Published online by Cambridge University Press: 31 May 2012
The apple aphid, Aphis pomi DeG., has long been a problem in British Columbia orchards (13), but has become particularly serious in the last few years (14, 15). Infestations are common on both bearing and young trees. Aphids occur especially at the terminal parts of new growth, suckers and sprouts. They reproduce extremely rapidly and large numbers cause curling and deformatinn of leaves. Further, this distortion of the leaves then protects the aphid colonies from spray application to some extent, and in clumps of such leaves, unharmed survivors are often found after the most thorough spraying. However, even where efficient spray application has been made before the leaf-curling stage has been reached, reinfestation and recolonization, presumably from outside sources, is a common occurrence. A search for “persistent” aphicides, that would at the same time give control of other common orchard pests such as codling moth, has been in progress at this laboratory for some years and in particular, Diazinon (15), Trithion (14), and Sevin (6) have been studied.