Stalk Borer Activity Rises Early Threatening Corn Fields This Season

By Andi Anderson

Stalk borer is a pest that occasionally affects corn crops but can become a serious problem in certain fields. It is usually found near areas with perennial grasses, such as fence rows, terraces, and waterways. These locations serve as overwintering sites where the pest survives before moving into nearby corn fields.

This year, stalk borer activity has started earlier than usual. Farmers are advised to act quickly and begin scouting their fields. One of the best ways to predict pest movement is by tracking growing degree days. Movement typically begins when 1,400 degree days have accumulated since January 1, and it reaches its peak at around 1,700 degree days. Since many regions have already reached these levels, larvae are now actively moving into corn crops.

Scouting is very important at this stage. Farmers should focus on fields with a history of stalk borer problems. Special attention should be given to field edges, as the larvae usually move from grassy areas into the first few rows of corn. Signs of infestation include “dead heads” in nearby grasses, which indicate stalk borer activity in the area.

The larvae can be identified by their purple color, white stripes, and a dark band across the middle of their body. Although they are not highly mobile, they can still cause significant damage. Young corn plants are especially vulnerable. The larvae feed on leaves and can destroy the growing point of the plant. However, once the crop reaches a certain growth stage, such as V7, it becomes less likely to be killed.

Management of stalk borer requires careful timing. There are no rescue treatments available once the larvae enter the stalk. Insecticides can only be effective when the larvae are still moving and exposed. After they bore into the plant, they are protected and cannot be controlled easily.

Therefore, farmers must use degree day tracking and regular field scouting to make informed decisions. Early detection and timely action are the key steps to reducing damage. Proper management can help protect corn crops and maintain yield during the growing season.

Photo Credit: gettyimages-oticki