ACARICIDE EFFICACY INTENDED FOR THE TWO-SPOTTED SPIDER MITE ON HOP, 2003

Acaricides were evaluated for efficacy against the TSSM in a 4.5-acre hop field at the Parma Research and Extension Center. The experiment was conducted in the summer of 2003 in a 46,800-ft2 section of field bordered on two sides by two rows of hop plants. The experimental design was a RCB, replicated four times, with four treatments, and an untreated check (UTC). Each plot consisted of 14 consecutive plants in a row (450 ft2). Envidor at 415ml/acre, Envidor at 533 ml/acre, TM-41301 at 915 ml/acre and Agrimek at 472 ml/acre treatments were applied at 150 gpa with an airblast sprayer on 25 Aug. Leaf samples were collected eight days after application, then every seven days (±1) thereafter. Ten randomly selected leaves were collected at two heights (2-8 ft and 8-16 ft) from each plot in the canopy and transported back to a lab for counting. The numbers of motile TSSM, TSSM eggs, motile PM and PM eggs per leaf were recorded. Data were analyzed by repeated measures analysis of variance (P ≤ 0.05).