MISSISSIPPI STATE -- Corn borers are inspiring growers to harvest corn as soon as possible, but producers must carefully weigh their decisions based on grain moisture content.

Erick Larson, corn specialist with Mississippi State University's Extension Service, said high populations of southwestern corn borers in the Delta and northeast Mississippi will cause substantial harvest losses if the corn is not harvested promptly. Growers can harvest corn after it reaches physiological maturity, which occurs when the grain measures about 30 percent moisture.

"However, grain elevators discount wet corn to account for drying expenses and weight lost during drying because wet corn cannot be safely stored until considerable moisture loss occurs," Larson said. "Improper grain handling, particularly with high moisture grain, can quickly promote aflatoxin development after harvest. Wet grain should be dried immediately to below 15 percent moisture."

Larson said elevators vary in amounts they dock corn for moisture. Producers should compare elevators carefully.

"Harvest losses are just as important as the moisture dockage rate in evaluating harvest timing decisions. The longer corn stays in the field, the greater the likelihood of substantial yield losses," Larson said. "Lodging caused by stormy weather or southwestern corn borers as well as excessive morning-glory growth from July rains could all inhibit harvest efficiency."

The corn specialist recommended growers harvest non-Bt hybrids infested with corn borers, early maturing hybrids and those fields with below-average stalk quality promptly and before other hybrids. Producers should watch closely for loss while the combine is harvesting. Two corn kernels per square foot or one dropped ear per 100 feet of row equals about one bushel per acre yield loss.

"Research generally indicates combine efficiency is best when corn grain moisture is about 20 to 22 percent," Larson said. "So for maximum profitability, growers should strive to finish harvest before grain moisture falls below 15 percent."

Don Respess, Bolivar County Extension director, said while corn borers may have caused some lodging, the corn is generally looking good.

"By and large, it's been a good growing year from most crops. Most corn growers are anticipating a better-than-average yield due to cooperative rains, and we haven't had extremely high temperatures," Respess said. "Harvests began in the earliest fields the first of August and will be underway in most fields by the middle of August."

1994 was the first year Mississippi growers averaged 100 bushels per acre. Counting that year, they have achieved 100 bushels or better six out of the last eight years. Mississippi growers planted 540,000 acres of corn this year, compared to 400,000 last year.