Efficacy of a buckwheat intercrop on soybean aphid management in organic soybean

Organic soybean producers lack effective managment options for controlling the economically damaging soybean aphid, Aphis glycines Matsumura. Biological control by natural enemies is an important control measure in an organic agricultural system, and intercropping with flowering crops such as buckwheat can enhance biological control by attracting natural enemies. The purpose of this project was to investigate whether intercropping organic soybeans with buckwheat can be an effective management option for suppressing soybean aphid populations. IIn 2010 field experiments were conducted at two locations in Minnesota to investigate 1) whether a soybean/buckwheat intercrop could effectively manage soybean aphid populations and 2) if natural enemy recruitment was a mechanism involved. Natural enemies were sampled using a combination of sweeps and visual plant inspections. Comparisons between intercropped plots and soybean-only plots showed few differences between aphid and natural enemy numbers for both locations. At Evansville, MN, intercropping demonstrated higher natural enemy population, but whether this was due to recruitment from buckwheat or higher aphid densities is unclear.