Plum leaf gall midge

Systematic position: The plum leaf gall midge (Putoniella pruni) belongs to the order Diptera and the family Cecidomyiidae. This insect is a specific pest known for inducing the formation of characteristic galls on the foliage of various stone fruit trees.

Host plants: The pest primarily attacks species of the genus Prunus. Its most common hosts include domestic plums (Prunus domestica), myrobalan plums, blackthorn, and occasionally other stone fruit varieties that exhibit similar susceptibility to gall-forming dipterans.

Biology and life cycle: The lifecycle of the plum leaf gall midge is closely synchronized with the development of the host tree. Larvae hibernate in the soil beneath the canopy. Upon the arrival of spring, they pupate and emerge as adults. Females then deposit eggs on the surface of young, developing leaves, where the larvae feed, stimulating the plant to develop protective gall structures.

Nature of damage and pest status: The feeding activity of the larvae triggers the plant to form elongated, cylindrical galls along the leaf midrib. These galls are often red or brown, causing the leaf tissue to curl, deform, and lose functional area for photosynthesis. Heavy infestations result in severe leaf yellowing and premature leaf drop, which stunts tree growth and reduces fruit quality.

Control measures: Effective management requires a combination of cultural and chemical tactics. Key strategies include:

• Cultivation of the soil under the trees to expose and destroy overwintering larvae.
• Removal and destruction of infested leaves before the larvae emerge.
• Timely application of systemic or contact insecticides during the adult emergence and egg-laying period.
• Maintaining healthy tree vigor to help the plant withstand minor levels of damage.