Venturia inaequalis

Apple scab disease

Description

The apple scab disease is caused by the apple scab. The fungus overwinters as a mycelium on twigs or among fallen, infected leaves on the ground. Early in the spring, the ascospores start to mature and the spores are ejected. Wet and enough warm weather favour the disease spread. The spores infect newly sprouting leaves. The spores penetrate the cuticle and live inside the leaves tissue. On the leaves occur the dark and olive green spots, whose later darken and become necrotized. Both sides of the leaves can show the symptoms and common place is along the leaf nerves. The young fruit can be infected in the spring. The dark colored sharply bordered, brown, and corky blotches are apparent on the infected fruit. The spots grow along with the growth of the fruit. It is also possible for the fruit to develop scab symptoms during storage. It is one of the most serious diseases of apple and causes huge economic losses.

Symptom

The lesions are olive -green. Later on, the lesions become grey and fluffy. The lesions may merge. Infected fruits and leaves may fall off prematurely.

Tree Species: Apple Tree

Part of a plant- attacked: Leaf / Needle, Fruit / Seed

Pest significance: Harmful

Pest Category: Fungi

Invasive Species: No

Present in EU: Yes