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2017 Goss's Wilt Rating and Disease Information

By Maynard Orchs, Product Development Agronomist

Dark green to black “freckles” within oblong lesions are signs of Goss’s wilt.

Situation

Traditionally a problem disease in the western Corn Belt, Goss’s wilt is now prevalent across the Corn Belt and spreading into Canada. Once corn plants are infected, yield potential can be reduced by up to 50 percent. There are no effective chemical control measures for Goss’s wilt. The best way to limit spread of the disease is by selecting hybrids with strong Goss’s wilt tolerance.

This bulletin provides information about Goss’s wilt and tolerance ratings for Mycogen® brand corn hybrid families. The ratings are the result of 2011-16 field trials conducted in Illinois, Iowa, Minnesota, Nebraska, South Dakota and Wyoming.

Disease Information

Goss’s wilt is caused by the bacterium Clavibacter michiganensis subsp. nebraskensis. It overwinters in infected corn residue, primarily found on or near the soil surface. Inoculum in the infected residue primarily spreads by wind and splashing rain. To a minor degree, Goss’s wilt also can survive in seed.

To infect a corn plant, the bacterium needs an entry point or wound, which is generally caused
by heavy rainstorms, hail, wind, blowing sand or mechanical damage. Humid, wet weather is
another risk factor because moist or wet leaves are conducive to the spread of disease.

Factors to Consider

  • Goss's wilt can reduce corn yiled potential up to 50 percent.
  • The disease can infect plants throughout the growing season. 
  • Identify Goss's wilt by scouting for freckles in lesions.
  • Control the disease by selecting corn hybrids with a strong tolerance rating. 

Identifying Goss's Wilt

Scouting is important because infection can occur at any point during the growing season. Infested seedlings show systemic wilting, stunting and a variety of leaf symptoms.

More-mature plants demonstrate the foliar leaf blight version of the disease. The first signs of infection are dark green to black, oblong spots that are water-soaked with a greasy look that appear parallel to leaf veins. Streaks of freckles within the lesions are a distinctive feature of Goss’s wilt. Droplets of bacterial exudate ooze from the freckles, leaving a crystalline substance that glistens in direct sunlight. The spots coalesce as they enlarge, forming long lesions with wavy edges. As the lesions age, they turn tan and can blight much of the leaf. Systematically infected plants have discolored (orange) vascular tissue and likely slimy stalk rot.

Key Symptoms:

  • Freckles in lesions 
  • Crystalline deposits
  • Droplets of exudate

Commonly confused with:

  • Drought damage
  • Heat stress or sun scalding
  • Other leaf blights

Controlling Goss's Wilt

Because Goss’s wilt is a bacterial disease, it cannot be treated with fungicides. The best method of control is planting hybrids
with strong Goss’s wilt tolerance. Tables 1 through 4 demonstrate the wide range of tolerance in hybrids.

Summary

Growers can limit the spread of Goss’s wilt to uninfected fields by selecting tolerant hybrids, harvesting infected fields last and thoroughly cleaning harvest equipment. Destroying infected crop residue will lower the amount of bacteria present. This is most effective when done immediately after harvest. In most situations, rotating to a nonhost crop, such as soybeans, dry beans, sugarbeets or alfalfa, is a more viable option. Last, manage irrigation to reduce humidity in the field during the growing season.

Talk to your Mycogen Seeds sales representative or commercial agronomist to learn more about managing Goss’s wilt on your corn acres.

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Published on Friday, March 03, 2017