Spiny anthracnose

The fungus Colletotrichum spinosum is a significant plant pathogen responsible for causing spiny anthracnose. It primarily targets the vascular and structural tissues of its host, leading to cell death and necrotic lesion formation. As an opportunistic fungus, it thrives by exploiting both weakened and healthy plant tissues when environmental conditions are optimal.

Leguminous crops are the primary hosts for this pathogen, with soybeans being particularly susceptible. The fungus can infect various plant organs including stems, petioles, leaves, and pods. Beyond cultivated crops, it can survive on alternative weed hosts, making it a persistent challenge in integrated pest management programs.

Infection symptoms usually appear as sunken, dark lesions which eventually develop small, spore-bearing structures. In later stages, the tissue becomes brittle, often resulting in stem breakage or premature pod shattering. The presence of these lesions severely hampers the plant’s ability to photosynthesize and transport nutrients, leading to yield losses.

The spread of Colletotrichum spinosum is heavily dependent on moisture and temperature. Spore dissemination is most intense during periods of high humidity and rainfall, which facilitate the transport of spores from crop residue or soil surfaces to the canopy. Warm, humid weather patterns accelerate the incubation period of the disease.

Management strategies focus on reducing the initial inoculum and limiting the conditions conducive to infection. Essential practices include crop rotation, the use of certified disease-free seeds, and the application of fungicides when climatic models predict high disease pressure. Field sanitation is also critical to minimize carry-over infections.

• Implement a strict crop rotation schedule.
• Incorporate crop residue into the soil to accelerate decomposition.
• Apply fungicides as a preventive or early-curative measure.
• Select resistant or tolerant crop cultivars for high-risk areas.