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.