Diseases of Pear Trees

Updated April 17, 2017

Pear trees can be afflicted by serious fungal, bacterial, and viral infections. These diseases can damage individual branches and roots. If not treated properly, the diseases can kill the tree.

Blossom Blast Disease

A bacteria called Pseudomonas syringae causes blossom blast disease in pear trees. Symptoms include brown flowers, leaf spots, twig dieback, and bark lesions. The bacteria produce a toxin called syringomycin, which damages plant tissue.

Pear Decline Disease

Candidatus Phytoplasma pyri causes pear decline. It is marked by wilting and abnormal red leaves at the top of the pear tree. The foliage spread reduces in size and a brown line is present in the phloem tissue.

Pear Scab Disease

A fungus called Venturia pirina causes scab disease in pear trees. Symptoms include spots that appear on fruits, flowers, and stems. The spots gradually grow and eventually crack the tissue, resulting in scabs.

Vein Yellows Disease

Vein yellows disease is caused by the vein yellows virus, which produces small yellow spots on leaves. The affected leaves are half the size of normal leaves. A similar strain of the virus, called red mottle virus, produces red spots on pear tree leaves.


Pruning infected twigs and affected fruits will help prevent the spread of disease. Use resistant rootstock when planting new pear trees. Applying fungicide to the soil can help reduce risk of infection.

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