Pest & Disease Control for Filbert Hazelnut Trees

Every tree has the future potential for disease and insect damage. Factors such as location and weather will play a part in which issues your tree encounters. If available, disease-resistant trees are the best option for easy care; and for all trees, proper maintenance (such as watering, fertilizing, pruning, spraying, weeding, and fall cleanup) can help keep most insects and diseases at bay.

NOTE: This is part 5 in a series of 9 articles. For a complete background on how to grow filbert hazelnut trees, we recommend starting from the beginning.

Leaf Spot

Purple spots on leaves. May or may not have gray centers. Can be round but also fan-shaped. Can cause leaf curl. Many fungi cause spots and affect different varieties differently.

Control

  • Consult County Extension Agent

Leafroller

Pale yellow or ‘dirty’ green worms. Leaves are rolled and webbed together where insects feed. Eventually becoming skeletonized.

Natural Control

  • Natural Guard® Caterpillar Killer Spray w/BT

Powdery Mildew

Whitish-gray powdery mold or felt like patches on leaves or nuts. Leaves may fall off early, nuts may have split shucks and shriveled kernels. Disease hits so late in season, control often not needed.

Natural Control

  • Monterey Fruit Tree Spray Plus

Aphids

They are the size of a pinhead and vary in color depending on the species. Cluster on stems and under leaves, sucking plant juices. Leaves then curl, thicken, yellow and die. Produce large amounts of a liquid waste called “honeydew”. Aphid sticky residue becomes growth media for sooty mold.

Natural Control

  • Monterey Fruit Tree Spray Plus

Leaf Scorch

Appears as a yellowing or darkening of the leaf between the main veins or along the edges of the leaf. Trees that develop leaf scorch may lose many leaves during the summer months.

Natural Control

  • Adequate fertilizing and watering can help clear up sever cases of leaf scorch.

Other Control Options

  • Consult County Extension Agent

Eastern Filbert Blight

Fungal disease spread by the wind. Oval shaped black sores after extended periods of cold weather. Tree could die within 5 to 12 years if no action is taken to clear up the infection.

Natural Control

  • Infected branches should be cut a little less than a yard below the edge of where the sores appear. The fungus can continue to grow even after the branch is cut so they should be burned or chipped after removal.

Chemical Control

  • Ferti-lome® Broad Spectrum Landscape & Garden Fungicide

Canker

Dead portions of bark or branches, can lead to wood decay that makes the tree susceptible to damage from wind and snow. Dead portions of bark are also prime sites for wood rotting insects to invade.

Natural Control

  • Watering and pruning regularly can avoid cankers.
  • Protecting the tree from lawn equipment and vehicles will also help reduce the risk of cankers that form because of injury to wood.

Other Control Options

  • Consult County Extension Agent

Sooty Mold

Caused by black fungus that invades the leaves, branches and nuts. Mold spores stick to honeydew left behind on trees by aphids, mealybugs and whiteflies.

Natural Control

  • Wash the fungus off

Other Control Options

  • Consult County Extension Agent

Hazelnut Mosiac

Abnormal ring spot, line patterns and flecking on older leave.

Control

  • Consult County Extension Agent

Tent Caterpillars

Hairy caterpillars that enclose large areas in webbing and feed on enclosed leaves. Remove web with rake and burn. Caterpillars are pulled out with webs.

Natural Control

  • Natural Guard® Caterpillar Killer Spray w/BT

Chemical Control

  • GardenTech® Sevin® Concentrate Bug Killer

Filbertworm

Small moth with coloring of bronze, coppery or reddish brown, larvae is light brown to whitish. Larvae feed on the nut kernels.

Control

  • Consult County Extension Agent

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