Start Date: Jan 12, 2009
End Date: Feb 26, 2012
Collect Cercospora sojina isolates from the U.S., China, and South America to characterize isolates by pathogenicity group. Collect Macrophomina phaseolina isolates from widely dispersed geographical locations within the U.S. and determine virulence using soybean genotypes that have been characterized as having interaction phenotype of moderate resistance, moderate susceptible and susceptible under field environment. Determine the resistance of soybean germplasm and breeding lines for resistance to field isolates of C. sojina. Determine resistance of soybean germplasm, breeding lines, and cultivars for resistance to field isolates of M. phaseolina and Phomopsis longicolla. Determine optimum planting date for soybean maturity groups III, IV, and V cultivars. Determine effects of seeding rate and row spacing of different soybean plant types on yield and frogeye leaf spot incidence and severity. Establish optimum seeding rates for non-irrigated doublecrop maturity group III, IV, and V soybean in upper midsouthern United States. Determine effects of seeding rate and row spacing of different soybean plant types on yield and frogeye leaf spot incidence and severity in irrigated environment. Evaluate interactions of planting date, seeding rate, and fungicide and insecticide treatments on disease control, soybean yield, and yield components. Determine population dynamics of M. phaseolina population under six tillage methods in a field that has been in continuous soybean planting for 70 years.