Changes in the Growth-regulator Content of Plum Infested with Fruit Tree Red Spider Mite,Panonychus ulmi(Koch)

Abstract

Extracts and diffusates were collected from the extending region of Brompton plum shoots shortly after a reduced rate of extension was detected in those infested with fruit tree red spider mites. Bioassays showed greater amounts of gibberellin-like substances and smaller amounts of auxin-like substances, with the exception of IAA, in the mite-infested material. Although the extending internodes of infested plants contained significantly less IAA than the controls, there were similar amounts of IAA in the expanding leaves of infested and control plants.