Planted a Methley Plum earlier this year. All was well until recently. A white powdery substance appeared on the tops of the leaves and is spreading. Some leaves have died. others are in various stages of infection. We removed the badly damaged leaves to be burned, and have removed the mulch around the base of the tree. We have loosened the dirt around the base of the tree. Any recommendations? The leaves on the tree are beginning to sag but the branches look healthy. Is there a way to salvage the leaves?
Baltimore County Maryland
Hi- if you can wipe off and remove the white substance with your fingers then this may be some protective wax strands from an insect, such as planthoppers, or bits of dried flower parts from another tree species that drifted onto some of your plum leaves.
If you can't wipe it off, the white spots ("stipples") were caused by a sucking insect pest, such as aphids, leafhoppers, or planthoppers. The injury appears to be minor. Leaf yellowing and dieback could be occurring due to some other environmental stressors, such as high heat, compacted soil, damaged roots, etc. Digging around the base of the tree to loosen soil could injure the crown and roots. Spread an inch of compost under the tree canopy to help improve soil structure and provide slow-release nutrients.