Pear trees can face challenges from various pests that impact their health and productivity. Understanding these issues and implementing effective management strategies are crucial for a healthy harvest. This guide covers identifying and addressing common pear tree pest problems.
Common Pests Affecting Pear Trees
Common pear tree pests have distinct appearances and damaging habits. The codling moth (Cydia pomonella) adults are mottled grey moths, 1/2 to 3/4 inch long, with a coppery-brown band at their wing tips. Their larvae, white to light pink with dark brown heads, bore deep into fruit to feed on seeds after hatching from eggs laid on fruit or leaves.
The pear psylla (Cacopsylla pyricola) is another prevalent pest. Adults are tiny, 1/12 to 1/8 inch long, with transparent wings held roof-like over their dark brown to reddish bodies. Nymphs are flat, yellowish-green, and feed by sucking sap from leaves and stems, causing damage and excreting honeydew. Pear psylla can also transmit pear decline, a disease that can weaken or kill trees.
The pear slug (Caliroa cerasi) is the larva of a sawfly and a common sight. Larvae are olive-green to black, slimy, slug-like, and grow up to 1/2 inch long. They feed on the upper surface of leaves, leaving a skeletonized, lacy appearance. Adult sawflies are glossy black, wasp-like insects around 1/5 inch long, that lay eggs on pear leaves.
Aphids are small, soft-bodied insects ranging from green to pinkish-grey or black, often clustering on new growth. They overwinter as eggs on the tree, hatching in spring to rapidly build populations. Aphids feed by sucking sap from leaves and shoots, leading to distorted growth and honeydew excretion.
Recognizing Pest Damage and Symptoms
Pest infestation signs on pear trees are often visible even if insects are not. On leaves, symptoms include curling, distortion, or yellowing, sometimes with brown edges or discolored blotches. Skeletonized leaves, where only veins remain, indicate pear slug activity. Honeydew, a sticky residue, may also be present on leaves and fruit, often leading to black, sooty mold growth.
Fruit damage includes holes, sometimes with sawdust-like frass, indicating internal feeding by pests like the codling moth. Fruit may also appear deformed, russeted, or discolored. Premature fruit drop or fruit blackening from the base upwards also signals pest issues. New shoots and branches might exhibit stunted growth or dieback, and bark may show scales, sunken areas, or cracks.
Integrated Pest Management Principles
Integrated Pest Management (IPM) is a comprehensive and sustainable strategy for controlling pear tree pests. This approach emphasizes long-term prevention and uses combined methods to minimize environmental impact. Diligent monitoring, regularly inspecting trees for early pest activity or damage, is a primary IPM principle.
Prevention, another core tenet, focuses on maintaining tree health and vigor through sound cultural practices. This includes proper pruning, adequate watering, and balanced fertilization. Encouraging beneficial insects, natural predators of common pear pests, is also important. When interventions are necessary, IPM prioritizes least-toxic options, reserving chemical controls as a last resort only when pest populations reach damaging levels.
Effective Control Methods for Pear Tree Pests
Effective pear tree pest management combines strategies, starting with cultural practices that promote tree health and deter infestations. Regular pruning removes infested branches and opens the canopy, improving air circulation and reducing pest habitats. Sanitation, consistently removing fallen fruit, leaves, and debris from around the tree base, eliminates overwintering sites. Appropriate watering and fertilization ensure the tree remains vigorous and resilient to pest pressure.
Physical and mechanical controls offer direct intervention. Hand-picking visible pests or removing infested fruit is effective for smaller infestations. A strong stream of water can dislodge aphids from leaves. Traps (e.g., pheromone traps for codling moths, sticky bands on trunks) help monitor pest populations and prevent larvae from climbing. Bagging individual fruit also protects them from boring insects.
Biological controls encourage beneficial insects (e.g., ladybugs, lacewings, parasitic wasps, earwigs) that prey on common pear pests. When other methods are insufficient, organic and least-toxic sprays can be applied, including:
Dormant oil, applied during the tree’s dormant season, smothers overwintering eggs and pests like aphids, mites, and psylla.
Neem oil, which acts as a natural pesticide and growth regulator; insecticidal soaps are effective against soft-bodied insects like aphids and pear slugs.
Bacillus thuringiensis (Bt), which targets caterpillar pests like the codling moth.
Kaolin clay, which deters moths by creating an unappealing surface on the fruit.