Willow leaf spot

Stigmina deflectens is a fungal pathogen responsible for leaf spot disease in willow species (Salix). This condition is primarily classified as a foliar disease, often leading to premature defoliation and a decline in the plant's overall photosynthetic capacity during the growing season.

The host range is centered on various species of the Salix genus. It is particularly problematic in densely planted nurseries, hedges, and ornamental landscapes where environmental conditions remain humid and stagnant, facilitating the spread of fungal spores.

The symptoms of this infection are characterized by dark brown, often angular or irregular spots on the leaf blades. A key diagnostic feature is the presence of tiny, black fruiting bodies (stromata) that emerge in the center of these lesions as the fungus reproduces. When the infection is severe, these spots coalesce, causing significant tissue necrosis.

High moisture, frequent rainfall, and warm temperatures provide the ideal environment for the growth and dissemination of Stigmina deflectens. The fungus overwinters in fallen leaf litter and on infected twigs, serving as the primary source of inoculum for the following spring season.

Effective management requires a combination of sanitation and chemical interventions. Cultural practices are vital; removing and destroying all infected leaf litter reduces the pathogen load significantly. For intensive cultivation, applying broad-spectrum or copper-based fungicides at the onset of symptoms and during high-risk weather conditions can help maintain plant health.