Corn lodging, during rapid vegetative growth just before pollination, is not a welcome site. No surprise, it generally follows a storm front that includes rain and winds, as you may have noticed characterized the remnants of Hurricane Beryl moving through the Midwest earlier this week. Shallow roots (e.g., compaction), soggy soils coupled with high winds, rootworm feeding, etc, can solely, or contribute to, significant lodging. To properly assess, go to a damaged area, dig up roots with a shovel, clean off the soil, and evaluate. Rootworm feeding scars are noticeable by the brown discoloration anywhere on the root system – there is nothing that looks quite like rootworm feeding. This damage alone is not likely to significantly reduce the root’s anchoring ability. Root pruning, especially whole nodes of roots missing, would likely implicate rootworm as the cause of observed lodging. This video will contrast two root systems with rootworm damage, representing significant and minor feeding.
Another giveaway is the density of rootworm beetles flying about as you enter the field. Rootworms have been emerging for 2 weeks or so, and if you are finding bunches of western corn rootworm beetles in lodged fields, and Bt-RW corn was planted, this is reason for concern and you will want to contact seed company personnel. As a first step and before assuming any resistance issues, plants should be tested for the presence of the appropriate Bt protein.
