2005 Year in Review

From The Fields - Corn Flea Beetles-Stewart's Wilt

Corn Flea Beetles

Leaf stripe, leaf blight, wilting, and death of corn seedlings; first phase of Stewart's wilt disease.

Necrotic lesions on mature leaves; second phase of Stewart's wilt disease.

The potential for corn flea beetles to cause early-season disease problems in northwestern Illinois appear to be limited. Corn flea beetles are the main vector (carrier) of Stewart’s wilt and their survival is dependent upon winter temperature.

Warmer winters result in greater survivorship of corn flea beetles, thus increasing the potential for Stewart’s wilt. The projected risk of Steward’s wilt is based on the average temperatures of December, January, and February. If this average is 27 degrees F or less, the probability of early-season wilt is absent and the probability of late-season blight is a trace. At Freeport and DeKalb this average was 24 and 28 degrees, respectively. These are predictions, as the exact number of surviving corn flea beetles are not known.

According to Kelly Cook, University of Illinois Extension entomologist, corn flea beetles become active in the spring when temperatures rise above 65 degrees F. The insect feeds on and infects seedling corn plants enabling bacterium to spread systemically throughout the plant. Most commercial corn hybrids are resistant to Steward’s wilt, but the disease is still a concern for susceptible seed corn and sweet corn hybrids.

Cook indicates that the seedling wilt stage occurs when corn seedlings become infected at or before the V5 stage. The seedling wilts, becomes stunted, and dies. The leaf blight phase of Stewart’s wilt occurs after tasseling and is characterized by long, yellow-to-chlorotic streaks, with wavy margins along the leaves.

More information on corn flea beetles and Stewart’s wilt can be found in a new corn flea beetle fact sheet Corn Flea Beetle and the sweet corn disease nursery web site Stewart's Wilt

by  Editor, theCity1.com
March 25, 2005