Willow anthracnose

The disease is caused by the pathogenic fungus Colletotrichum salicis, which specializes in attacking the Salix genus. As a result of infection, the plant develops necrotic lesions on leaves and shoots, which significantly impairs the tree's photosynthetic capacity and overall health status during the growing season.

Willow anthracnose primarily affects various species of willow, posing a significant threat to nurseries and landscape gardening. The pathogen survives on fallen leaves and dead wood, which serves as a primary inoculum source for the following season. Under favorable conditions, the fungus can cause significant defoliation and shoot dieback.

Typical symptoms are manifested as dark brown or black spots on the leaf blade, often with a paler center. In humid conditions, small fruiting bodies called acervuli appear on these spots, producing masses of spores. This leads to leaf curling, premature browning, and eventually, the premature shedding of leaves, leaving the branches bare before the end of the season.

The development of the disease is strictly dependent on moisture levels. High humidity, frequent rainfall, and stagnant air in the canopy are critical factors that facilitate the germination of fungal spores. The spread of the disease is exacerbated by overhead irrigation, splashing rain, and the movement of contaminated pruning tools within the planting area.

Effective management requires a combination of cultural and chemical methods. Cultural practices include the removal and destruction of all infested debris to reduce the inoculum load in the garden. For chemical control, applying fungicides at the first sign of symptoms during the early stages of the growing season is crucial for protecting young shoots and maintaining the health of the willow specimens.