Corn rootworm (CRW) is not new to the tri-state area, but it has generated more talk this season. Northern and western corn rootworm populations have been documented in northern Minnesota and North Dakota. Typically, this has only been a southern MN and eastern South Dakota issue. However, with the most corn-on-corn we have seen since 2012, populations are on the rise.
Corn rootworm can cause extensive yield losses. Often, CRW causes anywhere from 15-45% yield damage to your corn. Predict losses by measuring damage to root development and silk feeding. CRW feeding on corn roots in the larvae stage causes yield loss. Larvae injure the roots and significantly inhibit nutrient and water uptake.
Typical root injury
Consequently, less-developed roots lead to a weaker plant, resulting in goose necking and/or being susceptible to wind damage, as seen below. Adult corn rootworms can also cause significant yield loss during pollination. The adults feed on the silks, which cannot capture pollen. Adult corn rootworm beetles occupy later-planted and later-silking corn that attract large numbers of beetles from neighboring fields.
Tactics for next season: