Branches, Trunk Split Because of Weather
Although pear wood is inherently very hard and durable, Callery pear trees tend to have splitting problems. Their branching habit is to form narrow crotches, which, with age, sometimes cause the breaking away of large, spreading branches or even sections of the trunk during winds or storms.
There is no way to prevent this. Be prepared that your tree will have a short lifespan or choose any of the varieties, such as ‘Aristocrat’, which has more open angled, horizontal branching.
Withered, Dead Blossoms
Fireblight - Fireblight fungus is one of the most serious pests of pear trees. On the whole, ornamental pear trees are resistant to this disease, but it is important to be able to recognize it. It can be controlled by correct fertilization and pruning and by using resistant varieties of pear trees.
Shoots infected with fireblight turn brown or black as though scorched. The blossoms wither and die. Water-soaked bark lesions appear that are reddish in color, and on warm days they ooze an orange-brown liquid. Later they become brown and dry.
The best defense against fireblight is diligent pruning. In the winter look for affected branches with visible cankers and prune them off just a few inches below the spot. On limbs too large to remove, pare away diseased tissues. In the summer, watch for blackened leaves, stems or fruits and cut them off 12 inches below any sign of disease. Also, snap off any vigorous suckers that grow vertically from the branches or the rootstock. They are prone to fireblight. Disinfect your pruning tools by dipping them for a few seconds in a solution of hot water and household bleach after each cut.
Foliage Curls, Puckers, Turns Yellow
Aphids - When foliage on pear trees curls, puckers and turns yellow, and the blooms become stunted, suspect aphids. Look for clusters of soft-bodied, pear-shaped insects abut the size of a pin head on the undersides of young leaves. They may be green, brown or pink. Look for ants on the trees also. They are attracted to a sticky honeydew secreted by aphids. If your tree is small, and the foliage is accessible, spray the aphids with a vigorous water spray first thing in the morning, once every other day for three days. For more information see the file on Controlling Aphids
Gypsy Moth - Newly hatched gypsy moth caterpillars are about 1/16 inch long and grow, ultimately to about 2 to 2 1/2 inches. They are gray and have long brown hairs. Their eggs are light brown to yellow and are laid by adult moths on tree trunks and branches from August through to the following April. The young caterpillars infest many types of trees in the Northeast. While their favorites are oaks, they attack other trees as well. Masses of caterpillars are obvious as they eat tree foliage, eventually defoliating the entire tree. For more information see the file on Controlling Gypsy Moth
Leaves Are Stippled Yellow
Mites - Mites are tiny insects about the size of a head of a grain of black pepper. They may be red, black, or brown. Pear tree leaves that are stippled, yellow and dried, or that have pale yellow spots or blotches, signal the presence of spider mites. They suck the chlorophyll from the leaves, causing small pale dots to appear. They simultaneously inject toxins into the leaves, which discolor and distort them. If your trees are small and young, spray their foliage with a vigorous stream of water in the morning three times, once every other day to disrupt their lifecycle and knock them from the leaves. For more information see the file on Controlling Mites