Diagnosing and Managing Goss’s Wilt in Corn

Goss’s Wilt (caused by the bacterium Clavibacter michiganensis subsp. nebraskensis) is a serious corn disease that has the potential to cause significant yield loss in susceptible corn products when inoculum is present and conditions are favorable. Goss’s Wilt can be observed in two distinct phases: a systemic wilt that appears early in the season, and more commonly, a leaf blight that appears mid-season. Plant tissues that show symptoms of Goss’s Wilt should be evaluated by a plant diagnostic clinic.

 

What to Watch For

 

The systemic wilt phase of Goss’s Wilt occurs early in the season, and may resemble drought stress symptoms. This type of infection moves throughout water-conducting tissues within the plant and can be visible as orange to brown discoloration of vascular tissues followed by wilting and plant death (Figure 1). 

The more commonly occurring leaf blight symptoms that appear mid-season are long, gray-green to black water-soaked streaks with wavy margins. Smaller, darker water-soaked lesions, often referred to as freckles, are apparent inside the larger lesion. The lesions may ooze bacteria laden droplets in the morning. As the droplets dry, a crystalline sheen develops on the leaves. Eventually, the lesions will fade to a tan color and may cover large areas of leaves. 

Symptoms of the leaf blight phase may appear similar to and can be confused with other causes of leaf necrosis such as: drought, heat stress, nutrient deficiency, northern corn leaf blight and Stewart’s wilt. For this reason, it is important to properly identify the cause of the symptoms in order to formulate the best management approach. Plant tissues that show symptoms of Goss’s Wilt should be evaluated by a plant diagnostic clinic in order to effectively manage the disease in future plantings.

Figure 1. (Top) Corn plants displaying symptoms of Goss’s Wilt systemic infection. (Bottom) Mid-season leaf blight symptoms. Figure 1. (Top) Corn plants displaying symptoms of Goss’s Wilt systemic infection. (Bottom) Mid-season leaf blight symptoms.

Disease Development

 

The bacterium responsible for Goss’s Wilt overwinters in crop residue and enters plants through wounds created by injury caused by wind, sand, or hail. The disease can spread from one field to another through displacement of crop residue. Within a field, initial infection can occur as rain or irrigation water splashes bacteria from infected crop residue onto corn plants.

In addition to crop residue, grass weeds such as green foxtail and shattercane can also serve as hosts for the bacteria.

Reduced tillage used in conjunction with continuous corn production allows corn residue to remain intact, which provides a place for the bacteria to overwinter and increases the risk for disease development. Low levels of the disease may go undetected until environmental conditions favor widespread disease outbreak. Weather conditions including damaging wind or hail can provide favorable conditions for bacterial infection. During hot, dry weather, the disease development will slow down and make symptoms of Goss’s Wilt harder to distinguish from drought stress and other disorders. The pathogen can survive in and on seed, however seed to seedling pathogen transmission is very low (about 2%).2

Figure 2. Figure 2. Comparison of corn products tolerant (left) and susceptible (right) to Goss’s Wilt. Figure 2. Figure 2. Comparison of corn products tolerant (left) and susceptible (right) to Goss’s Wilt.

Tips To Manage

 

Goss’s Wilt management should center around product selection, crop rotation, tillage practices, and weed management. The primary consideration for growers should be product selection; evaluating products on a field-by-field basis, matching yield, agronomic traits, and disease tolerance to each unique farming operation. When active infection is found, growers should scout fields this year to note the locations and severity of the disease in preparation for next season. Scouting fields can be done from VE through R6. Because injury from hail or high winds usually plays a direct role in initial infection of Goss’s Wilt, scouting after strong wind or hail may be particularly helpful. The following management practices may help to limit occurrence of Goss’s Wilt:

  • Rotating to a non-host crop, such as alfalfa, oats, wheat, or soybeans.
  • Any tillage operation which buries infected crop residue, encouraging decomposition, can be effective in reducing bacterial populations and the rate of new infection. However, this is not a practical option where conservation tillage is used.
  • Controlling grass weeds such as green foxtail, shattercane, and barnyard grass that act as alternative hosts for this disease.
 

If you need assistance in confirming the presence of Goss’s Wilt in your fields, laboratory testing may be necessary. Samples should be accompanied by completed forms and packaged according to laboratory instructions. Be sure to include any information that may be useful for a correct diagnosis such as factors that you suspect may have caused symptoms similar to Goss’s Wilt.

 

Sources:

1 Jackson, T.A., Harveson, R.M., and Vidaver, A.K. 2007. Goss’s bacterial wilt and leaf blight of corn. NebGuide, G1675. University of Nebraska –Lincoln. htttp://extensionpublications.unl.edu/

2 Wise, K., Ruhl, G., and Creswell, T. 2010. Goss’s bacterial wilt and leaf blight. BP-81-W. Purdue University Extension. https://www.extension.purdue.edu/

3 Freije, A., Ikley, J., Wise, K., and Johnson, B. 2015. Goss’s wilt on grass hosts. BP-88-W. Purdue University Extension. https://extension.purdue.edu/

4 Biddle, J.A., et. al. 1990. Seed transmission of Clavibacter michiganense subsp. Nebraskense in corn. Plant Disease 74:908-911. https://www.apsnet.org/

Web sources verified 07/17/18.

180716122901.

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