EFFECTS OF IMIDACLOPRID AS A SOIL TREATMENT ON COLONIZATION OF GREEN PEACH APHID AND MARKETABILITY OF LETTUCE

Imidacloprid insecticide, applied as a soil treatment, protected lettu ce plants from developing infestations of green peach aphid, Myzus per sicae (Sulzer), for 60-100 d after planting based on two small plot an d two commercial field trials. Imidacloprid applied 7.6 cm sub-seed fu rrow provided longer and more consistent protection from green peach a phid than treatments applied to the soil surface, as a side-dress, or 15.2 cm sub-seed furrow. Surface band applications of imidacloprid pro vided inconsistent control probably because of inadequate hydrological incorporation into the soil. In small plot trials, effective control of aphids by imidacloprid applied 7.6 cm sub-seed furrow resulted in g reater than 90.0% marketable heads while the untreated plots contained 20.0% marketable heads. When used in a commercial setting, imidaclopr id applied 7.6 cm sub-seed furrow on leaf lettuce prevented aphid colo nization (<3 aphids per plant) for approximately 100 d after planting, while the untreated and commercial standard treated areas contained 3 0.7 and 26.8 aphids per plant respectively at 100 d after planting. In addition, marketability of lettuce was greater in imidacloprid treate d plots. As a sub-seed furrow treatment, imidacloprid provides a more suitable approach to aphid control than is currently available with fo liar insecticides.