Clover anthracnose

Clover anthracnose is a fungal disease caused by the pathogen Colletotrichum trifolii, which primarily affects various clover species and related forage legumes. This disease is known for its ability to devastate fields by killing stems and reducing the overall stand density, leading to significant economic losses in the agricultural sector.

The host range includes red clover and other leguminous plants grown for forage. The pathogen is particularly aggressive in regions where the climate is warm and humid. Once the disease is established in a field, it can spread rapidly, especially in dense stands where air circulation is limited, making it a persistent challenge for farmers.

Symptoms initially appear as small, dark, sunken lesions on stems and petioles. As the fungus progresses, these lesions enlarge and girdle the stem, causing it to wilt and collapse, often curling into a distinct shepherd’s crook shape. The affected areas may show a dark, fuzzy mass of fungal spores during periods of high humidity, confirming the presence of the pathogen.

Development and spread are favored by moderate to warm temperatures and moisture from rainfall or heavy dew. The fungus overwinters in crop residues and can survive in the soil for several years. Spores are dispersed through rain splashes, wind, and agricultural equipment, which facilitates the rapid movement of the disease across infected plots.

Integrated management is the most effective approach for controlling clover anthracnose. Key strategies include:

• Planting resistant clover varieties.
• Following a proper crop rotation cycle.
• Ensuring clean and certified seed usage.
• Applying balanced fertilization to promote plant vigor.
• Proper field sanitation to reduce inoculum levels.