Goss’s wilt is a bacterial disease that affects corn (maize) crops, caused by the bacterium Clavibacter michiganensis subsp. nebraskensis. It can cause significant yield losses in affected fields. Here’s an overview of its symptoms, recommendations, causes, and preventive measures:

Symptoms:

1. Leaf Blight:
   • Goss’s wilt initially presents as irregular water-soaked lesions on corn leaves, which later turn brown and necrotic.
   • Lesions may have wavy margins and appear translucent when held up to light, giving them a characteristic “frosted” or “frosty” appearance.
   • Lesions can coalesce, leading to extensive blighting of leaves.
2. Systemic Infection:
   • In severe cases, the bacterium can infect vascular tissues, leading to systemic wilting and browning of entire corn plants.
   • Infected plants may exhibit “firing,” where leaves and stalk tissues turn brown and die from the tip downwards.
3. Streaking on Stems:
   • Brown to black streaks may develop on corn stalks and leaf midribs, especially in older plants.
4. Dark Green Water-Soaked Areas:
   • In some cases, dark green water-soaked areas may be visible between veins on infected leaves, particularly on the upper surface.

Recommendations for Management:

1. Crop Rotation:
   • Rotate corn with non-host crops to reduce the buildup of Goss’s wilt inoculum in the soil.
   • Avoid planting corn in fields with a history of Goss’s wilt or where infected crop residues are present.
2. Resistant Varieties:
   • Plant corn hybrids that are resistant or tolerant to Goss’s wilt, if available.
   • Resistant hybrids can significantly reduce disease incidence and severity in fields where Goss’s wilt is a recurrent problem.
3. Tillage:
   • Incorporate crop residues into the soil through tillage to accelerate decomposition and reduce the survival of the Goss’s wilt bacterium.
4. Hygiene Practices:
   • Practice good field hygiene by removing and destroying crop residues, especially from infected fields.
   • Avoid moving soil and plant material between fields to prevent the spread of the bacterium.

Causes:

1. Bacterial Pathogen:
   • Goss’s wilt is caused by the bacterium Clavibacter michiganensis subsp. nebraskensis.
   • The bacterium overwinters in crop residues and can survive in the soil for extended periods, particularly in corn debris.
2. Wounding:
   • The bacterium enters corn plants through natural openings or wounds, such as insect feeding sites, hail damage, or mechanical injury.
3. Environmental Factors:
   • Warm and humid conditions during the growing season favor the development and spread of Goss’s wilt.
   • Stress factors such as drought, heat, or nutrient deficiencies can weaken corn plants and make them more susceptible to infection.

Preventive Measures:

1. Seed Treatment:
   • Use seed treatments with appropriate fungicides or bactericides to protect corn seedlings from Goss’s wilt infection.
   • Seed treatments can provide early-season protection and help reduce the spread of the bacterium within fields.
2. Field Monitoring:
   • Regularly scout corn fields for symptoms of Goss’s wilt, especially during periods of high disease pressure.
   • Early detection allows for timely management interventions to minimize yield losses.
3. Fungicide Applications:
   • In some cases, foliar fungicide applications may be warranted to manage Goss’s wilt, particularly if disease pressure is high and resistant hybrids are not available.
   • Consult with local agricultural extension services or crop advisors for recommendations on fungicide use.
4. Integrated Management:
   • Implement integrated disease management strategies that combine cultural practices, crop rotation, resistant hybrids, and chemical control measures to effectively manage Goss’s wilt.

By incorporating these preventive measures into corn production practices, growers can reduce the impact of Goss’s wilt on yield and crop quality. Early detection and proactive management are key to minimizing losses associated with this bacterial disease.