At this time soybeans are grown on more acres in Ohio, than alfalfa, corn, and wheat together. Soybeans are used for a wide array of uses both domestically and for export. Ohio has a large acreage dedicated to food grade beans for tofu, meal for animal feed, oil for processing, and numerous other uses.
A high proportion of Ohio’s soybeans are grown on poorly drained soils, which provides the perfect environment for many soil borne pathogens. Phytophthora sojae, which causes root and stem rot, can be recovered from most fields in Ohio. This pathogen can totally wipe out a field if a highly susceptible variety is planted combined with saturated soil conditions. Yield losses are very visible with P. sojae, unlike another very widely distributed pest, soybean cyst nematode. We have measured as much as 50% less yield without any symptoms when SCN populations are near 2,000 eggs/cup of soil. There are other root rotters: a large number of watermolds (Pythium spp.), Fusarium graminearum, Rhizoctonia solani, Macrophomina phaseoli as well as the sudden death syndrome pathogen, Fusarium virguliforme.
The first and most effective management strategy to deploy is host resistance. Once a soybean variety is chosen with the appropriate disease resistance package additional management options such as seed treatments, drainage improvements, and crop rotation may also be needed.