Corn producers in Minnesota have historically had few widespread and significant problems with leaf diseases, in contrast to most major Midwestern corn-producing states. A leaf and stalk disease on corn called Goss's leaf blight and wilt (or just Goss's wilt) has been increasing in Minnesota since 2009.
This disease, appearing as large elongated tan lesions with irregular margins kills leaf tissue. Dark green spots ("freckles") and shiny patches of dried bacterial ooze develop in the lesions, and severe stalk infection can occur. See University of Minnesota Extension's Crops Disease website for Goss's wilt photos at www.extension.umn.edu/go/1080.
Goss's wilt has been known in Nebraska since 1969 and in the past few years has spread across the Midwestern Corn Belt. This disease was first confirmed at two locations in Minnesota in 2009, although it likely appeared a year or two before this.
Goss's wilt was reported in about two dozen fields scattered across southern Minnesota in 2010, and now in 2011 has been found in many more fields, especially in the southern and central parts of the state. Fortunately, it has caused minor damage and is unlikely to reduce yields significantly in most fields.
This can be an important disease that is capable of causing yield losses of at least 60 bushels per acre in Minnesota. We cannot predict the seriousness of Goss's wilt in any particular field in the future, but there are a few facts that should be considered.
Goss's wilt is caused by a bacterial pathogen called Clavibacter that survives from year to year in infected corn residue. Infection and spread are favored by hail, sandblasting, and strong winds and storms. Goss's wilt tends to be more common in corn-on-corn fields, although it also occurs in fields that have been rotated.
Fungicides are not effective for management of Goss's wilt. Good options available for disease management include crop rotation, planting hybrids with resistance to this disease, and management of corn residue. Given the relatively low known risk of severe Goss's wilt developing in most fields next year, management options for this disease must be considered carefully and balanced with other factors to be managed to optimize yield and profitability in each field.
A University of Minnesota research team, with funding assistance from the Minnesota Corn Growers Association, and has begun a project aimed at improving the management and diagnosis of Goss's wilt.
More information and photos of Goss's wilt and other crop diseases can be found on Extension's Crop Diseases website at www.extension.umn.edu/cropdiseases. For more educational resources on corn production in Minnesota, visit Extension's corn website at www.extension.umn.edu/corn.