Issue No. 15, Article 4/July 15, 2011
Goss's Wilt of Corn
A few observations of Goss's wilt of corn, caused by the bacterium Clavibacter michiganense subspecies nebraskensis, have been reported in Illinois. Corn fields that have been subjected to hail, high winds, and/or heavy rainfall are most likely to be affected by Goss's wilt. Symptoms are large tan to gray lesions on the leaves, with dark spots, often referred to as freckles, within the lesions. Edges of lesions may appear "water-soaked," and bacterial exudates (ooze) may be visible on the surface of affected leaf areas. If the bacterium enters the plant xylem, wilting may occur. In some cases, the vascular tissue may be darkened in affected plants if a cross-section is cut through the stalk.
Corn leaf with Goss’s wilt symptoms.
Bacterial exudate (sticky ooze) on corn leaf affected by Goss’s wilt. (Photo courtesy J. Pataky, University of Illinois.)
Symptoms of Goss's wilt may be confused with other foliar diseases, including Stewart's wilt, northern leaf blight, and Diplodia leaf streak. Proper identification is important, so suspicious samples should be sent to the University of Illinois Plant Clinic. No in-season control options are available to protect against Goss's wilt or to reduce the spread of disease within a field. Foliar fungicides are not effective in controlling Goss's wilt because it is caused by a bacterial pathogen rather than a fungal one. The primary management method is planting corn hybrids with higher levels of resistance (check with your seed dealer for Goss's wilt ratings). Any fields affected by Goss's wilt this year should be tilled after harvest to bury infected residue and rotated to a nonhost crop, such as soybean, next season.--Carl A. Bradley
Carl A. Bradley