plum pocket[′pləm ‚päk·ət]
a disease of plums caused by the ascomycetous fungus Exoascus pruni. The fungus infects the ovaries of the flowers. Instead of fruits, long, hard, flattened, and hollow saclike formations without stones develop. Plum pocket is prevalent in Europe, Asia, and North America. In the USSR it is found in the northwestern and central regions of the RSFSR, northern Armenia, the mountainous regions of Uzbekistan, and the Far East. The plant is infected with spores of the fungus during the flowering period. The infected flowers produce diseased fruits, and sacs with spores are formed under the cuticle. When the sacs mature, the cuticle ruptures and the spores scatter. They lie dormant throughout the winter on tree crowns, in cracks in the bark, and between the bud scales. Plum varieties with a relatively late and prolonged flowering period are most severely infected. Control measures include the collection and destruction of the pockets and the application of fungicides to the trees.