Effect of DDT, Xanthone, and Nicotine Bentonite on the Woolly Apple Aphid

Abstract

The use of DDT on apple trees in the Pacific Northwest results in greatly increased infestations of the woolly apple aphid by interfering with the Aphelinus parasite. This may become serious enough to require control measures if entire orchards are sprayed with DDT. Nicotine bentonite definitely reduces the numbers of woolly aphids, and they would not be a problem if it were used throughout the season. Xanthone resulted in the lowest infestation of any of these materials and seems to have a greater effect on the aphids than nicotine bentonite, although there is no evidence that it directly kills them. Even if some DDT is used with the xanthone, the infestation remains at a low level.