1995 Annual Report for ANC95-029
Utilization of Oilseed Rape as a Biocontrol Agent for Nematodes Parasitizing Corn in Illinois
Summary
The objective of this project is to determine if a nematoxic cover crop could replace the need for a commercial nematicide for controlling corn nematodes.
Plots were established in northwestern Illinois in 1995 in a corn field known to have economically damaging populations of root-feeding plant parasitic nematodes. Each plot treatment consisted of a crop rotation variable (continuous corn or a corn/soybean rotation) and a nematicide treatment. The nematicide treatment consisted of a commercial pesticide applied to the corn at planting, the planting of a nematoxic cover crop to be disked prior to planting or no treatment. Oilseed rape was planted in the fall of 1995 but was winter killed and replaced by a spring planted crop of brown mustard, also known to contain nematoxic compounds. All crops were managed consistent with recommended practices for soybeans and corn in the Midwest. Soil samples were collected monthly from planting (May) until harvest (October) and analyzed for nematode genera and population levels. Plots were harvested in October and yields computed.
The use of the spring planted mustard crop improved yields over the three years of the experiment, indicating that farmers could select such a crop to replace nematicides. A fall planted crop, generating more biomass, could provide even greater benefits. Initial and final yields for continuous corn were (in bushels per acre): 1995: without nematicide - 27.4, with nematicide - 59.8, with cover crop - 47.4; 1997: without nematicide - 84.4, with nematicide - 158.4, with cover crop - 100.6. Initial and final yields for corn/soybean rotation were: 1995: without nematicide - 63.6, with nematicide - 70.3, with cover crop - 33.2; 1997: without nematicide - 109.6, with nematicide - 129.2, with cover crop - 121.7.
Farmers could plant a nematoxic cover crop to replace a commercial pesticide and realize a gain in yield without the hazards normally associated with pesticides. Although the yield increase was not as great with the cover crop as with the nematicide for continuous corn, farmers concerned about possible off-site effects of pesticides could replace the nematicide with the cover crop and combine this with crop rotation to achieve almost comparable yields. The use of the cover crop would provide additional benefits in terms of soil protection and conservation, especially on very sandy areas. North Central Region SARE 1997 Annual Report.