Willow bark necrosis

Sillia ferruginea is a fungal pathogen responsible for causing significant necrosis in the bark and cambium of willow trees (Salix spp.). This disease acts as a opportunistic parasite, primarily targeting weakened or damaged trees and leading to dieback of branches and stems.

The causal agent is an ascomycete fungus. Its life cycle begins when spores enter the host through bark wounds, frost cracks, or pruning cuts. Once established, the fungus colonizes the cambial tissue, gradually blocking nutrient transport and causing localized tissue death.

Symptomatology typically involves the formation of sunken, discolored lesions on the bark, which can range from light brown to a dark rusty red color. Over time, the affected bark may crack or peel, exposing the underlying wood, and fruiting bodies often emerge from these spots during wet weather.

Environmental conditions play a crucial role in disease development. High humidity, mild temperatures, and stress factors such as drought or poor site selection increase susceptibility. Spores are easily disseminated by wind and splashing rain, allowing the disease to spread rapidly through a willow grove.

• Prune and destroy infected branches immediately.
• Sterilize pruning tools to prevent cross-contamination.
• Apply fungicide sprays in early spring for protection.
• Ensure proper site drainage and tree vitality.
• Monitor for early signs of bark discoloration.

Effective management relies on a combination of cultural practices and chemical control. By maintaining tree health and reducing the availability of fungal entry points, the risk of severe damage from Sillia ferruginea can be significantly mitigated.