White Mold
Trial
2007
MICHIGAN WHITE MOLD SOYBEAN
PERFORMANCE
REPORT
D. Wang and J. F. Boyse, Department
of Crop and Soil Science
This report provides information on the performance of soybean varieties when challenged with white mold, which is also known as Sclerotinia stem rot.
TESTING PROCEDURES
The white mold test was grown at one location (Ingham)
with four replications. The Ingham County site was inoculated with white
mold sclerotia and irrigated to promote infection. The entries were tested
in plots planted 20 feet long, 6-rows wide with a 15-inch row spacing.
The planting rate was 210,000 seeds/acre. Varieties were replicated four
times in a lattice design. The test included
64 commercial varieties entered
by 13 seed companies. The plots were planted, harvested, and rated
as described for the Conventional Variety Trial.
TEST SITE INFORMATION
Ingham County
Nearest City: East Lansing
Cooperators: Michigan State University
Planting date: 5-24-07
Harvest date: 10-29-07
Previous crop: Corn
Soil type: Capac Loam
Fertilizer: 150 lbs. 0-0-60
Herbicide: Preemerge - .06oz. FirstRate 84DG,
1.33 pt. Dual II Magnum
GROWING CONDITIONS
The Ingham County field was irrigated daily during
flowering. Cool temperatures during flowering,
coupled with
excess rainfall, promote maximum disease pressure.
USING THE DATA
Results are presented in Table 7. These evaluations
were done to provide information on the relative susceptibility of varieties
to white mold. Although no varieties have been identified that have complete
resistance to the disease, there are varieties that have lower infection
rates than others when the disease is present. The selection of varieties
that have low infection rates and high yields can help growers profitably
in fields where white mold infections occur.
The following traits were rated using the procedures outlined in the Michigan
Central and Southern Conventional Soybean Variety Trial Report: yield,
maturity date, height, and lodging. White mold levels were determined
by rating 30 random plants in the center rows of each plot. Each plant
was rated on a scale of 0 to 3 with 0 = no infection, 1 = infection only
on branches, 2 = infection on the main stem but pod fill was normal, and
3 = infection on the main stem resulted in plant death and poor pod fill.
The scores of the 30 plants rated for each plot were totaled. The total
was divided by 90 (the total if all 30 scored plants were given a rating
of 3) and multiplied by 100 to give a disease severity index (DSI). A
DSI of 100 would be given to a plot where all evaluated plants had a rating
of 3 and a DSI of 0 would be given to a plot where all evaluated plants
had a rating of 0.
DSI and yield values are given as averages of the replications and for
multi-year. Maturity, plant height, and lodging values are given as averages
over the replications for 2007. LSD (least significant difference, found
at the bottom of each data column) values are given for each test. The
LSD values are useful for comparing two varieties in the same test and
are explained in detail in the Michigan Central and Southern Conventional
Soybean Variety Trial Report. The C.V. (coefficient of variation, found
at the bottom of each data column) is indicative of the trial precision.
Lower C.V. value indicates more precise trials.
SPECIALTY SOYBEAN VARIETIES
Ten special-use varieties were tested in
this year’s white mold trial. This information will help soybean
growers compare the potential profitability of special-use varieties to
that of conventional varieties. DF Seeds
DF222 Super2, Dairyland's DSR-218, and Hyland's Sherwin
are widely accepted for various food-grade
uses such as soy milk and tofu production.
Zeeland Farm Services ZFSelect 251 LS, ZFS 291 LS, ZFS
722 LS and ZFS
725 LS are low-saturated fat soybean varieties that have been grown for oil production. Zeeland Farm Services ZFSelect 252 LL and ZFSelect 261 LL and ZFSelect 625 LL are low-linolenic acid soybeans.