About Goss’s WiltLife Cycle Goss’s Wilt is caused by a gram-positive bacterium called Clavibacter michiganensis. This bacterium overwinters in diseased plant debris and soil for up to about 10 months. Transmission occurs through lesions created by leaf injury as a result of heavy winds, hail, or blowing sand. Splashing rain and/or irrigation water helps spread bacteria from infected crops to healthy crops with lesions. Once infected, bacteria will spread throughout the leaves of the plant, creating large, brown lesions and scattered black flecks. Premature wilting and/or death may occur, which cause leaves to fall, allowing bacteria to shelter in the dead plant materials or soil. Goss’s Wilt Identification and HabitatIdentification Leaf blight is often the most identifiable trait of this disease. Blight will appear as large, brown lesions on the centers or edges of the leaves. Small to large black flecks will also appear scattered throughout the leaves. After rain or in the morning, bacterial ooze can be visible on lesions surfaces. When the ooze dries it becomes very shiny in the light. The disease can cause severe wilting and/or death of the infected plant. To identify when the disease is at this stage, take a look at the vascular tissue of the stalk. If the stalk is discolored to an orange or brown color, then the plant is vulnerable to heavy damage soon. The discoloration is a result of bacteria flowing through the plant’s xylem. Habitat Warm conditions are beneficial for the development of Goss’s wilt. The disease’s main method of infection is through wounds on the plant, so conditions with sand-blasting, hail, rain, wind, and storms can facilitate infection. Humidity can also help the disease develop and spread quicker. Overly hot and dry weather will slow down the development of the disease, sometimes making it harder to distinguish from other problems like drought stress. Lack of crop and soil maintenance can promote spread of disease because bacteria will remain in dead plant materials in the soil. Goss’s Wilt Management and Control MethodsCultural Control Before planting, selecting disease-free seed for the appropriate field locations is essential. Planting less vulnerable plants in the proper field will make it harder for diseases to infect crops. Scouting fields for signs of Goss’s wilt can be useful to know what to grow next season. Tilling fields is great for reducing the amount of plant residue in the soil. This will help lessen the chances of bacteria spreading further and overwintering for next season. Furthermore, managing weeds like foxtail is crucial to reduce bacteria spread from plant to plant in the field. Fields should be maintained and monitored frequently so that infected plants can be removed quickly and effectively. Rotating crops for two or more years is a good idea to allow infected residue to degrade and decrease. Chemical Control To date there are no chemical controls available to treat Goss’s wilt. Keep in mind that because the disease is bacterial, fungicides will not be effective to control the disease. Alternative Goss’s Wilt Names- Goss’s Bacterial Wilt and Leaf Blight
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