Onion Thrips Control, 1983

Abstract

Onions were seeded in 18 in rows at the M.S.U. Muck Crops Exp. Farm, Bath, Mich. (Clinton Co.). Onions, cv. Downing Yellow Globe, for Experiment 1, were planted in 18-in rows on 13 May with tractor-mounted. Planet Junior seeders and soil insecticide treatments were applied with a Gandy granular applicator. Plots were 15 rows by 15 ft long and treatments were arranged in a randomized complete block design with two replications of foliar treatments within each soil treatment. The soil treatments were not replicated, although samples were taken from randomly selected plants within each treatment. Foliar treatments were applied approximately weekly with a tractor-mounted boom sprayer (30 gal/acre) beginning when thrips populations began building up. Onions, cv. Spartan Banner, for Experiment 2 were planted on 15 May in 18-in rows with a vee-belt seeder. Plots were 1 row by 19 ft long and treatments were arranged in a randomized complete block design with five replications per treatment. Plots were part of a larger (13 treatment) experiment evaluating onion maggot control, reported separately. All of the onion maggot control plots, including the Dyfonate-treated and untreated plots reported here, were sprayed with Pydrin (0.1 lb(AI)/A) for thrips control beginning 2 Aug., and were not intensively sampled for thrips. Onion plants were sampled visually for thrips approximately weekly. Sixty plants per treatment (15 per plot) were sampled in Experiment 1 and 50 per treatment (10 per plot) in Experiment 2. Data was analyzed using standard ANOVA analysis with each plant (= subsample) being treated as a replication, since the variability between plants far exceeded the variability between plots.