Miticide Efficacy Test, 1982

Abstract

Abstract This experiment was conducted in a late-planted, flood-irrigated corn field in northern Grant Co, KS. Ten treatments were arranged in a randomized complete block design with 4 replications. Each plot was 3 m wide (4 rows) and 15.2 m long surrounded by a 3 m-wide border of untreated corn. The treatments were applied on 1 of 2 dates except for 1 treatment that received 2 applications. The early treatments were applied on Jul 30 when the corn was in the 16-leaf stage (pre-tassel) and the late treatments were applied on Aug 10 when the corn was in the tassel stage. The chemical treatments were made with a high clearance sprayer using a 3-m boom with 3 nozzles directed at each row (1 nozzle directly over the row and 2 suspended on 46 cm drop hoses). The equipment was calibrated to deliver 20 gal of water/acre at 30 psi of CO2pressure. Counts were made by searching the leaves on 1 side of 2 plants in each of the 2 center rows to give 4 half-plant samples per plot. Plants were selected at random on the first sampling date and flagged so that the same plant could be counted on each sampling date. A visual search was used to record adult female spider mites and active stages of predator mites. Representative samples of spider mites were mounted for microscopic examination and all were determined to be the Banks grass mite.