Walnut anthracnose (Gnomonia juglandis) – identify and control

Walnut anthracnose (Gnomonia juglandis) is a widespread disease and is considered one of the most common diseases of walnut trees.

Symptoms. The attack is manifested on leaves and fruits in different stages of development and less often on shoots. On the upper part of the leaves, small (2-5 mm diameter), brown, more or less circular spots appear at the beginning. Later, these spots that are initially located between the leaf veins will converge and gradually increase.
On the lower part of the leaflets next to the spots, there are smaller black dots, with a concentric arrangement. As a result of the attack, the leaves turn brown, dry out, and drop. Also, the ripening of fruits and shoots is abnormal.
On the young fruits attacked by walnut anthracnose, small, circular, brown spots appear, deep in the pericarp and as a result of the attack the fruits remain small, darken and fall. On the attacked young branches elongated brown spots appear, which deepen in the substrate having the appearance of open cancers.

The pathogen. Gnomonia juglandis, the fungus overwinters in the form of perithecia in the fallen leaves on the ground. And in the form of resistance as a mycelium in the bark of the branches.

Prevention and control. It is recommended to gather and destroy by burning the fallen leaves or to bury them by deep plowing. The infected shoots will be cut and burned as well.
The chemical treatments will be applied once the trees start growing and will be repeated throughout the vegetation period. The application of specific fungicides is recommended.

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Walnut anthracnose (Gnomonia juglandis) – identify and control
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