Common stalk borer scouting has started across the state of Iowa.
According to Iowa State University Extension and Outreach field agronomist Aaron Saeugling, stalk borers tend to re-infest the same fields annually. Farmers are encouraged to prioritize fields with a history of stalk borers for scouting first with extra attention to the field edges.
Saeugling says female moths prefer to lay eggs in weedy areas in August and September, so managing weeds earlier in the growing season can help make fields less attractive.
“They actually lay eggs in grassy areas outside of our crop fields the previous season,” Saeugling said. “These eggs would have been laid in 2019. Based on growing degree days and the warmer it gets, that migration begins into our crop fields. That’s essentially the development of how they migrate. They cause us issues in corn in particular.”
Saeugling says young corn is vulnerable to severe injury and that plants are unlikely to be killed once they reach V7.
“Stalk borers that go unnoticed or ignored for a variety of reasons can be kind of devastating to the outside portion of the field,” he said. “Usually they don’t infest the entire field. It’s usually confined to the outside 8-to-12 rows of a field, but traditionally they can be pretty problematic in terms of complete defoliation of the plant.”
Saeugling says scouting should already be underway, especially in areas south of Interstate 80 in the southern part of the state.
“It’s really easy to scout for,” Saeugling said. “It’s probably one of the easiest pests. Just walk those head lands next to grassy areas. If you have CRP buffers, set-asides or waterways, that’s where those moths would have laid those eggs last year. Look for those deformed plants.”
More information on stalk borer scouting can be found at crops.extension.iastate.edu.