Keeping Watch for Goss’s Wilt Disease in Corn
Goss’s Wilt was first identified in Nebraska in the late 1960s, but it has since spread throughout the Corn Belt in the United States and into parts of Canada. It can be found in susceptible varieties of sweet corn, popcorn and dent corns. Are you keeping an eye out for this corn disease? Here's how.
Goss’s Wilt is classified as a “wilt disease” that is caused by a bacterium found in corn residue and some grassy weed residues, such as green foxtail, barnyard grass and shattercane.
How does Goss’s Wilt damage corn plants?
By definition, “wilt diseases” are those that attack the corn plant’s vascular system.
Yield losses from Goss’s Wilt can be significant, and that yield loss is reflected directly upon the growth stage of corn plants when the Goss’s Wilt bacterium enters the plant. As with any bacterial disease, fungicides used for treatment of corn leaf fungus diseases have no effect on Goss’s Wilt. In fact, there is no known treatment for control of Goss’s Wilt disease after symptoms have been positively identified.
How do corn plants get Goss’s Wilt?
The initial infection of Goss’s Wilt occurs when the bacterium contained on crop and weed residue is transferred to growing corn plants, but corn plants first have to sustain some form of damage or injury that serves as an entry point for bacteria to infect the plant. This happens most often during a weather event—high winds can damage leaves, while a sandblasting of soil against the plant leaves or stalk and hail events can all cause plant injury—or from mechanical injury.
Like other bacterial diseases, Goss’s Wilt disease thrives in warm temperatures and high-humidity environments. Scouting for Goss’s Wilt presence should begin 7-14 days after corn has suffered some injury. Fields that have a history of Goss’s Wilt disease, or fields with several host weed species, should be scouted weekly after emergence.
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Phases of Goss’s Wilt
Once the bacterium has entered the corn plant it can become identifiable in two phases:
Leaf blight phase: With the leaf blight phase, long, tan lesions form on the tissue of the corn leaves and typically run along the leaf veins. The lesions become necrotic and their margins have a wavy, water-soaked appearance. Look on the infected tissue for black freckles that cannot be rubbed off—you can use these black specks to help distinguish Goss’s Wilt from Stewart’s Disease. You may notice that the leaf surface, when dry, gives a shiny appearance to corn leaves. In severe cases, leaves can be totally destroyed. This can result in corn yield loss due to poor kernel fill.
Vascular wilt phase: The second phase of identification is vascular or systemic wilt. Though it is less common than the leaf blight phase, this phase has been reported to reduce corn yields up to 60 percent. It begins when bacterium contacts the vascular system of the corn plant and can then move throughout the plant. Look closely at corn plants showing early wilting or death, lodging and the leaf blight stage of Goss’s Wilt. At any stage of corn plant growth, if stalks are split or cut, look for brown xylem to confirm the vascular wilt stage.
Managing Goss’s Wilt
While incidence of Goss’s Wilt has increased over the years, it has never reached epidemic proportions. The best management practice known to help control Goss’s Wilt is to select a corn hybrid that has a good tolerance to the disease, but there are a handful of other options to help reduce inoculum (the live microorganism) in fields:
A two-year crop rotation
Burying or removing corn and host-weed residue
Eliminating host-plant growth in corn fields