Urbana, Illinois, USA
July 22, 2010
Goss’s wilt was detected in a corn leaf sample last week at the University of Illinois Plant Clinic. Although Goss’s wilt has been observed in Illinois in past years, it is not typical, said U of I Extension plant pathologist Carl Bradley.
Goss’s wilt, caused by the bacterium Clavibacter michiganense subspecies nebraskensis, is commonly found after hail storms, high winds, and heavy rainfall. Symptoms of this disease appear as large tan to gray lesions on the leaves with dark spots, often referred to as “freckles,” within the lesions.
“Some plants may wilt, as the pathogen can infect the xylem,” Bradley said. “In some cases, darkening of the vascular tissue can be observed in affected plants if a cross-section is cut through the stalk.”
Bradley said symptoms of Goss’s wilt may be confused with other foliar diseases such as Stewart’s wilt, northern corn leaf blight, or Diplodia leaf streak. In order to properly diagnose this disease, send suspicious samples to the U of I Plant Clinic (http://plantclinic.cropsci.illinois.edu/).
No in-season control options are available to protect against Goss’s wilt infection or to reduce disease spread within a field, he said. Foliar fungicides are not effective, either.
The best method of controlling Goss’s wilt is to plant corn hybrids with high levels of resistance. Bradley recommends checking with your seed dealer to obtain Goss’s wilt ratings.
Bradley said, “Fields affected this season should be tilled after harvest to bury affected residue and rotated to a non-host crop, such as soybean, the next season.”
For more information, read The Bulletin online at http://ipm.illinois.edu/bulletin.
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