Start Date: Feb 04, 2013
End Date: Aug 31, 2013
Objectives 1 and 2. Four commercial soybean varieties (maturity group-MG 2.0-2.5) will be planted on 1-2 research farms in IN, WI, and MI. Treatments will be irrigated/infested, irrigated/non-infested, non-irrigated/infested, and non-irrigated/non-infested and arranged in a split-randomized complete block design with irrigation being the main plot. Soil populations (colony forming units-CFUs) of M. phaseolina will be assessed post-planting and pre-harvest. Disease development and colonization by M. phaseolina (plant CFUs) will be assessed at soybean growth stages VC, V5, R2, R4, R6, and R8. Yield will be assessed at maturity. Obj 1. Commercial farms in OH with a history of charcoal rot will be grid-sampled for soil CFUs of M. phaseolina to determine areas of high and low disease pressure. A commercial variety will be grown and yield and plant CFUs assessed at maturity. Comparisons will be made between plants grown in high disease pressure areas versus low. Obj 3. Twenty commercial soybean varieties will be planted on 2 research farms in IN (MG 2.5-3.5), WI (1.0-2.0), and MI (2.0-2.5). Plots will be irrigated or non-irrigated and all will be artificially infested with M. phaseolina. Soil CFUs will be determined postplant and pre-harvest and disease developed at stages VC, V5, R2, R4, R6, and R7. At maturity, varieties will be assessed for yield and plant CFUs.