156.4 176.8 143.5 167.0 123.7 131.7 -- 167.7 169.7 129.7 -- 169.3 138.3 138.7 165.6 137.8 179.3 140.4 111.4 181.1 148.7 141 138 144 133 132 123 145 143 129 -- 116 -- 145 151 132 136 -- 139 143 -- 146 136 -- 126 157 -- -- -- -- -- -- 124 119 122 109 119 106 123 121 113 -- 101 -- 124 130 116 121 -- 122 123 -- 126 124 106 132 -- 133 139 126 120 141 -- -- 107 133 145 130 134 -- 137 -- 141 146 -- -- -- -- -- -- -- -- -- -- -- -- -- 115 110 107 104 119 -- 96 -- 114 126 117 118 120 -- 124 126 -- -- -- -- -- -- -- -- -- -- -- -- -- 2.4 3.5 7.4 17.1 6.9 5.8 0.0 0.8 6.9 7.1 2.1 7.9 5.5 4.4 0.0 5.1 6.1 4.9 5.3 0.8 4.7 0.8 0.8 0.0 11.0 7.6 4.9 10.2 6.8 7.9 14.1 14.7 3.5 0.0 3.6 1.5 10.3 11.3 1.4 1.5 7.1 3.6 12.1 3.6 0.8 0.0 5.6 5.6 7.2 2.3 5.7 3.6 5.1 5.4 1.5 0.8 7.5 8.6 3.8 0.7 -- -- -- 4 -- -- -- -- -- -- 2 4 0 3 1 4 3 2 0 -- -- -- -- 6 -- -- -- -- -- -- -- 2 2 5 4 2 0 3 4 1 1 9 0 4 3 3 3 3 0 5 4 1 2 6 3 2 0 4 2 0 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 5 1 3 5 3 -- 7 4 3 2 5 3 0 3 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 6 1 3 3 4 -- 4 4 2 1 4 3 1 -- 1 2 Super Crost S27 (2X) Table 1 Continued 33 -- 28.1 Super Crost 1901 (2X) 28.2 32 -- Cardinal SX105 (2X) 28.2 Super Crost S25 (2X) 33 28.7 Funk G-4444 (2X) 33 Asgrow RX64 (2X) 28.7 33 -- 28.0 33 Pioneer 37 (2X) 28.8 -- Northrup King PX46 (2X) 28.8 33 Funk G-4366 (3X) 28.9 34 Michigan 575-2X (2X) 28.9 34 -- -- Funk G-W302 (Sp.) 29.4 35 Cowbell 7440 (2X) 34 29.7 1,2 Security SS105 (2X) 29.8 -- 1,2 Michigan 5802 (2X) 29.8 -- 1,2 Migro M-1130 (2X) 30.2 35 -- 1,2 Pioneer 3716 (3X) 30.3 1,2 P.A.G. SX69 (2X) 31.5 35 1,2 Acco UC 3301 (2X) 31.5 35 1,2 Pioneer 3535 (2X) 31.6 -- -- Cowbell 7480 (2X) 32.0 36 -- Average 26.1 30 -- Range 21.8 to 32.0 25 to 36 155.5 166.1 145.8 166.4 153.8 166.5 154.0 160.1 170.2 167.4 158.8 167.4 173.1 187.6 170.3 172.7 169.9 206.5 200.8 157.2 -- 147.4 153.9 118.8 134.7 114.6 135.0 133.1 132.6 131.7 -- 140.5 131.8 135.2 122.3 125.9 145.7 151.3 138.8 137.4 141.6 157.0 124.1 124.6 -- 145 144 130 148 136 142 138 133 148 138 148 -- -- 149 138 163 132 134 106.3 to 206.5 80.4 to 157.2 104 to 163 -- -- -- -- 119 121 110 128 123 121 113 115 126 115 122 -- 123 122 131 119 115 83 to 132 -- -- -- -- -- -- -- -- 126 143 -- 137 133 137 -- -- 142 138 155 -- 128 104 to 155 -- 108 124 -- 118 -- 115 117 -- -- -- 120 -- 120 127 -- -- -- -- -- 111 85 to 127 30 32 31 -- 31 32 -- -- 33 -- 33 33 29 24 to 33 Least significant difference 1 Significantly better than average yield, irrigated 1975. 2 Significantly better than average yield, not irrigated 1975. 10.9 14.2 8 1 2 0.9 0.7 7 5 5 1.7 3.1 0.7 3.8 3.0 3.0 2.2 2.2 1.5 4.6 8.8 0.7 0.7 0.0 4.9 4.5 3.5 1.4 2.3 7.0 4.5 1.6 3.6 1.6 2.8 6.2 3.7 0.8 6.5 6.0 4.5 15.5 0.0 5.9 1.4 4.9 2.1 2.8 1.4 0.8 7.8 4.6 1 3 0 2 2 2 1 1 2 5 1 2 2 1 4 3 -- -- -- -- -- 0.0 to 16.8 empty table cell 0.0 to 18.7 empty table cell 0 to8 empty table cell 1 2 1 2 3 2 3 3 2 0 1 2 2 1 4 3 -- -- -- -- -- -- 3 -- -- -- -- -- -- -- -- -- -- 1 3 2 2 -- 2 2 3 3 0 to 9 0 to 7 -- -- -- -- -- -- -- -- -- -- -- 1 2 2 -- 3 3 3 3 4 3 1 to 7 empty table cell empty table cell empty table cell Table 1 Continued Planted Harvested Soil Type Previous Crop Population Rows Fertilizer Irrigation Soil Test: pH Soil Test : P Soil Test : K 1975 May 7 Oct. 15 Montcalm sandy loam Clover 20,700 30 255-110-110 9 inches 6.5 268 (very high) 257 (high) Farm Cooperator: Theron Comden, Lakeview County Extension Director: James Crosby, Stanton 1974 May 4 Oct. 26 Montcalm sandy loam Sorghum - Sudan seededto rye in fall 20,500 30" 150-120-170 8 inches 6.1 340 (very high) 190 (high) 1973 May 8 Oct. 17 Montcalm sandy loam Sorghum - sudan seededto rye in fall to rye in fall 18,700 30 277-130-130 5 inches 5.6 297 (very high) 175 (medium) Table 2 gives the average, highest and lowest yields for corn hybrids irrigated and not irrigated for an 8-year period, 1968-1975. The average yielding hybrid has given a response of 44 bushels to irrigation. The highest yielding hybrids have responded with 59 bushels added yield while the lowest yielding hybrids have given only 27 bushels added yield with irrigation. These results demonstrate the importance of choosing high yielding hybrids to maximize returns from irrigation with little, if any, additional cost. Plant Population x Irrigation Five hybrids at four plant populations irrigated and not irrigated were grown in each of eight years, 1968-1975, Table 3. Over the eight-year period, a population of 23,300 has given the highest average yield (171 bushels) when irrigated while 19,200 has given the highest yield (117 bushels) without irri­ gation. The 23,300 population irrigated gave the highest yield in seven of the eight years. Moisture content of grain at harvest has averaged .5-1.0% higher for the higher plant populations. Stalk lodging has increased slightly with inc increased plant population. Table 2. Average, highest and lowest yields for corn hybrids irrigated and not irrigated for 8 years, 1968-1975. No. of hybrids tested Average Average Highest Lowest Irrigated Not Irrigated Irrigated Highest Not Irrigated Irrigated Lowest Not Irrigated 75 76 72 72 56 64 63 56 154 112 114 157 163 144 146 136 141 125 103 101 137 28 103 86 96 97 207 134 138 206 211 194 185 182 182 157 122 120 179 42 128 109 123 123 106 65 78 99 91 95 97 92 90 80 58 73 91 11 70 56 65 63 Year 1975 1974 1973 1972 1971 1970 1969 1968 Averagesempty table cell Table 3. Average yield at four plant populations irrigated and not irrigated for eight years, 1968-1975. Year 1975 1974 1973 1972 1971 1970 1969 1968 Average 15, 300 Irri­ gated Not 15, 300 Irri­ gated Irri­ 19,200 gated Not 19,200 Irri­ gated Irri­ 23,300 gated Not 23,300 Irri­ gated Irri­ 27,600 gated 27,600 Not Irri­ gated 158 118 108 152 173 122 126 144 138 136 100 97 132 37 91 91 114 100 183 130 134 187 189 144 158 169 162 164 111 116 159 35 112 109 130 117 196 135 128 191 191 158 173 193 171 151 98 106 149 20 93 96 107 103 172 120 108 161 181 151 148 178 152 146 94 102 144 11 85 86 89 95