Maintaining corn yield increases in the presence of new and evolving insect and pathogen pests has required sustained improvements in corn genetics, crop management practices and pesticides. Advances in insect resistant and herbicide tolerant GMO technologies combined with high corn values to create an environment where pest management was taken for granted. Insect, disease and weed control was often handled in a “one size fits all,” prophylactic manner. With more effective pest management and difficulties in interpreting survey data under widespread use of new GMO technologies, long-term, public pest survey efforts were largely abandoned during the late 1990s. This greatly diminished survey activity seemed wise initially, but it reduced our ability to detect and understand how risks from key corn pests were shifting.
Currently, corn growers face several issues that make understanding changes in pest problems increasingly important:
- More arthropod pests of corn have populations resistant to insecticides (e.g. corn earworm, corn rootworm, and wo-spotted spider mite), Bt traits (e.g. western bean cutworm, fall armyworm, corn earworm, Western corn rootworm) or crop rotation (e.g. northern corn rootworm). These biotype shifts create integrated pest management (IPM) challenges with respect to viable hybrid trait and insecticide options for pest management.
- Changes in the complex of existing and new corn pathogens (e.g. bacterial leaf streak, northern leaf blight, Goss’s wilt) require corn growers and their advisors to understand these risks to react with appropriate management.
- Environmental concerns may limit the future scope of pesticide tools available.
- Migratory insects (e.g. true armyworm, black cutworm), and other insects and pathogens, can become more problematic with changes in weather and cropping practices (e.g. tillage, cover crops).
- Growers may react to current low commodity prices by reducing genetic traits (e.g. Bt) or pesticide (e.g. at-plant rootworm) inputs. From an (IPM) perspective, a reduction in pest management inputs is advisable when it is based on knowledge of a pest population that indicates an economic advantage to do so. Our ability to select corn hybrids with high, stable yields requires understanding near and long-term changes in pest populations.
As new pests and diseases become problems and pest resistance to widely used genetic and pesticide tools increases, understanding risk from pests becomes increasingly important to corn growers, particularly when farm revenues decrease. How will this information be obtained and how will Minnesota’s corn growers find the information needed to help make these decisions?