Corn stubble in several western Kentucky counties was checked recently for signs of Southwestern corn borer to determine the pest’s potential infestation this year.

“The good news is looks like it’s low this year,” said Ric Bessin, Extension entomologist with the University of Kentucky College of Agriculture.

Southwestern corn borer can overwinter in corn stubble and stubble is checked in early spring for damage and surviving larva. Low numbers in the survey indicate there will be low numbers later in the season when they can cause damage to the 2004 corn crop.

This is the sixth year the survey has been conducted and the numbers have been low for the past two years, Bessin said.

Southwestern corn borer has two or more generations per year. The first generation attacks whorl-stage corn and can cause yield losses by stunting or killing plants. The second generation occurs during mid- to late summer and increases harvest losses through stalk breakage due to the insect tunneling in the stalk.

Southwestern corn borer was the worst corn pest in the state prior to the winter of 1977-78, when a severe winter killed out the population. Between then and 1992, they did not occur in the state but have since migrated back.

 “We know winter weather conditions have the ability to kill out the insect,” Bessin said. “Because of this, we follow the insect’s survival over winter to give us a heads up to make seed selection and management decisions.”

Winter survival is just one of the variables that determine the potential for problems. Planting date is also a key variable. Typically, fields planted after May 10 have an increased potential for this type of damage.

If conditions are wet and farmers are still planting after May 25, Bessin said they should consider using a Bt hybrid. Bt corn contains a built in insecticide for corn borer.

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