Flax anthracnose

Flax anthracnose is a destructive fungal disease caused by the pathogen Colletotrichum lini. This pathogen affects the flax plant throughout its entire growth cycle, impacting both the quality of the fiber and the seed yield, which makes it a significant concern for flax producers worldwide.

The disease primarily attacks flax crops (both fiber and oilseed types). The fungus survives primarily within infected seeds and on contaminated plant debris left in the soil. It can also persist in the soil for several years, acting as a primary source of inoculum for subsequent plantings.

Symptoms initially appear as yellow or brown spots on cotyledons and stems. As the infection progresses, these spots develop into dark, sunken lesions. Under conditions of high humidity, the fungus produces visible fruiting bodies (acervuli) that appear as small black dots, often characterized by the presence of small, stiff hairs (setae).

The development of Colletotrichum lini is highly dependent on environmental conditions. High humidity (above 80%) and moderate temperatures ranging from +18°C to +22°C create an ideal environment for the rapid germination of conidia and the infection of healthy tissue. Rainfall and irrigation assist in the dispersal of spores throughout the field.

Integrated management is essential for controlling flax anthracnose. Key strategies include:

• Utilizing certified disease-free seeds.
• Treating seeds with effective fungicides before sowing.
• Practicing strict crop rotation, ensuring a gap of 5–6 years between flax crops.
• Implementing deep plowing to bury infected plant residues, which reduces the overwintering capacity of the fungus.