Insects of Field Corn in Arkansas and Their Management

Corn acreage in Arkansas increased from 93,000 A in 1995 to 220,000 A in 1998. These increases were due to several factors including low price of other commodities, need for alternative crop rotations and the relatively short growing season for field corn. Although acreage decreased in 1999 due to high levels of aflatoxin in the 1998 crop and from reduced corn prices, field corn will continue to be produced at substantial levels in Arkansas. New improved corn cultivars (Fig. 1) should result in an increase in corn yield in Arkansas. However, numerous factors including weather, diseases, weeds, low fertility, and insects will continue to suppress yield increases unless they are better managed.

Insects represent a serious threat to field corn produced in the mid-south. Numerous soil dwelling insects attack newly planted corn seed and seedlings. These include wireworms, seed maggots, and chinch bugs. Rootworms may reduce growth vigor by feeding on corn roots. Armyworms and the corn earworm directly affect the ear and may assist in transmitting pathogens responsible for aflatoxin production. Although the entire plant may be attacked and this attack may occur throughout the production season, in Arkansas the most significant threat is generally from corn borers that tunnel into stalks and ear shanks. Corn borers can reduce plant vigor, cause stalk lodging and ear drop and can reduce kernel size thereby reducing corn yield. Corn plants under stress from corn borers also may become more susceptible to high levels of aflatoxin. In order to reduce the impact of insects on corn production the insect must first be identified, its biology understood, and optimal management practices must be followed. This communication seeks to provide the information needed by Arkansas producers to make correct management decisions with field corn insects. Initially, the communication will be limited to corn borers, i.e., the southwestern corn borer, Diatraea grandiosella Dyar, and the European corn borer, Ostrinia nubilalis (Hubner). As additional information becomes available for other insects, it will be incorporated into the communication.