Anthracnose

Early symptoms appear as small, circular, brown, or grayish lesions that typically develop a lighter colored center as they mature.

As the disease progresses, these lesions expand, coalesce, and cause necrotic zones on leaves, stems, and fruits, leading to overall plant decline.

In high humidity environments, the lesions often display gelatinous spore masses, forming characteristic fungal fruiting bodies called acervuli.

Severe infection results in premature leaf drop, dieback of shoots, and visible cracking of stems, which hinders nutrient transport within the plant.

• necrotic spots with dark borders;
• fruit deformity and decay;
• premature wilting of foliage;
• visible spore masses on lesions.

The disease is caused by the fungus Colletotrichum johnstonii, a member of the Deuteromycetes group, acting as an obligate parasite on a wide range of host plants.

The fungal life cycle involves the production of conidia, which serve as the primary source of infection in susceptible plant tissues during the growing season.

Infection spreads through wind, rain splashes, and human activity, effectively allowing the spores to travel across agricultural fields.

The mycelium colonizes plant tissues, invading intercellular spaces and degrading cell walls through enzymatic action to extract essential nutrients.

High adaptive potential enables this pathogen to survive in diverse environments, posing a persistent threat to global agricultural output.

The development of Colletotrichum johnstonii is favored by high relative humidity, typically exceeding 85%, which is essential for spore germination.

Optimal temperatures for pathogen growth and infection lie within the range of +22°C to +28°C, which commonly occurs during spring and summer.

Prolonged leaf wetness resulting from rainfall, dew, or irrigation creates the perfect environment for the fungus to establish itself.

Plants under physiological stress or those with existing wounds are significantly more susceptible to successful colonization by the pathogen.

Poor field hygiene and continuous cropping facilitate the build-up of inoculum, ensuring the disease persists year after year.

Anthracnose significantly reduces plant productivity by damaging the photosynthetic surface area and disrupting the overall physiological balance.

Direct damage to fruits and pods makes the harvest unmarketable and leads to significant post-harvest losses due to rot development.

Seedling blight caused by this fungus leads to stand loss, forcing farmers to perform costly replanting and increasing production expenses.

The pathogen compromises the quality and nutritional value of the harvest, impacting both commercial grade and storage capability.

In cases of severe infestation, crop yields can drop by as much as 30-70% if appropriate control measures are not implemented on time.

Implementing a balanced crop rotation system is a foundational practice to disrupt the fungal infection cycle and reduce pathogen load in the soil.

Strict field sanitation, including the removal and destruction of crop residues, is vital for minimizing the carryover of infection between seasons.

Application of systemic fungicides at the first sign of symptoms is highly effective in curbing the spread and severity of the disease.

Selecting disease-resistant varieties is the most sustainable approach to long-term management and reduces the reliance on chemical inputs.

Treating seeds with appropriate fungicides before planting provides a critical defense layer, protecting young seedlings from early-season colonization.