Pear Tree Diseases
Pear trees (Pyrus communis) are hardy, deciduous trees native to Asia and Europe. They typically grow very quickly, bearing fruit three to five years after planting. Pear trees have glossy green leaves and are easy to grow, but they can be susceptible to diseases.
Fire blight (Erwinia amylovora) is a bacterial disease that causes severe symptoms. Blighted pear blossoms are brown, shriveled and wilted, while blighted pear shoots turn black.
Fabraea Leaf Spot
Fabraea leaf spot (Fabraea maculate) causes affected pear trees to defoliate early, resulting in smaller fruit and fewer fruit buds. It can be identified by small, circular purplish-black spots on leaves, fruits and shoots.
Pear scab, often called black spot, is caused by a fungus (Venturia pirina). This fungal disease causes round, brown lesions to form on the pear tree’s petioles and leaves.
Stony pit is a viral disease common to the Bosc pear variety. Stony pit causes pear pit cells to fuse into a stony, cone-shaped mass.
Several management practices can reduce the risk of pear tree diseases, including controlling the insect population. Pear trees should not be overfertilized or watered with overhead sprinklers.
Bartlett Pear Tree Diseases
Bartlett pear trees are susceptible to fire blight, a common pear disease that begins to appear in warm, humid weather in the spring after rainfall. The disease, caused by Erwinia amylovora bacteria, spreads through insects including aphids, bees, flies and leafhoppers as well as by splattered water, wind, pruning tools and humans brushing against infected branches. Rake up and burn all plant debris. Spraying infected trees every three to five days with copper compounds may help control the onset of fire blight, but pruning is the only sure way to get rid of it. Crown gall is a bacterial disease caused by Agrobacterium tumefaciens. If roots are infected, replacing the tree is usually the best solution. Powdery mildew appears in humid spring weather as a white or gray dusty coating on the pear tree's leaves.
- Enchanted Gardens: Fruit Trees, Flowering Trees
- Sunset Western Garden Book; Kathleen Brenzel, Editor
- University of California, Integrated Pest Management Program: Fire Blight
- University of Kentucky, Extension: Plant Pathology Fact Sheet: Crown Gall
- University of California at Davis, Extension Service: Apples and Pears: Calendar of Operations for Home Gardeners
- National Sustainable Agriculture Service: Pears: Organic Production
- University of California, Integrated Pest Management: Pear Decline