Colletotrichum caudasporum

The primary sign of infection is the appearance of small, sunken spots that eventually turn brown or dark gray, surrounded by a darker peripheral margin.

On the surface of affected areas, especially in high humidity, fungal sporulation structures called acervuli form. These appear as tiny black dots arranged in concentric circles.

When stems are affected, necrotic constriction of tissues occurs, leading to wilting and subsequent death of individual plant parts or the entire above-ground biomass.

Leaf blades may become deformed, curled, and drop prematurely, significantly reducing the plant's photosynthetic surface area.

Fruits and seeds, when infected, develop water-soaked lesions where the fungal mycelium penetrates deep into the tissues, causing rot and loss of marketability.

The causative agent of the disease is the microscopic fungus Colletotrichum caudasporum, which belongs to the order Phyllostictales. This pathogen features characteristic spores with long appendages, a trait reflected in its scientific species name.

The fungus is a parasite that infects vegetative and reproductive organs of various agricultural and ornamental crops. It is capable of surviving in the soil and on plant debris as mycelium or conidia.

The pathogen's life cycle includes an active growth phase during high humidity and a dormant phase. Inside plant tissues, the fungus spreads intercellularly, breaking down parenchyma with the help of secreted enzymes.

The infection spreads through agroecosystems primarily via conidia, which are dispersed by wind, rain splashes, or during routine agricultural operations.

This species is classified as an anthracnose-causing agent, affecting a wide range of plants, including woody species and herbaceous crops.

Optimal conditions for the mass development of Colletotrichum caudasporum include relative humidity levels above 85-90% combined with moderately warm temperatures.

The temperature range from +20°C to +28°C is considered most favorable for active spore germination and the formation of new infection hotspots.

Excessive soil moisture, lack of ventilation in dense crops, and the presence of liquid water on leaves facilitate the rapid spread of the disease.

Plant stress, caused by nutritional imbalances or mechanical tissue damage, significantly increases susceptibility to fungal colonization.

The infection pressure increases substantially under monoculture conditions, as the pathogen accumulates in the topsoil over consecutive growing seasons.

The harmfulness of Colletotrichum-related diseases lies in a drastic reduction of yield due to premature leaf senescence and fruit rot, which renders produce unsuitable for long-term storage.

The disease disrupts photosynthesis and metabolic processes, leading to plant exhaustion and increased vulnerability to winter conditions or further environmental stress.

Crop quality suffers significantly: seeds become shriveled, with reduced germination and vigor, leading to sparse plant stands in the following season.

Economic damage is further compounded by the costs associated with protective measures, fungicide applications, and the loss of marketable yield during shipping.

In severe cases, complete death of seedlings during the propagation stage is possible, necessitating replanting and additional resource expenditure.

The defense strategy relies on using certified, healthy seed material and cultivating crop varieties that possess genetic resistance to anthracnose.

The most critical agronomic practice is strict adherence to crop rotation, with a break of at least 3-4 years before returning a susceptible crop to the same field to interrupt the fungal life cycle.

Deep plowing and thorough removal or incorporation of plant residues in the fall help significantly reduce the inoculum load in the soil.

Chemical control involves spraying crops with systemic or contact fungicides, including triazoles, strobilurins, or copper-based compounds, at the first sign of symptoms.

• Maintaining optimal plant spacing to ensure adequate air circulation.
• Timely weed control, as weeds can act as reservoirs for the infection.
• Prophylactic seed treatment with appropriate fungicides.
• Monitoring nitrogen levels to avoid excess, which can increase tissue susceptibility.