1996 MICHIGAN POTATO RESEARCH REPORT VOLUME 28 Michigan State University Agricultural Experiment Station In Cooperation With The Michigan Potato Industry Commission THE MICHIGAN POTATO INDUSTRY COMMISSION February 5,1997 To All Michigan Potato Growers & Shippers: The Michigan Potato Industry Commission, Michigan State University’s Agricultural Experiment Station, and Cooperative Extension Service are pleased to provide you with a copy of the results from the 1996 potato research projects. This report includes research projects funded by the Michigan Potato Industry Commission as well as projects funded through the USDA Special Grant and other sources. Providing research funding and direction to principal investigators at MSU is a function of the Michigan Potato Industry Commission’s Research Committee. Best wishes for a prosperous 1997 season, The Michigan Potato Industry Commission THE MICHIGAN POTATO INDUSTRY COMMISSION • 13109 SCHAVEY RD., STE. 7 • DEWITT, Ml 48820 • (517)669-8377 TABLE OF CONTENTS INTRODUCTION AND ACKNOWLEDGEMENTS, WEATHER AND GENERAL MANAGEMENT page 1 MICHIGAN STATE UNIVERSITY POTATO BREEDING PROGRAM — 1996 STATUS REPORT David S. Douches, K. Jastrzebski, Chris Long, Kim Walters and Joe Coombs 5 1996 POTATO VARIETY EVALUATIONS D.S. Douches, R.W. Chase, K. Jastrzebski, R. Hammerschmidt, W. Kirk, C. Long, K. Walters and J. Coombs 11 POTATO VARIETY AND MANAGEMENT STUDIES R.W. Chase and D.S. Douches 32 FUSARIUM DRY ROT RESEARCH R. Hammerschmidt and H. Ray 39 POSTHARVEST SUPPRESSION OF FUSARIUM DRY ROT AND OTHER STORAGE DISEASES OF MINITUBERS OF POTATO TUBERS BY APPLICATION OF BIOACTIVE FUNGAL INOCULUM DURING PLANT GROWTH Gene R. Safir and Raymond Hammerschmidt 41 NITROGEN STEWARDSHIP PRACTICES TO REDUCE NITRATE LEACHING AND SUSTAIN PROFITABILITY IN AN IRRIGATED PRODUCTION SYSTEM ML. Vitosh, D.R. Smucker, E.A. Paul, R.R. Harwood and J.T. Ritchie 42 1996 POTATO NEMATODE RESEARCH GW. Bird 60 COLORADO POTATO BEETLE MANAGEMENT — 1996 RESEARCH REPORT Edward Grafius, Beth Bishop, and Ellen McEnhill 71 CHEMICAL CONTROL OF POTATO LATE BLIGHT 1996 W.W. Kirk, B. Kitchen, J.M. Stein, N.M. Kirk and R. Nobis 88 CONTROL OF COLORADO POTATO BEETLE UTILIZING TRANSGENIC POTATOES AS A BARRIER CROP AND TREATING A CONVENTIONAL BARRIER CROP WITH IMIDACLOPRID Mark E. Whalon and Michael R. Bush 105 SCREENING GREEN PEACH APHIDS FOR RESISTANCE TO IMIDACLOPRID AND OTHER INSECTICIDES USED BY MICHIGAN GROWERS IN POTATOES Mark E. Whalon and Michael R. Bush 107 CONTRIBUTION OF AMINO ACIDS AND REDUCING SUGARS TO COLOR DEVELOPMENT IN POTATO CHIPS V. Chonhenchob, J.N. Cash and R. Brook 108 1996 MSU POTATO RESEARCH REPORT R.W. Chase, Coordinator Introduction and Acknowledgements The 1996 Potato Research Report contains reports of potato research projects conducted by MSU potato researchers at several different locations. The 1996 report is the 28th report which has been prepared annually since 1969. This volume includes research projects funded by the Special Federal Grant 95-34141-1399, the Michigan Potato Industry Commission and numerous 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 also acknowledge the tremendous cooperation of individual producers who cooperate with the numerous on-farm projects. It is this dedicated support and cooperation that makes for a productive research program for the betterment of the Michigan potato industry. We further 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 determining the needs and direction of Michigan’s potato research. Thanks go to Dick Crawford, for the farm management at the MSU Montcalm Research Farm; Chris Long, CSS Potato Technician and Dr. Kazimierz Jastrzebski, visiting scientist from Poland. Also, a special thanks to Jodie Schonfelder for the typing and preparation of this report and to MSUE Don Smucker, Montcalm CED for maintaining the weather records from the Montcalm Research Farm computerized weather station. Weather Weather during the 1996 growing season was variable. The average minimum temperatures were near normal for the season (Table 1), slightly below the average in April and July and above average in May, June, August and September. The average maximum temperature for the season was 3° below the average and below average for each month except August and September. The temperature exceeded 90° on only two days in early August and was greater than 85° on ten days throughout the season. Rainfall for the season was nearly 2 inches above the 15 year average (Table 2). Rainfall was above average in May and nearly double the 15 year average for June. The greater soil moisture and cooler temperatures in April and May resulted in some emergence delay. Weather during September was very good for plot harvesting. Table 1. The 15 year summary of average maximum and minimum temperatures during the growing season at the Montcalm Research Farm. Empty table cell April April Min 28 28 34 38 36 36 31 32 NA 40 34 33 34 31 31 Max 53 47 54 58 60 61 52 56 NA 60 51 54 57 51 50 May May Max 72 60 60 70 70 77 74 72 64 71 70 68 66 66 64 Min 46 38 39 44 46 46 46 34 43 47 42 45 43 45 44 June June Min 44 49 54 46 50 56 53 53 55 59 50 55 55 57 57 Max 70 76 77 71 77 80 82 81 77 82 76 74 78 81 75 July July Min 53 57 53 55 59 63 60 59 58 60 54 61 60 60 55 Max 80 85 78 81 82 86 88 83 79 81 76 81 79 82 76 August August Min Max 76 48 57 82 83 55 75 54 51 77 77 58 61 84 55 79 78 57 80 57 75 51 60 79 75 55 65 82 80 59 September September Min Max 66 44 70 46 45 69 70 50 72 50 72 52 71 49 71 44 47 72 69 47 69 46 64 46 73 51 70 45 70 51 6-Month 6 Month Average Average Min Max 70 44 70 46 70 47 71 48 49 73 76 52 75 50 74 46 NA NA 74 52 69 46 70 50 71 49 72 50 50 69 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 15-YR. AVG. 55 33 68 43 77 53 81 58 79 56 70 47 72 48 Table 2. The 15 year summary of precipitation (inches per month) recorded during the growing season at the Montcalm Research Farm. Year 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 15-YR. AVG. April 1.43 3.47 2.78 3.63 2.24 1.82 1.82 2.43 1.87 4.76 3.07 3.47 3.84 3.65 2.46 2.85 May 3.53 4.46 5.14 1.94 4.22 1.94 0.52 2.68 4.65 3.68 0.47 3.27 2.63 1.87 3.99 3.00 June 5.69 1.19 2.93 2.78 3.20 0.84 0.56 4.85 3.53 4.03 1.18 4.32 6.04 2.30 6.28 3.31 July 5.53 2.44 3.76 2.58 2.36 1.85 2.44 0.82 3.76 5.73 3.51 2.58 5.16 5.25 3.39 3.41 August 1.96 2.21 1.97 4.72 2.10 9.78 3.44 5.52 4.06 1.75 3.20 6.40 8.05 4.59 3.69 4.23 September 3.24 5.34 3.90 3.30 18.60 3.32 5.36 1.33 3.64 1.50 3.90 3.56 1.18 1.38 2.96 4.17 Total 21.38 19.11 20.48 18.95 32.72 19.55 14.14 17.62 21.51 21.45 15.33 23.60 26.90 19.04 22.77 20.97 Growing Degree Days Table 3 summarizes the cumulative, base 50F growing degree days (GDD) for May through September. Similar to 1995, May was again very cool and the lowest since 1991. It continued to be the lowest throughout the season except for 1992 which had 1,956 GDD. Table3. Growing Degree Days* - Base 50F. empty table cell Cumulative Month Totals Cumulative Month Totals Cumulative Month Totals Cumulative Month Totals May June July August September Cumulative Month Totals 1991 1992 1993 1994 1995 1996 452 282 261 231 202 201 1014 718 698 730 779 681 1632 1210 1348 1318 1421 1177 2185 1633 1950 1780 2136 1776 2491 1956 2153 2148 2348 2116 *1991 and 1992 data calculated from Vestaburg weather station in Montcalm County (Dr. Jeff Andresen, Geography). 1993-1996 data from the weather station at MSU Montcalm Research Farm (Don Smucker, Montcalm County Extension Director). Previous Crops and Fertilizers The general research plot area was planted to rye in the fall of 1994 and harvested for seed in 1995, disced and re-seeded to rye. The plot area was not fumigated and the following fertilizers were used in the general plot area during 1996: Application Plowdown In-furrow Hilling - Round whites - Long/Snowden Hilling Fertigation - (two applications) Analysis 0-0-60 20-10-10 45-0-0 45-0-0 28-0-0 Rate 250 lbs/A 300 lbs/A 125 lbs/A 225 lbs/A 15 gpa (2X) Nutrients 0-0-150 60-30-30 56-0-0 101-0-0 84-0-0 Soil Tests Soil tests for the general plot area: lbs/A lbs/A pH 5.9 lbs/A P2O5 360 K2O 216 Ca 655 lbs/A Mg 89 Cation Exchange Capacity 3.5 me/100 g Herbicides and Hilling Hilling was done in late May, just prior to potato emergence, followed by a tank mix of metolachlor (Dual) at 2 Ibs/A plus metribuzin (Sencor) at 2/3 lb/A. Irrigation Irrigation was initiated on June 28 and nine applications were made at 0.75 inches per application. There was one application in June, four in July three in August and one in September. Insect and Disease Control Admire was used in all plantings with excellent control of CPB. One foliar insecticide application was made in late August using Asana + PBO and Monitor. Fungicide applications were initiated on June 13 and continued on a 7-10 day schedule using Bravo. MICHIGAN STATE UNIVERSITY POTATO BREEDING PROGRAM 1996 STATUS REPORT Funding Fed. Grant/MPIC David S. Douches, K. Jastrzebski, Chris Long, Kim Walters and Joe Coombs Department of Crop and Soil Sciences Cooperators: R.W. Chase, Ray Hammerschmidt, Ed Grafius Jerry Cash and Willie Kirk INTRODUCTION The MSU program has a multi-faceted approach to variety development. We conduct variety trials of advanced selections, develop new genetic combinations in the breeding program and identify exotic germplasm that will enhance the varietal breeding efforts. With each cycle of crossing and selection we expect to see directed improvement towards improved varieties. We are also using the European germplasm as a source of disease resistance and quality traits. In addition, our program integrates genetic engineering to introduce traits. We feel that these in-house capacities (both conventional and biotechnological) put us in a position to respond and focus upon the most promising directions. The breeding goals at MSU are based upon current and future needs of the Michigan potato industry. Traits of importance include yield potential, disease resistance (scab, late blight, Fusariun dry rot, soft rot, early die and virus resistance), chipping and cooking quality, bruise resistance, storability, along with shape, internal quality and appearance. PROCEDURE Varietal Development Each year, during the winter months, approximately 500 crosses are made between the most promising cultivars and advanced breeding lines. The parents are chosen on the basis of yield potential, processing or tablestock quality, specific gravity, disease resistance, adaptation, lack of internal and external defects, etc. These seeds are being used as the breeding base for the program. Approximately 30,000 seedlings are grown annually for visual evaluation at the Montcalm and Lake City Research Farms as part of the first-year selection process of this germplasm each fall. Then each selection is then evaluated for specific gravity and chip­ processing. These selections each represent a potential variety. This step is followed by evaluation and selection at the 8-hill, 20-hill stages. The best selections are then tested in replicated trials over time and locations. This generation of advanced seedlings is the initial step to breed new varieties and this step is an on-going process in the MSU program since 1988. Integration of Genetic Engineering with Potato Breeding Our laboratory is set up to use Agrobacterium-mediated transformation to introduce genes into important potato cultivars. We presently have genes that confer resistance to PVY, PLRV, Colorado Potato Beetle, Potato tuber moth and broad-spectrum disease resistance. We also have the glgC16 gene or starch gene from Monsanto to influence starch and sugar levels in potato tubers. We have transgenic lines that express the PVYcp and Bt genes. Transformations with the starch gene and disease resistance gene are presently being conducted. Correlation of Chip-processing in Greenhouse and Field-grown Tubers The initial field selection of single hills in the breeding program leaves a large percentage of seedlings behind (90%). If chip-processing quality is of primary importance, we must devise a procedure to identify the superior chip-processors. We are testing whether the greenhouse­ generated tubers would chip-process and give comparable readings as in the field. If so, we can compare greenhouse chip color in place of field-grown chip color and save the field evaluation only for chip-processors. This study was established for 1995. Germplasm enhancement We have a "diploid" (2x chromosomes) breeding program in an effort to simplify the genetic system in potato (which normally has 4x chromosomes) and exploit more efficient selection of desirable traits. In general, diploid breeding utilizes haploids (half the chromosomes) from potato varieties, and diploid wild and cultivated tuber-bearing relatives of the potato. These represent a large source of valuable germplasm, which can broaden the genetic base of the cultivated potato and also provide specific desirable traits such as tuber dry matter content, cold chipping and dormancy, along with resistance to disease, insects, and virus. Even though these potatoes have only half the chromosomes of the varieties in the U.S., we can cross these potatoes to transfer the desirable genes by conventional crossing methods via 2n pollen. The diploid breeding program germplasm base at MSU is a synthesis of five species: S. tuberosum (adaptation, tuber appearance), S. phureja (cold-chipping, specific gravity), S. tarijense and berthaultii (tuber appearance, insect resistance) and S. chacoense (specific gravity, low sugars, dormancy). We are also using other sources of germplasm to introgress disease resistance and tuber quality. Many European cultivars have high yield potential and resistance to various diseases such as scab, late blight and Erwinia soft rot. Some also have superior cooking qualities. These cultivars are being used in the crossing block each year. Dr. John Helgeson (USDA/ARS) has developed somatic fusion hybrids that have resistance to Erwinia soft rot, PLRV, Early Blight or Late Blight. We have those lines and have been crossing them to our best lines to initiate the adaptation of this germplasm source to Michigan. RESULTS AND DISCUSSION One of our objectives is to develop improved cultivars for the tablestock industry. Efforts have been made to identify lines with good appearance, low internal defects, high marketable yield and resistance to scab. From our efforts we have identified mostly round white lines, but we have a number of yellow fleshed and russet selections which carry many of the characteristics mentioned above. We are also looking for a dual-purpose russet. Some of these lines were tested in on-farm trials in 1996, while others were tested under replicated conditions at MRF. Our goal now is to 1) improve further on the level of scab resistance, 2) incorporate resistance to late blight and 3) select more russet lines. Another one of the objectives is to develop potato varieties that will not accumulate reducing sugars in cold storage (40F). We commonly call these varieties "cold chippers". There is a question as to which temperature is most appropriate to screen for cold-chipping. This storage season we have lowered the storage temperature from 45F to 42F, as our initial screen, to chip-process directly out of cold storage. We feel there is no long-term value in 2-4 week reconditioning out of 40F storage. We lowered the screening temperature because we felt that we have been identifying many selections from that process from 45F. As desirable cold­ chipping genes accumulate in the breeding program, we will reduce the storage temperature for screening to 40F. Some of the parents used in the crossing block over the past few years has included Snowden, ND860-2, MS702-80, Atlantic, S440, S438, Lemhi Russet, Pike, Chipeta, W877, and W870. In addition, we have advanced into the crossing block new MSU selections that have enhanced chip quality directly out of 45F storage and other new 45F chippers from the US and Europe such as ND2417-6, NDO1496-1, NDA2031-2 and Brodick. These clones constitute a diverse genetic base from which to combine good chipping quality with agronomic performance. For the 1996 field season over 400 crosses have been planted. Of those 20% of the crosses were between long types, 75% between round whites, and 5% to select red-skinned and yellow-flesh varieties. During the 1996 harvest, approximately 1400 selections were made from the 30,000 seedlings grown at the Montcalm Research Farm and Lake City Experiment Station. Following harvest, specific gravity was measured and chip-processing (from 50F storage). The single hills in 1995, when chipped directly out of 45F storage, about 20% of the single-hill selections had acceptable chip color. These selections were evaluated as 8-hill selections in 1996. Of the 8-hill selections from 1995, 25% of the 300 clones chip-processed with acceptable color directly out of 45F. From the 90 twenty-hill plots, 30% had acceptable chip color from 45F storage. The best selections from the 20-hill plots will be advanced to replicated trials in 1997. A high priority objective of the breeding program is to identify sources of late blight resistance and use these sources for incorporating resistance. Based upon greenhouse screenings, we have been using USDA/ARS and European sources of late blight resistance in our crossing block. We have made selections from these crosses and, in preliminary greenhouse screenings, some selections show some resistance to late blight. We will continue to evaluate these selections for resistance and agronomic performance. The best parent source of resistance at this time is the Ukrainian variety Zarevo. Performance of fifty-four MSU seedlings are reported in the 2x23-hill and Adaptation trials in 1996 (Tables 1 and 2). There are many promising seedlings with high yield potential and good appearance. These include E018-1, E048-2y, E041-1, E202-3, E221-1, C103-2, B073- 2, F349-1, F373-8, F059-1 and F020-23. The Erwinia soft rot and Fusarium dry rot tests, scab trial results and blackspot bruise tests are discussed in the 1996 Potato Variety Trial Report. In the diploid germplasm about 20 of the best lines with differing pedigrees formed the crossing block to generate new populations in 1995. From this material we expect to find improved diploid Solanum species parents to be used in crosses to select new varieties (4x-2x crosses). In 1996 selections were made in these crosses at Lake City. These lines will be tested as 8-hill plots in 1997. We added to the germplasm enhancement program a number of genetic lines that are derivatives of cell (protoplast) fusions between S. brevidens (from Argentina) and the cultivated potato. These lines were developed by J. Helgeson at the University of Wisconsin and have been noted for their Erwinia soft rot, early blight and PLRV resistance. Through further crossing and evaluation we hope to incorporate these resistances into the breeding populations we have been selecting for chip-processing. These populations were in the field in 1995 and 1996. Selections have been made and we are advancing some through the breeding program. Special attention will be placed upon these selections for disease resistance. This germplasm enhancement (diploid and protoplast fusion) is the base from which long-term genetic improvement of the potato varieties in the MSU breeding program is generated. Transgenic lines, developed at MSU, which express the PVYcp and Bt genes were tested at MRF. Agronomic performance of these lines were similar to their non-transgenic derivative variety. These lines will be field tested again in 1997 using tubers rather than tissue culture transplants. Table 1 Empty table cell CWT/A US#1 CWT/A TOTAL E018-1 E048-02Y E041-1 ATLANTIC E220-3 E202-3 E226-4Y E221-I E273-8 MSB110-3 C103-2 E149-5Y B057-2 B073-2 E066-04 E247-2 NT-1 C121-7 SNOWDEN E230-6 B094-1 E228-11 ND2676-10 B040-3 AF1433-4 E228-9 P84-13-12 B0952-1 E263-3 C148-A C122-1 C120-1Y B027-1R ND860-2 MEAN LSD 0.05 566 474 448 442 424 404 404 403 384 382 363 359 352 350 349 334 332 324 317 315 304 303 288 287 271 268 259 257 236 224 222 222 202 135 330 63 625 534 516 489 460 506 477 437 433 466 385 416 438 406 407 424 377 365 370 471 356 376 346 321 317 297 308 309 338 288 312 276 268 241 393 63 1 SIZE B - 2" A - 2-3.25" OV- 3.25" PO - PICKOUTS 3 SCAB Rating 1996 from Scab Trial 1 - NO INFECTION 3 - INTERMEDIATE 5 - HIGHLY SUSCEPTABLE PLANTED MAY 7, 1996 ADAPTATION TRIAL MONTCALM RESEARCH FARM SEPTEMBER 17, 1996 (133 DAYS) PERCENT OF TOTAL 1 PERCENT OF TOTAL 1 PERCENT OF TOTAL 1 As Bs US#1 QUALITY 2 OV PERCENT OF TOTAL 1 PO SP GR SFA HH PERCENT OF TOTAL 1 TUBER TUBE TUBER R QUALITY 2 I QUALITY 2 VD BS TUBER QUALITY 2 TOTAL CUT BC SCAB 3 MAT 4 9 89 87 90 92 80 85 92 89 82 94 86 80 86 86 79 88 89 86 67 86 80 83 89 85 90 84 83 70 78 71 80 75 56 8 8 10 9 8 15 14 5 10 18 2 9 20 13 12 19 12 11 14 31 12 19 15 9 14 7 15 16 30 22 26 17 23 43 6 70 66 81 71 52 76 67 67 79 46 55 78 82 61 69 82 83 78 66 82 75 81 77 78 65 82 74 70 73 66 76 68 56 27 19 20 10 21 28 8 25 22 3 49 32 2 5 25 9 6 5 8 1 3 6 1 13 8 25 2 9 0 5 5 4 7 0 1 4 3 0 0 5 1 3 1 1 3 5 0 0 3 2 0 0 1 2 3 0 2 2 0 3 1 1 0 0 2 2 1 0 1 0 8 0 2 1 1 0 4 1 2 0 1 0 1 1 0 0 4 0 1 2 0 0 1 1 0 0 0 1 0 2 1 0 0 0 0 4 1 0 0 0 0 2 1 2 2 0 1 1 0 2 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 4 0 0 0 1 0 0 0 0 2 0 0 0 0 0 2 0 0 0 4 1 0 0 0 0 0 1 1 0 0 0 40 40 40 40 40 40 40 30 40 30 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 0 3.0 2.0 3.5 3.5 3.5 2.0 1.5 1.0 3.0 4.5 2.0 2.0 3.0 1.5 3.0 1.5 1.0 4.0 3.0 1.5 3.0 3.0 1.5 1.0 3.0 1.5 3.0 2.5 3.5 2.5 1.5 2.5 4.0 5.0 5.0 4.8 3.3 3.8 4.5 3.8 2.3 4.0 4.8 4.3 3.8 3.4 3.5 3.0 3.3 3.3 1.3 1.3 3.5 2.3 3.5 1.5 2.3 1.5 3.0 1.8 1.8 1.8 2.3 1.5 3.0 1.0 empty table cell1.0 2.0 - 3.0 1.5 2.0 - - - 2.0 1.5 0 19 1 14 28 11 0 1 1 0 0 3 0 0 0 3 1 0 3 1 0 0 1 4 0 1 1 0 0 3 3 0 5 0 1.088 1.084 1.083 1.093 1.083 1.078 1.068 1.072 1.078 1.084 1.075 - 1.068 1.077 1.082 1.068 1.081 1.084 1.076 1.083 1.090 1.080 1.085 1.073 1.071 1.074 1.078 1.083 1.077 1.079 1.080 1.077 1.078 1.071 1.077 1.079 empty table cell 0.004 empty table cell - - 1.5 - 1.5 2.0 - 1.5 1.5 - - 1.5 1.5 - - 1.0 1.5 1.5 1.0 - - - 1.0 empty table cellempty table cell empty table cellempty 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 cell2.9 empty table cell empty table cell 2 QUALITY HH - HOLLOW HEART BC - BROWN CENTER VD - VASCULAR DISCOLORATION IBS - INTERNAL BROWN SPOT 4 Maturity 1 - EARLY 5 - LATE Table 2 empty table cell CWT/A TOTAL CWT/A US#1 F349-1Y F373-8 F020-23 ATLANTIC ONAWAY F059-1 SNOWDEN F002-01 F019-2 F100-1 F165-6RY E228-1 F019-11 F001-02 E026-A F023-4 E217-B F060-6 F376-1 F205-5 F017-3 F015-1 E192-8 RUS F087-3 F099-3 F014-9 F093-7 MEAN LSD 0.05 463 447 391 389 387 386 374 359 349 344 343 341 336 317 317 313 310 294 292 285 285 270 263 257 253 249 224 327 89 504 468 517 432 438 417 430 397 387 400 383 372 416 368 360 373 347 321 327 324 305 316 340 372 282 295 305 378 92 MSU BREEDING LINE EVALUATION MONTCALM RESEARCH FARM SEPTEMBER 9, 1996 (125 DAYS) PERCENT OF TOTAL 1 PERCENT OF TOTAL 1 As PERCENT OF TOTAL 1 Bs US#1 TUBER TUBER TUBE R QUALITY 2 QUALITY 2 QUALITY 2 PERCENT OF TOTAL 1 OV PERCENT OF TOTAL 1 IBS TUBER QUALITY 2 VD PO SP GR SFA HH TOTAL CUT PARENTS BC - 92 95 76 90 88 92 87 90 90 86 89 92 81 86 88 84 89 92 89 88 93 85 77 69 90 84 74 8 2 24 7 8 7 13 8 10 14 8 8 19 14 12 15 11 8 9 9 7 15 21 29 10 15 25 74 42 65 69 68 41 83 70 74 84 82 82 75 84 77 68 74 54 63 70 65 72 62 65 87 82 69 18 53 11 21 20 52 4 20 16 2 7 9 6 2 10 16 16 37 26 18 29 13 16 4 2 2 5 0 3 0 3 3 1 0 1 0 0 2 1 0 0 0 1 0 0 2 3 0 0 2 2 0 1 2 1.084 1.076 1.079 1.088 1.067 - 1.075 1.087 1.074 - 1.080 1.083 1.077 1.077 1.083 1.082 1.083 1.091 1.091 1.081 1.081 1.076 1.070 1.097 1.064 1.087 1.087 1.072 - 1.077 1.5 1.5 1.5 - 1 2 2 - - 3 2 - 1 1 2 - - 2 1.0 - - 1.5 - 0 2 0 12 0 0 0 1 3 1 0 0 5 6 0 13 3 2 11 0 0 2 1 0 1 0 5 0 0 0 0 0 0 3 0 0 0 1 0 0 0 2 0 0 2 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 0 0 1 0 0 0 0 0 0 0 2 0 1 0 1 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 RG X W887 E57-13 X W870 - - STB X CHALEUR - ATL X CHALEUR E57-13 X LR SND X LR SUP X RG RN X SP E57-13 X LR ATL X CHIPETA 20 20 MS702-80 X NY88 20 20 20 20 20 20 20 20 20 20 20 20 20 MN13740 X SP 20 20 20 20 20 20 20 20 20 20 20 20 LR X W877 SUP X S465 STB X 702-80 PREST. X W877 STB X W952 E55-44 x LR Pike x W877 A- X R. NORK PIKE X LR SND X CHALEUR PIKE X 702-80 E55-44 X ND860- empty table cellempty table cell empty table cellempty table cell empty table cell empty table cell empty table cell empty table cell empty table cell empty table cell 1.080 empty table cell 0.006 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 MAT 3 5.5 4.5 3.5 4.0 1.5 5.0 4.0 4.5 3.0 4.0 2.0 5.0 1.5 2.0 3.0 5.0 1.5 5.0 4.0 2.0 2.0 4.5 3.0 4.0 4.5 2.0 1.0 3.4 empty table cell 1 SIZE B - < 2” A - 2-3.25” OV - > 3.25” PO - PICKOUTS 2 Quality HH- HOLLOW HEART BC - BROWN CENTER VD - VASCULAR DISCOLORATION IBS - INTERNAL BROWN SPOT 3 MATURITY 1 - EARLY 5 - LATE PLANTED MAY 7, 1996 Funding Fed. Grant/MPIC 1996 POTATO VARIETY EVALUATIONS D.S. Douches, R.W. Chase, K. Jastrzebski, R. Hanunerschmidt, W. Kirk, C. Long, K. Walters and J. Coombs Departments of Crop and Soil Sciences and Botany and Plant Pathology Michigan State University East Lansing, MI 48824 The objectives of the evaluations are to identify superior varieties for fresh market or for processing and to develop recommendations for the growing of those varieties. The varieties were compared in groups according to the tuber type and skin color and to the advancement in selection. Each season, total and marketable yields, specific gravity, tuber appearance, incidence of external and internal defects, chip color (from field, 45 and 50 F storage), dormancy (at 50F), as well as susceptibilities to common scab, Fusarium dry rot, Erwinia soft rot and blackspot bruising are determined. We are now in the process of integrating late blight resistance testing into the evaluation procedure. Six field experiments were conducted at the Montcalm Research Farm in Entrican, MI. They were planted in randomized complete block design with four replications. The plots were 23 feet long and spacing between plants was 12 inches. Inter-row spacing was 34 inches. Supplemental irrigation was applied as needed. Both round and long variety groups were harvested at two dates. They are referred to as the Date-of-Harvest trials. The other two field experiments were the North Central Regional and European trials. In each of these trials the yield was graded into four size classes, incidence of external and internal defects in > 3.25 in. diameter or 10 oz. potatoes were recorded, and samples for specific gravity, chipping, dormancy, disease tests, bruising and cooking tests were taken. Chip quality was assessed on 25-tuber samples, taking two slices from each tuber. Chips were fried at 365°F. The color was measured visually with the SFA 1-5 color chart. Tuber samples were also stored at 45 or 50°F for chip-processing out of storage in January and March. A. Round White Varieties Results Seven varieties and 13 breeding lines were compared at two harvest dates. Atlantic, Snowden and Onaway were used as checks. The average yield as well as specific gravity levels were typical. The results are presented in Tables 1 and 2. In the early harvest trial (94 days), AF1470-17 (Quaggy Joe), NY101, Onaway and Atlantic had the highest yields of the 20 entries. At the later harvest (140 days), AF1470-17 and NY101 were still the top yielders. The MSU advanced seedling, MSB107-1 was third highest at 450 cwt/A, 52% higher than at the early harvest. Internal defects within the trial were variable, however vascular discoloration was more prevalent than in previous years. Variety Characteristics Mainestay (AF1060-2) - late, fresh market variety of high yield potential and excellent internal quality, but low specific gravity. It is susceptible to scab. Mainestay performed above average in the trials but has shown higher yield potential in some on-farm trials, but may have sticky stolons at harvest. St. Johns - medium-late fresh-market variety of above average yield potential, but low specific gravity. There was some variation in shape, but general appearance was good with large tubers and excellent internal quality. It is susceptible to scab infection. MSB076-2 - this MSU selection has high yield potential, has very high specific gravity, acceptable chip quality and resistant to scab. It is between Atlantic and Snowden in maturity and we observed, in some instances, a tendency for hollow heart in oversize tubers. It has a large and upright vine type. NorValley (ND2417-6) - a cold-chipping selection with above average yield potential, but moderate specific gravity. It has performed well in regional trials, but it is susceptible to scab. NY103 - a chip-processing/fresh market selection from New York which has high yield potential, excellent internal quality and smooth, bright appearance, but the specific gravity may be too low for chip-processing. NY103 is equivalent to Atlantic for scab reaction. This selection has had excellent yield potential in on-farm trials. NY101 - a light-yellow-fleshed selection from New York. This line has an excellent shape, with netted tubers and very high yield potential. It is resistant to scab. In general, internal defects are low, but in 1995 we observed IBS in the oversize tubers. Pike (E55-35) - an average yielding selection from New York. It chip-processes well and is resistant to scab similar to Superior. At times it has shown IBS in the tubers. MSB083-1 - an MSU selection with a bright round appearance. This selection is in grower trials and its performance has been variable. IBS was noted in the oversize tubers for the first time. MSB107-1 - an MSU selection for the tablestock market. It is a bright-skinned with large, round tubers with excellent internal quality. This selection performed well in grower trials in 1996. MSA091-1 - an MSU selection for chip-processing. Yields have been variable, but it has some scab resistance. Quaggy Joe (AF1470-17) - a high yielding tablestock selection from Maine. It produces large tubers, but is highly susceptible to scab. Brown centers were observed in the oversize tubers in 1996. NY111 - a New York selection with chip-processing potential. It had average yield and equivalent to Atlantic in scab susceptibility. B. Long Varieties Five varieties and eight breeding lines were tested. Russet Burbank, Shepody and Goldrush were grown as check varieties. The first date-of-harvest trial was dug 107 days from planting rather than 94 days to give the trial greater time to bulk. Most of the entries in the long-type trial were late maturing resulting in low yields and small tuber size at the first date-of-harvest (Table 3). At the second harvest on September 23 (140 days), yields for all entries had increased substantially (Table 4). Yield and specific gravity values were higher than 1995. Within the 13 long-type entries, Century Russet and A7961-1 produced the highest yields at 107 days. Most of these entries have a late maturity, so tuber sizing is generally small. At the later harvest (140 days), Century Russet, JS111-28, Shepody and Russet Burbank produced yields greater than 300 cwt/A. Hollow heart was the most significant internal defect and was greatest in MSB106-8 and C082142-4. Variety Characteristics Century Russet - a russet variety from Oregon with high yield potential. It has excellent internal quality and bulks early despite a late vine maturity. It is susceptible to scab. JS111-28 - provided by J.R. Simplot. JS111-28 has high yield potential with good general appearance, good russeting and shallow eyes. It is a somaclonal derivative of Lemhi Russet selected for lower incidence of blackspot bruise. It is also highly scab resistant. A7961-1 - is an USDA-Aberdeen entry with above average yield. It has uniform appearance, heavier russeting than Russet Burbank and minimal internal defects. It can be used for frozen- processing. AO82611-7 - this selection was below average in 1996. It is reported to have some resistance to early dying. Tuber shape is long but tuber width is narrow. Many pickouts were observed in 1996. Legend (COO83008-1) - is an Oregon selection from the Colorado breeding program. Yields were below average in 1995 and 1996. The tubers were well shaped with good type. Newleaf Russet Burbank - a variety from NatureMark which expresses the Bt gene for beetle control. Yield was below average this year despite good vine growth. C. North Central Regional Trial The North Central Trial is conducted in a wide range of environments, in 9 states to provide adaptability data for the release of new varieties from North Dakota, Minnesota, Wisconsin, and Michigan. Ten breeding lines and seven varieties were tested in Michigan. The results are presented in Table 5. The range of yields were wide. The MSU selections, MSB076-2 and MSB106-7, performed well. W1313, a Wisconsin seedling, had the highest yield but had almost one-third of its oversize tubers with hollow heart. The Minnesota selection, MN16489, had a high overall merit in the trial, but it has a blush skin which may limit its marketablity. The North Dakota seedling, ND2676-10, has a nice appearance, some possible scab resistance and a good chip score, but it had a below average yield and a specific gravity under the industry standards. D. European Trial Fourteen European varieties and advanced selections were tested along with three yellow- fleshed MSU seedlings. Yukon Gold, Michigold and Saginaw Gold were used as checks. The results are summarized in Table 6. Most of the European selections and varieties were late to very-late in maturity and many of these lines produced a small percentage of oversize tubers. Picasso, Latona, Morning Gold and Lily had yields over 500 cwt/A of US No. 1 potatoes. Erntestolz, SW88-112, SW88-113 and MSA097-1Y were the entries which exceeded 400 cwt/A. Internal defects were not serious except for 32% hollow heart in the oversize tubers of Morning Gold. The rose-skinned, yellow-fleshed selection from MSU, Julianna Rose (MSD040-4RY), has excellent eating quality and may fit well in a roadside stand or specialty market. Many of the European entries are oval to oblong in shape and flesh colors off-white to yellow. E. Post-harvest Disease Evaluation: Fusarium Dry Rot and Erwinia Soft Rot As part of the postharvest evaluation, resistance to Fusarium sambucinum (fusarium dry rot) was assessed by inoculating 10 whole tubers post-harvest from each line in the variety trials. The tubers were held at 20°C for approximately three weeks and then scored for disease incidence and severity of the dry rot infection. In the first round of testing 55 out of 150 entries showed little to no infection. Many of these lines were diploid selections from the germplasm enhancement program. These lines with little infection will be retested to discriminate resistant lines from escapes. Erwinia soft rot tests were conducted on tuber slices this fall. Most selections from the trials were tested along with somatic fusion hybrids from Dr. J. Helgeson which were noted to have some resistance to soft rot. All lines tested in 1996 had moderate to heavy levels of soft rot. Moderate rot levels were observed in 22 of the 150 lines. These lines will be retested. G. Potato Scab Evaluation Each year a replicated field trial at the MSU Soils Farm is conducted to assess resistance to common and pitted scab. The varieties are ranked on a 1-5 scale based upon a combined score for scab coverage and lesion severity. Usually examining one year’s data does not indicate which varieties are resistant but it should begin to identify ones that can be classified as susceptible to scab. Our goal is to evaluate important advanced selections and varieties in the study at least three years to obtain a valid estimate of the level of resistance in each line. We now have had three years of good trials (i.e. high levels of infection in susceptible lines). Table 7 summarizes the 1994-6 scab trial results for the lines in these trials. Many russet lines showed resistance to scab infection with Century Russet an exception to this trend. The MSU lines, MSE192-8Rus and MSE202-3Rus, showed some resistance to scab in 1996. Some round white tablestock clones have resistance such as Superior, Onaway, Prestile, MSB040-3, and MSE221-1. Yellow-fleshed selections with resistance are NY101, MSE048-2y and MSA097-1y. Scab resistance was also identified in the chip-processing clones Pike and MSU selections MSB076-2, MSA091-1, MSB073-2, and MSNT-1. G. Blackspot Susceptibility Increased evaluations of advanced seedlings and new varieties for their susceptibility to blackspot bruising has been implemented in the variety evaluation program. Check samples of 25 tubers were collected (a composite of 4 reps) from each cultivar at the time of grading. A second 25 tuber sample was similarly collected and was placed in a hexagon plywood drum and tumbled 10 times to provide a simulated bruise. Both samples were peeled in an abrasive peeler in October and individual tubers were assessed for the number of blackspot bruises on each potato. These data are shown in Table 8. Section A summarizes the data for the samples receiving the simulated bruise and Section B, the check samples. The bruise data are represented in two ways: percentage of bruise free potatoes and average number of bruises per tuber. A high percentage of bruise-free potatoes is the desired goal; however, the numbers of blackspot bruises per potato is also important. Cultivars which show blackspot incidence of 3 or more spots per tuber from the simulated bruise are approaching the bruise-susceptible rating. In addition, the data is grouped by trial, since the bruise levels can vary between trials. These results become more meaningful when evaluated over 3 years which reflects different growing seasons and harvest conditions. Bruising was more severe in 1996 than in 1995. H. Late Blight Trial In 1996 a late blight trial was conducted at the MSU Soils Farm in East Lansing. Over 150 entries were evaluated in replicated plots. The field was inoculated on July 30 and ratings were taken during August and September. Most lines were highly susceptible to the US-8 genotype of late blight. Lines with the least infection were AWN86514-1, B0767-2, B0718-3 and Zarevo. Lines that showed slower infection spread were Libertas, Pimpernel, Hampton, Island Sunshine, Lily, Matilda, MSA091-1, MSB110-3, Ontario and Picasso. Table 1 empty table cell AF1470-17 NY101 ONAWAY ATLANTIC NY103 NY111 ST. JOHNS MSB076-2 MAINESTAY AF1426-1 FL1833 MSB107-1 FL1863 FL1867 MSA091-1 MSB083-1 PIKE SNOWDEN ND2417-6 FL1887 MEAN LSD 0.05 ROUND WHITES: EARLY HARVEST MONTCALM RESEARCH FARM AUGUST 8, 1996 (94 DAYS) CWT/A US#1 CWT/A TOTAL PERCENT OF TOTAL 1 US#1 PERCENT OF TOTAL 1 Bs PERCENT OF TOTAL 1 As TUBER TUBER TUBE R QUALITY QUALITY 2 QUALITY 2 2 VD OV PERCENT OF TOTAL 1 PERCENT OF TOTAL 1 IBS TUBER QUALITY 2 HH TOTAL CUT PO SP GR 3-YR AVE BC - 335 314 296 266 253 247 241 240 240 236 228 217 216 215 203 202 192 178 172 137 231 48 388 360 330 310 288 308 286 281 309 288 261 239 243 272 244 272 238 234 263 167 279 50 86 87 90 86 88 80 84 85 78 82 88 91 89 79 83 74 81 76 65 82 13 13 10 13 12 20 15 14 22 5 12 8 11 21 17 25 19 23 34 17 74 86 84 81 82 80 84 84 76 69 81 84 77 78 81 74 78 73 65 80 12 2 6 5 6 0 0 2 2 13 7 7 12 1 2 1 3 3 0 2 1 0 1 1 0 0 1 1 0 13 0 1 0 0 0 1 1 1 1 1 1.063 1.069 1.070 1.085 1.071 1.084 1.066 1.076 1.073 1.072 1.081 1.069 1.078 1.090 1.081 1.075 1.082 1.085 1.075 1.070 0 0 0 8 2 3 0 1 0 0 3 3 0 7 0 0 2 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 4 0 0 2 0 1 39 31 40 40 40 40 40 40 40 40 40 40 40 40 40 31 40 40 40 40 339* 281 280 311* - 286 261* 282 312* 267 200* 274* - - 199* 207* 212* 252 - empty table cell empty table cellempty table cell empty table cell empty table cellempty table cell empty table cell empty table cell empty table cell empty table cell 1.076 empty table cell 0.006 empty table cell empty table cell empty table cell empty table cell empty table cell empty table cell empty table cell empty table cellempty table cell empty table cellempty table cell 1 SIZE B - < 2” A - 2-3.25” OV- >3.25" PO - PICKOUTS * - two-year US # 1 average PLANTED MAY 6, 1996 2 QUALITY HH - HOLLOW HEART BC - BROWN CENTER VD - VASCULAR DISCOLORATION IBS - INTERNAL BROWN SPOT Table 2 CWT/A CWT/A TOTAL 517 495 462 429 438 420 473 415 417 405 403 432 409 407 375 349 357 344 387 310 412 53 empty table cell US#1 463 463 450 405 403 399 397 384 374 367 367 366 357 340 339 335 317 305 300 261 370 55 AF1470-17 NY101 MSB107-1 FL1887 ATLANTIC FL1833 MAINESTAY NY103 NYI11 ST. JOHNS MSB076-2 MSB083-1 SNOWDEN AF1426-1 ONAWAY FL1863 MSA091-1 PIKE ND2417-6 FL1867 MEAN LSD 0.05 1 SIZE B - < 2" A - 2-3.25" OV- > 3.25" PO - PICKOUTS 3 SCAB Rating 1996 from Scab Trial 1 - NO INFECTION 3 - INTERMEDIATE 5 - HIGHLY SUSCEPTABLE * - two-year US #1 average PLANTED MAY 6, 1996 ROUND WHITES: LATE HARVEST MONTCALM RESEARCH FARM SEPTEMBER 23, 1996 (140 DAYS) PERCENT OF TOTAL 1 PERCENT OF TOTAL 1 US#1 90 93 97 94 92 95 84 93 90 91 91 85 87 84 90 96 89 89 78 84 Bs 10 6 2 4 6 4 14 7 10 9 8 15 12 5 9 4 9 11 22 16 PERCENT OF TOTAL 1 As 73 70 50 46 61 73 73 71 82 76 82 81 79 50 77 75 73 82 74 80 TUBER TUBER TUBE R QUALITY 2 QUALITY 2 QUALITY 2 OV PERCENT OF TOTAL 1 PERCENT OF TOTAL 1 PO SP GR SFA HH IBS TUBER QUALITY 2 VD TOTAL CUT BC SCAB 3 MAT 3 - 17 23 47 49 31 22 11 21 8 15 9 4 9 34 14 21 16 7 4 4 1 1 1 2 1 0 2 0 0 0 1 0 1 11 1 0 2 0 1 0 1.062 1.070 1.076 1.080 1.086 1.084 1.074 1.069 1.083 1.069 1.086 1.077 1.082 1.071 1.065 1.081 1.081 1.086 1.074 1.086 1.5 - 1.0 1.5 1.0 - 1.5 1.0 - 1.5 1.5 1.0 - - 1.0 1.5 1.0 1.5 1.0 1 0 1 0 10 9 0 0 6 0 2 0 2 0 0 1 0 1 0 4 1 1 3 14 0 2 1 2 2 6 1 9 11 9 1 1 5 1 1 0 1 4 1 7 2 2 0 0 1 0 0 0 0 0 0 2 2 9 0 0 11 0 0 0 0 0 0 0 0 0 0 1 0 2 0 0 0 0 0 0 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 4.0 1.0 2.5 3.0 3.5 1.5 4.5 3.0 3.0 4.0 1.5 3.0 3.0 1.0 1.5 2.0 1.0 1.5 3.5 2.0 1.8 3.5 4.0 4.5 3.3 3.1 2.0 1.6 2.0 2.5 2.5 3.3 2.8 2.8 1.0 2.5 3.1 3.3 1.5 1.6 3-YR AVE 459* 534* 386* - 437 429 438 454* - 401 395 382* 396 370* 359 401* - 308 370 - Empty table cellEmpty table cellEmpty table cell Empty table cellEmpty table cellEmpty table cell Empty table cell Empty table cell Empty table cell Empty table cell 1.077 Empty table cell 0.002 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 cell2.6 Empty table cell Empty table cell0.6 Empty table cell 2 QUALITY HH - HOLLOW HEART BC - BROWN CENTER VD - VASCULAR DISCOLORATION IBS - INTERNAL BROWN SPOT 4 MATURITY 1 - EARLY 5 - LATE LONG TYPES: EARLY HARVEST MONTCALM RESEARCH FARM AUGUST 21, 1996 (107 DAYS) CWT/A PERCENT OF TOTAL 1 CWT/A US#1 TOTAL US#1 PERCENT OF TOTAL PERCENT OF TOTAL 1 As TUBE R QUALITY 2 PERCENT OF TOTAL 1 OV PERCENT OF TOTAL 1 HH PO SP GR TUBER TUBE R QUALITY 2 QUALITY 2 IBS TUBER QUALITY 2 VD TOTAL BC CUT 3-YR AVE Table 3 Empty table cell 491 414 437 370 348 333 390 281 253 260 244 294 139 327 90 CENTURY RU 377 330 A7961-1 A082611-7 288 284 JS111-28 SHEPODY 280 267 GOLDRUSH 261 R. BURBANK 220 C0083008-1 209 C082142-4 A84118-3 188 187 MSB106-8 164 NEWLEAF C081082-1 81 241 80 MEAN LSD 0.05 1 SIZE B - < 4 oz. A - 4 - 10 oz. OV - > 10 oz. PO - PICKOUTS * - two-year US #1 average PLANTED MAY 6, 1996 Bs 23 16 19 18 13 19 31 19 16 24 20 41 39 77 80 66 77 80 80 67 78 82 72 77 56 59 66 56 45 58 44 62 59 67 57 58 49 53 53 11 24 21 19 37 18 8 11 26 14 28 3 5 0 5 15 5 7 1 2 2 2 3 3 3 3 1.072 1.071 1.073 1.072 1.069 1.065 1.073 1.074 1.068 1.073 1.073 1.069 1.065 1 0 3 4 5 0 0 1 7 10 15 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1 0 0 0 0 0 0 0 0 1 0 1 2 0 0 0 1 0 40 40 40 40 40 40 40 40 40 40 40 40 30 253* 212 217 221* 238* 201 170 168 - 118* - - - Empty table cellEmpty table cellEmpty table cellEmpty table cell Empty table cellEmpty table cellEmpty table cellEmpty table cell Empty table cell Empty table cell 1.071 Empty table cell 0.003 Empty table cell Empty table cell Empty table cell Empty table cell Empty table cell Empty table cell Empty table cell Empty table cellEmpty table cell Empty table cellEmpty table cell 2 QUALITY HH - HOLLOW HEART BC - BROWN CENTER VD - VASCULAR DISCOLORATION IBS - INTERNAL BROWN SPOT Table 4 Empty table cell Cwt/a CWT/A TOTAL US#1 PERCENT OF TOTAL 1 US#1 LONG TYPES: LATE HARVEST MONTCALM RESEARCH FARM SEPTEMBER 23, 1996 (140 DAYS) PERCENT OF TOTAL 1 PERCENT OF TOTAL 1 As TUBER TUBE TUBER R QUALITY 2 QUALITY 2 QUALITY 2 IBS TUBER QUALITY 2 HH VD OV PERCENT OF TOTAL 1 PERCENT OF TOTAL 1 TOTAL CUT PO SP GR BC SCAB 3 MAT 4 3-YR AVE 375* 376* 311* 256 323 285* - 274* 215* 300 244 - - Empty table cell Empty table cell Bs 16 13 8 25 18 11 9 16 15 14 13 36 30 82 75 86 70 81 87 90 81 80 64 87 60 64 55 44 36 56 56 52 51 58 49 40 68 48 50 27 31 50 15 25 35 39 23 31 24 19 12 14 2 12 6 5 1 2 1 2 5 23 1 4 7 1.079 1.077 1.074 1.078 1.077 1.081 1.076 1.068 1.084 1.078 1.078 1.072 1.067 1 3 7 8 0 19 12 0 9 2 1 0 1 0 0 1 4 0 0 1 0 5 1 0 1 0 0 0 0 2 0 0 1 0 0 1 0 1 0 0 0 0 0 0 0 0 0 0 0 1 1 0 40 40 40 40 40 40 40 40 40 40 40 40 30 3.5 1.0 4.0 1.0 1.0 - 4.0 1.0 1.0 1.0 1.0 1.0 3.0 4.4 2.9 2.5 2.5 2.1 3.8 4.0 2.0 4.0 3.8 3.6 2.3 1.0 Empty table cellEmpty table cellEmpty table cell Empty table cellEmpty table cellEmpty table cell Empty table cell Empty table cell Empty table cell Empty table cell 1.076 Empty table cell 0.002 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 cell3.0 Empty table cell0.5 2 QUALITY HH - HOLLOW HEART BC - BROWN CENTER VD - VASCULAR DISCOLORATION IBS - INTERNAL BROWN SPOT 4 Maturity 1 - EARLY 5 - LATE 498 436 361 428 370 334 316 349 337 411 294 345 139 355 67 409 326 309 302 298 289 284 284 270 262 255 208 88 276 61 CENTURY RU JS111-28 SHEPODY R. BURBANK A7961-1 MSB106-8 C082142-4 GOLDRUSH A84118-3 A082611-7 C0083008-1 NEWLEAF C081082-1 MEAN LSD 0.05 1 SIZE B - < 4 oz. A - 4 - 10 oz. OV- > 10 oz. PO - PICKOUTS 3 SCAB Rating 1996 from Scab Trial 1 - NO INFECTION 3 - INTERMEDIATE 5 - HIGHLY SUSCEPTABLE * - two-year US #1 average PLANTED MAY 6, 1996 NORTH CENTRAL REGIONAL TRIAL MONTCALM RESEARCH FARM SEPTEMBER 16, 1996 (132 DAYS) CWT/A CWT/A TOTAL US#1 PERCENT OF TOTAL 1 US#1 PERCENT OF TOTAL 1 PERCENT OF TOTAL 1 As Table 5 Empty table cell W1313 MSB106-7 MSB076-2 RED PONTIAC ATLANTIC MN16489 NORLAND W1242 MSB007-1 R.BURBANK SNOWDEN ND2676-10 NORCHIP ND2225-1R W1151RUS MN16180 RNORKOTAH MEAN LSD 0.05 1 SIZE B - < 2" A - 2-3.25" OV - > 3.25" PO - PICKOUTS 457 424 389 374 345 313 313 299 296 280 277 273 271 250 228 228 149 304 82 496 505 459 415 387 361 352 330 345 401 330 329 334 334 286 340 235 367 81 3 SCAB Rating 1996 from Scab Trial 1 - NO INFECTION 3 - INTERMEDIATE 5 - HIGHLY SUSCEPTABLE * - two-year US # 1 average PLANTED MAY 7, 1996 Bs 6 14 13 6 8 12 9 8 13 18 12 16 18 24 20 32 35 92 84 85 90 89 87 89 91 86 70 84 83 81 75 80 67 63 TUBER TUBE TUBE R QUALITY 2 QUALITY 2 R QUALITY 2 IBS TUBER QUALITY 2 VD HH PERCENT OF TOTAL 1 OV PERCENT OF TOTAL 1 PO SP GR SFA TOTAL CUT BC SCAB 3 MAT 4 MERIT RATING 69 65 81 47 73 82 83 80 74 53 73 79 77 74 60 65 58 23 19 4 43 16 5 6 10 12 16 11 4 4 1 19 2 5 2 2 2 4 2 1 2 2 1 13 5 1 1 1 0 1 2 1.095 1.071 1.094 1.064 1.092 1.075 1.063 1.085 1.070 1.082 1.086 1.076 1.077 1.065 1.065 1.072 1.070 1.5 3.0 1.5 4.0 1.5 1.5 3.5 1.5 2.5 3.5 1.5 1.5 1.5 3.0 3.0 2.0 3.5 13 0 3 9 20 0 2 14 0 12 1 1 1 0 0 6 2 1 1 0 1 0 0 0 0 0 0 2 1 2 1 0 0 0 0 2 0 0 3 0 2 0 0 3 0 1 1 1 0 2 1 2 0 0 0 1 0 0 1 0 0 0 3 0 0 0 2 0 40 40 40 40 40 40 40 30 40 40 30 30 40 40 30 40 40 2.5 3.0 1.5 4.0 3.5 2.0 2.0 3.0 4.0 1.0 3.0 1.5 3.0 2.0 1.5 3.0 - 2 3 5 4 1 4.0 2.8 3.0 3.8 Empty table cell 3.5 Empty table cell 2.0 1.3 4.0 Empty table cell 3.8 Empty table cell 4.3 Empty table cell 3.0 Empty table cell 3.0 Empty table cell 3.0 Empty table cell 1.8 Empty table cell 3.8 Empty table cell 2.0 Empty table cell 1.5 Empty table cell Empty table cellEmpty table cell Empty table cellEmpty table cell Empty table cell Empty table cell Empty table cell Empty table cell Empty table cell Empty table cell 1.077 Empty table cell 0.002 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 cell3.0 Empty table cell Empty table cell Empty table cell Empty table cell 2 QUALITY HH - HOLLOW HEART BC - BROWN CENTER VD - VASCULAR DISCOLORATION IBS - INTERNAL BROWN SPOT 4 MATURITY 1 - EARLY 5 - LATE EUROPEAN TRIAL MONTCALM RESEARCH FARM SEPTEMBER 19, 1996 (136 DAYS) CWT/A PERCENT OF TOTAL 1 US#1 CWT/A TOTAL US#1 PERCENT OF TOTAL 1 PERCENT OF TOTAL 1 As TUBE R QUALITY 2 PERCENT OF TOTAL 1 OV PERCENT OF TOTAL 1 PO SP GR SFA HH TUBER QUALITY 2 VD TUBE R QUALITY 2 IBS TUBER QUALITY 2 TOTAL CUT BC SCAB 3 MAT 4 Bs 6 16 10 14 10 14 14 7 26 23 29 21 11 20 10 26 18 21 18 25 92 82 88 84 90 85 86 93 72 76 68 77 87 77 89 72 81 78 81 75 586 541 528 528 485 453 432 412 379 377 372 360 341 331 330 312 269 245 230 212 386 81 636 658 599 629 540 531 503 442 523 497 545 465 392 432 372 436 331 312 282 283 470 80 59 78 74 74 78 82 72 73 71 75 65 74 81 76 74 70 74 78 79 73 33 4 14 10 12 3 13 20 2 1 3 3 6 0 15 1 7 0 2 2 2 2 2 2 0 1 1 0 2 1 3 2 2 3 1 3 0 0 1 0 1.065 1.075 1.071 - 1.070 1.067 1.086 1.066 1.072 1.081 1.072 1.069 1.068 1.071 1.080 1.076 1.076 1.074 1.072 1.074 1.084 3.5 - - 2.5 2.0 2.5 - - 2.5 2.5 1.5 1.5 3.0 2.0 2.5 - - - - 2 3 13 2 1 5 0 0 0 1 1 1 0 0 4 0 8 0 0 0 0 1 0 2 2 0 0 0 1 0 0 2 0 1 0 1 2 0 0 0 0 1 4 2 1 1 1 2 0 0 0 2 1 0 1 0 1 0 1 0 0 0 2 0 0 0 0 0 0 0 0 0 0 0 4 0 0 0 1 0 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 20 1.5 - - 4.5 3.5 - 2.0 2.0 2.0 4.0 2.0 4.0 2.5 5.0 2.0 3.5 4.0 3.0 4.5 4.0 3.8 4.3 3.3 4.5 2.8 3.5 3.0 2.3 4.0 3.0 4.4 1.8 1.8 3.0 1.0 2.0 2.0 1.0 3.8 1.8 MERIT RATING 2 Empty table cell 5 Empty table cell Empty table cell 1 3 4 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 Table 6 Empty table cell PICASSO LATONA MORNING GOLD LILI SW88-112 ERNTESTOLZ SW88-113 MSA097-1Y MATILDA AMINCA DIITA ROMINA SAGINAW GOLD FELSINA YUKON GOLD PREMIERE MICHIGOLD MSD029-3Y IS. SUNSHINE MSD040-4RY MEAN LSD 0.05 1 SIZE B - < 2” A - 2-3.25” OV- >3.25” PO - PICKOUTS Empty table cellEmpty table cell Empty table cellEmpty table cell Empty table cell Empty table cell Empty table cell Empty table cell Empty table cell Empty table cell 1.073 Empty table cell 0.010 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 2.8 Empty table cell 0.8 Empty table cell Empty table cell 2 QUALITY HH - HOLLOW HEART BC - BROWN CENTER VD - VASCULAR DISCOLORATION IBS - INTERNAL BROWN SPOT 4 maturity 1 - EARLY 5 - LATE 3 SCAB Rating 1996 from Scab Trial 1 - NO INFECTION 3 - INTERMEDIATE 5 - HIGHLY SUSCEPTABLE PLANTED MAY 7, 1996 Table 7A Ranking of Important Potato Varieties and Advanced Breeding Lines in Scab Trial (1994-1996) Low Infection A7961-1 GoldRush Legend (C0083008-1) MSA091-1 MSA097-1Y MSB076-2 MSE221-1 NY101(Y) Onaway Pike Prestile R. Burbank R. Norkotah Superior Intermediate Atlantic Century Russet FL1833 MSB106-7 MSB107-1 NY103 Portage St. Johns Yukon Gold Empty table cell Empty table cell Empty table cell Empty table cell Empty table cell Highly Susceptible Agria Mainestay MSB110-3 ND01496-1 NorValley Penta Quaggy Joe Ranger Russet Red Pontiac Shepody Empty table cell Empty table cell Empty table cell Empty table cell Table 7B 1994-96 MICHIGAN SCAB TRIAL RESULTS MSU Soils Farm Line A082611-7 A7961-1 A84118-3 A8495-1 AC PTARMIGAN AF1426-1 AF1433-4 AF1470-17 AF875-15 AGRIA Aminca ATLANTIC ATX 85404-8 B0717-1 B9922-11 BC0894-2 BRODICK C0008011-5 C0083008-1 C081082-1 C082142-4 CENTURY RUSSET CHALEUR DITTA ESTIMA FELSINA FL1533 FL1833 FL1863 FL1867 FL1887 GOLDRUSH HINDENBURG ISLAND SUNSHINE JS111-28 LEMHI RUSSET LILI MAINESTAY MATILDA MICHI GOLD MN15111 MN16180 MN16489 MS716-15 MSA091-1 MSA097-1Y MSB007-1 MSB027-1R MSB040-3 MSB057-2 MSB073-2 1994 Rating 1 2.5 1.0 - 1.5 1.5 - 1.0 4.0 2.0 3.5 - 2.5 - - 1.0 - 1.0 1.0 1.0 - - 2.5 1.5 - 4.0 - 2.5 3.0 - - - 1.5 - - - 1.0 - 4.0 - 2.0 1.5 - - 4.0 2.0 1.5 3.0 3.0 1.0 3.0 - - - 1995 Rating 1.0 1.0 1.5 1.0 1.5 1.5 - 4.0 - 3.5 - 3.0 1.0 1.0 - 1.0 1.0 - - - 3.0 - 4.0 - 3.0 2.0 3.0 - - 1.0 - 2.5 - 1.0 2.0 3.0 2.0 - - - - - 1.5 - 4.5 - - - - 1996 Rating 1.0 1.0 1.0 - - 1.0 3.0 4.0 4.0 - 4.0 3.5 3.0 - - 2.0 - - 1.0 3.0 4.0 3.5 - 2.0 - 5.0 - 1.5 2.0 2.0 3.0 1.0 1.0 4.5 1.0 - 4.5 4.5 2.0 4.0 - 3.0 2.0 - 1.0 2.0 4.0 4.0 1.0 3.0 1.5 Line MSB076-2 MSB083-1 MSB094-1 MSB095-2 MSB0952-1 MSB106-7 MSB106-8 MSB107-1 MSB110-3 MSB1254-1 MSC010-20Y MSC098-2 MSC103-2 MSC120-1Y MSC121-7 MSC122-1 MSC125-8 MSC126-6 MSC148-A MSD029-3Y MSD040-4RY MSE007-8 MSE011-25 MSE011-7 MSE018-1 MSE041-1 MSE048-1Y MSE048-2Y MSE149-5Y MSE192-8 MSE202-3 MSE220-3 MSE221-1 MSE222-5Y MSE222-8 MSE226-4Y MSE228-1 MSE228-3 MSE228-9 MSE228-11 MSE230-3 MSE230-6 MSE247-2 MSE250-2 MSE263-3 MSE273-8 MSNT-1 ND01496-1 ND2225-1R ND2417-6 ND2471-8 - - - - - - - - - - - - - - - - - - - - - - - - - - - 1995 Rating - - 1994 Rating 1.0 1.5 2.0 2.0 2.0 1.0 2.5 2.5 1.5 2.5 - 2.0 3.0 1.0 3.0 1.5 1.0 2.5 3.0 1996 Rating 1.5 3.0 3.0 - 2.5 3.0 - 2.5 4.5 4.0 2.0 3.5 2.0 2.5 4.0 1.5 2.0 1.0 2.5 3.0 4.0 - - 4.5 3.0 3.5 - 2.0 2.0 - 2.0 3.5 1.0 - - 1.5 - 1.0 1.5 3.0 - 1.5 1.5 - 3.5 3.0 1.0 - 2.0 3.5 5.0 1.5 2.5 - 3.0 - 1.0 2.5 3.0 1.5 - - - - - - - 2.5 - 2.0 1.0 2.0 1.5 3.5 3.0 2.0 1.5 - 1.0 - - 1.5 2.0 1.0 1.5 2.0 1.0 1.5 3.5 3.0 2.5 2.0 2.0 2.0 4.0 - 4.5 3.5 3.5 3.0 4.5 - 3.5 4.0 - Line R. NORKOTAH R. NUGGET RANGER R. RED GOLD RED NORLAND RED PONTIAC REDDALE ROMINA ROSE GOLD SAGINAW GOLD SANTE SHEPODY SNOWDEN ST. JOHNS SUPERIOR SW88-112 SW88-113 W1149 W1151 W1242 W1313 YUKON GOLD - - - 1994 Rating 1.5 - 4.0 4.5 2.0 5.0 - - 4.0 3.0 3.5 - 2.0 3.0 1.0 - 3.0 - - 1995 Rating - 1.0 - - - 2.5 - - - 3.0 3.0 4.5 3.5 3.0 1.5 - 3.0 3.5 - 3.0 - 3.5 1996 Rating - - - - 2.0 4.0 2.0 4.0 - 2.5 - 4.0 3.0 4.0 - 3.5 2.0 - 1.5 3.0 2.5 2.0 Table 7B, cont. Line ND2676-10 ND860-2 NDA2031-2 NEWLEAF-RB NORCHIP NY101 NY102 NY103 NY111 ONAWAY P84-13-12 P88-13-4 P88-15-1 P88-9-8 PEMBINA CHIPPER PENTA PICASSO PIKE PORTAGE PREMIER PRESTILE R. BURBANK 1994 Rating 1 - 3.5 3.0 - 1.5 1.5 2.0 - - 1.0 1.0 - 2.5 3.0 1.0 3.0 - - 3.5 - 1.0 2.0 - 1995 Rating - - 3.5 - 1.0 3.0 3.5 - 1.5 1.5 2.0 3.5 3.0 1.5 4.5 - 1.0 2.5 - 1.0 2.0 1996 Rating 1.5 3.0 - 1.0 3.0 1.0 - 3.0 3.0 1.5 3.0 - - - - - 1.5 1.5 - 3.5 - 1.0 1 SCAB RATING 1 = practically no infection 2 = low infection 3 = avg. susc. (i.e. Atlantic) 4 = susc. (high) 5 = severe susc. TABLE 8 1996 BLACKSPOT BRUISE SUSCEPTIBILITY SAMPLES A. SIMULATED BRUISE SAMPLES* VARIETY NUMBER OF SPOT PER TUBER NUMBER OF SPOT PER TUBER NUMBER OF SPOT PER TUBER 0 1 2 NUMBER OF SPOT PER TUBER 5+ AVE % NUMBER OF SPOT PER TUBER 4 BRUISE FREE TOTAL TUBER 3 NUMBER OF SPOT PER TUBER SPOTS/TUBE DATE OF HARVEST: LONG-LATE DATE OF HARVEST: LONG-LATE DATE OF HARVEST: LONG-LATE DATE OF HARVEST: LONG-LATE DATE OF HARVEST: LONG-LATE DATE OF HARVEST: LONG-LATE DATE OF HARVEST: LONG-LATE DATE OF HARVEST: LONG-LATE DATE OF HARVEST: LONG-LATEDATE OF HARVEST: LONG-LATE C0083008-1 CENTURY R C081082-1 NEWLEAF GOLDRUSH C082142-4 A7961-1 A84118-3 R. BURBANK JS111-28 SHEPODY A082611-7 MSB106-8 27 25 23 24 23 20 21 18 15 18 13 17 16 1 1 2 3 5 6 4 5 9 3 12 2 6 Empty table cellEmpty table cell Empty table cell Empty table cell Empty table cellEmpty table cell Empty table cellEmpty table cell Empty table cellEmpty table cell Empty table cellEmpty table cell Empty table cellEmpty table cell Empty table cell Empty table cell Empty table cell 1 Empty table cell 1 1 DATE OF HARVEST: ROUND WHITES-LATE 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 1 DATE OF HARVEST: ROUND WHITES-LATE 28 Empty table cell26 Empty table cell25 Empty table cell27 Empty table cell28 Empty table cell26 Empty table cell26 Empty table cell24 Empty table cell25 Empty table cell26 Empty table cell27 Empty table cell25 Empty table cell26 DATE OF HARVEST: ROUND WHITES-LATE 0.036 0.038 0.080 0.111 0.179 0.231 0.231 0.292 0.440 0.538 0.593 0.600 0.654 96 96 92 89 82 77 81 75 60 69 48 68 62 1 1 1 4 2 5 2 DATE OF HARVEST: ROUND WHITES-LATE DATE OF HARVEST: ROUND WHITES-LATE DATE OF HARVEST: ROUND WHITES-LATE DATE OF HARVEST: ROUND WHITES-LATE DATE OF HARVEST: ROUND WHITES-LATEDATE OF HARVEST: ROUND WHITES-LATEDATE OF HARVEST: ROUND WHITES-LATE Empty table cellEmpty table cell Empty table cell Empty table cell NY101 PIKE ST. JOHNS ONAWAY AF1426-1 AF1470-17 MSA091-1 FL1887 FL1867 NY111 NORVALLEY MAINESTAY SNOWDEN FL1833 MSB083-1 MSB107-1 ATLANTIC MSB076-2 NY103 FL1863 24 22 19 18 19 18 19 17 13 15 11 11 9 13 7 5 7 6 6 2 1 3 6 6 4 4 5 7 7 4 9 5 3 2 8 6 5 8 6 3 1 Empty table cell Empty table cellEmpty table cell Empty table cellEmpty table cell Empty table cell 1 Empty table cell Empty table cell 1 Empty table cell 1 1 2 2 4 2 3 6 4 5 Empty table cell Empty table cell Empty table cell Empty table cell Empty table cell 1 Empty table cell Empty table cell 1 Empty table cell 2 Empty table cell 1 Empty table cell 2 2 4 Empty table cell 5 25 Empty table cell26 Empty table cell25 Empty table cell24 Empty table cell24 Empty table cell24 Empty table cell26 Empty table cell26 Empty table cell24 Empty table cell25 Empty table cell24 Empty table cell25 Empty table cell25 2 24 Empty table cell25 Empty table cell22 1 22 Empty table cell27 3 25 7 25 1 1 1 2 3 5 3 6 11 4 6 7 4 3 6 3 96 85 76 75 79 75 73 65 54 60 46 44 36 54 28 23 32 22 24 8 0.040 0.192 0.240 0.250 0.250 0.375 0.423 0.423 0.667 0.720 0.750 1.120 1.240 1.250 1.280 1.545 1.591 1.778 1.800 3.160 * Tuber samples were collected al harvest, graded, and placed in a six-sided plywood drum and turned ten times to produce simulated bruising. Samples were abrasive-peeled and scored on October 28, 1996. NORTH CENTRAL REGIONAL TRIAL NORTH CENTRAL REGIONAL TRIAL NORTH CENTRAL REGIONAL TRIAL Empty table cell Empty table cell Empty table cell NORTH CENTRAL REGIONAL TRIAL NORTH CENTRAL REGIONAL TRIAL NORTH CENTRAL REGIONAL TRIAL NORTH CENTRAL REGIONAL TRIAL NORTH CENTRAL REGIONAL TRIAL NORTH CENTRAL REGIONAL TRIAL NORTH CENTRAL REGIONAL TRIAL NORLAND ND2225-1R R. PONTIAC W1151RUS ND2676-10 MN16489 R. NORKOTAH R. BURBANK W1242 NORCHIP MSB007-1 MN16180 SNOWDEN W1313 MSB076-2 ATLANTIC MSB106-7 EUROPEAN TRIAL YUKON GOLD ROMINA MICHIGOLD IS. SUNSHINE MSDO29-3Y FELSINA DITTA SW88-112 PICASSO SW88-113 MSA097-1Y AMINCA ERNTESTOLZ PREMIER MATILDA MORNING GOLD LATONA SAGINAW GOLD LILI JULIANNA ROSE 20 20 18 18 13 18 17 16 16 14 14 12 5 3 3 3 2 5 4 7 7 4 4 6 7 5 5 6 7 9 12 5 3 4 24 22 21 22 20 20 21 22 22 20 18 15 13 14 14 13 10 13 15 10 2 2 4 2 5 5 2 5 2 4 4 5 5 5 7 7 9 5 4 12 80 80 72 72 72 72 68 64 64 61 56 46 20 13 12 12 8 0.200 0.240 0.280 0.280 0.333 0.400 0.400 0.480 0.520 0.652 0.760 0.846 1.720 1.833 2.200 2.760 2.875 92 92 84 88 80 80 88 79 85 77 75 68 59 61 58 57 50 57 60 38 0.077 0.083 0.160 0.200 0.200 0.200 0.208 0.250 0.269 0.308 0.333 0.409 0.591 0.609 0.667 0.696 0.700 0.739 0.800 0.962 EUROPEAN TRIAL EUROPEAN TRIAL EUROPEAN TRIAL EUROPEAN TRIAL EUROPEAN TRIAL EUROPEAN TRIAL EUROPEAN TRIAL EUROPEAN TRIAL EUROPEAN TRIAL 1 1 3 2 1 4 2 3 6 4 1 1 2 2 2 4 3 2 2 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 1 2 1 1 4 Empty table cell5 2 3 8 8 5 2 Empty table cell 2 1 1 1 3 7 8 3 Empty table cell 25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell18 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell23 Empty table cell25 Empty table cell26 25 24 Empty table cell25 25 24 3 5 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 cell1 Empty table cell Empty table cell Empty table cell1 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 cell1 Empty table cell1 Empty table cell1 Empty table cell Empty table cell 26 Empty table cell24 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell24 Empty table cell28 Empty table cell26 Empty table cell26 Empty table cell24 Empty table cell22 Empty table cell22 Empty table cell23 24 23 20 Empty table cell23 Empty table cell25 Empty table cell26 1 2 Empty table cell Empty table cell Empty table cell Empty table cell Empty table cell 1 1 Empty table cell Empty table cell Empty table cell Empty table cell 2 2 1 3 3 1 MSU BREEDING LINES 2 X 23 TRIAL MSU BREEDING LINES 2 X 23 TRIALMSU BREEDING LINES 2 X 23 TRIAL MSU BREEDING LINES 2 X 23 TRIAL MSU BREEDING LINES 2 X 23 TRIAL MSU BREEDING LINES 2 X 23 TRIAL MSU BREEDING LINES 2 X 23 TRIAL MSU BREEDING LINES 2 X 23 TRIAL MSU BREEDING LINES 2 X 23 TRIAL MSU BREEDING LINES 2 X 23 TRIAL F014-9 E228-1 F096-8 E217-F F380-5 El 92-8 E026-A? F002-01 F085-3 F097-1 F020-23 F092-3 F194-3 F099-3 F001-02 F165-6RY F059-1 F373-8 F349-1 F090-9 F326-1 F087-3 F023-4 F205-5 F382-2 F019-2 E217-D E217-B F019-11 SNOWDEN F015-1 ATLANTIC F060-6 F017-3 F026-7 F100-1 F093-7 F093-6 F012-5 19 19 19 17 19 16 15 15 8 15 13 13 15 13 13 15 13 12 8 11 9 8 9 6 6 9 7 6 7 3 4 5 3 6 2 3 2 2 2 1 1 1 1 2 3 4 4 1 3 6 6 1 5 4 2 3 2 6 5 6 5 6 9 7 4 5 5 3 5 6 2 4 1 5 4 3 3 4 2 2 5 1 2 4 3 3 4 3 7 5 4 2 4 4 3 2 Empty table cell2 1 0 1 1 2 2 1 3 1 2 1 3 2 2 2 2 4 5 2 4 2 3 8 2 Empty table cell Empty table cell Empty table cell Empty table cell Empty table cell Empty table cell Empty table cell 1 1 1 1 1 1 1 2 2 4 1 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 Empty table cell Empty table cell Empty table cell Empty table cell Empty table cell Empty table cell2 Empty table cell1 Empty table cell3 1 1 Empty table cell Empty table cell1 Empty table cell1 Empty table cell Empty table cell Empty table cell3 Empty table cell Empty table cell 20 Empty table cell20 Empty table cell20 Empty table cell18 Empty table cell21 Empty table cell20 Empty table cell20 Empty table cell20 Empty table cell10 Empty table cell20 Empty table cell20 Empty table cell20 Empty table cell19 Empty table cell20 Empty table cell21 Empty table cell20 Empty table cell19 Empty table cell18 Empty table cell20 Empty table cell21 Empty table cell20 Empty table cell20 20 19 Empty table cell19 Empty table cell19 Empty table cell18 Empty table cell18 Empty table cell17 Empty table cell19 20 Empty table cell18 18 20 20 19 19 21 21 3 4 3 7 5 4 10 2 2 1 2 2 1 3 1 3 2 0 4 5 6 95 95 95 94 90 80 75 75 80 75 65 65 79 65 62 75 68 67 40 52 45 40 45 32 32 47 39 33 41 16 20 28 17 30 10 16 11 10 10 0.050 0.050 0.050 0.056 0.095 0.250 0.300 0.300 0.300 0.400 0.400 0.400 0.421 0.450 0.571 0.600 0.632 0.667 1.000 1.000 1.000 1.100 1.100 1.105 1.105 1.105 1.111 1.278 1.353 1.737 1.800 1.889 2.333 2.350 2.400 2.684 3.000 3.238 3.905 ADAPTATION TRIALADAPTATION TRIAL ADAPTATION TRIAL ADAPTATION TRIAL Empty table cell ADAPTATION TRIAL Empty table cell ADAPTATION TRIAL Empty table cell ADAPTATION TRIAL ADAPTATION TRIAL ADAPTATION TRIAL 1 4 5 5 5 6 2 4 9 5 6 7 8 4 10 5 10 6 9 3 4 4 10 4 9 23 21 20 20 20 19 20 18 15 17 16 15 15 17 10 11 11 15 8 8 12 10 7 8 8 9 10 3 1 2 B073-2 B0952-1 E012-1 ND2676-10 E228-9 C121-7 AF1433-4 E221-1 B094-1 E149-5Y C125-8 E228-11 E263-3 E202-3 E220-3 E273-8 E230-6 C103-2 SNOWDEN ONAWAY B040-3 E041-1 E226-4Y MSB110-3 E048-2Y C120-1Y B057-2 E018-1 NT-1 ATLANTIC P84-13-12 C148-A ND860-2 E247-2 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 3 Empty table cell2 Empty table cell Empty table cell Empty table cell 2 3 1 2 1 2 1 4 1 2 5 5 1 1 6 5 4 5 2 9 2 Empty table cell9 3 9 4 5 Empty table cell 5 Empty table cellEmpty table cell4 Empty table cell Empty table cellEmpty table cell2 1 2 1 1 1 3 4 3 2 3 6 2 5 9 7 10 4 Empty table cell4 1 3 3 8 6 4 1 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 1 Empty table cell1 1 ADAPTATION TRIAL Empty table cell 24 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell24 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell26 Empty table cell26 Empty table cell26 Empty table cell25 Empty table cell22 Empty table cell25 Empty table cell26 Empty table cell24 Empty table cell18 25 24 24 Empty table cell24 25 Empty table cell25 25 Empty table cell23 25 25 26 25 23 25 2 2 1 9 10 17 6 1 1 3 1 1 1 1 2 1 1 3 1 3 6 8 8 5 96 84 80 80 80 76 80 75 60 68 64 58 58 65 40 50 44 58 33 44 48 42 29 33 32 36 40 13 4 8 0 0 4 0 0.042 0.160 0.200 0.200 0.200 0.240 0.320 0.417 0.440 0.480 0.560 0.577 0.615 0.654 0.800 0.818 0.880 0.885 1.000 1.111 1.200 1.292 1.333 1.333 1.400 1.600 1.960 2.087 2.280 2.360 2.808 3.880 4.087 4.480 B. CHECK BRUISE SAMPLES ** NUMBER OF SPOT PER TUBER NUMBER OF SPOT PER TUBER VARIETY 0 1 DATE OF HARVEST: LONGS-LATE DATE OF HARVEST: LONGS-LATEDATE OF HARVEST: LONGS-LATE NUMBER OF SPOT PER TUBER NUMBER OF SPOT PER TUBER 5+ DATE OF HARVEST: LONGS-LATE TOTAL TUBER DATE OF HARVEST: LONGS-LATE % BRUIS E FREE NUMBER OF SPOT PER TUBER 4 DATE OF HARVEST: LONGS-LATE DATE OF HARVEST: LONGS-LATE DATE OF HARVEST: LONGS-LATE AV E SPOTS/TUBE DATE OF HARVEST: LONGS-LATE DATE OF HARVEST: LONGS-LATE NUMBER OF SPOT PER TUBER 2 3 DATE OF HARVEST: ROUND WHITES-LATE DATE OF HARVEST: ROUND WHITES-LATEDATE OF HARVEST: ROUND WHITES-LATE DATE OF HARVEST: ROUND WHITES-LATE DATE OF HARVEST: ROUND WHITES-LATE DATE OF HARVEST: ROUND WHITES-LATE DATE OF HARVEST: ROUND WHITES-LATE DATE OF HARVEST: ROUND WHITES-LATE DATE OF HARVEST: ROUND WHITES-LATE NEWLEAF SHEPODY CENTURY R A7961-1 C081082-1 C082142-4 R. BURBANK MSB106-8 C0083008-1 GOLDRUSH A84118-3 A082611-7 JS111-28 25 25 25 25 24 23 23 23 24 20 15 17 15 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 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 25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell27 Empty table cell25 Empty table cell25 Empty table cell25 1 Empty table cell26 1 1 1 Empty table cell MSB107-1 ST. JOHNS NY101 MSA091-1 MAINESTAY AF1470-17 SNOWDEN PIKE FL1887 MSB076-2 MSB083-1 ATLANTIC ONAWAY NORVALLEY NY111 FL1833 NY103 FL1867 FL1863 25 25 25 24 24 23 20 21 20 20 20 17 20 17 17 16 15 19 2 DATE OF HARVEST: ROUND WHITES-LATE 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 cell1 1 1 1 1 1 2 Empty table cell1 3 1 2 3 Empty table cell5 8 5 6 4 2 3 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 25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell24 Empty table cell26 Empty table cell1 Empty table cell25 Empty table cell Empty table cell25 23 0 Empty table cell25 Empty table cell Empty table cell 25 Empty table cell24 2 Empty table cell24 31 3 22 3 Empty table cell 1 Empty table cell Empty table cell1 Empty table cell 2 2 1 4 3 2 1 ** Tuber samples were collected at harvest and graded, with no further bruising. Samples were abrasive-peeled and scored on October 29, 1996. 1 1 1 7 1 1 1 1 2 2 2 2 3 8 1 8 1 1 1 4 3 2 4 3 6 100 100 100 100 96 92 92 92 89 80 60 68 58 0.000 0.000 0.000 0.000 0.040 0.080 0.080 0.080 0.148 0.320 0.520 0.600 0.654 100 100 100 96 96 92 80 84 83 77 80 68 87 68 68 67 63 61 9 0.000 0.000 0.000 0.040 0.040 0.120 0.240 0.240 0.292 0.346 0.360 0.400 0.435 0.440 0.520 0.583 0.917 1.290 2.409 NORTH CENTRAL REGIONAL TRIALNORTH CENTRAL REGIONAL TRIAL NORTH CENTRAL REGIONAL TRIAL NORTH CENTRAL REGIONAL TRIAL Empty table cell NORTH CENTRAL REGIONAL TRIAL Empty table cell NORTH CENTRAL REGIONAL TRIAL Empty table cell Empty table cell NORTH CENTRAL REGIONAL TRIAL NORTH CENTRAL REGIONAL TRIAL NORTH CENTRAL REGIONAL TRIAL 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 Empty table cell Empty table cell1 2 2 3 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 2 Empty table cell NORTH CENTRAL REGIONAL TRIAL Empty table cell 25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 25 Empty table cell25 Empty table cell25 EUROPEAN TRIAL 100 96 96 92 92 92 92 88 84 80 76 76 64 68 84 60 52 0.000 0.040 0.040 0.080 0.080 0.080 0.080 0.120 0.160 0.200 0.240 0.280 0.480 0.560 0.640 0.680 1.080 EUROPEAN TRIAL EUROPEAN TRIAL EUROPEAN TRIAL 2 1 3 2 Empty table cell1 3 3 5 4 EUROPEAN TRIAL EUROPEAN TRIAL EUROPEAN TRIAL EUROPEAN TRIAL EUROPEAN TRIAL 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 cell1 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 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 25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell23 Empty table cell25 Empty table cell25 Empty table cell23 Empty table cell25 Empty table cell Empty table cell Empty table cell Empty table cell Empty table cell1 Empty table cell Empty table cell 1 1 1 1 2 Empty table cell Empty table cell1 100 100 100 100 96 96 96 96 92 92 92 92 88 88 78 76 60 65 52 0.000 0.000 0.000 0.000 0.040 0.040 0.040 0.080 0.080 0.080 0.120 0.120 0.120 0.200 0.217 0.240 0.440 0.565 0.600 NORLAND R. NORKOTAH MSB007-1 ND2676-10 NORCHIP MN16489 W1I51RUS R. PONTIAC W1242 MN16180 ND2225-1R R. BURBANK SNOWDEN MSB106-7 MSB076-2 ATLANTIC W1313 EUROPEAN TRIAL MSD029-3Y SW88-112 PICASSO ROMINA MICHIGOLD IS. SUNSHINE DITTA AMINCA SW88-113 ERNTESTOLZ FELSINA LILI MSA097-1Y SAGINAW GOLD LATONA PREMIER JULIANNA ROSE MORNING GOLD MATILDA 25 24 24 23 23 23 23 22 21 20 19 19 16 17 21 15 13 25 25 25 25 24 24 24 24 23 23 23 23 22 22 18 19 15 15 13 1 1 2 2 2 2 3 4 5 6 5 6 4 1 1 1 2 2 1 1 3 2 5 6 9 5 11 ADAPTATION TRIALADAPTATION TRIAL E220-3 E263-3 E228-9 E226-4Y ND2676-10 C103-2 E228-11 B094-1 E041-1 C125-8 B0952-1 B073-2 C121-7 E202-3 SNOWDEN E230-6 MSB110-3 E273-8 E048-2Y E221-1 E012-1 AF1433-4 B040-3 NT-1 B057-2 C120-1Y E149-5Y E247-2 ATLANTIC E018-1 ND860-2 C148-A P84-13-12 24 23 25 25 25 24 22 23 23 23 22 23 22 22 22 22 20 15 19 21 19 19 20 20 18 13 14 8 4 8 3 3 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 Empty table cell Empty table cell Empty table cell1 ADAPTATION TRIAL Empty table cell 24 Empty table cell23 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell23 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell26 Empty table cell25 Empty table cell25 Empty table cell26 Empty table cell25 Empty table cell22 Empty table cell25 Empty table cell25 Empty table cell25 Empty table cell26 Empty table cell25 25 Empty table cell25 Empty table cell24 Empty table cell25 25 25 24 26 23 25 1.00 1.00 1.00 1.00 1.00 0.96 0.96 0.92 0.92 0.92 0.88 0.92 0.85 0.88 0.88 0.85 0.80 0.68 0.76 0.84 0.76 0.73 0.80 0.80 0.72 0.54 0.56 0.32 0.16 0.33 0.12 0.13 0.00 Empty table cell2 3 3 5 7 5 2 4 1 1 5 0.000 0.000 0.000 0.000 0.000 0.040 0.043 0.080 0.080 0.120 0.120 0.120 0.154 0.160 0.200 0.269 0.280 0.318 0.320 0.360 0.360 0.423 0.480 0.520 0.640 0.667 0.920 1.320 2.000 2.042 2.462 2.609 3.000 ADAPTATION TRIAL Empty table cell ADAPTATION TRIAL Empty table cell ADAPTATION TRIAL Empty table cell ADAPTATION TRIAL Empty table cell ADAPTATION TRIAL ADAPTATION TRIAL ADAPTATION TRIAL 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 Empty table cell Empty table cell Empty table cell Empty table cell Empty table cell Empty table cell 1 1 1 2 1 2 1 1 2 2 1 3 1 4 2 1 2 3 7 4 Empty table cell Empty table cell Empty table cell Empty table cell Empty table cell Empty table cell2 Empty table cell1 1 4 4 2 Empty table cell3 1 2 Empty table cell3 2 3 2 1 6 5 1 8 5 7 1 2 8 5 8 8 4 4 5 4 1 1 1 1 2 1 4 1 3 4 5 2 4 POTATO VARIETY AND MANAGEMENT STUDIES Funding Fed. Grant/MPIC R.W. Chase and D.S. Douches Department of Crop and Soil Sciences Introduction On-farm potato variety trials in Michigan have a long history of contributing to the introduction of new potato varieties into the Michigan potato industry. In 1996, in cooperation with the MPIC Processing Committee, there were five locations where eighteen entries were evaluated for both chip and frozen French fry processing. There were four other locations where twelve entries were evaluated for the fresh market. Russet Burbank has been grown for many years in Michigan, however, there has been no recent Michigan studies comparing seed preparation prior to planting. A study was initiated in 1995 and continued in 1996 to assess pre-plant seed management strategies. A similar Shepody study was initiated in 1996 at the MSU Montcalm Research Farm. A. Procedure for Qn-Farm Variety Trials and Results Twenty-five pound samples of each of the 18 processing variety entries were planted on the cooperating farms of W.J. Lennard and Sons, Inc. (Monroe), Crooks Farms (St. Joseph), Fertile Valley Farm (Allegan), Sandyland Farm (Montcalm) and L. Walther and Sons, Inc. (Tuscola). Seven of the entries for chip processing (MSB083-1, MSB110-3, MSB076-2, MSA091-1, MSB073-2, MSB095-2 and MSB0952-1) were from the MSU potato breeding program and were compared with the standard varieties of Snowden, Atlantic and Pike. Other chip entries were ND2417-6 (NorValley) and NY103. There were six entries also included to assess for frozen French fry processing. These entries were A7961-1 (USDA-Aberdeen), JS111-28 (J.R. Simplot), Legend (C0083008-1), Shepody, Russet Burbank, and Russet Burbank NewLeaf®. For the fresh market trials, there were 12 entries planted on the cooperating farms of Terry Groulx (Bay), Hansen Farms, Inc. (Montcalm), Smith Bros. (Monroe) and Allen Erke (Presque Isle). Five of the entries (MSB107-1, MSB083-1, MSB106-7, MSB106-8 and MSC122-1) were from the MSU potato breeding program. Other entries were St. Johns, Mainestay, Quaggy Joe, AF1426-1 (all from Maine), NY103, Onaway and Goldrush. Results The overall average yields, size distribution and specific gravity are shown in Table 1 for the five processing trial locations. Among the chipping varieties, Snowden produced the highest yields of U.S. No. 1 potatoes followed closely by NY103 and Atlantic. The NY103 produces round white potatoes which are smooth, shallow eyes and have very good general appearance, however, the specific gravity is lower than desired for chip processing. MSB083-1 had above average yields, however, there have been some locations where internal brown spot was noted. NorValley (ND2417-6) produced good yields, however, specific gravity values have been medium. Its area of adaptability appears to be similar to Norchip. MSB110-3 was noted to have very good chip color, however, it appears to be susceptible to scab and testing will not be continued. MSB076-2 plants are large and very upright throughout the growing season. It has high specific gravity and yield potential with good tolerance to scab. Tubers are oblong to oval in shape and some hollow heart has been noted. MSA091-1 yields were variable and it does have some scab resistance. MSB0952-1 and MSB095-2 had the lowest yields. Among the frozen processing entries the A7961-1 advanced seedling from USDA-Aberdeen produced the best yields. This seedling has produced well at the MSU Montcalm Research Farm also. Specific gravity is similar to that of Shepody and it has medium-late maturity. Its strengths are resistance to malformations, internal defects and shatter bruise, however, it is reported to have occasional sugar build up in storage. JS111-28 is an entry provided by J.R. Simplot. Yields are good and it has a very good tuber type. Legend (C0083008-1), a Colorado cross selected in Oregon had very good general appearance. It appears to have a small set and yields in Michigan have been below average. Russet Burbank NewLeaf® did not perform well in 1996. Plant growth appeared normal for Russet Burbank, however, yields and particularly tuber sizing were below average. Table 1. 1996 Processing Potato Trial Overall Average — Five Locations Entry Yield (cwt/A) Yield (cwt/A) No. 1 Total A. Chip Processing Percent Size Distribution No. 1 Perce Size Distribution <2" Perce Size Distribution 2-3 1/4" Perce Size Distribution >3 1/4" Culls Perce Size Distribution S.G. 414 Snowden 408 NY103 400 Atlantic MSB083-1 359 ND2417-6(NorValley)356 MSB110-3 347 343 MSB076-2 MSA091-1 334 MSB073-2 314 314 Pike 260 MSB095-2 MSB952-1 222 445 436 438 430 410 434 399 373 351 346 318 277 93 93 91 84 87 80 85 89 89 91 81 79 7 5 6 15 12 19 13 8 10 9 18 21 79 75 71 73 79 73 82 75 84 82 77 73 14 18 20 11 8 7 3 14 5 9 4 6 0 2 3 1 1 1 2 2 1 0 1 0 1.083 1.073 1.082 1/ 1.077 1.072 1.083 1.090 1.079 1.084 1.085 1.080 1.079 2/ Empty table cellEmpty table cell B. Frozen Processing Empty table cell No. 1 85 77 69 76 83 53 385 377 397 334 274 348 <4 oz 4-10 oz 11 14 23 13 16 42 51 54 55 38 60 43 >10 oz Culls Empty table cell 34 23 14 38 23 10 4 9 9 11 1 4 1.079 1.077 1.078 1.075 1.080 1.074 A7961-1 JS111-28 R. Burbank Shepody Legend R.B. NewLeaf 329 290 275 255 229 186 1/ Four locations. 2/ Three locations. Summary data for the four locations of the fresh market trial are shown in Table 2. St. Johns, MSB107-1 and Mainestay all produced over 400 cwt/A of U.S. No. 1 potatoes. In our Montcalm Research Farm trials, St. Johns has averaged 401 cwt/A over the past three years, Mainestay has averaged 438 cwt/A and in two years of trials, MSB107-1, 386 cwt/A. The interest in Mainestay has declined as it has shown sticky stolons, growth crack and some shatter bruise. In Maine during 1996, purple streaking in the flesh was also noted. MSB107-1 is a bright skin, round white with excellent internal quality. AF1470-17 was named Quaggy Joe in 1996 for a mountain in Maine. Yields were very good and it was the highest yielder at the late harvest at the Montcalm Research Farm. Internal quality was good except brown center was noted at two farm locations and the Montcalm Research Farm. It is scab susceptible. NY103 was also included in the fresh trial because of its desirable tuber appearance. It has good fresh market prospects. It is intermediate in scab tolerance. MSB106-7 has good yields and scab reaction similar to Atlantic. AF1426-1 had several defects in tuber type and testing will be discontinued. MSB106-8 and MSC122-1 will also be deleted from further testing. Table 2. 1996 Freshpack Potato Variety Trial Overall Average — Four Locations Yield (cwt/A) No. 1 (cwt/A) Yield Total Percent Size Distribution No. 1 Percent Size Distribution <2" Percent Size Distribution Percent Size Distribution 2-3 1/4" >3 1/4 Percent Size Distribution Culls 414 411 404 381 377 370 358 357 307 278 267 197 444 442 453 439 439 396 418 420 347 335 307 252 93 93 89 87 86 93 88 85 88 83 86 76 4 5 9 4 9 6 10 12 5 15 13 21 71 66 78 61 65 71 71 72 56 63 68 74 22 27 11 26 21 22 17 13 32 20 18 2 3 2 2 9 5 1 2 3 7 2 1 3 S.G. 1.075 1.082 1.078 1.070 1.068 1.071 1.085 1.070 1.076 1.072 1.086 1.080 Entry St. Johns MSB107-1 Mainestay Onaway AF1470-17 (Quaggy Joe) NY103 MSB083-1 MSB106-7 AF1426-1 * Goldrush MSB106-8 MSC122-1 *Two locations. B. Procedure for Seed Preparation Studies Russet Burbank and Shepody seed were obtained from J.R. Simplot Co. in April and held at 40F. The Russet Burbank trial was initiated in 1995 and Shepody in 1996. At 12, 6, 3 and 1 day(s) before planting, whole seed was removed from the 40F storage and held for cutting just prior to planting. A second set of seed was also removed from 40F storage, warmed for 1 day and then pre-cut at 12, 6 and 3 days at 52F until planting. Seed size was approximately 2 ounces and was not treated. The seed was hand planted at a 12 inch spacing for Russet Burbank and 10 inch spacing for Shepody in plots 23 feet long with four replications on May 8, 1996 at the MRF. Soil and air temperatures were 48F and 58F, respectively. The Shepody plots were harvested on September 10 and Russet Burbank on September 23, 1996. Results Table 3 shows the plants emerged, relative plant vigor and stem counts for Shepody. On June 3, 26 days after planting, plant emergence was greatest for pre-cut seed and cut and plant seed warmed for 12 days. These differences were not evident on June 11, 8 days later. There were no differences in stem counts. The yields, size distribution, specific gravity and internal tuber quality are shown in Table 4. Size distribution and specific gravity were all very similar. Previous studies conducted in 1986-87 did result in a significant yield difference in favor of pre-cut seed. The advantage of pre-cut Shepody seed likely has the greatest effect during the period from planting to emergence and could be affected by adverse soil and weather conditions. Shepody has a more sparse distribution of eyes than Russet Burbank and eyes located near the stem end appear to be slower to develop. Holding pre-cut seed before planting under proper conditions of relative humidity, temperature and air will enhance suberization of the cut surface and more uniform sprout development. Table 5 shows the plants emerged, relative plant vigor and stem counts for Russet Burbank. There was very little difference in plant stand counts on June 3 and on June 11. Plant vigor appeared better than average for cut and plant seed pre-warmed for 12 and 6 days and pre-cut seed held for 6 days, however, this did not result in the highest yields. Similar to the Shepody, there were no differences in stem numbers that resulted from these treatments. Yields, size distribution, specific gravity and internal tuber quality are shown in Table 6. There were no significant differences in the yields of U.S. No. 1 potatoes except that pre-cut seed held for 6 days (PC-6) was significantly higher than for cut and plant seed pre-warmed for 3 days (CP-3). It appears that in 1996 seed which was warmed up to 6 days before planting produced higher yields than seed warmed for 12 days. Table 7 shows a summary of the yield results for the two years of the Russet Burbank study. These results show that the higher yields of U.S. No. 1 potatoes appeared to result from seed which was pre-warmed whole and then cut and planted. Seed which was pre-cut and held at 50F for 12 days resulted in the lowest yields. The Russet Burbank study will continue in 1997 and the Shepody study will continue in 1997 and 1998. This will provide three years of data which will represent different planting and growing seasons. Table 3. Emergence, vigor and stem counts for Shepody (1996). Plants Emerged 2/ Emerged 2/ Plants Treatment 1/ June 3 June 11 CP-12 CP-6 CP-3 CP-1 PC-12 PC-6 PC-3 6.7 4.0 4.8 2.0 9.0 7.7 5.5 25.8 25.0 23.5 24.8 24.0 26.3 26.0 Vigor 3/ Rating June 11 A+ A- A- A- A A+ A+ Stems/Plant 2.9 2.4 2.3 2.3 2.5 2.5 2.4 1/ CP = cut and plant — days held prior to planting. PC = pre-cut — days held prior to planting. 2/ 28 seed pieces planted. 3/ A = Average vigor. Table 4. Yields, size distribution, specific gravity and tuber quality of Shepody (1996). Yield Yiel d (cwt/A) (cwt/A) Treatment No. 1 Total Percent Size Distribution U.S. No. 1 Percent Size Distribution Percent Size Distribution Percent Size Distribution <4 oz 4-10 >10 Internal Internal Quality * Quality * Pick Percent Size Distribution Outs IBS S.G. HH Internal Quality * Internal Quality * BC VD PC-3 CP-6 CP-1 PC-12 CP-3 PC-6 CP-12 387 382 382 375 374 362 333 442 433 431 427 428 425 396 87 88 89 88 87 85 84 9 10 9 10 10 11 12 48 53 47 53 48 49 50 39 36 41 35 39 36 34 3 2 2 2 3 4 4 1.075 1.076 1.076 1.077 1.075 1.075 1.075 8 7 9 5 8 2 8 3 1 2 1 3 1 2 0 0 0 0 0 0 0 0 1 0 0 0 0 1 *Number of tubers with defect out of a total of 40 cut. Table 5. Emergence, vigor and stem counts for Russet Burbank (1996). Treatment 1/ June 3 June 11 Plants Emerged 2/ Emerged 2/ Plants CP-12 CP-6 CP-3 CP-1 PC-12 PC-6 PC-3 15.3 17.3 15.5 17.8 13.8 17.0 13.8 19.3 22.3 20.5 20.8 20.3 21.5 19.5 Vigor 3/ Rating June 11 A+ A+ A- A A At A- Stems/Plant 3.1 3.4 2.5 2.7 2.4 3.3 2.8 1/ CP = cut and plant — days held prior to planting. PC = pre-cut — days held prior to planting. 2/ 23 seed pieces planted. 3/ A = Average vigor. Table 6. Yields, size distribution, specific gravity and tuber quality of Russet Burbank (1996). Yield Yiel d (cwt/A) (cwt/A) Treatment No. 1 Total Percent Distribution U.S. No. 1 Percent Distribution Percent Distribution Percent Distribution < 4 oz 4-10 > 10 Internal Quality * Pick Percent Distribution VD Outs S.G. Internal Quality * HH Internal Quality * Internal Quality * BC IBS PC-6 PC-3 CP-6 CP-1 PC-12 CP-12 CP-3 350 325 322 311 307 306 299 450 414 432 419 400 400 392 78 79 74 74 77 77 76 21 19 23 20 20 19 18 63 59 63 57 59 56 55 15 20 12 17 18 21 21 1 3 3 6 3 4 5 1.079 1.079 1.076 1.076 1.078 1.078 1.078 1 1 3 1 3 4 1 0 0 0 0 0 0 0 0 1 0 0 1 2 1 0 0 0 0 1 1 0 * Number of tubers with defect out of a total of 40 cut. Table 7. Two year average yields from Russet Burbank seed pre-warmed either whole or cut for various days prior to planting. Treatment * No. 1 1995 Total No. 1 1996 Total Average No. 1 Total 1995 1996 Average CP-1 CP-6 CP-12 PC-6 PC-3 CP-3 PC-12 376 346 348 303 313 276 226 488 486 493 439 439 408 369 311 322 306 350 325 299 307 419 432 400 450 414 392 400 343 334 327 326 319 287 266 453 459 446 444 426 400 384 *CP = cut and plant — days held prior to planting. PC = pre-cut — days held prior to planting. Funding Fed. Grant FUSARIUM DRY ROT RESEARCH R. Hammerschmidt and H. Ray Department of Botany and Plant Pathology Michigan State University Fusarium dry rot, caused primarily by the fungus Fusarium sambucinum, is an important pathogen of tubers in storage as well as a cause of seed piece decay. However, because of the resistance of F. sambucinum to thiabendazole and thiophanate methyl, there are no choices for post-harvest chemical control of this disease in Michigan. Because of this, other means of chemical and non-chemical control are needed. Over the last several years, we have investigated several aspects of the resistance of tubers to this pathogen. Overall, the results have not been very conclusive and have not led to any straightforward information that could be easily used in the breeding of Fusarium dry rot resistant tubers or in the engineering of potato that would have more resistant tubers. As an alternative strategy, research was undertaken to attempt to understand the nature of pathogenicity of F. sambucinum by means of a genetic analysis of the pathogen in relation to its virulence on tuber tissue. In addition, testing of newer seed piece treatment materials was initiated. Results: As an initial step in determining the complexity of virulence in F. sambucinum, crosses were made between highly virulent and less virulent or non-virulent isolates of the fungus. The offspring of the crosses were tested for their ability to cause disease in tubers, resistance to thiabendazole, and for traits that are hypothesized to be related to pathogenicity. TBZ Resistance: Crosses between strains that were resistant or sensitive to TBZ were carried out. The offspring of the crosses were tested for growth on media containing TBZ and for the ability to cause disease. The results indicated that TB resistance was controlled by one gene. In addition, there appeared to be no relationship between the resistance of the pathogen to TBZ and virulence on tubers. Steroid alkaloid resistance: When injured, potato tubers naturally produce steroid glycoalkaloids solanine and chaconine. In addition to being negative quality factors, these compounds are antimicrobial and may function in the resistance of injured tubers to infection. Our previous research had shown that at the wounded surface of potato tubers, high enough quantities of glycoalkaloids accumulated to inhibit the growth of F. sambucinum. However, since F. Sambucinum can detoxify other defenses of potato, relationship of virulence of F. sambucinum to glycoalkaloid sensitivity was evaluated. In general, it was found that the most virulent strains of F. sambucinum were the most tolerant or resistant to the glycoalkaloids while the less virulent isolates were more sensitive. Since more than one alkaloid occurs in tubers, the effects of mixing various amounts of solanine and chaconine were tested. In the more sensitive strains, there was a synergistic effect of having both alkaloids in the test. This was not evident in the most resistant strain. The relationship between alkaloid production and resistance to Fusarium was tested by comparing the amount of disease that developed on Gold Rush with that on Lenape (a variety with very high glycoalkaloid content. Our samples contained 19mg TGA/100 grams of tuber tissue. This is more than sufficient to inhibit the pathogen). Lenape was much more resistant to Fusarium dry rot than was Gold Rush. The most alkaloid sensitive strains were clearly the least pathogenic on Lenape. Crosses between alkaloid resistant and susceptible Fusarium isolates were tested on Lenape, and there was a correlation between resistance to the alkaloid and the amount of disease produced on the tubers. There was less of a correlation between the level of virulence and alkaloid tolerance when the same fungal offspring were tested on Gold Rush. However, if the wounded surface of Gold Rush was treated with alkaloids prior to inoculation, the more tolerant isolates of the pathogen were able to cause more disease. Analysis of the numbers of glycoalkaloid resistant to sensitive offspring suggested that resistance to the alkaloids was controlled by a single gene. Fusarium colonizes potato tissue, in part, by growing through and between the potato tuber cells. Because of this and the observation that the pathogen cannot grow through a well suberized periderm, the role of enzymes that the pathogen might use in tissue colonization were evaluated. Although Fusarium was capable of producing cellulose and pectin-degrading enzymes as well as some non-specific esterases, there was no correlation between enzyme production and the ability to cause disease. Different strains of the pathogen are also known to produce different colors in culture (from red to orange to yellow to white). No correlation between color and pathogenicity was found. Conclusions Virulence of Fusarium sambucinum appears to be controlled by several genes. Thus, it is unlikely that resistance will be based on single genes in the potato. Of significance is the finding that virlence appears to be associated with the tolerance of more virulent isolates of the pathogen to the steroid glycoalkaloids chaconine and solanine. Both of these compounds are synthesized by tubers at the site of wounding, and thus they probably function to help the wounded tuber fend off infection until a new periderm is established. Thus, it appears that part of the mechanism that F. sambucinum uses for successful infection is by being tolerant of these natural defenses. The role of alkaloids in resistance is partly supported by the results with Lenape. However, the fact that Lenape also expressed higher levels of resistance to infection by the alkaloid tolerant Fusarium isolates than were seen in Gold Rush suggests that Lenape may have other resistwnc mechanisms and, thus, could serve as a source of this resistance. Funding MPIC POSTHARVEST SUPPRESSION OF FUSARIUM DRY ROT AND OTHER STORAGE DISEASES OF MINITUBERS OF POTATO TUBERS BY APPLICATION OF BIOACTIVE FUNGAL INOCULUM DURING PLANT GROWTH Gene R. Safir and Raymond Hammerschmidt Department of Botany and Plant Pathology Michigan State University, East Lansing, MI PROGRESS AND JUSTIFICATION: The Fusarium storage rots of potato are among the most important postharvest pathogens worldwide. Current methods for control of Fusarium storage rot rely on cultural practices and some chemical treatments, however, complete control of this problem has proved to be difficult. Research by Niemira, Safir and Hammerschmidt in cooperation with Sklarczyk Seed Farm, Johannesburg, MI has shown that growing tissue culture derived potato plantlets, for the production of prenuclear minitubers, in a commercial peat based fungal mycorrhizal inoculum (Micori-Mix, Premier Peat Moss, Quebec, Canada) can alter minituber production. Significantly, more of the valuable No. 1 and 2 as opposed to the less valuable No. 3 prenuclear minitubers were produced in the presence of the biological inoculum (Micori-Mix). Initial observations of minitubers in cold storage suggested that the minitubers that were produced in the presence of Micori-Mix had less dry rot than did the minitubers produced in the absence of the inoculum. Additionally, in subsequent experiments at both Sklarczyk Seed Farm and Michigan State University, minitubers that were produced in the presence of the inoculum again had substantially less dry rot when challenged with the dry rot fungus Fusarium sambucinum. The use of this commercial biological inoculum would become even more economical if it could be used in the field during tuber production and would result in increased tuber resistance to Fusarium and other storage rots. We would like to expand our studies to determine if this commercial inoculum, when used in the field for potato tuber production, will result in a significant reduction in both Fusarium sambucinum and Phytophthora infestans storage rots as well as late blight development. This would provide a potential economical and environmentally friendly partial control for these problems. Preliminary experiments have been conducted to determine if the mycorrhizal inoculum offers stored minitubers any protection against Phytophthora infestans. Minitubers of potato c.v. Atlantic produced in the presence and absence of the commercial biological inoculum were injected with approximately 1000 zoospores/minituber of the pathogen Phytophthora infestans race US8 (provided by W. Kirk). The minitubers produced in the presence of the commercial biological inoculum had lower levels of disease. Since the preliminary results suggest that the commercial inoculum may offer some protection against these two pathogens we are proposing to expand our studies as follows: 1. 2. Determine if the use of a commercial biological inoculum in the field will result in the production of potato tubers that are more resistant to storage rots caused by Fusarium sambucinum and Phytophthora infestans. Determine if the commercial biological inoculum will enhance resistance of potato foliage to Phytophthora infestans. Funding MPIC/MDA NITROGEN STEWARDSHIP PRACTICES TO REDUCE NITRATE LEACHING AND SUSTAIN PROFITABILITY IN AN IRRIGATED PRODUCTION SYSTEM M. L. Vitosh, D. R. Smucker, E. A. Paul, R. R. Harwood and J. T. Ritchie Department of Crop and Soil Sciences and Montcalm Extension Service A collaborative effort by MSU crop and soil specialists, Michigan Department of Agriculture (MDA), Michigan Potato Industry Commission (MPIC), and Cooperative Extension Service (CES) was initiated to demonstrate how on-farm N stewardship practices influence farm profitability and nitrate leaching to groundwater. We proposed to (a) establish N stewardship plots on potato farms and evaluate petiole sap nitrate testing as a tool for adjusting mid-season N fertilization, and (b) install lysimeters to intensively monitor on-farm N leaching losses as affected by N practices and crop rotation for three consecutive years. We also plan to identify peak leaching periods and quantify nitrate losses to groundwater in relation to rainfall and irrigation. MATERIALS AND METHODS Installation of Lysimeters In 1995 three types of undisturbed soil drainage lysimeters were installed on three irrigated potato farms in the Montcalm county. Lysimeter types were (a) zero-tension 6-ft long, semicircular troughs of 12 inch diameter, (b) low-tension quartz soil water samplers, and (c) medium-tension soil solution access tubes (SSAT). These types were selected to increase the precision of measurements and reduce the effects of variability due to channeled flow. At each site, lysimeters were laid out into eight separate workstations, four located inside and four outside the N stewardship plot. Each workstation consisting of one trough, one quartz, and one 3-ft long SSAT located at a depth of three feet and installed perpendicular to the rows. The 6-foot long troughs extended across two potato rows. These lysimeters were installed in April, before field preparation time to enable farmers to plant potatoes over the lysimeters. After the crop emerged, three additional SSAT's were installed, two at 12-inch depth, and one at 18-inch depth in the row between plants, to monitor soil solution nitrate levels in the root zone. In 1996 seven different irrigated potato fields were selected to demonstrate nitrogen stewardship practices. This time the N stewardship plots were much larger, extending the entire length of the field. Trough and quartz lysimeter were not installed in the 1996 plots. Instead, six sets of SSAT’s were installed. Three sets inside and three outside of the stewardship area. Each SSAT was installed in the potato row at depths of 12, 24 and 36 inches. In another collaborative effort, MSU scientists, MPIC and CES have established a large drainage lysimeter facility at the Montcalm Research Farm. This facility provides direct measurements of nitrate leaching amounts for a potato-corn production system. This project was initiated in 1987 at the Montcalm Research Farm with the relatively long-term objectives of monitoring nitrate leaching as influenced by nitrogen fertilizer management. Data collected from these lysimeters and other research plots are being used to test and improve a computer simulation model, SUBSTOR which predicts not only crop growth and yield but also the important soil processes affecting nitrate leaching. This research will be used to establish the credibility of the model which will be used to predict long-term leaching from the Montcalm site and other locations in Michigan. Establishment of N Stewardship Plots The N stewardship plots were established at strategic locations, to serve as a reference point to judge the N status of the entire field. In 1996, the N stewardship plots were strips extending the entire length of the field. The width of each strip varied from six to 24 rows depending on the equipment available for applying fertilizer and harvesting. Each stewardship plot received a reduced N rate, about 60-120 lb/A less N than the conventional rate applied to the rest of the farm. The differential N rates were applied either at first cultivation or at hilling. Residual Soil Nitrate and Soil Solution Nitrate Testing Soil samples were taken to a depth of three feet, in one foot increments, prior to planting and after harvest to evaluate the initial and final residual soil nitrate levels. Soil solution samples were collected from each SSAT on a weekly basis starting June 10 and ending August 5. All samples were analyzed for nitrate N using an auto-analyzer. Weekly Petiole Sap Testing and Leaf Chlorophyll Readings Weekly testing of potato petiole sap commenced on June 25 and ceased on August 8. Four replicates of petiole samples were taken from inside the window and four replicates from outside. The test results were faxed to the growers on the next day via the Montcalm Extension Service. The results were used to assess N status of potatoes and adjust mid-season N fertilizer applications. Additionally, the sap testing service was available to other interested potato growers. We also worked closely and offered advice to private consultants who relied on the sap nitrate testing to manage N on clientele farms. Leaf chlorophyll readings were also made at the same time petiole samples were collected. Approximately 150 readings were made in each plot with a hand held Minolta SPAD 502 chlorophyll meter. These readings were later correlated with the corresponding petiole nitrate content. Drainage Water Sampling for Nitrate Analysis In 1995 drainage water samples from the undisturbed lysimeters were collected throughout the growing season. In the fall the drainage tubes were buried just prior to harvest and brought back to the surface after a cover crop was established. Sampling resumed in November until the ground was frozen and again in April when the ground and tubes were free of frost. The tubing was again buried prior to planting of the 1996 crop and brought back to the surface after planting. Water samples from the tension lysimeters were used to measure nitrate concentration in soil water as it passes below the root zone. Water samples from the trough lysimeters were used to measure both the volume of drainage water and nitrate N in the leachate. Potato Harvest In 1996 potatoes were harvested in September and October with the farmers equipment. Four to twelve rows, 800 to 2000 feet long, were harvested and loaded into truck which were weighted at the nearest certified scale. Tuber yield and specific gravity from inside and outside the N stewardship plot were compared. Small samples of tubers were graded according to size and analyzed for specific gravity. For the round variety Snowden and Pike, US #1 grade included all tubers greater than 2 inches in diameter. Tubers smaller than 2 inches were graded as B's. Tubers greater than 3 1/4 inches were classified as premium oversized. For the long variety, Russet Burbank, tubers under 4-oz were graded as B's. Those weighing over 10-oz were classified as premium oversized. RESULTS AND DISCUSSION Rates and times of N application are presented in Table 1. These data include the large lysimeter plots at the Montcalm Research Farm, site number 8. Nitrogen fertilizer rates varied from a low of 160 lb/acre to a high of 283 lb/acre. The number of applications varied from two to seven times. The varieties grown were Snowden, Pike and Russet Burbank. Potato Yield Potato yield data from the eight N stewardship plots are presented in Tables 2. We were unable to calculate statistical differences due to the fact that strips were not replicated. At several sites we harvested more than one load from each strip. At other sites we harvested the entire strip into one truck load. Harvest strips varied from four to 12 rows wide and 800 to 2000 feet long. Truck loads varied from seven to 15 tons of fresh weight tubers. In general higher rates of N produced the highest yields. Site number 6 and 8 were the only sites where the lowest N rate resulted in the highest yield. Yields at the Montcalm Research Farm were calculated from small plots, two rows 50 feet long. These plots were unreplicated because there are only two large drainage lysimeters installed at the site. The largest difference in tuber size distribution was in the premium oversize category (those greater than 3 1/4 inches in diameter or heavier than 10 ounces). On average the highest N rates produced 5 percent more premium size tubers. Specific gravity of tubers decreased slightly with the higher N rates. Net economic returns, calculated as the gross margin minus the fertilizer N costs, favored the higher N rates by $77/A. Differences between high and low N rates varied from a loss of $362 per acre for site number 8 to a gain $346 per acre for site number 7. A price of $6.60/cwt for potatoes and $0.22/lb of N fertilizer was used in the analysis. Although the yield data here do not appear to support the N stewardship practice of reducing N fertilizer use, we would like to caution everyone from making false conclusions. These data are not statistical proof that higher N rates will produce larger and more profitable yields. These yields were not from replicated plots, therefore, we do not have an estimate of experimental error. These yield differences may be due to normal field and sampling variability and not the N treatments. The use of farm equipment to harvest large plots has several advantages over small plot harvesting but we still need to characterize field variability by including replicated strips in future trials before we can draw definitive conclusions. SAP NITRATE TEST AND LEAF CHLOROPHYLL READINGS Weekly petiole sap nitrate tests from inside and outside the stewardship plots are summarized in Figures 1-8. The bar chart in these figures shows the critical sap nitrate levels we have established for that variety and planting date. Arrows point to in-season N fertilization events when they occurred during the sap testing period. The effects of different N fertilizer rates on petiole sap nitrate levels were not always evident. At most sites, there were few noticeable differences between the two N treatments. The biggest difference occurred at sites three and eight. At these sites higher nitrate concentrations were closely associated with higher N fertilizer rates. The difference in total yield at site number 3 was smaller (38 cwt/acre) than we expected. Visual symptoms of N deficiency at this site were very evident early in the growing season. The reduced N strip at this site was established as a 6-row strip, however early in the season, only four rows were visible N deficient. Later in the season only two rows were visible in some areas of the strip. It appeared that the two outside border rows were being affected by the higher N rate on either side. Cross-contamination of the border rows may be the explanation for the small difference in yields observed between the two N rates. Leaf Chlorophyll readings were also made each week when petioles were sampled for nitrate. Previous research has shown that leaf chlorophyll is closely correlated with N content of the leaf. Most scientists have shown that it is best to present the data as a percent of the high N treatment. Relative SPAD readings are shown in Figures 1-8 at the top of the chart using the right axis for interpretation of the values. The relative SPAD reading stayed above 90% throughout the sampling season at all sites except site number 3. At this site there was a steady decline throughout the season (Figure 3). The value dropped below 90% on about July 10th. Figure 13 shows the correlation between the actual SPAD readings and the sap nitrate concentration for both N treatments throughout the sampling season for site number 3. A very good correlation (R2 = .88) was found between leaf chlorophyll readings and sap nitrate levels. From this preliminary information we conclude that the chlorophyll meter has great potential for use as a diagnostic tool in evaluating the N status of the potato crop. Soil Water Analysis The weekly nitrate N concentration and the volume of drainage water data were collected from the zero-tension trough lysimeters. Since the installation of these lysimeters in the spring of 1995, there has been very little drainage water collected in the trough lysimeters. There is also considerable variability in the volume of water collected from each trough. This can probably be attributed to the capillary rise of water above the trough and to preferential flow through the soil profile around the trough lysimeters. As a result of these findings, we have decided to cease collecting data from the trough lysimeters. Biweekly soil solution nitrate N concentrations from the medium-tension SSAT lysimeters were collected at each site. For most sites, the nitrate N concentration at 12-inch depth was higher at the beginning and decreased toward the end of the season while the nitrate concentrations at the 36-inch depth were initially low and increased with time. These trends however, are less evident when looking at the average of the eight sites (Figures 9 and 10). The general trends show evidence of nitrate uptake by plants from the surface foot and downward movement through the profile with time due to leaching. The nitrate N concentrations at many of these sites were extremely high at times, well in excess of 100 ppm. The implications of this are that excess N was probably available for plant growth at most of these locations and that excess rain could easily have caused considerable loss of N due to leaching. Growers need to be more conscious of the N uptake pattern of potatoes and apply N more timely to meet the daily demands of the crop. From these data we were not able to determine a critical nitrate level in the surface foot for plant growth. The only site which might be classified as N deficient was the N stewardship plot at site number 3. At this site the inside area had concentrations in excess of 40 ppm throughout the sampling season except for the last date of August 8 (Data not shown here). There appears to be considerable variability between tubes, dates and locations which makes it difficult to establish a critical nitrate N level for optimum plant growth in the field using the SSAT’s. The data for the Quartz and SSAT lysimeters installed in the 1995 sites are presented in the Technical report to MDA. A summary of this information, showing average values for the three sites, is shown in Figures 11 and 12. There appears to be some differences between the three sites and the flow of nitrates through the soil, particularly site 1 versus 2 and 3. High levels of nitrate reached the 36 inch depth earlier at site 1 than the other two sites. Figure 14 shows the correlation between Quartz and SSAT lysimeters. A correlation coefficient of 0.77 was obtained indicating that there is a good relationship between the two lysimeter types and that either lysimeter type may be used to monitor nitrate leaching through soils. Preplant And Post-harvest Residual Soil Nitrate The residual soil nitrate N prior to planting and after harvest are presented in Table 3 and 4. Except for site number 7, relatively little soil nitrate (less than 20 lb N/acre) was found in the three-foot profile. At site number 7 there was a total of 32 lb N/acre-3 feet. Two-thirds of this N (19 lb/acre) was found below 24 inches deep. After harvest, some sites contained significant quantities of nitrate N ranging from 16 to more than 140 lb N/acre-3 feet. The average for all outside areas contained 22 lb more N per acre-3 feet than the inside areas (55-33). On average, the outside areas of the field received 67 lb more N fertilizer than the N stewardship plots and produce 17 cwt/a more yield. The higher average yield from the outside areas removed approximately 50 lb more N (17 cwt/acre x .33 lb N/cwt) leaving about 17 lb of N unaccounted for in the soil (67-50 = 17). Surprisingly the calculated value and the measure value for residual soil nitrate are very close. Substor Potato Model Simulation Study Considerable time was spent collecting and inputting weather data for each the 1996 sites into the SUBSTOR potato simulation model, version 2.0. A cursory study of the model indicates that it is very sensitive to water input and as a result does not estimate yields accurately. More time is needed to study and validate the model. The model appears to be giving good realistic information on drainage and runoff. If the yields can be properly estimated then we will be able to get realistic values on crop removal and the amount of N leached from out plots. We plan to continue to working on this model throughout the winter months so that we can give potato growers a more realistic estimate of their N losses to groundwater. Nine years of drainage and N leaching data have now been collected from the large lysimeters at the Montcalm Research Farm. This data will be very valuable in validating the SUBSTOR potato model and predicting N losses from growers fields. CONCLUSIONS Since this project was inaugurated in April 1995, we have made good progress toward achieving our objectives. With a combination of N stewardship plots, sap nitrate testing, and on-farm lysimeters, we have been able to demonstrate that N stewardship practices are (a) effective in maintaining potato yields and profitability; (b) reducing soil nitrate N residues at harvest, and (c) lowering nitrate N concentration of drainage water at a depth of 36 inches, compared to conventional N practices. Furthermore, the weekly petiole sap nitrate testing program has gained acceptance as an excellent tactical approach to in-season N management of potatoes. The use of a chlorophyll meter for evaluating the N status of the potato crop appears promising. Once we have obtained a good calibration of the instrument with petiole nitrate content, it can be used in the field to quickly determine the N status of the crop. Trough lysimeters do not appear to be suitable for evaluating nitrate N losses from potato fields. The use of soil solution access tubes (SSAT) is a practical way to follow nitrate movement in soils but inherent soil variability and preferential water flow are causing a great deal of variability in the values obtained. This variability will make it difficult to establish critical nitrate levels in the root zone for optimum plant growth. In summary our data suggest that there is environmental justification to reducing the current N application rates on potatoes and that N stewardship practices can be utilized effectively. Table 1. 1996 Nitrogen fertilizer application rates for nitrogen stewardship plots. lb/N per Acrelb/N per Acre lb/N per Acre lb/N per Acre lb/N per Acre lb/N per Acre Site No Treatment 1&2 Date applied Preplant Pike & SnowdenRed flag Pike & Snowden Yellow flag Pike & Snowden Outside 21 21 21 3 Pike Pike 4 Date applied Preplant Inside Outside -- — Date applied Preplant Snowden Snowden Inside Outside — — 5 Date applied Preplant Russet BurbankInside Burbank Russet Outside — — 5/8 29 29 29 5/7 47 47 5/7 84 84 5/8 50 50 6 Date applied Preplant 5/25 Snowden Snowden Inside Outside — — 55 55 7 Date applied Preplant 5/25 Snowden Snowden Inside Outside — — 8 (MRF) Date applied Preplant Snowden Snowden Research Conventional — — 40 40 5/8 60 60 6/13 — 85 85 6/11 51 110 6/1 62 62 6/15 60 90 6/5 45 45 6/5 60 lb/N per Acre lb/N per Acrelb/N per Acre 6/19 6/28 6/21 1.5 1.5 76 18 0.7 0.7 7/10 Total 0.7 0.7 198 225 7/1 69 69 69 76 0.7 0.7 1.5 6/15 Empty table cell 120 Empty table cell 120 Empty table cell 6/15 Empty table cell Empty table cell 86 130 Empty table cell 7/17 Empty table cell 100 Empty table cell 100 Empty table cell 6/28 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 7/2 Empty table cell Empty table cell 0 60 Empty table cell 7/6 Empty table cell Empty table cell 91 Empty table cell 105 105 6/28 0 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 283 Empty table cellTotal Empty table cell218 Empty table cell277 Empty table cellTotal Empty table cell232 Empty table cell276 Empty table cellTotal Empty table cell210 Empty table cell240 Empty table cellTotal Empty table cell205 Empty table cell265 Empty table cellTotal Empty table cell191 Empty table cell 267 Empty table cellTotal Empty table cell160 Empty table cell260 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 91 76 60 6/1 Empty table cell 100 Empty table cell 200 Empty table cell Table 2. Tuber yield, size distribution, specific gravity and nitrogen economic returns for the nitrogen stewardship plots -1996. N Rate US#1 Total Percent of the Total US#1 Percent of the Total B’s Percent of the Total A’s Percent of the Total OV Percent of the Total PO Sp Gr 198 225 283 198 225 283 218 277 232 276 205 265 191 267 160 260 202 269 443 447 456 356 391 369 na na 448 464 441 438 357 387 367 422 369 317 397 407 459 466 472 379 409 388 365 403 469 487 508 502 372 406 391 449 387 327 416 429 96 96 97 96 94 95 na na 95 95 81 87 96 85 94 94 95 97 93 94 4 91 4 87 4 83 5 8 13 6 4 5 86 90 88 4 7 7 -- — — — — — na na na — na na — na 90 87 6 9 74 8 73 15 82 14 81 15 83 11 77 17 -- — 15 7 — — — — 9 — 86 82 15 — 4 5 4 5 4 5 6 6 5 3 4 5 85 82 8 13 — 1.084 1.082 1.092 1.090 1.096 1.088 1.083 1.083 1.088 1.081 1.085 1.085 1.081 1.080 1.083 1.083 1.082 1.079 1.073 1.072 Gross Margin ($) * $2878 $2899 $2945 $2298 $2537 $2374 $2364 $2596 $2908 $3001 $2864 $2838 $2313 $2498 $2380 $2726 $2400 $2038 $2550 $2627 Site No. 1 2 3 4 5 6 7 1 1 2 2 3 4 5 6 7 Variety Pike Pike Pike Snowden Snowden Snowden Pike Pike Snowden Snowden Snowden Snowden Snowden Snowden Russet Burbank210 240 Burbank Russet 8 MRF 8 MRF Snowden Snowden Overall MeansLow N Means High N Overall * Gross margin = Gross returns - N fertilizer variable costs (based on $6.60/cwt for US#1 potatoes and $0.22/lb for N fertilizer). Table 3. Preplant soil nitrate nitrogen for eight nitrogen stewardship plots. 1996, Sample Depth (inches) Site Sample Depth (inches) 0 -12" lb Nitrate Nitrogen per Acre 12 - 24" 24 - 36" Sample Depth (inches) Total lb Nitrate Nitrogen per Acre lb Nitrate Nitrogen per Acre lb Nitrate Nitrogen per Acre 1 2 3 4 5 6 7 8 Mean 3.7 4.5 4.1 2.0 4.1 2.3 3.6 1.5 3.2 1.8 1.4 5.9 0.0 2.5 1.4 9.6 4.1 3.3 1.3 1.3 7.4 0.4 8.6 1.9 19.0 9.5 6.2 6.8 7.2 17.4 2.4 15.2 5.6 32.2 15.1 12.7 Table 4. Post harvest soil nitrate nitrogen for eight nitrogen stewardship plots. 1996 Sample Depth (inches) Sample Depth (inches) Sample Depth (inches) Site Location 0 -12” lb Nitrate Nitrogen per Acre 12 - 24" 24 - 36" Total lb Nitrate Nitrogen per Acre lb Nitrate Nitrogen per Acre lb Nitrate Nitrogen per Acre 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 Inside Outside Inside Outside Inside Outside Inside Outside Inside Outside Inside Outside Inside Outside Research Conventional Mean Mean Inside Outside 6.8 4.6 12.2 12.4 28.5 23.1 13.5 14.9 6.7 8.2 7.2 6.9 8.9 15.2 29.7 68.2 14.2 19.2 8.3 5.0 5.5 14.9 6.3 17.7 13.5 24.6 3.3 4.5 5.4 12.0 11.7 18.5 26.4 74.4 10.1 21.5 9.5 11.8 11.0 25.7 7.3 12.9 11.6 19.1 6.3 7.8 6.8 18.9 16.8 19.9 — 9.9 16.6 ----- 24.6 21.4 28.7 53.0 42.1 53.7 38.6 58.6 16.3 20.5 19.4 37.8 37.4 53.6 56.1 142.6 32.9 55.2 Fig 1. Petiole sap nitrate concentration in N stewardship plots. Site 1 - Pike 1996 Fig 2. Petiole sap nitrate concentration in N stewardship plots. Site 2 - Snowden 1996 Fig 3. Petiole sap nitrate concentration in N stewardship plots. Site 3 - Pike 1996 Fig 4. Petiole sap nitrate concentration in N stewardship plots. Site 4 - Snowden 1996 Fig 5. Petiole sap nitrate concentration in N stewardship plots. Site 5 - Russet Burbanks 1996 Fig 6. Petiole sap nitrate concentration in N stewardship plots. Site 6 - Snowden 1996 Fig 7. Petiole sap nitrate concentration in N stewardship plots. Site 7 - Snowden 1996 Fig 8. Petiole sap nitrate concentration in N stewardship plots. Site 8 - Snowden 1996 Fig. 9. Soil solution nitrate N at three depths measured by SSAT lysimeters Eight Sites Combined - Inside -1996 Fig. 10. Soil solution nitrate N at three depths measured by SSAT lysimeters Eight Sites Combined - Outside -1996 Fig. 11 Soil Solution Nitrate SSAT Lysimeters - 36 " Depth Fig. 12 Soil Solution Nitrate Quartz Lysimeters - 36" depth Fig 13. Sap Nitrate vs SPAD Readings Site No. 3-1996 Fig 14. Correlation of Lysimeter type Quartz vs. SSAT- 36 " Depth Funding MPIC/Industry 1996 Potato Nematode Research G. W. Bird, Professor Department of Entomology Michigan State University East Lansing, MI 48824 The root-lesion nematode (Pratylenchus penetrans) is an important limiting factor in Michigan potato production. In addition, it is likely that the relatively recent introduction of carrots into some MI potato rotations may increase potato production risk to the root-lesion nematode, and also create an environment that will allow the northern root-knot nematode (Meloidogyne hapla) to become a limiting factor in MI potato production. Historically, the root-lesion nematode has been managed through the use of crop rotation, fumigant nematicides, non-famigant nematicides and chemigants. It is highly probable, however, that nematicides will be less readily available in the future than in the past. The objective of the Michigan State University Potato Nematode Research Project is to provide new information about the best way to utilize existing nematode management strategies and tactics, and to discover ways to grow high quality and high yielding potato crops without the use of nematicides. The 1996 Michigan State University Potato Nematode Research Project consisted of a non- fumigant nematicide trial, fumigant nematicide trial, evaluation of a bionematicide, a long-term (1991-2000) potato rotation study and a long-term (1994-2003) potato - carrot - nematicide investigation. In addition, one Master of Science Thesis investigating potato nematodes was completed in 1996. The following is a summary of the results of these research initiatives. 1996 Non-Fumigant Nematicide Trial The 1996 non-fumigant nematicide trial consisted of seven treatments and a control, involving three nemticides (Mocap, Vydate and Temik). The highest tuber yield (420 cwt per acre) was obtained with Temik 15G applied at 3.0 lbs a.i. per acre in the fertilizer furrow at planting (Table 1). This nematicide also provided the best root-lesion nematode control (Table 2). Mocap 6EC at 6.0 lb a.i. per acre and Mocap 10G at 3.0 lb a.i. per acre did not increase tuber yields or reduce population densities of P. penetrans. as much as 9.0 lb a.i. per acre of Mocap 6EC. In-furrow application of Mocap 10G followed by a 14-day post-emergence application of Vydate 2L resulted in the second highest tuber yield response, and the second highest level of nematode population reduction. 1995 - 1996 Fumigant Nematicide Trial The objective of the 1996 fumigant nematicide trial was to determine if two-years of control of P. penetrans and M. hapla could be obtained with a single application of Vapam at 50 gallons per acre before planting carrots in the spring of 1995. Application of Vapam resulted in tuber yields that were 123 cwt per acre greater than the control, and provided excellent two-season population reduction of P. penetrans (Table 3). By the end of 1996, however, population densities of M. hapla had increased significantly. 1996 Bionematicide Trial ABG-9017 is a recently registered bionematicide derived from a killed fungus. Although it was possible to obtain increased tuber yields through use of this material, the data did not indicate that the response was due to control of the root-lesion nematode (Table 4). Long-Term Nematode Management - Crop Rotation Project The objective of the long-term (1991-2000) nematode management - crop rotation project is to develop ways to grow high quality potato crops in root-lesion nematode risk sites in the absence of synthetic nematicides. The research site consists of six different cropping systems divided among ten treatments, each replicated eight times (Table 5). In 1996, the decision was made to spend the last four years of the study on the most promising components identified during the first six years of the project. These include a two-year alfalfa standard, oats and red clover, oilseed radish, buckwheat and composting. Until 1996, the highest tuber yields were always associated with the two-year alfalfa rotation with potato. This is indicated in the data analysis as a relative yield of 1.00 (Table 6). In 1996, however, over-yielding the standard was observed for the oilseed radish and buckwheat-compost rotations. Tuber yields associated with the sixth year of continuous potato production continued to remain significantly higher than relative yields from second, third or fourth year of continuous potato production. Tuber bulking took place much earlier in the buckwheat compost, oilseed radish, alfalfa and hairy vetch rotations than with continuous potato production. There were other very striking differences, including stolon length and the quality of young tubers. Final tuber yields ranged from 334 cwt per acre for the buckwheat-compost rotation to 219 cwt per acre for the continuous potato regime (Table 7). Numerous striking and potentially very important preliminary conclusions can be drawn from the nematode population dynamics data (Table 8). The first is that the population density of P. penetrans stabilizes and remains low after six years of continuous potato production. The population density of M. hapla, however, increased, and may be a limiting factor in relation to tuber yield. Population densities of both nematodes are always much lower after the second year of alfalfa, compared to the densities following a single year of alfalfa. The use of oilseed radish as a green manure crop provides excellent nematode control. The greatest population reduction of both nematodes was associated with the buckwheat rotation. Preliminary conclusions related to composting will not be made until after the 1997 growing season. Long-Term Carrot - Potato - Nematicide Project The objective of the long-term (1994-2003) carrot-potato-nematicide trial is to determine the best way to minimize risk to the root-lesion and northern root-knot nematodes in carrot - potato production systems. The research site was established in 1994 and consists of six systems divided among nine treatments, each replicated six times (Table 9). 1996 potato tuber yields were highest following carrots grown in soil treated with Vapam in 1995, and lowest following carrots in non­ treated soil (Table 10). The second highest tuber yield response was associated with the fallow/marigold-compost regime. Carrot is an excellent host for both P. penetrans and M. hapla (Table 11). Population densities of both nematodes were significantly lower following two years of alfalfa or two years of hairy vetch, compared to those present after a single year of these crops. Oats resulted in a reduction in the population density of both species. Vapam applied in 1995 prior to a carrot crop resulted in low population densities of both P. penetrans and M. hapla in 1996, compared to the non-treated carrot-potato control. Application of Vydate did not provide multiple year nematode control. Miscellaneous Potato Nematode Research Rebecca Gore completed her Master of Science Dissertation entitled, “Relationship Between Selected Biological and Management Attributes of Michigan Potato Production Systems” (1996, Department of Entomology, 130 pp). The thesis includes a reasonably thorough analysis of existing literature related to the Potato Early-Die Disease and questions the theory of synergism related to P. penetrans and Verticillum dahliae. Likewise, synergism was also only demonstrated infrequently in Dr. Carl Chen’s Ph.D. dissertation entitled, “Feature, Function and Nature of Pratylenchus penetrans and V. dahliae interactions associated with Solanum tuberosum (MSU Department of Entomology, 1995, 196 pp). A recent preliminary research report on photosynthesis and respiration rates associated with potato plants raised in the presence and absence of these organisms indicates the likelihood of two separate diseases, rather than synergism associated with a disease complex. Table 1. Impact of 1996 non-fumigant nematicide applications on potato tuber yields. Treatment Tuber Yields (cwt per acre) Tuber Yields (cwt per acre) a Tuber Yields (cwt per acre) b j Tuber Yields (cwt per acre) Total Control Mocap 6EC 1 Mocap 6EC 2 Mocap 10G 3 Temik 15G 4 Vydate 2L 5 Vydate 2L 6 Mocap 10G Vydate 2L 7 256 281 307 270 288 306 298 302 11 11 9 10 8 12 13 9 64a 47a 65a 59a 124b 71a 64a 90ab 331a 338ab 380ab 338ab 420b 390ab 375ab 401ab ANOVA 0.241 0.043 0.003 0.025 1 6.0 lb a.i. per acre, broadcast, pre-plant incorporated.. 2 9.0 lb a.i. per acre, broadcast, Pre-plant incorporated.. 3 3.0 lb a.i. per acre, in-furrow, at planting. 4 3.0 lb a.i. per acre, in-furrow, at planting. 5 2.0 lb a.i. per acre, in-furrow, at planting. 6 2.0 lb a.i. per acre, 14 days post emergence, directed foliar spray. 7 3.0 lb a.i. per acre, in-furrow, at planting plus 2.0 lb a.i. per acre, 14 days pest emergence, directed foliar spray. 1996 Table 2. Impact of 1996 non-fumigant nematicide applications on mid-season (July 16) population densities of root-lesion nematodes (Pratylenchus penetrans). Treatment No./100 cm3 soil No./1.0g root tissue Total Control Mocap 6EC 1 Mocap 6EC 2 Mocap 10G 3 Temik 15G 4 Vydate 2L 5 Vydate 2L 6 Mocap 10G Vydate 2L 7 ANOV 20b 9ab 9ab 8ab 6a 5a 8ab 8ab 65b 25ab 41ab 27ab 1a 9a 13a la 85c 34ab 50bc 35ab 7a 14ab 21ab 9ab 0.017 0.001 0.001 1 6.0 lb a.i. per acre, broadcast, pre-plant incorporated.. 2 9.0 lb a.i. per acre, broadcast, Pre-plant incorporated.. 3 3.0 lb a.i. per acre, in-furrow, at planting. 4 3.0 lb a.i. per acre, in-furrow, at planting. 5 2.0 lb a.i. per acre, in-furrow, at planting. 6 2.0 lb a.i. per acre, 14 days post emergence, directed foliar spray. 7 3.0 lb a.i. per acre, in-furrow, at planting plus 2.0 lb a.i. per acre, 14 days pest emergence, directed foliar spray. Table 3. Impact of Vapam, applied as a soil fumigant in the spring of 1995 prior to a crop of carrots, on 1996 potato tuber yields and final 1996 population densities of the root-lesion nematode (Pratylenchus penetrans) and northern root-knot nematode (Meloidogyne hapla). Treatment Tuber yield (Cwt/acre) P. penetrans No./100 cm3 soil plus 1.0 g root tissue M. hapla No./100cm3 soil plus 1.0 g root tissue Control Vapam (50 gal/acre) 233 356 25 3 604 287 Table 4. Influence of ABG-9017 bionematicide on 1996 tuber yields and mid-season population densities of the root-lesion nematode (Pratylenchus penetrans). Treatment Tuber yield (cwt/acre) Tuber yield (cwt/acre) Tuber yield (cwt/acre) a b j Tuber yield (cwt/acre) Total P. penetrans per 100 cm3 plus 1.0 gram root tissue 25 lb/acre 50 lb/acre 100 lb/acre Control 312 319 315 279 13 11 11 11 36 46 36 36 351 375 326 325 30.8 36.7 27.7 17.7 ANOVA 0.075 0.485 0.386 0.085 0.569 Table 5. Ten year nematode management - crop rotation research project design (1991-2000). System 1. Continuous potato (Treatment 1). System 2. Continuous potato - compost (Treatment 3). System 3. Potato - two-year alfalfa rotation (Treatments 4, 6, & 7). System 4. Potato - [oats - red clover] rotation (Treatment 5). System 5 Potato - oilseed radish rotation (Treatments 8 & 9). System 6 Potato - Buckwheat rotation (Treatments 2 & 10). Ten Year Crop Rotation Study, Potato Research Farm, 1991-2000. 1996 Potato 1997 Potato 1998 Potato 1999 Potato 2000 Potato Potato Buck-wheat Potato empty table cellempty table cell Alfalfa Alfalfa Oats Oats/ R. Clover Potato compost Potato Potato Potato compost Alfalfa Oats/ R. Clover Potato compost Alfalfa Potato Potato compost Potato empty table cell Treatment 1 2 3 4 5 6 7 8 9 1991 Potato Rye Alfalfa Oats 1992 Potato Rye Potato Rye Alfalfa 1993 Potato Rye Potato Rye Potato Oats Alfalfa Alfalfa Oats Oats Oats Oats Oats Potato Rye Soybean Rye Soybean Rye Soybean Rye Soybean Rye Potato Rye Alfalfa LRK Rye LRK Rye LRK Rye 1994 Potato Rye Potato Rye Potato Potato Rye Potato Rye Alfalfa Alfalfa Green pea Green pea 1995 Potato Hairy vetch Tri-mix Annual ryegrass Potato 30T/A compost Alfalfa OS radish Potato 10 Oats Soybean Rye LRK Rye Green pea Buckwheat 30T/A compost Alfalfa Alfalfa Potato Alfalfa Alfalfa Potato Potato OS radish Sudax 30T/A Compost Potato Alfalfa Alfalfa Potato Alfalfa OS radish Potato Potato OS radish OS radish Potato Potato empty table cell Buckwheat Potato Empty table cell empty table cell Table 6. Relative tuber yields associated with the ten-year nematode-management-crop rotation research project. Rotation Cropping Sequences 1 Cropping Sequences 1 Cropping Sequences 1 Relative Yields, U.S. No. 1 2 Relative Yields, U.S. No. 1 2 Relative Yields, U.S. No. 1 2 Relative Yields, U.S. No. 1 2 1994 P P P 1993 1991 Cropping Sequences 1 P A A O O O O O O O Cropping Sequences 1 1992 P P A A P S S s s s Kb Kb Kb Kb A P A P P P P P A A Pe Pe Pe 1995 P Hv Tm A Rg P+Co A Osr P Bw+Co Cropping Sequences 1 1996 Relative Yields, U.S. No. 1 2 1991 1992 1993 P P O A O/Rc A+Co p p Osr P 1.00 — — — — — — — — — 0.69 1.00 — — 0.97 — — — — — 0.34 0.54 1.00 — 0.53 — — — — — 1994 0.29 0.34 0.57 1.00 0.32 — — — —— — 1995 0.79 — — — — 1.00 — — 0.93 — 1996 Relative Yields, U.S. No. 1 2 0.87 0.95 — — — — 1.00 1.14 — 1.35 1 2 3 4 5 6 7 8 9 10 1 Cropping Symbols; P = Potato; A = Alfalfa; Hv = Hairy Vetch; Tm = Nematode Mix (annual ryegrass, hairy vetch, marigold); O = Oats; R = Annual Ryegrass; S = Soybean; Kb = Light Red Kidney Bean; Pe = Green Pea, Osr = Oil Seed Radish, Co = Compost. 2 Relative Yields calculated by giving the highest annual yield a value of 1.00 and dividing the other yields by the highest value. Table 7. 1996 potato tuber yields associated with the ten-year nematode management - crop rotation research project. Rotation Tuber yield (cwt/acre) Tuber Yield (cwt/acre) Continuous potato Hairy vetch Two-year alfalfa standard Oilseed radish Buckwheat - compost a Tuber yield (cwt/acre) b 173 177 194 223 250 35 47 42 47 57 j 11 14 16 18 27 Total Tuber Yield (cwt/acre) 219 238 252 288 334 Table 8. Influence of rotation crops on the population dynamics of the root-lesion nematode (Pratylenchus penetrans) and northern root-knot nematode (Meloidogyne hpala) associated with the ten-year nematode-management crop rotation project. Rotation (1995-1996) Nematodes per 100 cm3 soil plus 1.0 Nematodes per 100 cm3 soil plus 1.0 g root tissue P. penetrans Nematodes per 100 cm3 soil plus 1.0 g root tissue M. hapla Nematodes per 100 cm3 soil plus Nematodes per 100 cm3 soil plus 1.0 g root tissue M. hapla g root tissue P. penetrans 1.0 g root tissue M. hapla Pi96 Pf96 Pf95 Pi96 Pf96 11 19 24 10 31 9 9 6 13 2 3a 25ab 21a 114ab 1144c 319b 26ab 60ab 34ab 40ab 557 3221 90 2463 20 161 451 4 183 2 341 532 181 118 19 51 126 17 129 2 1288 2840 100 861 2470 3095 1457 829 83 318 Nematodes per 100 cm3 soil plus 1.0 g root tissue P. penetrans Pf95 10 359 119 196 295 7 28 75 15 9 empty table cell empty table cell 0.009 empty table cell empty table cell 0.047 Continuous potato Hairy vetch - potato Tri-mix - oats Alfalfa - alfalfa Ryegrass -oats/red clover Potato/compost - alfalfa Two-year alfalfa - potato Oilseed radish - potato Potato/compost - oilseed radish Buckwheat/compost - potato ANOVA Table 9. Cropping system design for the long-term (1993-2003) mineral soil carrot - potato - nematicide rotation research project. System No. 1 Continuous carrots (Treatment 1). System No. 2 Continuous carrots plus compost (Treatment No. 9). System No. 3. Potato/Vapam - carrots (Treatments 2 & 6). System No. 4. Carrot/Vapam - potato (Treatments 4 & 6). System No. 5 Oats - carrots - potato (Treatments 3 & 8) System No. 6 Hairy vetch - carrots (Treatment 7). Tmt 1 2 3 4 5 6 7 8 9 1995 Potato Carrots Carrots 1994 Green peas Green peas Green peas Green peas Green peas Green peas Hairy Vetch Alfalfa Fallow Marigold Compost Carrots (Vapam) Potato (Vapam) Carrots (Vydate) Hairy Vetch Alfalfa 1996 Carrots 1997 Carrots 1998 Carrots 1999 Carrots 2000 Carrots 2001 Carrots 2002 Carrots 2003 Carrots Potato Carrots Oats Potato Potato (Vapam) Carrots Carrots Oats Potato (Vapam) Potato Carrots Carrots Potato (Vapam) Oats Carrots Potato Potato Carrots (Vapam) Potato Potato Potato Potato Carrots (Vapam) Potato Potato (Vapam) Hairy Vetch Oats Carrots Compost Potato Carrots (Vapam) Carrots Hairy Vetch Carrots Carrots Compost Carrots (Vapam) Potato Potato (Vapam) Carrots Potato Carrots Compost Potato Carrots (Vapam) Carrots Hairy Vetch Oats Carrots Compost Carrots (Vapam) Potato Potato (Vapam) Hairy Vetch Carrots Carrots Compost Potato Carrots (Vapam) Carrots Carrots Potato Carrots Compost Carrots (Vapam) Potato Potato (Vapam) Hairy Vetch Oats Carrots Compost Table 10. 1996 potato tuber yields associated with the long-term carrot - potato - nematicide rotation research project. Crop rotation (nematicide) (1994- 1996) Tuber yields (cwt/acre) Tuber yields (cwt/acre) Tuber yields (cwt/acre) Tuber yields (cwt/acre) a b j Knobs Tuber yields (cwt/acre) Total Green peas/carrots/potato 182 Green peas/carrots(Vapam)/potato 220 Green peas/carrots(Vydate)/potato Hairy vetch/hairy vetch/potato Alfalfa/alfalfa/potato Fallow/marigold-compost/potato 199 193 218 232 11 12 12 12 14 8 18 84 30 34 59 60 21 40 18 20 18 18 233 356 259 258 277 292 ANOVA 0.402 0.059 0.014 0.021 0.042 Table 11. Influence of long-term carrot - potato - nematicide rotations on the population dynamics of the root-lesion nematode (Pratylenchus penetrans') and northern root-knot nematode (Meloidogyne hapla). Rotation (nematicides) Nematodes per 100 cm3 soil plus 1.0 g Nematodes per 100 cm3 soil plus 1.0 g root tissue M. haplaPf96 Nematodes per 100 cm3 soil plus 1.0 g root tissue P. penetrans Nematodes per 100 cm3 soil plus 1.0 Nematodes per 100 cm3 soil plus 1.0 g root tissue P. penetrans root tissue M. hapla g root tissue P. penetrans Nematodes per 100 cm3 soil plus 1.0 g root tissue M. hapla Pf95 Pi96 Pf95 Pi96 Pf96 Green peas/potato/carrots 448 265 2877 86 Green peas/carrots/potato 2238 Green peas/carrots/oats 2238 Green peas/carrots (Vapam)/potato Green peas/potato (Vapam)/carrots(Vapam) Green peas/carrots (Vydate)/potato Hairy vetch/hairy vetch/ potato Alfalfa/ alfalfa/potato Fallow/marigold -compost/potato 46 83 62 35 0 0 2238 101 115 227 24 278 268 19 604 27 287 779 705 699 720 175 252 252 252 86 252 6 8 14 62 41 61 9 0 39 69 17 32 483 46 25 0 3 51 41 14 87 Funding Fed. Grant/MPIC/Industry Colorado Potato Beetle Management 1996 Research Report Edward Grafius, Beth Bishop, and Ellen McEnhill Department of Entomology Michigan State University Summary: Colorado potato beetle management research in 1996 included several 1) monitoring populations for resistance to Admire (imidacloprid), projects: and development of a resistance test for Admire, 2)the use of bt transgenic plants and other non-insecticide controls as a barrier and to reduce resistance development, 3) evaluation of crop rotation systems for Colorado potato beetle control, and 4) insecticide efficacy tests for Colorado potato beetle control. Monitoring Colorado potato beetle for resistance to Admire (imidacloprid) Imidacloprid (Admire or Provado, Bayer Corp.) was registered for control of Colorado potato beetle on potatoes in 1995. Because of its effectiveness and the high level of resistance to other insecticides, over 80% of the potato acreage in Michigan was treated with Admire in 1995 and nearly 90% was treated in 1996. Such high use levels raise serious concerns about resistance development. The objectives or our research were to survey fields for Colorado potato beetle adults and larvae surviving Admire treatment and test for possible development of resistance. Characterization of resistance may help to design effective resistance management strategies. Resistance to Imidacloprid - "Montcalm-R" strain. Twenty Colorado potato beetle adults were found on June 24 in an Admire-treated commercial potato field in Montcalm Co. Michigan. An additional 15 adults were collected from this site on June 27. These were not found on the border row or on row ends (as might be expected if they were new arrivals), but were two to five rows in from a field border, on plants scattered the length of the field. They were fed field-collected foliage for 1 day, then fed foliage from greenhouse potato plants (cv. ’Snowden’) treated with Admire at normal field rate at planting. On both types of foliage, many of the beetles went through periods of intoxication (laying on their back, legs extended to the side, uncontrolled movement of legs, inability to walk, inability to right themselves) followed by periods of normal activity and feeding. Approximately 2/3 (21 out of 35) survived and were placed on untreated greenhouse potato foliage after 5 days on foliage from Admire-treated plants. Eggs were collected and larvae were reared on untreated potato foliage. Adults from these larvae were used in topical insecticide trials described below. Thirty-five large larvae (4th instars) and 14 adults were collected from the same field on July 19 and returned to the lab for testing. Levels of imidacloprid in the foliage in the field had declined by this time (80% of susceptible Colorado potato beetle adults survived on it). However, these larvae must have been present for 2-3 weeks to be in the final instar. Fed on foliage from greenhouse plants treated with Admire, approximately 95% of the field- collected larvae and 85% of the adults survived. Beetles that survived a dose of >0.1 (mu)g in topical assays were kept for rearing and future testing. A single female from the Montcalm-R strain survived a dose of 1.0 (mu)g (over 10 times the average lethal dose) in preliminary tests. A male that survived a dose of 0.1 (mu)g was put in the cage with the female and eggs are being collected for future rearing and testing as a separate strain. "Admire-selected" strain. Adults were collected from commercial potatoes treated with Admire in 1995 and fed on Admire-treated greenhouse plants for 2-3 days. Survivors were reared on greenhouse plants. Adults of the next generation were tested for resistance to imidacloprid in topical assays (no significant resistance was found in early generations) and survivors of the higher insecticide doses were used for the next generation. "Montcalm" strain. These were susceptible beetles collected from a field research site at the M.S.U. Montcalm Potato Research Farm, Entrican, Michigan. They were summer adults, collected 1 week before the experiment, and fed on potato foliage to ensure that they were at least 1 week old, healthy and well fed. This strain is maintained in laboratory culture for use as a susceptible strain. "BT Susceptible" strain. This strain has been reared in the laboratory for 7 years (approximately 30 generations), fed on greenhouse-grown potato foliage, without exposure to insecticides. Only 30 adults were available for treatment at the time of these experiments, too few to do statistical calculations, but mortality data is included for comparison with results for the other strains. Topical insecticide tests. To determine levels of resistance, adults of each strain (1 to 2 weeks old) were treated on the underside of the abdomen with technical grade imidacloprid in acetone (1 (mu)l/beetle, 0.001 to 1.0 (mu)g imidacloprid/pl of solution). They were placed in petri dishes in groups of 5- 10 per dish and kept at 25°C, photoperiod 16h light: 8 h dark. Intoxication was evaluated at 24, 48, 72 and 96 hours after treatment. Affected beetles were unable to walk their own body length forward and unable to hold onto and climb a pencil or pen. They often lay on their backs, with legs out to the sides and twitching. If upright, they showed abnormal leg movement and were unable to walk forward. Beetles still intoxicated after 72 hours were considered dead. Log dose-probit mortality regressions were used to analyze the data and calculate the dose required to kill 50% of beetles of each strain (LD50). Admire-selected strains were significantly higher than the LD50 value for beetles collected from the Montcalm Research Farm (Figure 3). The Montcalm- R and Admire-selected strains were 3.8 and 4.5 fold resistant, respectively, to imidacloprid compared with the field collected strain. Although resistance to insecticides is commonly 10 to 50 fold or greater, this low level of resistance is apparently sufficient to allow survival in the field, at least under some conditions. Mortality was higher for beetles from the susceptible and Montcalm strains than for beetles from the Montcalm-R and Admire-selected strains (Figure 1). Differences were largest at doses of 0.05 (mu)g and 0.1 (mu)g/beetle. Mortality at 0.05 (mu)g/beetle was over 40% in the two susceptible strains and 10% or less in the Montcalm-R and Admire-selected strains (Figure 2). Beetles collected from the Collins Rd. Entomology Farm at M.S.U. where Admire had never been used were also tested at this dose and mortality was 69%. In the Admire-selected strain, 100% mortality did not occur until a dose of 1.0 (mu)g/beetle and, as mentioned above, a single Montcalm-R female survived a dose of 1.0 (mu)g/beetle in preliminary tests. LD50 values (dose required for 50% mortality) for the Montcalm-R and Figure 1. Mortality after 72 hours of Colorado potato beetles treated topically with a range of doses of imidacloprid. Mortality was defined as an ability to walk forward one body length. Other symptoms included beetles on their backs, legs rigid out to the side and twitching. Figure 2. Mortality after 72 hours of Colorado potato beetles treated topically with 0.05 (mu)g imidacloprid per beetle. Figure 3. LD50 values (dose lethal to 50% of the beetles) 72 hours after treatment with imidacloprid. Resistance ratios are the ratio of the LD50 for the resistant strain (Montcalm-R or Admire-selected) divided by the LD50 for the susceptible (Montcalm) strain. Recovery from toxic effects. Some beetles in the Montcalm-R and Admire-selected strains recovered from topical treatment after 2 days of intoxication and after expressing symptoms that led to death in other beetles (Figure 4). One group of Montcalm-R beetles treated with 0.25 (mu)g/beetle was kept for observation beyond the 4-day experiment, because they were still moving, although they were unable to walk and expressed other symptoms of intoxication. One day after treatment, all ten beetles were scored as intoxicated. After the first 4 days, one had recovered and the other nine were scored as intoxicated. At the end of 8 days, six out of ten of the beetles had recovered completely from toxic effects and were feeding, mating and laying eggs. This level of recovery indicates that future resistance assays need to be run for a longer time than 72 - 96 hours normal for topical treatment studies. The LD50 values calculated after 72 hours, above, would likely be higher if more time was allowed for recovery of the intoxicated beetles. The recovery after exposure to imidacloprid observed in the topical assay is similar to the recovery exhibited by the field collected Montcalm-R strain beetles fed on foliage from Admire-treated plants and may indicate that detoxification is occurring. Recovery following non-lethal intoxication could allow beetles to survive in the field until Admire levels in the plants decline to non-toxic levels. Leaf dip assay. In a leaf-dip assay, beetles 2 to 4 weeks old were fed potato foliage dipped in a range of concentrations of Admire 2E. Foliage was allowed to dry for 1 hour and then fed to beetles for 24 hours. Uneaten foliage was removed after 24 hours and new foliage provided every 1 to 2 days. Number of beetles affected were assessed daily for 7 days. A portion of the beetles were followed to day 10. The LC50 value after 7 days was significantly higher for the Admire-selected strain than for either of the other strains (Figure 6); the resistance ratio for the Admire-selected strain was 4.5 compared to the UP strain. As in the previous study, significant recovery from intoxication occurred at low concentrations of Admire, up to 10 days after treatment (Figure 7). Figure 4. Percent of beetles affected 24, 48 and 72 hours after topical application of 0.05 (mu)g imidacloprid per beetle. Figure 5. Recovery from intoxication of Montcalm-R strain beetles 1 to 8 days after treatment topically with 0.25 (mu)g imidacloprid per beetle. By 7 days after treatment beetles had either recovered or were dead (no movement, darkened color, abdomen sunken and dry). Figure 6. Concentrations lethal or affecting 50% of beetles (LC50 values) after 7 days for Admire-Selected resistant strain (n=89) and two susceptible strains in a leaf dip assay (n=123 for UP and 60 for Montcalm strains). Days after treatment Figure 7. Recovery after feeding with Admire-treated foliage, 1 to 10 days after feeding. These resistance levels are relatively low, but they are similar to resistance levels to Temik in a Monroe Co. Michigan potato beetle population in 1984 (4.4 fold). This level of resistance seems to be enough to allow beetles to recover from intoxication from feeding on foliage from Admire-treated plants (and may be higher if time for full recovery is allowed). Behavioral resistance may also add to the beetle's ability to survive Admire treatment. For example, if the feeding rate was slower than normal, beetles would eat less imidacloprid before beginning to experience effects and might not consume a toxic dose, before getting sick and stopping feeding. Late emergence from overwintering would also contribute to survival on potatoes treated at planting with Admire. A low level of resistance, as reported here, could be especially important combined with late emergence of Colorado potato beetle from overwintering or during a season with early potato planting but late potato beetle emergence. Further studies of the effects of imidacloprid ingestion on beetles from the three strains, long-term recovery studies and studies of the interaction between resistance and feeding behavior and of the effects of non-lethal doses of imidacloprid on mating and egg laying are planned. Continued study of these resistant strains will be necessary to determine the speed at which resistance increases, the inheritance of resistance and potential resistance mechanism(s). Management implications. Management strategies were widely discussed when imidacloprid was first introduced. Research results from these two resistant strains may help determine optimal management strategies. While it is not good news that resistance is appearing in only the second year of imidacloprid use, resistance levels are low and research at this time may help manage the build-up of resistance. Differences between populations in survival of first instars fed artificial diet were recently reported, although no field survival was indicated (Olsen et al. 1996). Alternation of insecticides as a resistance management strategy assumes that resistance decreases in the absence of exposure to the insecticide. Unfortunately, resistance to insecticides in Colorado potato beetle is often very stable. For example, Michigan beetles are still resistant to DDT, although it has not been used since 1968. In some cases, resistance may be unstable at first, but become stable with continued use of the insecticide. Research results on the stability of imidacloprid resistance will be important. High doses as a resistance management strategy assumes that resistance is inherited as a recessive gene and beetles carrying only one copy of the gene will not survive a high insecticide dose. Unfortunately, many insecticide resistance factors in Colorado potato beetle involve dominant genes and even very high doses are unable to kill beetles carrying one or two copies of the resistance gene (Bishop and Grafius 1996, Ioannidis 1990, Ioannidis et al. 1992). Also, imidacloprid in the potato plant from Admire treatment at planting starts as a high dose early in the season and then degrades to a low dose. Again, results from these resistant strains will help determine if a high dose strategy will be useful. There are advantages and disadvantages to the use of Admire at planting versus Provado (imidacloprid registered for foliar application). Admire at planting always will degrade into a low dose at some time. A foliar spray of Provado will also degrade into a low dose, but will last only a few days. Using Admire only on late planted potatoes would increase the likelihood that late- emerging beetles would find high levels of Admire in the plants. In early- planted fields, Provado foliar sprays could be used instead of Admire; two or three foliar applications of Provado, at times of peak populations, would reduce the time beetles are exposed to low levels of the insecticide. Use of Provado instead of Admire would also reduce the proportion of the population that was contacted; some beetles in every field would remain susceptible to Admire/Pro vado. Combining Admire treatment with another insecticide such as Agri-Mek (abamectin, Merck) might result in little or no survival of Admire-resistant beetles. However, a few beetles with resistance to both insecticides might survive - the worst possible outcome. At this time, the most conservative strategy would be to avoid using Admire or Provado in 1997 at or near locations where it was used in 1996. Changing mortality agents to another insecticide and non-chemical mortality such as crop rotation and propane flaming would reduce the numbers of imidacloprid-resistant beetles surviving (although not reduce the proportion of imidacloprid-resistant beetles in the population). Preliminary research results will likely be available before next spring to help with management decisions. Demonstrating the use of Bacillus thuringiensis transgenic potatoes and other non-chemical controls for management of resistance to Admire (imidacloprid) in the Colorado potato beetle. The objectives of this study were to demonstrate that Bt transgenic potatoes could be used, alone or in combination with other control methods to reduce selection pressure from imidacloprid (Admire), thereby delaying the development of resistance to imidacloprid by the Colorado potato beetle. Genetically-engineered Russet Burbank potatoes (NewLeaf®, NatureMark) were planted at three commercial sites in Montcalm County, MI in the spring of 1996. NewLeaf potatoes were planted on the edge of rotated potato fields, adjacent to fields that were in potatoes in 1995. Cool, wet weather in the spring delayed planting, and prevented us from establishing plots until late June. Heavy rains in mid-June also caused flooding; as a result one of the three sites was dropped from the study. Up to three different plots, each 150 ft long and consisting of different treatments, were set up along the field edge at each site. The "Bt" treatment consisted of several rows of NewLeaf potatoes planted along the border of the potato field. The rest of the field was planted to non-transformed Russet Burbanks, to which "Admire" had been applied at planting. The "Trench" plot was similar, consisting of several rows of NewLeaf potatoes, followed by non­ transformed Russets. Next to the first NewLeaf row, and parallel with the plot, a 150 ft long black plastic-lined trench (ca 6 in wide and 6 in deep) was constructed. Beetles migrating from overwintering sites in the 1995 potato field first encountered the plastic-lined trench, then the NewLeaf potatoes. At the "Schmeid Rd." site only, copper fungicide (Kocide DF @ 2 LB/A) was applied to the first three rows of non-transformed potatoes. The third treatment ("Admire", at the Schmeid Rd. site only) consisted of a field of non-transformed Russet Burbanks, to which Admire had been applied at planting. At the "Schmeid Rd." site all three treatments were used. The field was bordered on the east by between 28 and 40 rows of NewLeaf potatoes. Demonstration plots were set up on the south end of the field, with a 40 rows NewLeaf border. The "Bt” and the "Trench" plots were adjacent and were separated from a corn field on the east by a farm road. The "Admire" plot was south of the NewLeaf field and was bordered on the east by a bean field, with no separating farm road. At the "Cemetery" site, 40 Acres of NewLeaf potatoes were planted along the north field edge. The rest of the field consisted of Admire-treated Russet Burbanks. The potato field was bordered on the north by a hedge row, across from which was a field that was in potatoes in 1995. The "Bt" and the "Trench” treatments were set up at the "Cemetery" site. However, no Kocide was applied. Colorado potato beetles were collected from locations throughout Montcalm County, MI. They were transported to the lab, and were marked with paint pens (DecoColor ®, Uchida of America, Corp.) before being released. The color and pattern of the markings indicated the date, site and plot in which they were released. Beetles were released across from the potato field and half-way between the length of the plot (ca 75 ft from each end). Release sites were on the other side of the farm road for the "Schmeid Rd." site, the "Bt" and the "Trench" plots. In the "Admire" treatment at the "Schmeid Rd. site" beetles were released directly next to the first row of potatoes. At the "Cemetery" site, Colorado potato beetles were released on the edge of the hedge row across from the plots. Kocide DF (2 LB/A, 30 GPA) was sprayed on rows 41, 42 and 43 of the "Trench" plot at the "Schmeid Rd." site with a hand-held CO2 sprayer on 26 Jun and 30 Jul, 1996 (1 day before beetles were released). Beetles were released at the release sites on 27 Jun. and 30 Jul 1996. Several hours after release, dead beetles at the release site were counted and removed. Potatoes were sampled 1, 3 and 7 (second release only) after release. For the first release, 15 ft of every other row in the first 40 rows of potatoes was searched in each plot for marked beetles. Very few of the marked beetles were found in the potatoes on the first and the third day after release (Table 1). The majority of marked beetles found were in the first row of potatoes (46 out of 56 [82.1%]). Fifty-one beetles were found in the first five rows, and all beetles were found in the first 20 rows of potatoes. There was no discernible difference in beetle distribution between treatments (probably due to the low numbers of marked beetles recaptured). A number of marked beetles were found in the trench, but this did not affect the numbers found in the plots, for this release Table 1. Number of marked Colorado potato beetles released and recaptured in different plots. Release 1 (27 Jun 1996) Site Plot No. Beetles Released Cemetery Cemetery Trench Bt 309 313 Schmeid Rd.Schmeid Rd. Bt 316 Schmeid Rd. Admire 385 Trench 313 1 Day After Release (28 Jun 1996) Site Plot In Plot Cemetery Cemetery Trench Bt 2 8 0.6% 2.6% In Plot Schmeid Rd.Schmeid Rd. Bt 5 1.6% Trench 16 (5.1%) Schmeid Rd. Admire 15 (3.9%) In Trench 12 0 0 3 Days After Release (1 Jul 1996) Site Plot In Plot In Trench Cemetery Cemetery Trench Bt 1 0 6 0 Schmeid Rd. Bt 2 0 16 Schmeid Rd. Trench 1 1 0 Schmeid Rd. Admire 6 0 The method of searching for marked beetles was modified for the second release. At the "Cemetery" site, 3 different people each sampled 30 ft of row (90 ft of potato row total) in each plot. On 31 Jul (1 day after release), each person sampled rows 1,2,3,5,10,15 and 40. On 2 Aug (3 days after release), and on 6 Aug (7 days after release), each person sampled rows 1,2,3,4,5,7,10,20,40 and 43. At the "Schmeid Rd." site, 4 different people each sampled 20 ft of row (80 ft total) in each plot. On 31 Jul (1 day after release), each person sampled rows 1,2,5,10,15 and 40 from the "Bt" and the "Trench" plot . We were unable to complete sampling of the "Admire" plot on this day because aerial pesticide application of the field began before we were through. On 2 Aug (3 days after release) and 6 Aug (7 days after release), each person sampled rows 1-5, 7,10,20,40 and 43. Table 2. Number of marked Colorado potato beetles released and recaptured in different plots. Release 2 (30 Jul 1996) Site Plot No. Beetles Released Cemetery Cemetery Bt Trench 518 420 Schmeid Rd.Schmeid Rd. Bt 555 Schmeid Rd. Admire 400 Trench 578 Recaptured 1 Day After Release (31 Jul 1996) Site Plot In Plot Cemetery Cemetery Trench Bt 62 5 12.0% 1.2% Schmeid Rd. Bt 72 13.0% In Plot In Trench In Trench 65 12.5% In Other Plots* 3 In Other Plots* 0.6% 94 22.4% 5 1.2% 0 0.0% 0 0.0% Recaptured 3 Days After Release (2 Aug 1996) Site Plot In Plot Cemetery Cemetery Trench Bt 5 23 1.2% 4.4% Schmeid Rd. Bt 73 13.2% In Plot Schmeid Rd. Trench 11 1.9% Schmeid Rd. Admire Not Sampled Not Sampled 37 6.4% 17 2.9% Not Sampled Not Sampled Not Sampled Not Sampled Schmeid Rd. Trench 5 0.9% Schmeid Rd. Admire 95 23.8% In Trench In Trench 4 0.8% In Other Plots* 5 In Other Plots* 1.0% 12 2.9% 9 2.1% 2 0.4% 1 0.2% 2 0.4% 18 3.1% 0 0.0% 0 0.0% Cemetery Cemetery Trench Bt 1 3 3 5 0 1 Recaptured 7 Days After Release (6 Aug 1996) Site Plot In Plot In Trench In Other Plots* * Beetles released into "Trench” plots were found in potatoes in the "Bt" plots and beetles released into "Bt” plots were found in the "Trench” plots. No beetles that were released into the "Bt” or "Trench" plot were found in the "Admire" plot. Schmeid Rd.Schmeid Rd. Bt 2 2 0 Schmeid Rd. Admire 14 0 0 Trench 1 0 1 More marked beetles were found in the potatoes in the "Bt" plot than the "Trench" plot at both sites, 1, 3, and 7 days after release (Table 2). This difference was probably due to the trench, in which many of the marked beetles were found. In general the trench captured more beetles that had been actually released into the "Trench" plot, but it also captured a good number of marked beetles that had been released in the adjacent "Bt" plot (at least 75 ft from the trench). This may indicate that there is a good deal of beetle movement along the edges of potato fields. This is further supported by the finding that more beetles that were released into the "Trench plot" were found in the "Bt" plot than vice versa. Beetles may walk along the edge of the trench. A longer trench would minimize this problem. Table 3. Distribution of marked Colorado potato beetles recaptured in potatoes after second release (30 Jul 1996) Recaptured 1 Days After Release (31 Jul 1996) Site Plot Row No. 1 2 3 4 5 >5 Cemetery Cemetery Trench Bt No Beetles Found No Beetles Found 51 4 1 7 0 2 0 0 0 1 1 (row 40) 0 Schmeid Rd. Schmeid Rd.Schmeid Rd. Bt No Beetles FoundTrench No Beetles Found Not Sampled Not Sampled Not Sampled Not Sampled Not Sampled Not Sampled 64 8 0 0 0 0 11 0 0 0 0 0 Admire No Beetles Found Schmeid Rd. Schmeid Rd. Bt No Beetles FoundTrench No Beetles Found Schmeid Rd. Admire No Beetles Found Recaptured 3 Days After Release (2 Aug 1996) Site Plot Row No. 1 2 3 4 5 >5 Cemetery Cemetery Trench Bt No Beetles Found No Beetles Found 16 2 1 2 1 1 (Row 7) 1 0 2 2 0 0 4 0 1 0 0 0 89 4 1 1 0 0 47 6 5 3 5 7 (4 in row 7) (3 in rw 10) The highest proportion of marked beetles recaptured in the potatoes were in the "Admire" plot. This may have been a result of the beetles being released closer to the "Admire" plot than to the other two plots. The distribution of beetles in the potatoes may have been affected by treatment (Table 3). Although the majority of marked beetles found were on the first few potato rows, beetles were more widely distributed through the "Bt" plot than through the "Trench" and "Admire" plots. Crop rotation systems for controlling Colorado potato beetle During 1996 we conducted the second and final year of a study investigating the effects of crop rotation on Colorado potato beetle control. In both 1995 and 1996, large plots were set up at the same location on the Montcalm Potato Research Farm, Entrican, MI and the Collins Road Entomology Research Facility, E. Lansing MI. Plots were 50 ft x 100 ft at Montcalm and 50 ft x 140 ft at Collins Road. Plots were divided into subplots (50 X 50 ft at Montcalm and 50 x70 ft at Collins Road). Treatments included: potato and seed corn subplots and potato and seed corn interplanted with rye grass subplots. At Montcalm a third treatment consisting of two potato subplots was included (continuous potatoes). The positions of the subplots in 1996 were reversed from that of 1995—i.e., the 1996 corn subplot was in potatoes in 1995 and vice versa. Treatments were replicated four times and arranged in a randomized complete block design. The objective of this study was to compare Colorado potato beetle movement between subplots and the abundance of beetles and predators among different rotation treatments. Colorado potato beetle movement. To measure Colorado potato beetle flight, flight intercept traps were set up between subplots in each plot on 28 May at the Montcalm Farm only. These traps consisted of a slick, yellow, vertical, plastic panel, supported by wooden posts. Beetles flew into the panel, and slid down into a trough filled with soapy water. Each trap had two troughs, one on each side of the panel, so flight from each subplot could be distinguished. Troughs were checked regularly, and any beetles found in them were counted and removed to be brought to the lab and sexed. Troughs were checked every few days from May 29 through 1 July 1996. The first beetles were caught in traps on 3 Jun. We had repeated problems with the trough in plot 4 West leaking, and this subplot was eliminated from all flight trap analysis. Also, the trough in plot 12 West started leaking as of 24 Jun, and we were unable to repair the leak. Therefore, the number of beetles caught in each flight trap through 20 Jun includes plot 12 West while the number of beetles caught throughout the entire season does not include plot 12 West. Few Colorado potato beetles were caught in flight intercept traps (Table 4). There was no apparent difference in the number of beetles caught or the percentage of those caught that were female between west-facing and east­ facing traps, indicating no directional bias in flight. Fewer beetles were found in traps in corn & rye plots, but this difference was not significant. In most cases, most beetles caught in flight intercept traps were female, and this is especially true of traps facing potato subplots. To measure Colorado potato beetle movement between subplots, we collected, marked and released beetles in the non-potato side of each subplot. This simulates the emergence of overwintering beetles in a rotated potato field. Beetles were collected from the Montcalm Research Farm and other locations throughout Michigan, and were brought back to the lab and marked with paint pens (DecoColor, Uchida of America, Corp.). Beetles were then released into the non-potato subplot (or one of the potato subplots for the continuous potatoes treatment). The color and pattern of the marking denoted the release date and the plot the beetles were released into. Beetles were released at Montcalm on 13 and 24 Jun and at Collins Road on 20 and 26 Jun. Table 4. Mean number of Colorado potato beetles caught in flight intercept traps in different treatments through 20 Jun and through 1 Jul 1996. Through 20 June Total Number Caught Total Number Caught Mean 0.9 1.1 Std. Err. 0.4 0.4 Total Number Caught Mean Total Number Caught Std. Err. % Females Total Number Caught 72.7 83.3 % Females Total Number Caught Side__________ East West Side Treatment Corn & Rye Corn & Rye Corn & Rye Corn Corn Potatoes Potatoes Corn Potatoes Potatoes 0.3 0.5 1.5 1.3 1.1 0.3 0.3 1.0 0.3 0.5 0.0 100.0 66.7 80.0 88.9 Through 1 July Total Number Caught Total Number Caught Std. Err. Side__________ East West Mean 1.8 1.4 Total Number Caught % Females 0.5 0.5 61.9 71.4 Treatment Corn & Rye Corn & Rye Side Corn & Rye Corn Corn Potatoes Potatoes Corn Potatoes Potatoes Total Number Caught Mean Total Number Caught Std. Err. % Females Total Number Caught 1.0 1.0 2.0 1.8 1.8 0.6 0.6 1.4 0.3 0.5 0.0 33.3 62.5 57.1 92.9 The potato subplots were searched regularly for marked and unmarked Colorado potato beetles. The number and marking of any beetles found was recorded, but the beetles were not removed. For the first few samples at each location, 4 plants per row were searched. These samples were taken on 10, 12 and Jun at Montcalm and 20, 21 and 24 Jun at Collins Rd. For the last two samples at each site, 15 feet of every other row of potatoes were searched. These samples were taken on 25 and 28 Jun at Montcalm and 27 Jun and 1 Jul at Collins Rd. Few marked beetles were recaptured in the potatoes (Table 5). There were no significant differences between treatments. At Montcalm, the majority of marked beetles recaptured were found in the continuous potatoes. However, almost all of these were found in the same subplot they were released into. The mean number of unmarked adults and egg masses per plot varied considerably (Table 6). There were no real differences among treatments. Table 5. Percentage of marked beetles released into the non-potato subplot in each treatment that were recaptured in potatoes. Montcalm Released 13 Jun % Recaptured 14-Jun Released 24 Jun 24 Jun Released 25 - Jun % Recaptured 28 - Jun % Recaptured 1.0 4.0 4.5 1.5 1.2 1.0 2.9 1.5 6.9 Released 20 Jun Released 26 Jun Jun Released 26 21 - Jun % Recaptured 24 - Jun Released 20 Jun % Recaptured % Recaptured 27-Jun 1 Jul % Recaptured 0.4 1.9 2.3 1.1 0.8 1.6 6.6 4.1 Treatment Corn Corn & Rye Potatoes Collins Rd. Treatment Corn Corn & Rye Treatment Corn Corn & Rye Potatoes Collins Treatment Corn Corn & Rye Table 6. Mean of total number of Colorado potato beetle Adults and Egg masses counted in potato plots. Montcalm 12-Jun Adults 25.3 21.3 15.7 20 - Jun Adults 6.3 1 1.8 12-Jun Eggs 1.7 1.3 2.3 20 - Jun Eggs 15 8.3 14-Jun Adults 23.8 14.3 17.0 21 - Jun Adults 16.5 18.3 14-Jun Eggs 9.8 8.5 9.0 24-Jun Adults 9.8 1 3 25 - Jun Adults 23.3 28.3 28.3 28 - Jun Adults 14.3 23.3 20.8 27-Jun Adults 15.5 8.8 1-Jul Adults 7.5 7.8 Abundance of Colorado potato beetles and predators. The number of egg masses per plant were counted while searching for marked and unmarked beetles (see above) on 12 and 14 Jun at Montcalm and on 20 Jun at Collins Rd. Four plants per row in each plot were searched. Later, we sampled the number of eggs in various treatments and assessed egg predation. For first generation eggs, the number of egg masses were counted on 10 plants per plot (1 each in rows 1,2,3,5,7,9,11,13,15 and 17). One egg mass on each plant was flagged by tying loosely a piece of flagging tape around the leaf petiole. If a plant had no egg masses on it, other plants in the same row were inspected until an egg mass was found, and this was flagged. Flagged egg masses were checked at 2-4 day intervals. Eggs were classified as: unhatched, hatched (small larvae on leaf and egg mass broken up), chewed, collapsed (many eggs collapsed) sand blasted (broken up and pieces of soil in the remnants) or gone (all remnants of egg mass gone). First generation egg masses were counted and flagged at Montcalm on 20, 24 and 27 Jun and on 21, 25 and 28 Jun at Collins Rd. Second generation eggs were more scarce, and 5 egg masses per plot were flagged on 29 Jul at Collins Rd. Ten egg masses per plot were flagged at Montcalm on 5 Aug, and were assessed for predation several days later. These data are still being analyzed. To assess the abundance of Colorado potato beetles and predators, several sampling techniques were used. Entire plants were searched for Colorado potato beetles and predators at both locations three times during the season. Two plants per row in the same four rows in each potato subplot (one subplot in the continuous potatoes treatment) were searched. These “whole plant samples” were taken on 18 and 25 Jul and 1 Aug at Collins Rd. and on 19 Jul and 1 and 7 Aug at Montcalm. These data are still being analyzed. In addition, we vacuumed plants in each potato subplot (both subplots in the continuous potatoes treatment) using a modified leaf-blower. Potatoes in row were vacuumed thoroughly for 15 seconds. Arthropods were trapped in a nylon knee-high stocking, which was emptied into a plastic bag. Three of these samples were taken per plot. Bags were marked and then placed in a freezer; the samples were counted and sorted later. Vacuum samples were taken at Collins Rd. on 25 Jun, and 2, 15, and 22 Jul. Vacuum samples were taken at Montcalm on 26 Jun and 3,16, and 23 Jul. These data are still being analyzed. To sample for predators, pitfall traps were made from 8 dram glass vials, half filled with 50 % ethylene glycol. Ten traps were placed in each subplot by making a hole in the ground with a turf-borer and inserting the vial up to its rim. Pitfalls were placed between rows in the same locations in each subplot. Pitfalls were placed in plots on 20 Jun at Collins Rd. and were removed on 27 Jun. Pitfalls were placed in plots on 26 Jun at Montcalm and were removed on 3 Jul. A second set of pitfalls was placed in plots at Montcalm on 1 Aug and were removed on 8 Aug. Shortly after the pitfalls were removed from the plots, they were strained and the arthropods were placed in 70% ETOH. Arthropods were sorted and counted later. These data are still being analyzed. To assess parasitism by Tachinid flies, Myiopharus sp., fourth instars found “wandering” on the soil prior to pupation were collected on 8 Jul at both locations and were returned to the lab. Larvae were placed on the top of clay pots filled with potting soil, up to 50 larvae per pot, and were provided with food. The pots were covered with fiberglass screening secured with a rubber band. Larvae were kept separated by the plot they were collected from. Pots were checked daily, dead larvae were removed, and fresh potato foliage was added. When all larvae had entered the soil, the foliage was removed. Pots were checked daily for emergence of adult Colorado potato beetles or Tachinid flies. At 17 days after all larvae had entered the soil, the pot was searched for remaining pupae or flies. These data are still being analyzed. Insecticide Efficacy Tests for Colorado potato beetle control Fifteen insecticide treatments were tested at the MSU Montcalm Research Farm, in Entrican, MI, for control of Colorado potato beetles (CPB). ’Snowden' potatoes were planted 12 inches apart with a 34 inch row spacing on 9 May. Treatments were replicated four times in a randomized complete block design. Plots measured 40 ft long and were three rows wide. There was at least 6 ft of bare ground in between the plots and 5 ft of untreated potatoes between the plots in the same rows (see attached map). The Mocap treatment was applied in furrow at planting but due to rain, all of the rows had to be closed up before the Admire was applied. The Admire plots were then dug up the next day to expose the seed pieces and the Admire was applied. The first foliar treatment was applied, at 25% CPB hatch, on 27 Jun using a tractor-mounted sprayer (30 gal/A, 40 psi). Subsequent first generation CPB sprays were applied on 4 and 11 Jul. Insecticide effectiveness was determined by counting the number of CPB on two randomly chosen plants from the middle row of each plot on 24 Jun., 2, 9 and 16 Jul. Each plot was assessed for percent defoliation on 15 Jul. and 13 Aug. Because of poor stand, yield varied considerably among plots, and results are not included in this report. Overall the CPB pressure was very low this year (Table 8). Only two of the weekly counts showed any significant differences but both small and large larvae showed seasonal differences. Admire, the high rate of AC303630, and some of the EXP60145A treatments provided the best control. Table 7. Mean defoliation ratings Treatment Trigard 75WP Trigard 75WP followed by Trigard 75WP AC303630 2SC AC303630 2SC* AC303630 2SC* & Asana XL AC303630 2SC* & Provado 1.6F Admire 2F 3 & AC303630 2SC 4 EXP60145A 1.67SC** EXP60145A 1.67SC* EXP60145A 1.67SC & Sevin EXP60145A 1.67SC & Dimethoate Novodor Admire 2F 3* Admire 2F 3 & Monitor 4L 3 Admire 2F 3 & Mocap l0G 2 Asana & Rate 140 g ai/Ha 210 g ai/Ha 140 g ai/Ha 0.1 lb ai/A 0.2 lb ai/A 0.05 lb ai/A 4.8 fl oz/A 0.05 lb ai/A 3.8 fl oz/A 1.3 fl oz/1000 ft 0.075 lb ai/A 0.025 lb ai/A 0.050 lb ai/A 0.025 lb ai/A 1.0 lb ai/A 0.025 lb ai/A 1.0 pt/A 3.0 qt/A 0.9 fl oz/1000 ft 0.9 fl oz/1000 ft 1.5 pt/A 0.3 fl oz/1000 ft 2.1 lb/1000 ft 9.6 fl oz/A Mean % Defoliation 1 foliation Mean % De 15 July 8.8 abcd 7.8 abcde 6.2 abcde 0.7 cde 6.7 abcde 13 Aug Y 25.0 b 22.5 b 22.5 b 13.3 b 28.3 b 2.3 bcde 16.7 b 0.8 cde 15.3 b 0.5 cde 2.0 cde 4.0 abcde 10.0 b 23.3 b 25.0 b 3.0 abcde 14.8 b 6.8 abcde 5.3 abcde 0.0 e 22.5 b 11.7 b 10.3 b 0.3 de 3.8 b 10.0 abc 25.0 b Piperonyl Butoxide(PBO) 8.0 fl oz/100 gal Empty table cell Untreated* Untreated**empty table cell Means within a column followed by different letters are significantly different (P<0.05,Tukey’s HSD; a=0.05) Y Defoliation % taken from green stems 18.3 a 15.0 ab 70.0 a 27.5 b * Analysis calculated from 3 plots instead of 4 plots ** Analysis calculated from 2 plots instead of 4 plots 1 Data transformed for analysis with acrsin (x)^1/2 2 Treatment applied in furrow at planting 3 Treatment applied to second generation CPB Table 8. Seasonal mean number of first generation CPB Treatment Trigard 75WP Trigard 75WP followed by Trigard 75WP AC303630 2SC AC303630 2SC* AC303630 2SC* & Asana XL AC303630 2SC* & Provado 1.6F Admire 2F+ & Rate 140 g ai/Ha 210 g ai/Ha 140 g ai/Ha 0.1 lb ai/A 0.2 lb ai/A 0.05 lb ai/A 4.8 fl oz/A 0.05 lb ai/A 3.8 fl oz/A 1.3 fl oz/1000 ft AC303630 2SC inf. EXP60145A 1.67SC** EXP60145A 1.67SC* EXP60145A 1.67SC & Sevin EXP60145A 1.67SC & 0.075 lb ai/A 0.025 lb ai/A 0.050 lb ai/A 0.025 lb ai/A 1.0 lb ai/A 0.025 lb ai/A Dimethoate Novodor Admire 2F +* Admire 2F + & Monitor 4L inf. Admire 2F + & Mocap 10G + Asana & Piperonyl Butoxide(PBO) 1.0 pt/A 3.0 qt/A 0.9 fl oz/1000 ft 0.9 fl oz/1000 ft 1.5 pt/A 0.3 fl oz/1000 ft 2.1 lb/1000 ft 9.6 fl oz/A 8.0 fl oz/100 gal Mean number of CPB per plant ± SEM Egg masses 0.28 ± 0.09 a 0.44 ±0.15 a Mean number of CPB per plant ± SEM Mean number of CPB per plant ± SEM Small larvae 1.50 ± 0.33 abcd 1.06 ±0.53 abcd 0.06 ± 0.04 a 1.13 ± 0.44 bcde 0.88 ± 0.45 abcde 0.06 ± 0.04 a Large larvae Mean number of CPB per plant ± SEM Adults 0.19 ±0.11 a 0.29 ± 0.15 a 0.33 ±0.11 a 1.28 ± 0.74 bcde 0.97 ± 0.31 abc 0.13 ± 0.07 fg 4.17 ± 2.31 abc 0.08 ± 0.04 fg 2.04 ± 0.76 abc 0.06 ± 0.04 a 0.08 ± 0.04 a 0.00 ± 0.00 a 0.13 ± 0.07 a 0.88 ± 0.25 defg 0.88 ± 0.36 bcdef 0.04 ± 0.04 a 0.19 ± 0.08 a 0.06 ± 0.04 fg 0.19 ± 0.08 efg 0.19 ± 0.06 a 0.31 ± 0.19 a 0.21 ± 0.15 a 0.16 ± 0.03 a 0.00 ± 0.00 a 1.44 ± 1.31 efg 0.00 ± 0.00 a 1.00 ± 0.66 defg 0.91 ± 0.52 cdef 0.72 ± 0.18 abcde 0.06 ± 0.04 a 0.00 ± 0.00 g 0.17 ± 0.17 fg 0.34 ± 0.13 a 1.88 ± 0.60 abc 0.25 ± 0.11 defg 0.00 ± 0.00 a 0.16 ± 0.12 a 0.08 ± 0.08 a 0.03 ± 0.03 a 2.06 ± 0.67 ab 0.63 ± 0.51 efg 0.00 ± 0.00 g 1.88 ± 0.89 a 0.00 ± 0.00 a 0.83 ± 0.42 cdefg 0.08 ± 0.08 a 0.06 ± 0.06 fg 0.16 ± 0.08 a 0.03 ± 0.03 a 0.06 ± 0.04 fg 0.09 ± 0.06 fg 0.16 ± 0.08 a 0.06 ± 0.04 a 3.44 ± 1.18 a 1.94 ± 0.96 a 0.03 ± 0.03 a 0.13 ± 0.07 a 0.00 ± 0.00 a Empty table cell Empty table cell Untreated* Untreated** 1.63 ± 0.19 bcde 2.25 ± 0.81 ab 3.44 ± 2.56 bcde 3.06 ± 0.31 abc Means within a column followed by diferent letters are significantly different (P<0.05,Tukey’s HSD; a=0.05) Data transformed for analysis with log (x+1) * Analysis calculated from 3 plots instead of 4 plots **Analysis calculated from 2 plots instead of 4 + Treatment applied in furrow at planting inf. Treatment applied to second generation CPB 0.17 ±0.08 a 0.31 ± 0.31 a Funding Fed. Grant/ACE/Industry CHEMICAL CONTROL OF POTATO LATE BLIGHT 1996 W.W. Kirk, B. Kitchen, J.M. Stein, N.M. Kirk and R. Nobis Department of Botany and Plant Pathology Room 35 Plant Biology Building, Department of Botany and Plant Pathology Michigan State University, East Lansing, MI 48824, USA INTRODUCTION Several spray trials were carried out at the MSU Muck Soils Experimental Research Farm, Bath, MI. A selection of these trials are described in this report. Fungicides were applied as a protectant program according to protocols defined by the sponsors (outlined in results tables). The spray application timings used in one trial were delayed until late blight had been introduced or had become established throughout the experimental block. The objective of the protectant programs was to evaluate the comparative efficacy of several fungicides compared to standard programs and to establish dose responses for chemicals as required. The containment programs were initiated to evaluate the ability of different fungicides to control established late blight in the field. The efficacy of the fungicides registered under the Section 18 applied prior to and after the establishment of disease was compared with other treatments. METHODS Potato plots were planted with Snowden cut seed using a pick-type planter on 30 May 1996 into two rows by 50 foot plots (34 inch row spacing) and hilled on 23 June. Fertilizer was drilled into plots before planting, formulated according to results of soil tests. Additional nitrogen (28% N, to give 28 lb N/acre) was applied to the growing crop along with an irrigation on 26 July. Maximum, minimum and average air and soil (1/2 inch deep) temperatures; high, low and average percent relative humidity; amounts of precipitation (including irrigation) and leaf wetness periods were recorded for each day by a SENSOR weather station (available on request). Sprays were applied with a ATV-mounted R&D boom sprayer operated at 80 PSI at a ground speed (2.7 mph) calculated to deliver 25 gallons of liquid per acre. The plots were sprayed with three XR11003VS nozzles per row; two nozzles placed on both sides of each row at a 45-degree angle and one placed directly over the row for increased foliar surface coverage. The sprayer was calibrated several times during the spray season (10 July-22 Aug.) and all calibrations were in close agreement. All treatments for both trials were replicated four times in a randomized block design. Treatments together with rates of application (amount of formulation per acre) are shown in the tables. All trials were inoculated with spore suspensions of Phytophthora infestans US8/A2 mating strain. Inoculations were carried out in the late afternoon or evening hours on days when conditions were favorable for disease development. The center and outside double rows of each block along with a five foot central section of each block was inoculated with spore suspensions (suspensions contained about 500,000 sporangiophores/ml) on 23 July. The block containing trial 12 was completely inoculated to allow even disease development. Irrigation was applied on 22 July (0.8 inch), 4 August (1.0 inch) and 15 August (0.2 inch). All blocks were soaked for about one hour during dry days to maintain constant leaf wetness after inoculation and after disease had become established. A permanent irrigation system was established prior to the commencement of fungicide sprays. Fungicide sprays began on 10 July and ended on 22 August (7 applications or less according to protocols). Sprays were applied weekly. In the containment trial, the first spray was applied 72 hours after inoculation with the spore suspension for timing a, when foliar infection was about 5% (timing b) and 15% (timing c). Foliar infections were estimated visually. Plots in sections for timing a and b received only three applications at seven day intervals but plots in the section for timing c received only two applications. (This method is not recommended for disease management and was followed for experimental reasons). Herbicides and insecticides were applied as shown in Tables a and b. Table a. Herbicide applications (rates are formulation per acre) Herbicides applied Rate/acre Dual 8E Basagran Poast Diquat 1 qt. 1 qt. 1.5 pt. 1 pt. Table b. Insecticide applications (rates are formulation per acre) Insecticides applied Rate/acre Admire 2 F Sevin 80 S Thiodan 3EC Pounce 3.2EC 20 oz. 1.25 lb. 2.33 pt. 8 oz. Date(s) 23 May 5 Jun. & 3 Jul. 2 Aug. 4 Sep. & 8 Sep. Date(s) 30 May 3 Jul, 25 Jul. 8 Jul., 9 Aug. & 17 Aug. 12 Jul. The plots were visually rated for % foliar late blight infection on 8, 13, and 20 August and 1 September and for % petiole (percentage of petioles infected from a sample of ten plants per plot) and % stem infection (percentage of stem tissue infected from a sample of ten plants per plot) on 2 September. The disease progress was evaluated as the relative area under the disease progress curve. The plots were harvested on 17 - 21 Sep. and individual treatments weighed and graded (protectant trials only). Results and Discussion All fungicide programs in the test delayed the development and reduced the level of foliar late blight infection significantly in comparison with the untreated checks (Tables 1 - 6). No treatments applied in seven day programs gave significantly better disease control than the standard treatment program Bravo WS 6SC or Bravo ZN 4FL. Until the final assessments (9/1 - 38 days after inoculation) no treatment was significantly different from any other. Results, conclusions for individual trials and recommendations are shown on pages opposite the corresponding tables. Trial 1 - Table 1. The efficacy of Acrobat MZ (2.25 lb/a), Curzate M8 +Manzate (1.5 + 0.75 lb/a) and Tattoo C (2.3 pt/a) applied within protection programs was not significantly different when applied three times at seven day intervals measured as foliar disease development, percentage of petioles infected or percentage of the stem infected. The activity of these three fungicides within protection programs was greatly reduced when the interval between the applications was extended to 14 days and none of the three programs gave adequate disease control. The efficacy of Acrobat MZ was numerically decreased by the addition of Latron-B 1956 but slightly improved numerically by the addition of LI700. The programs incorporating the systemic or trans-laminar compounds gave similar levels of disease control to the standard Bravo WS applied on a 7-day spray schedule. No yield differences were recorded between any treatment. Recommendations Acrobat MZ, Curzate M8 and Tattoo C should not be applied at more than a 7-day interval during high disease pressure periods. A program to determine the efficacy of trans-laminar or systemic products applied early, mid and late season may be required to determine if these products have a specific appropriate timing in relation to disease development and canopy development in the field. Table 1. Control of potato late blight with Acrobat MZ, Curzate M8 and Tattoo C fungicides applied in protectant programs at seven day intervals in 1996. % Spray Schedule 1 Chemical Rate Formulation 7/23 4 % foliar late blight 2 8/8 15 dai pints or lbs/acre 1.5 pint 1.5 pint 0.13 1b 1.5 pint 2.25 lb 1.5 pint 2.25 lb 1.5 pint 2.25 lb 0.19 lb 1.5 pint 2.25 lb 0.5 pint 1.5 pint 1.5 lb 0.75 lb 1.5 pint 2.3 pint 1.5pint 2.25 lb 1.5 pint 1.5 1b 0.75 lb 1.5pint 2.3pint 7 day (1st six applns) 7 day to season end 7 day 7 day (final 2 applns) 7 day (first 4 applns) 7 day (next 3 applns) 7 day (first 4 applns) 7 day (next 3 applns) 7 day (first 4 applns) 7 day (next 3 applns) 7 day (first 4 applns) 7 day (next 3 applns) 7 day (first 4 applns) 7 day (next 3 applns) 7 day (first 2 applns) 14 day (next 3 applns) 7 day (first 2 applns) 14 day (next 3 applns) 7 day (first 2 applns) 14 day (next 3 applns) Empty table cell Empty table cell 1. BravoWS6SC BravoWS 6SC + SuperTin 80WP 2. Bravo WS 6SC Acrobat MZ 69WP 3. Bravo WS 6SC Acrobat MZ 69WP 4. Bravo WS 6SC Acrobat MZ 69WP + Latron B-1956 5. Bravo WS 6SC Acrobat MZ 69WP + Ll 700 6. Bravo WS 6SC Curzate M8 72WP + Manzate 75WP 7. Bravo WS 6SC Tattoo C 6.25SC 8. Bravo WS 6SC Acrobat MZ 69WP 9. Bravo WS 6SC Curzate M8 72WP + Manzate 75WP 10 Bravo WS 6SC Tattoo C 6.25SC 11. Untreated 1 applications initiated 7/10/96 and completed by 8/22/96 2 percentage of foliage infected as estimated visually on dates indicated 3 relative area under the disease progress curve 4 inoculation date, 5 numbers followed by same letter are nsd at p = 0.05 (Tukey) 0 0 0 0 0 0 0 0 0 0 0 % foliar late blight 2 % foliar late blight 2 % foliar late blight 2 RAUDPC 3 max =100 petiole infection 8/13 20 dai 1.3a 1.5a 1.8a 2.0a 8/20 27 dai 2.0 b 2.0 b 2.8 b 9/1 % foliar late blight 2 38 dai 8.3 d 2.3 bc 9/2 39 dai 2.0 c 8.3 d 2.1 bc 1.3c 9.0 d 2.6 bc 2.3 bc 4.5 b 19.5 d 4.7 bc 6.3 bc 1.5a 5 0.8a 1.3a 1.8a % stem infection Yield (cwt/acre) Yield (cwt/acre) 9/2 39 dai 0.8 b 0.3 b 0.3 b 1.3 b > 2” diameter Total 451.8a 552.8a 448.1a 534.5 423.6a 526.2a 433.2a 509.0a 0.5a 1.8a 2.3 b 5.5 d 1.7 c 1.0c 0.3 b 463.7a 559.4a 1.3a 1.0a 1.8 b 5.8 d 1.7 c 1.5 c 0.01 b 434.8a 523.4a 0.3a 1.0a 1.3a 0.5a 1.8a 2.8a 1.8a 1.5a 1.8a 2.0a 3.0 b 5.3 d 1.9 c 3.5 bc 1.0 b 464.9a 550.8a 11.3 b 57.0 b 11.5 b 43.8 b 25.3 b 465.3a 553.8a 3.5 b 56.3 bc 9.5 bc 30.0 b 11.0 b 475.8a 577.5a 2.5 b 20.5 c 4.0 bc 21.8 bc 4.3 b 481.2a 597.9a 32.0a 98.0a 22.5a 94.3a 75.0a 379.5a 449.1a Trial 2 - Table 2. The efficacy of Acrobat MZ (2.25 lb/a), Curzate M8 +Manzate (1.5 + 0.75 lb/a) and Tattoo C (2.3 pt/a) applied alone was not significantly different when applied at seven, ten or fourteen day intervals measured as foliar disease development, percentage of petioles infected or percentage of the stem infected. None of these three fungicide treatments applied at a spray interval greater than 7 days gave adequate disease control. The programs incorporating the systemic or trans-laminar compounds gave similar levels of disease control to the standard Bravo WS applied on a 7-day spray schedule. Numerical yield differences were recorded between some treatments but only the Acrobat MZ (10 day), Curzate M8 + Manzate, Tattoo C and Bravo ZN treatments were statistically different from the untreated plots at p = 0.05. Recommendations Acrobat MZ, Curzate M8 and Tattoo C should not be applied at more than a 7-day interval during high disease pressure periods. A program to determine the efficacy of trans-laminar or systemic products applied early, mid and late season and at different spray intervals may be required to determine if these products are more effective at different intervals at different stages of canopy development. Table 2. Control of potato late blight with Acrobat MZ, Curzate M8 and Tattoo C fungicides applied in protectant programs at seven, ten and fourteen day intervals in 1996.. Chemical Spray Schedule 1 Rate Formulation pints or lbs/acre % foliar late blight 2 % foliar late blight 2 % foliar late blight 2 7/23 4 % foliar late blight 2 8/8 15 dai 8/13 20 dai 1. BravoZN 4FL 2.2 pint 2. Acrobat MZ 69WP 3. Acrobat MZ 69WP 4. Acrobat MZ 69WP 5. Curzate M8 72WP + Manzate 75WP 6. Curzate M8 72WP + Manzate 75WP 7.Curzate M8 72WP + Manzate 75WP 8. Tattoo C 6.25SC 2.25 lb 2.25 lb 2.25 lb 1.5 lb 0.75 lb 1.5 lb 0.75 lb 1.5 lb 0.75 lb 2.3pint 9. Tattoo C 6.25SC 2.3 pint 7 day 7 day 10day 14 day 7 day 10 day 14 day 7 day 10 day 10 Tattoo C6.25SC 11. Untreated 2.3pin Empty table cell Empty table cell 14 day 1 applications initiated 7/10/96 and completed by 8/22/96 2 percentage of foliage infected as estimated visually on dates indicated 3 relative area under the disease progress curve 4 inoculation date, 5 numbers followed by same letter are nsd at p = 0.05 (Tukey) 0 0 0 0 0 0 0 0 0 0 0 0.5a 5 0.8a 0.8a 0.8a 0.5a 0.8a 0.5a 0.8a 1.3a 0.8a 1.8a 2.3a 1.3a 2.3a 1.8a 1.8a 1.5a 2.8a 2.3a 1.5a 1.5a 1.8a RAUDPC 3 max =100 % foliar late blight 2 9/1 38 dai 6.8 d 16.3 cd 20.8 cd 62.5ab 6.3 d 2.4 b 4.1 b 5.0 b 11.0 b 2.1 b % petiole infection 9/2 39 dai 4.0 c 5.8 bc 11.5 bc 28.8 b 1.5c % stem infection Yield (cwt/acre) Yield (cwt/acre) 9/2 39 dai 1.0 b 1.5 b 4.5 b 10.5 b 0.5 b > 2" diameter 551.9a 519.6a 533.9a Total 682.8a 627.6ab 647.7a 458.7ab 553.2ab 533.3a 657.5a 8/20 27 dai 4.0 b 5.8 b 6.0 b 6.3 b 3.5 b 6.5 b 36.3 bcd 7.2 b 11.0 bc 2.3 b 501.2a 604.7ab 4.0 b 40.0abcd 7.2 b 11.3 bc 2.8 b 451.4ab 535.7ab 2.3 b 12.0 b 6.5 b 36.3a 5.8 d 34.0 bcd 56.3abc 82.8a 1.9 b 8.3 b 10.1 b 21.3a 0.3 c 8.8 bc 21.3 bc 72.5a 0.3 b 2.3 b 6.5 b 58.8a 522.2a 630.3a 490.1ab 591.5ab 499.1a 393.2 b 596.7ab 469.4 b Trial 3 - Table 3. All treatments were statistically different in comparison with untreated plots in terms of disease development but there were no statistical differences in disease control between any treatments. The efficacy of Manex C8 +Manex (1.5 lb/a + 0.94 pt/a) was numerically inferior to Bravo ZN (2.2 pt/a), Manex (2.4 - 3.2 pt/a) and Manex + SuperTin (2.4 pt/a + 0.16 lb/a) applied at seven day intervals. Polyram applied alone or in combination with SuperTin gave similar levels of disease control but were numerically inferior to the standard treatment (Bravo ZN). The Manex followed by Manex C8 (1.25 lb/a) program gave poorer control than the standard treatments and was probably due to the combination of the reduced amount of systemic and protectant available in the lower rate of Manex C8. SuperTin applied alone (0.16 - 0.23 lb/a) did not give adequate control of late blight and is clearly effective at a precise stage of disease development and requires the protectant component which is supplied in mixture with the EBDC fungicides such as Manex and Polyram. Mankocide (1.8 - 3.0 ib/a) was ineffective against late blight under high disease pressure. The Kocide program also failed to give good initial disease control which allowed disease to become established which the low rate of Manex plus SuperTin failed to contain. All treatments gave numerically improved yield benefits over the untreated plots but only Manex C8 +Manex (1.5 lb/a + 0.94 pt/a) and Manex + SuperTin (2.4 pt/a + 0.16 lb/a) gave statistically significant differences at p = 0.05. Recommendations Manex C8 should not be applied at less than 1.5 lb/a in combination with Manex at ca. 1 pt/a. SuperTin should only be applied in combination with an EBDC. A dose rate response of SuperTin + EBDC should be established to determine phytotoxicity risk and efficacy of higher “rescue” rates of SuperTin. Mankocide should not be recommended for late blight control under high disease pressure situations. The approach to the use of copper-based products in potato late blight programs needs to be re­ evaluated. Table 3. Control of potato late blight with registered protectant fungicides and Manex C8 (active ingredient section 18 registration) applied in protectant programs at seven day intervals in 1996. Yield (cwt/acre) Spray Schedule 1 Yield (cwt/acre) % Chemical % foliar late blight 2 % foliar late blight 2 % foliar late blight 2 RAUDPC 3 max =100 % stem infection petiole infection 8/8 7/23 4 % foliar late blight 2 15 dai 0.3a 5 1.0a 8/13 20 dai 2.8a 2.3a 8/20 27 dai 2.8 b 3.5 b % foliar late blight 2 9/1 38 dai 4.8 b 9.3 b 1.8 b 2.8 b 9/2 39 dai 0.8 b 3.0 b 9/2 39 dai 0.5 b 1.8 b > 2" diameter 484.7a 419.1a Total 581.7ab 501.0ab 0.3a 1.8a 9.3 b 8.8 b 3.8 b 2.5 b 0.8 b 402.6a 488.3ab 0.8a 0.3a 0.8a 0.3a 0.3a 0.5a 0.3a 1.5a 2.0a 1.5a 2.5a 1.5a 2.0a 2.3a 3.0 b 3.5 b 5.3 b 7.3 b 5.0 b 21.5 b 4.5 b 35.5 b 2.5 b 4.8 b 4.0 b 15.0 b 1.9 b 2.3 b 5.2 b 6.7 b 1.6 b 3.6 b 0.8 b 0.3 b 440.4a 554.2ab 1.8 b 0.5 b 516.2a 635.6a 8.5 b 2.8 b 424.9a 524.0ab 13.0 b 2.5 b 417.9a 503.6ab 0.8 b 0.5 b 511.1a 613.8a 7.3 b 1.8 b 416.9a 501.9ab 6.3 b 14.3 b 4.0 b 5.8 b 2.0 b 427.4a 505.8ab 1.0a 2.0a 62.5a 98.3a 29.6a 94.5a 77.5a 325.4a 384.3 b Rate Formulation pints or lbs/acre 2.2 pint 2.0 lb 0.16 lb 0.5 pint 0.1 pint 2.0 lb 0.5 pint 0.1 pint 2.4 pint 3.2 pint 1.5 lb 0.94 pint 0.16 lb 0.23 lb 1.8 lb 3.0 lb 2.4 pint 0.13 lb 2.4 pint 1.25 lb 7 day 7 day 7 day 7 day first 4 applns 7 day to season end 7 day 7 day first 4 applns 7 day to season end 7 day first 4 applns 7 day to season end 7 day 7 day first 4 applns 7 day next 3 applns 7 day first 4 applns 7 day next 3 applns 1.6 pint 2.4 pint 0.13 lb Empty table cell Empty table cell 1. Bravo ZN4FL 2. Polyram 80DF + SuperTin 80WP + Silwet + Bond 3. Polyram 80DF + Silwet + Bond 4. Manex 4FL Manex 4FL 5. Manex C8 72WP + Manex 4FL 6. SuperTin 80WP SuperTin 80WP 7. Mankocide 39DF Mankocide 39DF 8. Manex 4FL + SuperTin 80WP 9. Manex 4FL Manex C872WP 10. Kocide 5.5FL Manex 4FL + SuperTin 80WP 11. Untreated 1 applications initiated 7/10/96 and completed by 8/22/96 2 percentage of foliage infected as estimated visually on dates indicated 3 relative area under the disease progress curve 4 inoculation date, 5 numbers followed by same letter are nsd at p = 0.05 (Tukey) 0 0 0 0 0 0 0 0 0 0 0 Trial 4 - Table 4. All treatments were statistically different in comparison with untreated plots in terms of disease development but there were no statistical differences in disease control between any treatments. There were however clear numerical differences between many of the treatments. The efficacy of Polyram 80DF plus SuperTin (2.0 lb/a +0.16 lb/a), Polyram 80DF (2.0 lb/a), Ensign (1.0 - 1.5 pt/a) and the alternate Polyram 80DF plus SuperTin (2.0 lb/a +0.16 lb/a)/Bravo ZN (2.2 pt/a) was numerically inferior to Bravo ZN (2.2 pt/a) applied in protectant programs at seven day intervals. Champ 2 4.6FL applied at increasing dose rates as the season progressed (1.33 - 2.67 pt/a) gave inadequate disease control in comparison with Bravo ZN applied at seven day intervals. When applied in a programmed approach in combination with Penncozeb 75DF, Champ 2 4.6FL was more effective in combination programs as the initial product in the program. All treatments gave numerically improved yield benefits over the untreated plots but no treatment comparisons were statistically significant different at p = 0.05. Recommendations An increasing rate strategy for all protectant fungicides, such as Polyram 80DF, Ensign 6SC, Penncozeb 75DF and Champ 2 4.6FL should be matched to canopy development and may provide the basis of a strategy for crop protection in varieties with different patterns of foliage development e.g. lower recommended rates in open and determinate varieties and increased application rates in dense canopied indeterminate varieties. Polyram should not be applied at less than 2.0 lb/a alone or in combination with SuperTin (0.16 lb) in a programmed approach for preventative control against potato late blight. Ensign 6SC should not be applied at less than 1.0 (early season) then 1.5 pt/a (after canopy closure) alone in a programmed approach for preventative control against potato late blight. The approach to the use of copper-based products in potato late blight programs needs to be re­ evaluated. Table 4. Control of potato late blight with EBDCs, chlorothalonil-based products and Champ (Copper-based product) fungicides applied in protectant programs at seven day intervals in 1996.. Yield (cwt/acre) Spray Schedule 1 Yield (cwt/acre) Chemical % foliar late blight 2 % foliar late blight 2 % foliar late blight 2 RAUDPC 3 max =100 % stem infection % petiole infection Rate Formulation 9/2 39 dai 0.8 b 2.3 b 2.8 b 2.5 b 6.5 b 9/2 39 dai 0.3 b 0.5 b 1.0 b 1.0 b 1.8 b > 2” diameter Total 424.4ab 512.6ab 431.6a 527.1a 453.2a 543.2a 402.5ab 481.4ab 446.1a 536.0a 1.6 b 2.1 b 2.3 b 2.1 b 4.6 b 1.5a 2.8 b 32.5 b 5.8 b 16.3 b 6.0 b 398.0ab 485.0ab 0.5a 1.3a 4.3 b 14.5 b 3.4 b 6.3 b 1.8 b 390.8ab 451.4ab 0.1a 1.5a 3.3 b 35.0 b 6.1 b 17.8 b 5.8 b 410.4ab 483.3ab 0.3a 1.8a 36.3a 98.5a 26.8a 95.5a 92.3a 320.7 b 378.5 b 7/23 4 % foliar late blight 2 8/8 15 dai 8/13 20 dai 9/1 % foliar late blight 2 38 dai 8/20 27 dai 2.0 b 2.3 b 2.8 b 2.0 b 5.3 b 8.8 b 10.3 b 9.3 b 9.5ab 14.5 b 1.8a 1.8a 1.8a 1.5a 1.5a 0.5a 5 0.3a 0.3a 0.3a 0.3a 1.0a pints or lbs/acre 2.2 pint 2.0 lb 0.16 lb 2.0 lb 1.0 pint 1.5 pint 2.0 lb 0.16 lb 2.2 pint 1.33 pint 2.0 pint 2.67 pint 1.33 pint 2.0 pint 2.0 lb 7 day 7 day 7 day 7 day (to inoculation) 4 7 day to season end 7 day (alternate) 7 day (alternate) 7 day (appln 1-2) 7 day (appln 3-6) 7 day to season end 7 day (appln 1-2) 7 day (appln 3-4) 7 day to season end 1.5 lb 7 day (appln 1-2) 2.0 lb 7 day (appln 3-4) 7 day (appln 5-6) 2.0 pint 7 day to season end 2.67pint Empty table cellEmpty table cell 1. Bravo ZN 4FL 2. Polyram 80DF + SuperTin 80WP 3. Polyram 80DF 4. Ensign 6SC Ensign 6SC 5. Polyram 80DF + SuperTin 80WP Bravo ZN 4FL 6. Champ 2 4.6FL Champ 2 4.6FL Champ 2 4.6FL 7. Champ 2 4.6FL Champ 2 4.6FL Penncozeb 75DF 8. Penncozeb 75DF Penncozeb 75DF Champ 2 4.6FL Champ 2 4.6FL 9. Untreated 1 applications initiated 7/10/96 and completed by 8/22/96 2 percentage of foliage infected as estimated visually on dates indicated 3 relative area under the disease progress curve 4 inoculation date, 5 numbers followed by same letter are nsd at p = 0.05 (Tukey) 0 0 0 0 0 0 0 0 0 Trial 5 - Table 5. All treatments were statistically different in comparison with untreated plots in terms of disease development but there were no statistical differences in disease control between any treatments applied at seven day intervals. Terranil 6SC (1.5 pt/a), Terranil 90DF (1.25 lb/a) and Terranil ZN 4FL (2.13 pt/a) gave very good control of potato late blight when applied at seven day intervals but all were marginally numerically inferior to the standard Bravo WS (1.5 pt/a). The Ridomil-Bravo 81WP program gave excellent disease control and was the same as the standard Bravo WS treatment. The Ridomil Gold program, although numerically inferior to the Ridomil- Bravo program also gave very good disease control. Many treatments gave numerically improved yield benefits over the untreated plots but no treatment comparisons were statistically significant different at p = 0.05. Recommendations An increasing rate strategy for all protectant fungicides, such as Terranil-based and Bravo-based products should be matched to canopy development and may provide the basis of a strategy for crop protection in varieties with different patterns of foliage development e.g. lower recommended rates in open and determinate varieties and increased application rates in dense canopied indeterminate varieties. Ridomil Gold 2.4SC should be recommended as a replacement for Ridomil pre-pack products in a programmed approach for preventative control against potato late blight. Table 5. Control of potato late blight with Ridomil Gold-based fungicides, Terranil products and Bravo ZN fungicides applied in protectant programs at seven day intervals in 1996. Chemical Rate Formulation Spray Schedule 1 1. Bravo WS 6SC 2. Terranil 6SC 3. Terranil 90DF 4. Terranil ZN 4FL 5. Bravo WS 6SC Ridomil-Bravo 81WP Bravo WS 6SC 6. Bravo WS 6SC Ridomil Gold 4EC Bravo WS 6SC 7. Bravo ZN 4FL 8. Untreated pints or lbs/acre 1.5 pint 1.5 pint 1.25 lb 2.13 pint 1.5pint 2.0 lb 1.5 pint 1.5pint 0.2 pint 1.5 pint 7 day 7 day 7 day 7 day 7 day (applns 1-2) 7 day (applns 3, 5 & 7) 7 day (applns 4 & 6) 7 day (applns 1-2) 7 day (applns 3, 5 & 7) 7 day (applns 4 & 6) 2.2 pint Empty table cell Empty table cell 7 day 1 applications initiated 7/10/96 and completed by 8/22/96 2 percentage of foliage infected as estimated visually on dates indicated 3 relative area under the disease progress curve 4 inoculation date, 5 numbers followed by same letter are nsd at p = 0.05 (Tukey) % foliar late blight 2 % foliar late blight 2 % foliar late blight 2 7/23 4 % foliar late blight 2 8/8 15 dai 8/13 20 dai 0 0 0 0 0 0 0 0 0.5a 5 0.5a 0.5a 0.1a 0.3a 0.1a 0.3a 0.3a RAUDPC 3 max =100 % petiole infection % stem infection Yield (cwt/acre) Yield (cwt/acre) 8/20 27 dai 1.8 b 2.0 b 2.8 b 1.3 b 2.0 b 9/1 % foliar late blight 2 38 dai 4.0 c 9.8 c 8.3 c 6.8 c 3.8 c 1.4 c 2.3 c 2.2 c 1.4 c 1.3 c 9/2 39 dai 1.8 c 2.8 c 2.3 c 2.5 c 0.5 c 9/2 39 dai 1.0 b 1.5 b 0.3 b 0.5 b 0.3 b > 2" diameter 387.8a 336.5ab 364.8a 406.4a 386.1a Total 464.7a 430.4ab 431.3ab 480.3a 456.6a 1.5a 1.5a 1.5a 1.0a 1.5a 0.8a 2.8 b 7.8 c 1.9 c 2.3 c 1.0 b 342.8ab 413.3ab 1.8a 2.3a 4.5 b 61.3a 5.8 c 92.8a 2.2 c 28.4a 1.3 c 82.5a 0.5 b 76.3a 361.8ab 241.2 b 442.7a 297.0 b Trial 6 - Table 6. All treatments were statistically different in comparison with untreated plots in terms of disease development but there were no statistical differences in disease control between any treatments applied at seven day intervals even when programs were initiated 72 hours after inoculation. There were no numerical differences between any of the IB 17022 4SC applied on a seven day interval treatments and initiated 72 hours after inoculation. The efficacy of IB 17022 4SC (0.11 - 0.18 pt/a) applied in containment programs against potato late blight was excellent and matched the standard Acrobat MZ 69WP (2.25 lb/a). IB 17022 4SC applied in combination with Silwet did not affect the control of late blight in this trial. Quadris 80WDG showed a clear positive dose response with increasing rate of application and gave best disease control at 0.31 lb/a applied either season long or alternating with Bravo WS (1.5 pt/a). Fluazinam 5SC (1.0 pt/a) gave excellent disease control applied at a 7 day interval. Many treatments gave numerically improved yield benefits over the untreated plots but no treatment comparisons were statistically significant different at p = 0.05. Recommendations An increasing rate strategy for all protectant fungicides, such as Fluazinam 5SC should be matched to canopy development and may provide the basis of a strategy for crop protection in varieties with different patterns of foliage development e.g. lower recommended rates in open and determinate varieties and increased application rates in dense canopied indeterminate varieties. The potato late blight containment properties of IB 17022 4SC should be re-evaluated. A dose response for Quadris 80WDG should be re-evaluated and the contribution of the product within a programmed approach for preventative control against potato late blight should be established. Table 6. Control of potato late blight with experimental fungicides (IB 17022, fluazinam and Quadris) applied in protectant and disease containment programat at seven day intervals in 1996. Chemical Rate Formulation Spray Schedule 1 % foliar late blight 2 % foliar late blight 2 % foliar late blight 2 RAUDPC 3 max =100 % petiole infection % stem infection Yield (cwt/acre) Yield (cwt/acre) 7/23 4 % foliar late blight 2 8/8 15 dai 8/13 20 dai 8/20 27 dai 9/1 % foliar late blight 2 38 dai 9/2 39 dai 1.0a 5 1.5a 1.3a 1.0a 1.5a 1.5a 2.3a 2.5a 1.5a 1.5a 2.3a 3.0a 2.8a 4.3a 2.0a 2.8a 2.8a 5.8a 7.3 b 7.5 b 8.3 b 6.3 b 7.5 b 21.3 b 2.3 b 2.9 b 2.2 b 2.1 b 2.5 b 5.3 b 1.8 b 3.0 b 4.3 b 1.8 b 2.8 b 7.8 b 9/2 39 dai 0.3 b 0.8 b 1.8 b 0.5 b 1.0 b 2.3 b > 2" diameter 435.6ab 451.4a 437.0ab 435.5ab 424.4ab 400.5ab Total 512.6a 545.7a 522.9a 528.2a 504.5a 501.9a 1. IB 17022 4SC 2. IB 17022 4SC 3. IB 17022 4SC 4. IB 17022 4SC + Silwet 5. Acrobat MZ 69WP 6. Quadris 80WDG + Bond Bravo WS 6SC 7. Quadris 80WDG + Bond Bravo WS 6SC 8. Quadris 80WDG + Bond Bravo WS 6SC 9. Quadris 80WDG + Bond Bravo WS 6SC 10. Quadris 80WDG + Bond 11. Fluazinam 5SC 12. Untreated pints or lbs/acre 0.11 pint 0.14 pint 0.18 pint 0.14 pint 2.25 lb 0.13 lb 0.1 pint 1.5 pint 0.19 lb 0.1 pint 1.5 pint 0.25 lb 0.1 pint 1.5 pint 0.31 lb 0.1 pint 1.5 pint 0.31 lb 0.1 pint 7 day (72 h after inoc.) 4 7 day (72 h after inoc.) 7 day (72 h after inoc.) 7 day (72 h after inoc.) 7 day (72 h after inoc.) 7 day (alternate) 7 day (alternate) 7 day (alternate) 7 day (alternate) 7 day (alternate) 7 day (alternate) 7 day (alternate) 7 day (alternate) 7 day 1.0 pint Empty table cell Empty table cell 7 day 1 applications initiated 7/10/96 and completed by 8/22/96 2 percentage of foliage infected as estimated visually on dates indicated 3 relative area under the disease progress curve 4 inoculation date, 5 numbers followed by same letter are nsd at p = 0.05 (Tukey) 0 0 0 0 0 0 0 0 0 0 0 0 0.5a 1.8a 4.3a 12.8 b 3.2 b 3.3 b 0.5 b 391.1ab 509.6a 0.3a 1.0a 1.8a 8.8 b 1.9 b 1.5 b 0.5 b 409.1ab 524.9a 0.8a 1.8a 3.0a 6.8 b 2.2 b 1.5 b 0.5 b 467.3a 560.7a 0.5a 0.8a 0.8a 1.3a 1.3a 1.5a 2.8a 2.3a 4.5a 6.3 b 5.8 b 90.8a 1.9 b 1.8 b 14.6a 1.0 b 1.5 b 52.5a 0.5 b 1.8 b 9.5a 465.5a 559.4a 452.6a 343.5 b 541.2a 425.0 a Trial 7 - Table 7a and 7b. This trial was conducted to establish the containment properties of several products and is not a strategy recommended for the effective control of potato late blight. Treatments applied 72 hours after inoculation gave better control than when applied after foliar disease had developed within the treatment block. Applications initiated after disease had developed to 5% within the block were generally ineffective although some treatments did hinder disease progress. When the treatments were delayed until disease had developed to 15% across the treatment block no treatment gave any disease control and were defoliated about 15 days after the first application of fungicide. Curzate M8 72WP plus Manzate 75WP (1.5 + 0.75 lb/a), Acrobat MZ 69WP (2.25 lb/a), Tattoo C (2.3 pt/a) applied alone or in combination with SuperTin 80WP (0.16 lb/a), Ridomil Gold 4EC + Bravo WS 6SC (0.2 + 1.5 pt/a), Polyram 80WP plus SuperTin (2.0 + 0.16 lb/a), Quadris 80WDG (0.31 lb/a) + Bond and IB 17022 4SC (0.18 pt/a) all showed excellent disease containment properties when applied 72 hours after inoculation. The addition of SuperTin made no numerical difference where applied to the trans-laminar/systemic products. Only Champ 2 4.6FL and Mankocide 39DF gave inadequate control of the disease (defined as >10% foliar infection). Where treatments were delayed until disease had established to 5% across the treatment block only Curzate M8 72WP plus Manzate 75WP (1.5 + 0.75 lb/a), Acrobat MZ 69WP (2.25 lb/a), Tattoo C (2.3 pt/a) applied alone or in combination with SuperTin 80WP (0.16 lb/a), showed some disease containment properties (defined as <35% foliar infection). Recommendations In situations where potato late blight has been identified within a crop at levels <1% (or has been confirmed within a potato growing locality) products such as Curzate M8 72WP plus Manzate 75WP (1.5 + 0.75 lb/a), Acrobat MZ 69WP (2.25 lb/a), Tattoo C (2.3 pt/a) applied alone or in combination with SuperTin 80WP (0.16 lb/a) Ridomil Gold 4EC + Bravo WS 6SC (0.2 + 1.5 pt/a) and Polyram 80WP plus SuperTin (2.0 + 0.16 lb/a) may give adequate containment of the disease. It is not recommended that growers wait until disease has been reported within their locality to begin their spray programs. This material was prepared with the support of a grant from the agriculture in Concert with the Environment (ACE) program, which is jointly funded by the U.S. Department of Agriculture, Co-operative State Research, Education and Extension Service and the Environmental Protection Agency program under Co-operative agreement No. 94-COOP-1 - 0809. Any opinions, findings conclusions or recommendations expressed herein are those of the authors and do not necessarily reflect the views of the U.S. Department of Agriculture or the Environmental Protection Agency. Table 7a. Control of potato late blight through plots treated with registered fungicides, section 18 fungicides and experimental fungicides after the introduction of disease into the plots, 1996. Chemical % foliar late blight 1 % foliar late blight 1 timing a % foliar late blight 1 timing b timing c % foliar late blight 1 % foliar late blight 1 7/23 8/13 % foliar late blight 1 timing a 8/20 8/29 % foliar late blight 1 timing a 8/8 timing b 8/20 8/29 % foliar late blight 1 timing b 8/14 % foliar late blight 1 timing c 8/20 8/29 % foliar late blight 1 timing c Rate Formulation pints or lbs/acre Spray Schedule 3 applications Timing a 72 hrs post inoc. Timing b 5% foliar inf'n Timing c 15% foliar inf'n* *= 2 applications 1. Untreated 2. Curzate M8 72WP + Manzate 75WP 3. Acrobat MZ 69WP 4. Tattoo C 6.25 SC 5. Mankocide 39DF 6. Ridomil-Gold 4EC + Bravo WS 6SC 7. Champ 2 4.6FL 8. Curzate M8 72WP + SuperTin 80WP 9. Polyram 80DF + SuperTin 80WP 10. Acrobat MZ 69WP + SuperTin 80WP 11. Tattoo C + SuperTin 80WP 12. Quadris 80 WDG + Bond 13. IB 17022 4SC Empty table cell Empty table cell 1.5 lb 0.75 lb 2.25 lb 2.3 pint 3.0 lb 0.2 pint 1.5 pint 2.67 pint 1.5 lb 0.16 lb 2.0 lb 0.16 lb 2.23 lb 0.16 lb 2.3 pint 0.16 lb 0.31 lb 0.1 pint 0.18 pint 7 day 7 day 7 day 7 day 7 day 7 day 7 day 7 day 7 day 7 day 7 day 7 day 1 percentage of foliage infected as estimated visually on dates indicated 2 = numbers followed by same letter are nsd at p = 0.05 (Tukey) inoc. date 21 dai 28 dai 35 dai 16 dai 28 dai 37 dai 22 dai 28 dai 37 dai 0 0 0 0 0 0 0 0 0 0 0 0 0 0.5a 2 0.8a 0.3a 0.3a 1.0a 0.5a 0.3a 0.5a 0.3a 0.3a 0.5a 0.5a 0.5a 9.8a 1.3a 2.5a 2.3a 3.5a 2.0a 5.3a 1.5a 3.8a 2.3a 1.5a 3.3a 2.8a 73.8a 4.3 b 4.8 b 5.5 b 10.0 b 5.0 b 19.5 b 3.5 b 8.3 b 4.0 b 5.3 b 7.0 b 8.8 b 5.0a 5.0a 5.0a 5.0a 5.0a 5.0a 5.0a 5.0a 5.0a 5.0a 5.0a 5.0a 5.0a 78.8ab 11.3 c 14.0 c 11.3 c 38.8abc 23.3 c 48.8abc 10.5 c 99.0a 22.5 d 22.5 d 26.0 d 77.5abc 55.0 bcd 83.0abc 25.5 d 15.0a 15.0a 15.0a 15.0a 15.0a 15.0a 15.0a 15.0a 86.3a 77.5ab 82.5ab 70.0ab 83.8ab 81.3ab 82.5ab 67.5 b 99.8a 99.3a 99.3a 94.0ab 99.3a 99.3a 99.8a 89.8 b 22.0 c 55.0 bcd 15.0a 78.8ab 98.8a 20.3 c 32.0 cd 15.0a 76.3ab 96.8ab 11.5c 23.3 d 15.0a 78.8ab 95.5ab 28.3 bc 61.0abcd 15.0a 83.8ab 99.3a 22.5 c 60.0abcd 15.0a 86.3a 99.3a Table 7b. Progression of potato late blight through plots treated with registered fungicides, section 18 fungicides and experimental fungicides after the introduction of disease into the plots, 1996. Chemical Rate Formulation Spray Schedule 3 applications Timing a 72 hrs post inoc. 1 Timing b 5% foliar inf'n Timing c 15% foliar inf'n 2 pints or lbs/acre Empty table cellEmpty table cell 1. Untreated 2. Curzate M8 72WP + Manzate 75WP 3. Acrobat MZ 69WP 4. Tattoo C 6.25 SC 5. Mankocide 39DF 6. Ridomil-Gold 4EC + Bravo WS 6SC 7. Champ2 4.6FL 8. Curzate M8 72WP + SuperTin 80WP 9. Polyram 80DF + SuperTin 80WP 10. Acrobat MZ 69WP + SuperTin 80WP 11. Tattoo C + SuperTin 80WP 12. Quadris 80 WDG + Bond 13. IB 17022 4SC 1.5 lb 0.75 lb 2.25 lb 2.3 pint 3.0 lb 0.2 pint 1.5 pint 2.67 pint 1.5 lb 0.16 lb 2.0 lb 0.16 lb 2.23 lb 0.16 lb 2.3 pint 0.16 lb 0.31 lb 0.1 pint 0.18 pint 7 day 7 day 7 day 7 day 7 day 7 day 7 day 7 day 7 day 7 day 7 day 7 day 1 = inoculation 7/23 2 = 2 applications 3 = numbers followed by same letter are nsd at p = 0.05 (Tukey) c:\ofFice\wpwin\muck96\reports\mpictabs.wpd Relative area under the disease progress curve (max = 100) Relative area under the disease progress curve (max = 100) Relative area under the disease progress curve (max = 100) Timing b 36.3a 7.8 d 8.6 cd 8.4 d 22.3abc 15.2 bcd 25.8ab 8.0 d 14.8 bcd 11.5 bcd 9.2 bcd 17.3abcd 15.6 bcd Timing c 33.5ab 31.7ab 32.7ab 29.5ab 33.0ab 32.5ab 32.8ab 28.5 b 31.9ab 31.1ab 31.5ab 33.0ab 33.5ab Timing a 9.5a 3 0.1 c 1.1 c 1.1 c 2.1 c 1.1 c 3.1 c 0.9 c 1.7 c 1.0 c 1.0c 1.6 c 1.6 c Funding Fed. Grant/MPIC PROGRESS REPORT FY 1996 TO THE MICHIGAN POTATO INDUSTRY COMMISSION Title: Control of Colorado Potato Beetle Utilizing Transgenic Potatoes as a Barrier Crop and Treating a Conventional Barrier Crop with Imidacloprid. Investigators: Mark E. Whalon & Michael R. Bush. Pesticide Research Center and Department of Entomology, Michigan State University Cooperator: Ed Grafius. Department of Entomology, Michigan State University Justification: In Michigan state, losses attributed to the Colorado potato beetle, Leptinotarsa decemlineata Say are estimated at $11 million/year or 13% of the gross crop value. CPB has developed resistance to virtually every insecticide used to control it. In our laboratory, we have even selected for CPB resistance to Bacillus thuringiensis (B.t.) insecticides. Last year, Michigan potato growers had two new tactics to control CPB. A novel insecticide, imidacloprid (Admire or Provado, Bayer Corp.) provided exceptional control of CPB throughout Michigan and over 80% of Michigan growers used Admire at planting last year. Transgenic russet burbank potatoes that express the Bacillus thuringiensis (B.t.) endotoxin (Newleaf, Naturemark) will offer yet another new tactic for CPB control. Nevertheless history has demonstrated over and over again, that CPB has the ability to overcome control measures. CPB resistance to B.t. in the field is anticipated. We recommended that researchers integrate B.t.s with other control tactics. We have also have warned growers to treat imidacloprid “like gold” and not to overuse, misuse or rely solely on imidacloprid to control CPB. Many growers have adopted crop rotation as one means to control CPB populations. This project uses B.t.-transgenic russet burbank potatoes and imidacloprid-treated russet burbank potatoes as barrier crops around the main crop of russet burbank potatoes in combination with crop rotation to reduce overwintering CPB from reaching the main crop. Ideally as overwintering CPB pass through the potato barrier crops, they are exposed to the toxic effect of imidacloprid or B.t. and most CPB fail to reach the main crop. Progress by Objectives: 1) To observe and compare adult CPB movement through barrier crop of B.t.-transgenic (Newleaf) potatoes and imidacloprid (Admire) treated potatoes. Studies in the greenhouse revealed that adult CPB moved through a 2- row B.t.-transgenic barrier faster than they moved through a convention potato barrier. When first exposed to the B.t. transgenic potatoes, beetles appeared to feed on the plants and either move on immediately or cease activity for 3 to 4 days and then move on. Over a 7-day period, 33% of the released male CPB died and 42% of the female CPB died when exposed to transgenic plant (compared to 23% male and 15% female mortality in conventional potatoes). CPB oviposition never occurred on the transgenic potatoes even though eggs were found on nearly all conventional potato plants. Studies in the field, supported greenhouse observations. Seven days after release, 80% beetles were found in the first row of each barrier crops. The fewest CPB were found in the transgenic potatoes with 60% of the CPB dead. Three-fold more CPB found were in the Admire- treated plots, but 42% of them were dead. Meanwhile, all CPB found in the untreated, conventional barrier were alive. By the end of July, we had observed very few egg masses or larvae on the transgenic plants and damage was almost nonexistent. Likewise, few egg masses were found on the imidacloprid treated plants. A few larvae were found on the imidacloprid barrier plants but only on the terminal leaves while damage was minimal and confined in the first row of the barrier. In the conventional potato barrier, egg masses and larvae were abundant and damage was apparent and scattered throughout the barrier. 2) To compare adult CPB movement into the main crop after passing through the barrier crops. In the greenhouse, 24 % of the released CPB passed through a 2-row barrier of conventional potatoes into the main crop over a 7-day period. In comparison, over 60% of the CPB passed through a 2-row barrier of transgenic potatoes into the main crop over 7 days. Planting the barrier two weeks in advance of the main crop did not effect these results, presumably because of the low CPB density in the greenhouse study. In the field, we recovered 4.7 % of the 1,500 marked CPB (released in front of the barrier potatoes) in trench traps located between the barrier crop and the main crop. Only 0.1% of CPB released adjacent to the conventional potato barrier passed through 24 rows to be captured in the trench; CPB appeared satisfied with feeding on these potatoes and did not move. Meanwhile, 0.1% of CPB released adjacent to the imidacloprid plot were recaptured in the trench. Presumably, most of these beetles perished in the barrier. However, 9.7% of the CPB released adjacent to the transgenic barrier were captured in the trench and few dead beetles were found suggesting that CPB movement was enhanced when exposed to transgenic plants. Conclusions: Based on plant damage, B.t. transgenic plants provided exceptional control of CPB in the greenhouse and in the field. CPB did not oviposit on these plants, larvae did not survive on these plants and there was some mortality among adults. However, both studies revealed that CPB adult movement was enhanced in transgenic potato crops. Therefore, a B.t.-transgenic barrier would not be an effective resistance management strategy against mobile CPB adults. Potatoes treated with imidacloprid provided control of CPB in the field and was active against adults as well as larvae. Results show that a 24-row barrier of imidacloprid treated potatoes did reduce CPB movement into the main crop by 99.9% at low beetle densities. Adults that reach the main crop may be exposed to other mortality agents such as grower applied insecticides (excluding Provado). This strategy will conserve CPB susceptibility to imidacloprid by exposing only the migrating adults to the toxic effect of imidacloprid. This resistance management strategy will help prolong the market life of imidacloprid and can reduce grower costs (but field monitoring of CPB density in the main crop is advised). Funding Fed. Grant/MPIC PROGRESS REPORT FY 1996 TO THE MICHIGAN POTATO INDUSTRY COMMISSION Title: Screening Green Peach Aphids for Resistance to Imidacloprid and Other Insecticides Used By Michigan Growers in Potatoes. Investigators: Mark E. Whalon & Michael R. Bush. Pesticide Research Center and Department of Entomology, Michigan State University Justification: In 1995, a new systemic insecticide, imidacloprid (Admire® and Provado®, Miles Corp.), was released to potato growers. This insecticide has a new mode of action (a nicotinergic acetylcholine receptor inhibitor, i.e. a nerve poison) that provided many Michigan growers with the only effective means to control Colorado potato beetle (CPB) populations. It is estimated that over 75% of the total potato acreage in Michigan was treated with imidacloprid. Although not the primary target of imidacloprid, this insecticide provides excellent control of green peach aphid (GPA) on potatoes early in the growing season. We anticipate that Michigan growers will continue to rely heavily on imidacloprid to control CPB and GPA, thus subjecting these pests to intense selection pressure. GPA has already demonstrated resistance to over seventy insecticides. This study generated the baseline susceptibility of GPA to imidacloprid. This baseline susceptibility will used by researchers to monitor for and confirm any reports of imidacloprid resistance. Progress by Objectives: 1) To determine base-line susceptibility to imidacloprid for green peach aphid We bioassayed each colony for their response to imidacloprid with a slide-dip technique. Adult aphids were exposed to serial doses of imidacloprid and their mortality assessed 48 hours after exposure. Standard probit-mortality analysis was used to produce an aphid dose-response curve to imidacloprid. The LD50 value of this curve was 8.0 ± 2.2 ppm imidacloprid. 2) To establish diagnostic doses of imidacloprid to screen green peach aphid for resistance. The resulting dose/response curve was analyzed to select diagnostic doses to screen other colonies and field populations. When using the slide-dip technique, researchers should expose GPA to a diagnostic dose of 15-20 ug/ml or 15-20 ppm imidacloprid, and assess mortality after 48 hours. This dose will kill almost all susceptible GPA and survivors are likely to be resistant individuals. Conclusions: Four-fold resistance in GPA to imidacloprid has been reported in Europe. Thus it is advisable that GPA populations in Michigan be screened for resistance with the technique and diagnostic dose reported here. MSU researchers should be contacted immediately if resistance is suspected. By detecting resistance early, we can better manage resistance and avoid a control problem for the green peach aphid in Michigan potatoes and other vegetable crops. Contribution of Amino Acids and Reducing Sugars to Color Development in Potato Chips V. Chonhenchob, J.N. Cash and R. Brook Funding Fed. Grant Introduction Browning or darkening of potato chips has received a great deal of study because consumers usually equate light colored potato chips with good quality. This dark color formed by frying potato slices into chips is due to the Maillard reaction involving reducing sugars, amino acids and high temperatures. Most previous studies have focused on the effect of sugar (reducing and non-reducing) concentrations in potato tubers at harvest or during storage and its relationship to chipping qualities of potatoes. Reducing sugar levels have usually been used as a predictive test of the suitability of material for processing. However, it has been shown that information on sugar alone may not always predict the final color formation of chips. This variation is most likely due to the differences in free amino acid content in the potato. A few studies have been aimed at determining the effect of amino compounds on color development in potato chips but more information in this area is needed. Objectives: The primary objectives of this study are: 1. To determine the contributions of selected amino acids on color development in potato chips, based on model systems. 2. To determble amino acid composition and amino group content of good chipping versus poor chipping potato varieties. Experimental Procedures: This work has been separated into model system studies and storage studies. Part I: Model system study 1 A. Filter paper disks impregnated with solutions of amino acids and sugars Stock solutions (0.05M) of amino acids (arginine, aspartic acid, glutamic acid, glycine, isoleucine, leucine, lysine, methionine, tyrosine, valine) and sugars (fructose, glucose, and sucrose) were prepared in 0.2M phosphate buffer solutions. The working solutions were adjusted to pH 6.5 with 0. IM HCI or 0.IM NaOH. Solutions for impregnation of filter paper disks were prepared as follows: 1) buffer only (control); 2) glucose only; 3) fructose only; 4) sucrose only; 5) each amino acid only; 6) glucose plus each individual amino acid; 7) fructose plus each individual amino acid; and 8) sucrose plus each amino acid. For each treatment solution 30 whatman No. 2 filter paper disks, 5.5 cm diameter, were soaked for 30 mins., air-dried and fried in fresh vegetable oil at 360F for 2 minutes with stirring. Each sample was done in duplicate. The color of chips was evaluated using Hunter CDM and Agtron E-10 colorimeter. 1 B. Filter paper disks impregnated with potato juices Five potato varieties, Atlantic, Mainestay, Shepody, Snowden, and Superior were obtained from the Michigan State University Montcalm Research Farm. Two hundred gms of tuber tissue were taken from the middle of 8 peeled potatoes and juiced in an Acme juicerator. The potato juice samples were centrifuged at 3,500 rpm for 2 min To each tube containing 9 mL phosphate buffer solution (pH 6.5) was added 1 ml juice sample and the solution was mixed. Filter paper disks were loaded with I ml juice solution and fried in vegetable oil at 360F for 2 min. The remaining juices were kept frozen for ninhydrin analysis. 2. Solutions of amino acids and sugars: Effect of type and concentration of amino acids Solutions ranging from 0.1 to 0.5M of glycine, leucine, and aspartic acid were prepared from IM stock solutions of these amino acids in 0.2M phosphate buffer (pH 6.5). One mL of each amino acid was mixed with I ml each of glucose and sucrose (0.IM prepared in 0.2M phosphate buffer, pH 6.5). The volume of the mixture was adjusted to 10 mL with 0.2M phosphate buffer. Tubes containing the mixture were vortexed for I min and heated to 300F for 2 mins, in an oil bath. Analytical methods 1. Sugar determination: YSI-2700 Glucose Analyzer The preparation of samples for glucose and sucrose analysis were according to Sowokinos and Preston (1988). The sugars in the extract were analyzed in duplicate using a YSI-2700 glucose analyzer (Yellow Springs instrument Co., Yellow Springs, OH). This instrument measures the hydrogen peroxide produced from the reaction of glucose with the immobilized glucose oxidase in the system. 2. Amino acid determination Potato extract containing free amino acid was prepared by passing the juice through a C18 filter (Sep-Pak, Water Associates, Inc.), and washing twice with distilled water. Sample was derivatized with PITC (Phenylisothiocyanate) before injecting in the HPLC column. The analyzer unit (Water Associate, inc.) consisted of, the model 710B Waters WISP solvent delivery system, a Pico-Tag column (3.9 x 300 mm i.d.), and a model 440 UV-Visible wavelength detector at 254 nm. The flow rate was set at 1.0 ml/min. Standard amino acids were obtained from Sigma Chemical Company (St. Louis, MO). 3. Amino group determination 1) Ninhydrin assay NinLydrin reaction was used to determine the concentration of free amino groups in potato juice samples. Ninhydrin was prepared by dissolving 2.0 g ninhydrin and 0.3 g hydrindantin in 75 mL dimethyl sulfoxide (DMSO). To the mixture was then added 25 mL of 4M lithium acetate buffer. One mL of sample solution was mixed with I mL ninhydrin solution in a test tube. The tube was vortexed and then heated in a boiling water bath for 15 mins. To the cooled reaction solution was added 6 mL of 50% ethanol-water. The tubes were vortexed and any insoluble particles were removed by centrifugation. Absorbance of the solution was read against a reagent blank. The mixture was diluted with additional 50% ethanol to get the absorbance within the most sensitive range. Concentration of free amino groups was determined spectrophotometrically at 570 nm. 4. Color measurement The color of the fried paper disks and potato chips were measured using the Agtron E- 10 colorimeter (Fillper Magnuson, Reno, NV) and the Hunter CDM. An Ultraspec II LKB Biochrom spectrophotometer was used to measure the absorbance of the model solutions at 420 nm. Data for mean scores were reported (> 60 = excellent, 56-60 = acceptable, 50-55= marginally acceptable). 5. Statistical Analysis Single and multiple regression analyses were performed using the Statview data analysis program. Research progress Part I: Model systems 1. Filter paper disks Development of color in filter paper disks simulating potato chips is presented in Figure 1. Individual amino acids in combination with each sugar when fried in vegetable oil at 360F for 2 min produced varying degrees of Maillard browning, as measured by the Agtron colorimeter. Lysine, tyrosine, and glycine produced unacceptable dark colored disks, as shown by their low Agtron numbers, while arginine, aspartic, and glutamic acid produced acceptable light colored disks with high Agtron numbers. As expected, amino acid-glucose systems produced more intense color than amino acid-sucrose systems. Filter paper disks impregnated with buffered sugar solutions yielded darker color than those with buffer alone since the Maillard reaction and caramelization of sugars can occur simultaneously upon heating. It is likely that some hydrolysis of sucrose may have occurred under these heating conditions at pH 6.5, generating glucose and fructose which could enter into the Maillard reaction. In contrast, buffered amino acid systems produced only slight color. 2. Solutions of amino acids and sugars (Figures 2,3 and 4). Sugar concentration of 0.1 M in phosphate buffer when mixed with different concentration of amino acids produced various degrees of brown color. The least intense colors were formed at 0.3M amino acids for amino acid-glucose systems and at 0.4M for amino acid-sucrose system. As expected, glucose produced markedly pronounced brown color as compared to sucrose. The results indicated that the color development in the model systems depends on the relative proportion of amino acids and sugars as expressed in terms of molar ratio. 3. Color comparison of filter paper disks impregnated with potato juice and actual potato chips. Five potato varieties, Atlantic, Mainstay, Shepody, Snowden, and Superior were selected based on their chipping qualities. Snowden and Atlantic generally produce light color chips, while Shepody and Mainstay generally give darker ships. The color development (Figure 5) of the model filter papers impregnated with potato juice of the these varieties was consistent with the color of chips produced from these tubers. 4. Comparison of amino acid content of selected varieties at harvest. Total amino acid contents of Snowden, Atlantic, Superior, Shepody and Mainestay were determined at harvest. Snowden and Atlantic both had thhe lowest amino acid content and Shepody had the highest content, with Superior and Mainestay at intermediate levels between these extremes (Figure 6). However, when chips were manufactured from these samples, Mainestay had a darker Agtron color than any other variety but it also had the highest glucose content of all the samples. Conclusions. 1. Amino acid content may be responsible for the variations in correlations between reducing sugar content and chipping color. 2. Amino acid type and amino group content may be significant in the Maillard browning reaction. 3. Prediction of chip color may be improved by combining information on amino acids with sugar content in chipping potato selections/ varieties. Figure 1. Color Development of Filter Paper Disks with Amino Acids and Sugars Figure 2. Color development with amino acid-sugar solutions at varying amino acid concentrations Figure 3. Color development with amino acid sugar solutions at varying amino acid concentrations Figure 4. Color development of amino acid-sugar solutions with varying concentrations of amino acids. Figure 5. Color comparison between filter paper disks impregnated with potato juice and potato chips. Figure 6. Total amino acid content of selected potato varieties.