Neoascochyta blight

Neoascochyta blight is a dangerous fungal plant disease caused by pathogens of the genus Neoascochyta. While many species within this group were previously classified under Ascochyta, recent molecular and genetic studies have established them as a distinct taxon. The pathogen is a typical conidial fungus capable of infecting both aerial plant parts and seeds.

Crops most susceptible to Neoascochyta blight include legumes (peas, chickpeas, lentils) as well as certain vegetable crops, such as cucumbers and other cucurbits. The pathogen can affect all parts of the plant: stems, leaves, pods, and seeds, posing a severe threat to commercial vegetable farming and grain production.

The primary symptoms of the disease include the formation of characteristic spots on leaves and stems. These spots are typically circular or irregular in shape, often characterized by a lighter center surrounded by a dark margin. Over time, pycnidia—small black dots containing fungal spores—develop on the infected areas, leading to premature drying and leaf drop.

The development and rapid spread of the disease are favored by high humidity levels (over 85%) and moderately warm temperatures (18–25°C). The infection is actively transmitted through contaminated seeds, plant debris left in the soil after harvest, and spores dispersed by wind or rain splashes during the growing season.

The economic impact of Neoascochyta blight is significant, as it causes a sharp decline in photosynthetic activity, disrupts nutrient uptake, and leads to substantial yield losses. In severe cases affecting legumes, seed quality deteriorates—becoming shriveled and losing viability—while internal mycelial infection can compromise future planting cycles.

Control measures are based on an integrated management approach:

• Using only certified, fungicide-treated seed lots.
• Practicing crop rotation, ensuring the host crop is not planted on the same field for at least 3–4 years.
• Thorough incorporation of crop residues into the soil and effective weed control.
• Applying systemic fungicides during the active growing season upon the first signs of infection.
• Cultivating resistant plant varieties and hybrids.