Bill Cissel, Extension Agent – Integrated Pest Management; bcissel@udel.edu
Congratulations to Kathleen Heldreth for correctly identifying the damage in the photo as corn rootworm damage and for being selected to be entered into the end of season raffle for $100 not once but five times. Everyone else who guessed correctly will also have their name entered into the raffle. Click on the Guess the Pest logo to participate in this week’s Guess the Pest challenge!
Guess the Pest Week #14 Answer: Corn Rootworms
The corn plants in the photo are damaged by corn rootworm larvae. As you can see, the larvae feed on the roots and root tissue of the plants causing the plant roots to be “pruned”. Older larvae will tunnel into the roots leaving visible entrance holes and blackened root tips. Plants with excessive root pruning will usually lodge and in reaching for the sun, become “goosenecked”. Corn rootworm infestations are unusual for Delaware and not something we typically have to manage for. Crop rotation is the preferred method of control in regions with sporadic populations. Corn rootworm females prefer to lay eggs in corn fields in August and September. The eggs do not hatch until the following spring. If the field is rotated out of corn, the larvae will starve to death in the absence of a suitable host plant.