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Stewart's Bacterial Disease


© Purdue University, Plant and Pest Diagnostic Laboratory

Pathogen(s) causing disease:

Erwinia stewartii

Symptoms:

 This disease has two phases and primarily is a problem on sweet corn and susceptible inbreds, although resistant hybrids may be affected if flea beetle populations are very high in the spring. The first phase affects corn seedlings. Seedling leaves have light green to yellow linear streaks with wavy margins that can follow the length of parallel veins. Plants can become necrotic and die. The plants may produce bleached tassels if it survives. The second phase is leaf blight after tasseling. Leaves develop light green or yellow streaks along veins. Infected areas will die. The disease can be severe enough to kill the entire leaf. With the absence of resistance, the leaf blight phase can be a threat to field corn.

Conditions:

Favored by high infestation levels of flea beetles in April through late June. High levels of soil phosphorus and nitrogen. High temperatures and soil moisture.

Management:

Use seed-applied insecticides early to control corn flea beetles, resistant hybrids. Disease forecasting is based on the sum of mean temperatures for December, January, and February. In mild winters, the corn flea beetle will have a high survival rate and disease severity may be high. In cold winters, corn flea beetles will have low survival and disease would likely be low severity or absent.

Sources:

Purdue University
University of Illinois

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