As the growing season progresses, the Iowa State University (ISU) Extension and Outreach is advising producers to begin scouting for stalk borers. Early identification and management of these pests are essential to minimize damage and protect crop yields. Understanding when and how to scout for stalk borers can help producers take timely action and maintain healthy fields throughout the season.
What Are Stalk Borers?
Stalk borers are a type of insect pest that can harm a variety of crops, including corn, soybeans, and other field crops. These pests are known for their tunneling behavior, which can severely damage plant stalks and disrupt the flow of nutrients and water within the plant. Stalk borer larvae hatch from eggs laid on grassy weeds and other host plants, eventually migrating to crops and boring into the stalks.
How to Scout Stalk Borers
Tracking degree days is an effective method for estimating when stalk borer larvae will begin migrating into cornfields from their overwintering hosts. Scouting for larvae should begin once 1,300-1,400 degree days (base 41°F) have accumulated. Fields with a history of stalk borers should be prioritized, especially around field edges where initial infestations typically occur.
Look for “dead heads” in nearby grasses or weeds as an indicator of stalk borers in the area. The larvae are identifiable by their purple bodies with white stripes and a dark saddle across the middle. Since they’re not highly mobile, they usually affect only the first four to six rows of corn, with young corn being particularly vulnerable to severe injury until they reach the V7 growth stage.
Treatments for Stalk Borers
To effectively manage stalk borers, producers should employ both cultural practices and chemical treatments.
Cultural Practices: Keeping field edges clean by mowing or applying herbicides to reduce weed hosts can significantly lower the risk of stalk borer infestations. Crop rotation and residue management also play a role in disrupting the life cycle of these pests.
Chemical Treatments: Insecticides can be applied to control stalk borer populations. The timing of these applications is crucial for effectiveness. It's best to apply insecticides when larvae are small and before they bore into the stalks. Once they’ve entered the stalk, insecticides will no longer be effective.
Take Action Against Stalk Borers
Stalk borers can wreak havoc on crops, but you can mitigate their impact with timely scouting and smart management practices. By starting your scouting efforts early and staying informed and proactive, you can protect your crops and ensure a thriving growing season.
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