Why Does My Filbert (Hazelnut) Look Unhealthy?

Are the nut kernels blackened and the nut shell has a small hole?

Are the new leaves twisted or curled and covered with a sticky coating?

Are the flower buds swollen?

Are the branches blighted, and with cankers?

Do you live somewhere in the eastern part of the country?

Are the leaves small, discolored, and drop early, clusters of honey-colored mushrooms may sprout at the base of the plant?

Do the leaves have a powdery white coating on them?

Are the leaves mottled yellow?

Filbertworms are larvae of a brown moth that feed on the inside of the nut. The easiest control is to keep trees free of ground debris, such as leaves, fallen nuts, and shells because the larvae pupate on the ground throughout the winter.

These symptoms usually indicate aphids. These tiny insects can vary in color, green, pink, black, gray to completely white. They cluster under leaves and on growing tips where they feed on plant sap. Leaves, stems, and buds get distorted and later leaves and flowers drop from the plant. You can control them by washing them off the plant with water spray. Insecticidal soap should be used with severe infestations.

Bud mites are known pests on Filberts. Infected flowers don’t produce nuts. Plant resistant cultivars, including ‘Barcelona’, ‘Cosford’, ‘Italian Red’, and ‘Purple Aveline’. In severe cases, spray trees with superior oil around May when the mites crawl out of the swollen buds to attack healthy buds.

Eastern blight is a fungal disease that has no cure. It is present in the East and carried on American filberts. Young branches are destroyed first, then older branches and the trunk, without killing the roots. American filberts have some tolerance for the fungus.

In the Pacific Northwest, blight is caused by western filbert blight, a bacterial disease. Small, angular spots appear on leaves, water-soaked at first, then turning reddish-brown. Cankers form on branches, which then may die. Control this blight by preventing sunburn and winter injury, especially on young plants, which are most susceptible. On older plants, only smaller twigs die. Spray with copper and prune out infected twigs in winter.

Armillaria root rot is a fungal disease that cannot be effectively controlled once it has become established in an orchard. Diseased or dead plants should be uprooted and removed.

White, powdery coating on the leaves is caused by a fungal disease Powdery mildew. Powdery mildew usually appears in damp places. Encourage good air circulation around the affected plants by thining any surrounding plants. Water plants from bellow to keep foliage dry. Any affected leaves should be cut off and removed. Any commercial fungicidal spray will protect your plant from further infections.

Hazelnut mosaic is a viral disease caused by

If the nuts are missing, the culprits may be animals like squirrels and chipmunks who steal the ripening nuts from the trees. Covering the trees with netting prevents squirrels or chipmunks from reaching the nuts.