Gardening Articles: Edibles :: Fruit & Nut Trees
Fireblight Disease on Pears (page 2 of 2)
by National Gardening Association Editors
Control Pests Too
Control aphids and pear psylla to prevent them from spreading the disease. The chief pest of pear trees in eastern and western (but not central) United States is the pear psylla. This reddish- brown insect rapidly develops resistance to chemical controls; it causes significant damage by spreading pear decline and fire blight and sucking out the plant sap. The insects emit a sticky substance called honeydew on which a black fungus grows. Yellow jackets may congregate around the black fungus, indicating pest activity. Control adults with dormant oil spray in the fall when they are most susceptible. A fall spraying is better than a spring spray because it will not affect many of the beneficial insects that are present in the trees in very early spring. If necessary use a dormant oil spray in the spring to inhibit egg-laying and to kill any active adults present. The adults begin to lay eggs when the temperature gets up to 70° F, sometimes at slightly lower temperatures on a sunny day with no wind. You will have to use a 10-power magnifying glass to see the little yellow eggs at the base of the bud scales. As soon as you find any eggs, the first oil spray should go on. Spray again 7 days later. The insects don't seem to like laying eggs on this oily surface. Be sure to cover the tree thoroughly - until it's dripping. During the growing season use an insecticidal soap spray to keep pear psylla activity down.