Agricultural Research Service scientists recently released a new corn germplasm line that will be a source for developing corn plants resistant to the Southwestern corn borer and the fall armyworm.

ARS researchers at the Crop Science Research Laboratory in Mississippi State, Miss., led by plant geneticist William P. Williams, have developed the corn germplasm line, Mp716, that is resistant to leaf-feeding by these formidable pests. The new line was developed by self-pollinating a cross between two other germplasm lines for eight generations and then selecting for the desired traits.

The milky-white larva of the Southwestern corn borer appears in early June throughout much of the South. After feeding on the whorl of the corn plant, it moves down the stalk and begins to tunnel within. If the larva feeds on the bud of the plant within the whorl, the plant's entire yield is lost. Female southwestern corn borers can lay from 300 to 400 eggs in their lifetime.

Agriculture Extension specialists in Mississippi estimate that this pest produces about $1 million dollars worth of damage annually in that state alone.

The fall armyworm attacks corn and a variety of other crops including tomato, cotton and alfalfa. Like the Southwestern corn borer, this pest also damages the whorl of the plant. This feeding produces frayed holes in the leaves that become apparent when they are unfurled. In addition, the larvae of the fall armyworm also feed on immature ears and tassels.

The new germplasm line was evaluated for three years by infesting plants in the whorl stage of growth with 30 young larvae and checking for damage 14 days later. Mp716 was found to be only moderately damaged by these insects.

The genetic material for this new germplasm line will be deposited in the National Plant Germplasm System where it will be made available for research purposes.

ARS is the U.S. Department of Agriculture's chief scientific research agency.