Effects of imidacloprid on colonization of aphids and silverleaf whitefly and growth, yield and phytotoxicity in cauliflower

Imidacloprid transplant drench root plug treatments of cauliflower and imidacloprid treatments proplant in-furrow soil injections were evaluated for their effects on colonization of silverleaf whitefly, Bemisia argentifolii Bellows and Perring, green peach aphid, Myzus persicae (Sulzer), and cabbage aphid, Brevicoryne brassicae (Linnaeus). Whitefly treatments included imidacloprid root plug treatments of 180, 270, and 360 g AI/ha, an in-furrow treatment of 360 g AI/ha, and an untreated control. Aphid treatments included imidacloprid root plug treatments of 90, 180, and 270 g AI/ha, an in-furrow treatment of 360 g AI/ha, and an untreated control. The untreated control plants had significantly greater numbers of apterous aphids and whitefly nymphs than imidacloprid treatments. The imidacloprid in-furrow treatment had significantly fewer whitefly immatures than other treatments on several sampling dates. Phytotoxicity evaluations revealed some leaf tissue necrosis from root plug treatments of imidacloprid during the fall planting. Plant growth was re retarded, harvest was delayed, and yield of kg of marketable heads was lower for the untreated control cauliflower plants due to higher whitefly infestation. Reduced yields due to aphids was not observed in the fall planting.