Plum rust mite

Insect

Aculus fockeui (Nalepa et Trouessart)

Distribution: Most fruit-growing states and provinces in eastern North America.

Photos

On plum, damaged leaves exhibit “chlorotic fleck,” a series of yellow spots 1-2 mm in diameter. B

Plum rust mites (PRM) generally restrict their feeding to new foliage, causing these leaves to brown and roll upward longitudinally. Female PRM overwinter in dead or shrunken buds, moving to foliage as buds begin to open in spring. As many as 15 generations occur per year, with peak populations generally occurring in late July. Light to moderate populations are suppressed by predaceous mites.

Monitoring: Monitor new terminal growth for browning in July. PRM is mostly a problem where chemical spray programs have lowered populations of predator mites. PRM should be monitored after harvest in cherry to ensure that population levels do not reduce tree vigor for the winter.

Crops Affected: cherries, peaches, plums

Damage

Attacks plum, peach and cherry. Mites live on upper and lower surfaces of leaves, along the midribs, feeding extensively on young foliage. Feeding causes leaves to roll upward longitudinally and turn brown. Early leaf injury may cause dwarfing of the foliage and a brown or bronze scurfy condition on the lower leaf surface (B). On plums, individual leaves may exhibit "chlorotic fleck", which is the occurrence of spots of abnormally yellow plant tissue up to 1â€“2 mm in size. In severe cases, the leaf may become twisted or rosetted. Partial defoliation may occur in cherries.

Management

Miticide sprays may be needed in cases of severe infestation, particularly after harvest in cherries.

Similar Species

*This species also called peach silver mite due to synonymy of Aculus fockeui with Aculus cornutus (Banks).