Onions were planted with a veebelt seeder in 18 in rows at three locations. Plots were: 10 ft of double row x four replications at Grant, (1-in planter shoe, planted 6 May); 19 ft of single row x five replications at the M.S.U. Muck Crops Experimental Farm (1-in shoe, planted 13 May); and 10 ft of double row x six replications at Hudsonville (2-in shoe, planted 5 May). Treatments were arranged in a randomized complete block design and applied in the furrow at planting (granular materials) or in a 2- to 3-in band over the row (soil drenches). Soil drenches were applied at 50 gal/acre with a hand sprayer with the initial application date corresponding to the first appearance of onion maggot eggs. Pydrin 2.4EC (0.1 lb. (AI)/acre) was applied to all plots twice during Aug. for thrips control. After plant emergence, but before onion maggot oviposition, 100-plant sections of row were marked out in each plot. Counts of onion maggot damaged plants within those 100-plant sections were made weekly through the end of the first generation damage (5 July). Stand counts within the 100-plant section were taken on 20 to 21 June and 5 July. Yields were taken from 5 ft of double row per plot at Grant and Hudsonville and 10 ft of single row at the M.S.U. Muck Farm on 29 Sept. and 1 Sept., and 4 Oct., respectively.

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.