Although green peach aphids are not always a serious pest every year, colonies of these greenish, smooth-looking aphids can start showing up in peach blocks around this time if they are going to be a problem. They cause curled leaves that may turn yellow or red in severe cases. Green peach aphids suck the sap from the new fruits and twigs, and are also found on plum, apricot, cherry, and many ornamental shrubs. Also, keep an eye out for black cherry aphid in your cherry trees after shuck fall. By midway through the growing season, the majority of leaves are hardened off and psylla development may then be limited primarily to the water sprouts.
Honeydew injury occurs when excess honeydew drips onto and congregates on lower leaves and fruit.
The honeydew is a good medium for sooty mold growth. For psylla control, we have historically recommended an application of an effective insecticide when nymphs start to build to the level of 1-2 per leaf after Petal Fall. More than one application of some material is often necessary. In the most recent past, the pyrethroids and Mitac have been the most widely used psylla products in our area. During the past 6 years, we have additionally been able to use Agri-Mek under Section 18 exemptions, as a Special Local Need use, and under its current status as a full federal and state label.