Plum gall mite

Systematic position: The plum gall mite (Eriophyes pruni) belongs to the phylum Arthropoda, class Arachnida, order Trombidiformes, and family Eriophyidae. These are microscopic, vermiform mites that are specialized plant parasites causing abnormal growth in host tissues.

Host plants: This pest primarily attacks various species of the genus Prunus, with plum (Prunus domestica) being the most susceptible. It can also be found on cherry plum and blackthorn, causing varying degrees of damage depending on the tree's health and environmental conditions.

Biology and life cycle: Adult females overwinter under the bud scales of the host plant. As the buds swell in spring, the mites migrate to the developing foliage. They pierce the leaf cells to feed, and the salivary secretions trigger the development of characteristic galls. Multiple generations may occur throughout the growing season.

Nature of damage: The primary symptom is the presence of numerous small, pimple-like galls on the upper leaf surface. While initially green, these galls eventually turn brown or black as they necroticize. Heavy infestations lead to early leaf drop, reduced tree vigor, and significant losses in fruit yield due to decreased photosynthetic surface area.

Control measures: Integrated pest management is essential. Cultural practices, such as the pruning and burning of heavily infested branches during the dormant season, help reduce the overwintering population. Chemical control involves the application of effective acaricides specifically timed before the mites enter the galls to provide protection during the growing phase.