Originally Posted by allen73

Plum trees are prone to the plum pocket disease caused by the Taphrina communis and Taphrina pruni fungi. T. communis is found in plum trees all over the world. The disease starts with the appearance of white, blistery spots on the fruit. The affected fruit tissue enlarges rapidly and makes fruit abnormally large sized. The seeds of infected fruit are destroyed entirely, leaving only a large, empty cavity within the swollen, rotting fruit. The fruit is spongy in texture and turns gray as the rotting worsens with visible mass spore production. Other ba href="http://advancednutrients.com/hydroponics/articles/fruit-trees-ornamentals"fruit trees/a/b part such as foliage and twigs are rarely affected.

The fungal spores produced on infected trees during spring and summer overwinter under the bud scales and tree bark. These spores start to infect new growth the following spring as they are spread through the tree by splashing water, rain and wind. Cool and wet springs favor rapid spore germination. Debris under the tree consisting of infected previous year fruit also becomes a frequent source of infection in new growth.

Using dormant fungicides on trees is among the preventive measures to keep the disease from infecting trees during spring. The fungicides will not cure disease after the infection has occurred. Recommended time to spray trees is when the tree is dormant and before bud swell or appearance of flowers. In cases where the infection had been severe during the past year, it is best to spray the tree twice -- once during late fall and then again during early spring. Recommended fungicides include products containing chlorothalonil or liquid lime-sulfur.