Aphids in plum tree
Gross as this may appear, the aphids curling the leaves are not really a serious problem for the tree. In an environment not much sprayed there are always many, many others who feast on aphids. If you want to attract such predators, just squish a bunch of aphids. That will send a chemical signal which can be picked up by those hungry helpers. Aphids curl the leaves to hide. Because of the different times just now, many businesses are changing their availability also. Sprays have difficulty reaching the hidden insects and systemic chemicals will affect the pollinators and the fruit. The eggs of the aphids overwinter on plum and prune trees. Apply superior type horticultural oil according to the directions in the dormant season. Spray in early November and then monitor the plant during the remainder of the dormant period. Read the manufacturer’s instructions for rate of application and amount of dilution. A forceful spray of the leaves with Neem oil or horticultual soap spray can reduce the numbers.