By Scout Nelson
In Nebraska, wheat stem maggots are again causing damage in cornfields planted after green cover crops like rye or wheat. Young corn plants are showing wilted or dead leaves, with larvae found inside the plant whorls. Infestation rates range from under 5% to over 50% depending on the region and timing of cover crop termination.
This issue is linked directly to corn planted into living rye or wheat cover crops. It was first recorded in Nebraska in 2017 and continues to be observed statewide. Yield losses of up to 30 bushels per acre have been reported.
“Most corn plants with damage survive and often produce tillers, which can still contribute to yield,” experts noted. The maggots rarely move between corn plants, especially if their current host remains alive.
To manage the issue, experts recommend scouting cover crops before termination. If adult maggots are found in high numbers, consider terminating the cover crop at least 14 days before planting. Avoid tank mixing insecticides with herbicides at cover crop termination, as this can kill beneficial insects and offer little protection.
If early termination isn’t possible, a follow-up insecticide spray 11 days after glyphosate might help—but only if maggot pressure is heavy and corn has emerged. However, this is not guaranteed to work.
Insecticide applications are not recommended once larvae are inside corn plants. Most damage has already occurred, and maggots do not move or reinfest. Moreover, spraying may harm natural pest predators and create new issues.
Before replanting, evaluate how many damaged plants are still growing or tillering. Replant only if a large percentage of the stand is affected, and recovery appears unlikely. Monitor flagged plants for recovery signs before making final decisions.
Photo Credit:gettyimages-eugenesergeev
Categories: Nebraska, Crops, Corn, Wheat