Cotton ascochyta blight

Cotton ascochyta blight is a serious fungal disease caused by the imperfect fungus Ascochyta gossypiicola. The disease affects cotton plants throughout their entire vegetation period, starting from the seedling stage through to the ripening of the bolls, posing a significant threat to commercial cotton production.

The main host crops for this pathogen are species of the genus Gossypium. The disease manifests as the formation of circular or irregularly shaped spots on leaves, stems, and bracts. These infected areas typically feature a gray center surrounded by a dark or reddish-brown margin, where pycnidia—the fruit bodies of the fungus—eventually develop.

The development of the disease is closely linked to environmental conditions. High humidity, frequent rainfall, and moderately warm temperatures act as catalysts for the rapid spread of fungal spores. The infection persists on plant debris in the soil and can also be transmitted via contaminated seed material, which establishes the primary infection source at the start of the season.

The damage caused by ascochyta blight includes premature defoliation and the drying out of infected stems, which leads to a significant decrease in the plant's photosynthetic capacity. When the bolls are infected, the quality and yield of the fiber drop substantially, and seeds lose their viability, resulting in direct economic losses for farmers.

• Strict adherence to crop rotation and spatial isolation of fields.
• Thorough removal and destruction of post-harvest crop residues.
• Use of high-quality treated seed material.
• Application of fungicides upon the first signs of an outbreak.
• Cultivation of disease-resistant cotton varieties.