Iowa State plant pathologists have confirmed that they found Goss's Wilt on June 24 in a Carroll County cornfield where they have a research study on Goss’s wilt of corn. Alison Robertson says the field has been in corn for several years and has a history of Goss’s wilt.
"The field was planted May 5 and was at growth stage V6 to V7," the Iowa State plant pathologist says. "We found plants with typical symptoms of the leaf blight and also the wilting stage of the disease.
"This is the earliest report of Goss’s wilt in Iowa that I am aware of. It is also the first time I have seen the wilting stage of the disease in this state."
Typical lesions of Goss’s wilt were characteristic of approximately 1% of the plants in the field, Robertson says. Long, dark brown to grey-green lesions were evident on the edge of the leaves or along folds in the leaf. Freckles, which are diagnostic for Goss’s, were present.
"On some plants, only one leaf was affected, while on other plants, all leaves were affected," Robertson says. "We also noticed some plants that were wilted. Closer examination of the plants revealed subtle lesions.
"When the stalk of the plant was cut, the vascular system of the plant was discolored orange-brown. In this case, infection of the plant by the bacterium was systemic. In other words, the bacterium was present in and plugging the vascular system of the plant."
There are no rescue treatments for Goss’s wilt. The disease is caused by the bacterium Clavibacter michiganenisis subsp. nebraskaenesis. Fungicides are not effective.
Management recommendations include planting resistant hybrids, rotation to a nonhost crop and residue management.