We have already begun to see some problem populations of green aphids in western N.Y. apple blocks, so it looks like this may be one of those years to keep a vigilant eye open. Large numbers of both may build up on growing terminals on apple trees during summer. Both species are apparently common during the summer in N.Y. orchards, although no extensive surveys have been done to compare their relative abundance in different production areas throughout the season. Nymphs and adults of both species suck sap from growing terminals and water sprouts. High populations cause leaves to curl and may stunt shoot growth on young trees.
Aphids excrete large amounts of honeydew, which collects on fruit and foliage.
Sooty mold fungi that develop on honeydew cause the fruit to turn black, reducing its quality. Aphids should be sampled several times throughout the season starting in mid-June. Inspect 10 rapidly growing terminals from each of 5 trees throughout the orchard. Record the percentage of infested terminals. The larvae of syrphid and cecidomyiid flies prey on aphids throughout the growing season.