What Is Wrong With My Pistachio Tree?

Are there any small, round reddish brown spots with white to grey centers on the upper surface of the leaves?

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

Are there any black circular spots on leaves, shoots, and rachis; black lesions may be present at the base of shoots?

Are there any small, angular, gray-brown spots with defined darker red-brown margins on leaves?

Are there any rust-colored spots on foliage?

Are the leaves covered with white powder?

Does the crown have swollen, tumor-like growths?

Are the growing shoots wilted or dying, a gummy exudate is present?

These symptoms indicate Alternaria leaf spot. Warm, wet conditions favor this fungal disease. Spray infected plants with copper and/or sulfur to prevent further disease development. Plant only pathogen-free seed from a reputable nursery.

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. Planting resistant rootstock is the most effective method of preventing the disease.

Panicle and shoot blight is a fungal disease that is very difficult to control and treatment relies on a combination of pruning, fungicide application, and good irrigation practices. Multiple applications of an appropriate fungicide are required over the summer months. Infected areas should be pruned by cutting 2 inches below symptomatic areas. If sprinkler irrigation is used then water should be directed away from the tree canopy.

These symptoms indicate fungal disease - Septoria leaf spot. Remove and destroy infected plant debris. Don't handle or brush against plants when they are wet. Rotate plantings. Remove weeds growing nearby.

Rust-colored spots on foliage indicate a fungal disease - Rust. Provide good air circulation around plants by thining them. Avoid making leaves wet when watering. All infected leaves should be removed. Spray leaves with sulfur early in the season to prevent rust or to treat mild infections.

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

Bacterial disease Crown gall causes wartlike swellings on Pistachio crowns. Plants can become stunted, subject to drought stress and wind damage. Large enough galls may cause girdling which results in plant death.

These symptoms may indicate Pistachio twig borers. These small caterpillars tunnel into growing shoots and fruits and feed on the inside. Prune off the affected fruits and shoots below the entry point and destroy them. If you find holes in larger branches, slide the wire into the hole to kill borers inside.

If the leaves are curling, turning yellow and necrotic the culprits are Pistachio psyllids. The eggs and larvae of this tiny insect overwinter on buds and infest new leaves in spring. At the first sign of damage, spray your plant with insecticidal soap, or pyrethrin for serious infestations.