Aphids and fire blight are the major problems for pears (Pyrus). In the lefthand column you'll find symptoms and signs of common pests and diseases, and to the right you'll find their cause as well as how to control them.
For any of the insecticides, herbicides or fungicides mentioned, always carefully follow the label's directions.
| Symptoms and signs | Cause | Control |
|---|---|---|
| Shoots and young leaves are crippled or stunted. Small sticky insects are present. | Aphids | Spray with insecticidal soap or malathion. |
| Numerous tiny dark brown bumps appear on both sides of leaves. | Leaf blister mites | Destroy infected leaves and fruits. Spray with lime sulfur in early spring. |
| Young fruits become deformed, often elongated or rounded. Later, fruits may crack, decay and fall. | Pear midges | As a preventative, spray with dimethoate or malathion when petals fall. Destroy all fallen fruits. |
| Leaf surfaces eaten; later, exposed veins brown and die. Small black caterpillars are visible. | Pear or cherry sawflies | Spray with Bacillus thuringiensis when insects are first seen. |
| Eggs are laid in young fruits. Larvae feed on and destroy fruits. | Plum curculios (weevils) | Spray with carbaryl or insecticidal soap at petal fall and 7 to 10 days later. Repeat at least twice more at 7- to 10-day intervals. |
| Full-sized fruits, on tree or in storage, show pale brown areas with concentric rings of small whitish or yellowish bumps. Sometimes fruits dry up on tree. | Brown rot (fungus) | Destroy all rotten and withered fruits on tree, on ground and in storage. When pruning, cut out and destroy dead shoots. Spray trees with captan or sulfur in late summer to reduce rotting of stored fruits. |
| Leaves turn brown and look burned, hang down from the branch, but do not fall. Cankers arise on branches. | Fire blight (fungus) | Prune out infected branches as soon as seen, cutting well inside problem. Spray with lime sulfur in late winter and with a copper fungicide as leaves unfurl. |
| Twigs or young stems have slightly sunken areas of dead tissue. These areas expand; central tissues eventually crack and flake off. Cankers girdle and kill stem. | Pear canker (fungus) | Cut out or pare off infected parts and destroy. Improve drainage if waterlogging occurs, as this may aggravate disease. Spray with Bordeaux mixture in spring. |
| Brownish or blackish spots appear on leaves and fruits; blisters and cracks develop on shoots in spring. | Pear scab (fungus) | Spray with captan, or thiram. Apply spray when flower buds are nearly open, when petals fall, and 3 weeks later. |
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Aphids cause the shoots and young leaves of pears to become crippled and stunted.
