Stewart's wilt

Stewart's wilt is a bacterial disease of corn caused by the bacterium Pantoea stewartii affecting plants, particularly maize. Its primary vector is the corn flea beetle, (Chaetocnema pulicaria).

The bacterium lives in the gut of the beetle during the winter and is spread between plants when the beetle feeds on the seedlings. The bacterium can also be spread via the plant seed, but this is quite rare and its incidence is insignificant compared to insect transmission. Thus, survival of the insect vector through the winter months, especially in the north central U.S., is the key factor in development of the disease.

Symptoms
The most diagnostic symptom of the disease is the presence on the leaves of yellow to brown stripes or streaks with wavy or irregular margins. These streaks may be quite short or may extend the entire length of the leaf. The symptoms of Stewart's wilt may sometimes be confused with those of fungus leaf blights or with frost injury.

Chemical
Apply early insecticide sprays for controlling the overwintering flea beetle population. In areas where Stewart's wilt is known to be a potentially severe disease, insecticides should be applied when the corn first breaks ground and should be continued for several applications thereafter until the stand is well established. Consult your county Extension agent for a list of registered insecticides and rates of application.

Cultural
Plant tolerant varieties, which will grow and produce well in spite of the presence of the pathogen. In general, later maturing varieties are more tolerant of the disease than earlier maturing ones, although several early maturing varieties are available with good tolerance to Stewart's wilt.