Marssonina juglandis

Walnut anthracnose

Description

A leaf, twig and fruit disease (anthracnose) caused by the Gnomonia leptostyla, sexual stage of Marssonina juglandis. Conidia are formed in brown blotches in one year, but it is only in spring when the sexual stage starts on the leaf litter. Minute brown spots on leaves and twigs appear as early as in early June, progressing into severe necrosis by the end of July. The pericarp surface suffers black and gradually sunken blotches with cracks. The fungus causes leaf fall and inhibits tree growth and fertility.

Symptom

Minute brown spots on leaves and twigs appear as early as in early June, progressing into severe necrosis by the end of July. The pericarp surface suffers black and gradually sunken blotches with cracks.

Tree Species: Walnut

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

Pest significance: Harmful

Pest Category: Fungi

Invasive Species: No

Present in EU: Yes