Sponsored: Don’t Let Goss’s Wilt Rob Yield
A yield-robbing disease that has the potential to cut corn yield by half is continuing to spread throughout the Corn Belt.
Long considered a Midwest disease, Goss’s wilt is a bacterial disease caused by Clavibacter michiganensis subsp. nebraskensis. Discovered in Nebraska in 1969, it has most recently been documented in Louisiana, Missouri and Canada.
The disease-causing bacterium has the ability to overwinter in crop residue and on the soil surface, and the disease can infect plants throughout the growing season. Corn plants are infected when bacteria enters the plant through wounds or abrasions caused by insect feeding, hail, heavy winds and mechanical damage.
Goss’s wilt inoculum in infected plant residue primarily spreads by wind and splashing rain. Humid, wet weather is another risk factor because moist or wet leaves are conducive to the spread of disease.
Identifying the disease
Goss’s wilt often is easily confused with other diseases, nutrient deficiency, chemical injury or drought damage.
The disease, which often has both a leaf blight phase and a systemic wilt phase, can cause the plant to wilt or die prematurely. It can be mistaken as drought stress. Infested seedlings show systemic wilting, stunting and a variety of leaf symptoms. More-mature plants demonstrate the foliar leaf blight version of the disease.
Goss’s wilt is identified by the black frecklelike spots located on long lesions that appear to have water-soaked edges and may be greasy in appearance. These frecklelike marks, found on often large lesions in the center or on the edges of leaf blades and running parallel to leaf veins, cannot be rubbed off. Streaks of freckles within the lesions are a distinctive feature of Goss’s wilt.
Choose a disease-tolerant hybrid
Because Goss’s wilt is caused by a bacteria, fungicides do not offer control of this disease. Instead, choosing resistant hybrids is key to preventing disease development.
The best method of disease control is planting hybrids with a strong Goss’s wilt tolerance rating. Tolerant hybrids with a Goss’s wilt rating of 6.5 and higher are recommended for continuous corn acres. Moderately tolerant hybrids with a Goss’s wilt rating of 5.2 to 6.4 are best in nonhost rotations. Goss’s wilt ratings of 4 to 5.1 should be acceptable in nonhost rotations in areas with a low incidence of Goss’s wilt. Susceptible hybrids with a Goss’s wilt rating below 4 are not recommended in fields with a history of the disease.
Plant pathologists also recommend growers rotate out of corn and into soybeans for at least one year in those fields with a history of Goss’s wilt. Management practices, such as employing tillage to remove residue, weed management to eliminate potential hosts and proper cleaning of harvest equipment, are recommended control practices.
For more information, visit www.Mycogen.com/agronomy.