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Late-planted corn and soybean fields attract more insects.

June 9, 2008

2 Min Read

Late-planted crops are at increased risk from insects that normally pose a lower threat, says Wayne Bailey, University of Missouri Extension entomologist. Black cutworm continues to threaten fields in north-central and northeastern Missouri.

"Due to small seedling size and the large size of black cutworm larvae, damage can be rapid and severe," Bailey notes. "With the relatively high price of corn, treatment is justified if 1% to 2% or more of plants are cut by this pest."

Due to multiple moth flights, cutting in northeastern Missouri continues on seedling corn. Producers should scout fields for signs of leaf damage or cutting until corn reaches the five-leaf stage.

Brown stinkbugs also pose a threat to corn this year due to planting delays and the small size of corn plants. "Stink bugs are present in high numbers this spring and have the potential to substantially damage seedling corn," he says.

To protect crops, scout field edges for stinkbugs hiding in corn plant whorls and feeding on seedling stems, Bailey advises. Spray field borders and cornrows along field edges to keep the stinkbug from migrating into fields.

"Most producers don't catch them until it's too late," he says. "At that time, you already have twisted plants and feeding damage. If you have a woody area nearby, or alfalfa, I would definitely be scouting. You might spray grassy borders as a preventative if you've had stink bugs before."

Soybean growers with early-planted fields should watch for bean leaf beetles. "Wet weather has limited soybean planting and allowed high numbers of beetles to accumulate in seedling soybean fields," Bailey says. "High numbers of adult beetles require insecticide application to reduce populations below the economic threshold."

Other pests to be aware of this season are corn earworm, white grubs, wireworms and Japanese beetles. For questions about pest infestations or damage to crops, contact your local MU Extension office.

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