We are starting to receive an increase in the number of reports, calls and/or emails regarding Goss's wilt of corn. Goss's wilt is caused by the bacterium, Clavibacter michiganensis subsp. nebraskense. This disease has been on the increase in the past two years, including being found in numerous seed corn and sweet corn fields in Wisconsin in 2010. Significant yield losses can occur in very susceptible hybrids.
Symptoms of Goss's wilt include: distinct light tan/yellow to gray lesions, with wavy or irregular margins that follow the leaf veins. Within the lesions, dark green to black specks or flecks [freckles] are common and the lesions often have a shiny appearance due to the bacteria oozing onto the leaf surface. As symptomology progresses, lesions can coalesce causing whole leaves to be blight, and furthermore, there can be wilting and stalk degradation leading to entire plant death. To examine the stalk for Goss's wilt, split the stalk and look for an orange to brown color with water-soaked and slimy tissue.
Currently, there is no good, in-season management tactic for control of Goss's wilt. As a bacterial disease, foliar fungicides are not effective.
Reports from Wisconsin follow on several recent reports from surrounding states. The links below will take you to several of these bulletins, which also provide several excellent photos of this disease:
Since yield losses can be significant, it is important to properly diagnose Goss's wilt in order to develop an effective management plan. This disease can be confused with another bacterial disease, Stewart's wilt, as well as fungal diseases like Northern corn leaf blight and Diplodia leaf streak. We recommend that you submit samples for proper identification of Goss's wilt to the Plant Disease Diagnostic Clinic. Make a note of the hybrid from fields where Goss's wilt was found and talk to your seed dealer about hybrids that have better Goss's wilt ratings if this disease has been confirmed. Cultural management includes tilling fields immediately after harvest and burying residue. Planting corn into the same field in the next growing season is not recommended. Instead, rotate to a non-host crop like soybean.