2002 Research Summaries

Evaulation of the effects of a soy protein supplement on factors related to prostate health in men at increased risk for prostate cancer. (Dr. Terry Hartman, Department of Nutrition, Penn State University, $19,972 Pennsylvania Soybean Board and $9,986 Northeast Region Soybean Board)

Prostate disease is very common among older men. Farmers, in particular, appear to be at increased risk for prostate cancer. Research suggests that soy may have beneficial effects on prostate health. The objective of this study is to determine whether soy protein will favorably alter markers for prostate health and sex hormone levels in men at increased risk for prostate cancer. Male subjects between 40 and 75 years of age with elevated levels of prostate specific antigen (PSA) will consume a soy protein (40 gm) supplement and a non-soy (milk) protein (40 gm) supplement in random order, each for eight weeks. All testing will be completed at the General Clinical Research Center, Penn State University. Recruitment for the study is under way and results should be available for next year's annual research report.

Can a cover crop improve continuous soybeans? (John O. Yocum, Penn State, $2,158)

The cover crops — rye, ryegrass, oats, wheat, timothy, rape — were established by hand broadcast seeding into standing soybeans. Seeding was done when most of the soybean leaves turned yellow, which was the later part of September at both locations - Lancaster and Centre counties. At the Lancaster County site, the rye cover treatment produced the three-year average lowest soybean plant population (128,000 plants/acre), and the wheat cover treatment produced the highest soybean plant populations (157,000 plants/acre). There was no significant effect of the cover treatments upon soybean yield two out of three years at the Lancaster site and both years at the Centre County site. The highest three-year average soybean yield at Lancaster was produced in the wheat cover treatment (45.4 bu/A) while the lowest soybean yield was from the no cover check (37.3 bu/A). The lower 2001 soybean yield at Lancaster could be from three continuous soybean plantings, three years of no-till or the effect of high dandelion weed populations during 2001. At the Center location, there was little difference in soybean yield (2.2 bu/a, highest to lowest).

In summary, grasses were successfully established in standing soybean two out of three years. The grasses provided sufficient soil cover to reduce soil erosion from harvested soybean fields. From these studies, winter wheat appeared to be the better choice of the grasses tested.

Survey to determine the intensity of soybean aphid and bean leaf beetle pressure in Pennsylvania soybean fields (Dennis Calvin, Penn State, $7,800.)

The soybean aphid, Aphis glycines, has been observed in each of the counties surveyed, which include York, Centre, Lycoming, Mercer and Bradford. Seventeen total soybean fields were surveyed. In addition, Dr. Jim Stimmel of the Pennsylvania Department of Agriculture has observed the aphid in Adams, York, Cumberland, Mercer, Lawrence, and Crawford counties. Based on the initial surveys it appears that the soybean aphid is present across all of Pennsylvania. In all but two fields where the aphid was observed, populations were very low and not likely to cause economic injury to the crop.

In the fields surveyed, no bean leaf beetle populations were observed . However, low levels of defoliation from Japanese beetle adults and soybean leafminers were observed in the majority of fields. No two-spotted spider mite infestations were observed. Across all fields surveyed, insect pressure was very low.

The seeding rates of farmers were quite variable, along with the stand density goal for the crop. Seeding rates varied from a high of 220,000 seeds per acre to a low of 175,000 seeds per acre. The average seeding rate was 184,375 seeds per acre. Stand density goals varied from 185,000 to 150,000 soybean plants per acre. The average stand density goal was 159,444 plants per acre. The Penn State Agronomy Guide suggests a 150,000 plant per acre stand goal for full season beans and a 200,000 plant per acre stand goal for double crop beans.

White mold of soybean: Field-testing of agronomic control measures and investigation of mechanisms of soybean resistance to white mold (Barbara Pennypacker, Penn State, $20.698)

Sclerotinia white mold is a serious problem on soybean in Pennsylvania when the weather is cool and wet. The field research funded by the Pennsylvania Soybean Promotion Board and the Northeast Regional Soybean Board was designed to test whether agronomic management such as row spacing and plant density could be altered to reduce the impact of white mold. In 2001, we tested the effect of row width (14, 21 and 28 inches) and plant density (75,000 and 150,000 plants per acre) and the effect of the growth enhancer and disease resistance enhancer "Messenger" on the incidence of white mold and on the overall growth of the soybean.

Unfortunately, the weather did not cooperate and the subsequent drought prevented development of white mold in our experiment. There was no yield advantage associated with the use of "Messenger" or with any of the other treatments, also possibly due to the drought. Greenhouse studies into the potential for using salinity as a surrogate screen for white mold resistance are continuing. We are testing a group of public cultivars with known white mold response to see whether their response to salt stress mirrors their response to white mold. An abiotic stress such as salt would be easier to use in the initial germplasm screen than the pathogen, which is so sensitive to the environment.

Evaluation of soybean germplasm under Pennsylvania conditions (Elwood Hatley, Penn State, $6,000.)

The results of the 2001 Pennsylvania Soybean Performance Report. are on the web at www.agronomy.psu.edu. The variety and germplasm testing program was conducted at two locations: Landisville in Lancaster County, and Rock Springs in Centre County. In 2001, 79 private and 3 public varieties were evaluated in the full season test (which included 16 normal germplasm, 60 RR and 6 STS varieties) at the Landisville site. Fifty-four private and three public varieties were evaluated in the full season test (which included 12 normal germplasm, 43 RR and two STS varieties) at the Rock Springs site. The double crop test at Landisville included 44 private and three public varieties (which included 13 normal germplasm and 34 RR varieties. Fourteen breeding lines, from the Mid-Atlantic testing program, were evaluated at the Landisville site. We continue to cooperate with researchers at USDA in evaluating forage breeding lines. In 2001, 36 advanced breeding lines were evaluated for yield and quality at the Rock Spring site.

Soybean Plant Populations (John O. Yocum, Penn State, $2,158)

At Lancaster and Centre counties, during 2000 and 2001, soybeans were seeded in 15-inch rows at final populations varying from 100,000 to 250,000 plants per acre. The soybeans were seeded assuming only 85 percent would produce plants. At both sites, there was no significant difference in yield due to plant population in 2001. When soybean yields were combined over locations and years (grand mean), the highest yield differential was only 1.3 bushels per acre. At the Lancaster site in 2001, plant populations did not effect plant maturity, plant lodging, plant height, seed size or seed quality.<div><font size. Based on this data and the conditions occurring during these trials, the current recommended soybean plant populations of 150 to 175,000 plants per acre seem to be correct. Soybean plant populations above this recommended amount only cost the grower additional seed costs without any additional yield potential.

The effect of soybean cultivar plant type on row width yield (John O. Yocum, Penn State. $3,221)

In 2000 and 2001, soybean cultivars with a wider canopy and a medium canopy growth type were seeded in replicated large plots in Lancaster and Centre counties. At both locations, the wider canopy cultivar produced the higher yield. Whether this yield advantage was due to plant canopy or due to genetics could not be determined. At the Lancaster location, 7-inch rows produced the highest two-year average yield (4.4 bu/a higher than 30-inch rows). . In Centre

County, there was little difference in the yield produced by 15-inch

and 30-inch rows. The difference between the two locations may have been the earlier planting date at the Centre County location and the later maturity of the cultivars at this location. In three out of the four tests (two years x two locations), there was no significant interaction between cultivar and row spacing. This would indicate that the canopy differences of these cultivars did not perform differently in the various row spacings. Based on these trials and the conditions during 2000 and 2001, selecting a canopy type cultivar for row spacing is not justified.

Effect of herbicide programs on weed shifts in corn-soybean rotation (William Curran, Penn State, $8.476)

A corn-soybean-corn (C-S-C) rotation and a soybean-corn-soybean (S-C-S) sequence were established in an experimental farm field with locally existing weed populations. Using six herbicide programs, two glyphosate-based programs, one ALS-based program, two mixed herbicide programs and an untreated check, an experiment was conducted over a four-year period starting in 1998. Glyphosate resistant corn and soybean were planted in all years. Observations and measurements (density counts, biomass) were taken periodically throughout the season to quantify the long-term effect of herbicide programs on weed population shifts.In summary, after four years of glyphosate or ALS-based herbicides in corn-soybean or soybean-corn rotation, only minor weed shifts have occurred. The weed seedbank and annual weed management tactics will determine the trajectory of present and future weed problems. If problem weed species exist, monitoring and altering management tactics will be important to preclude the development of future weed problems.