Witches' broom of cherry

Cherry leaf curl, caused by the fungus Taphrina wiesneri, is a destructive plant disease affecting various stone fruit species. This fungus is a biotrophic pathogen that overwinters as mycelium within the bud scales or bark crevices. As the trees enter their growth phase in spring, the fungus infects developing foliage, causing physiological disturbances.

Primary hosts for this pathogen are sweet and sour cherries (Prunus species). While the disease often presents as localized infection, severe cases can lead to widespread defoliation of the crown. The loss of photosynthetic surface area during the critical early growing season significantly impacts the tree's health and fruit development.

Symptoms are distinct and easily recognizable: leaves exhibit abnormal thickening, curling, and a characteristic reddish-purple discoloration. A fine, whitish bloom (the fungal spore layer) typically appears on the undersides of the distorted leaves. Affected leaves eventually become necrotic and fall off, causing premature defoliation and stressing the tree.

The development of Taphrina wiesneri is highly dependent on environmental conditions, specifically prolonged periods of cool, wet weather in early spring. High atmospheric humidity and moisture on leaf surfaces are crucial for spore germination and successful colonization of tender host tissues. When temperatures remain between 10°C and 15°C, the risk of an outbreak increases significantly.

• Apply copper-based fungicides in late winter or early spring before bud break.
• Prune and destroy infected twigs to reduce the primary inoculum load.
• Improve orchard hygiene by removing all fallen leaf debris during the dormant season.
• Ensure adequate tree spacing to promote air circulation and faster drying of foliage.
• Maintain optimal tree vigor through balanced fertilization and proper irrigation.