Onion Thrips Control, 1988:

Onions were direct seeded on 4 May at the Michigan State University Muck Soils Research Farm, Bath, Mich. Plots were 3 rows wide, 45.7 cm between rows, and 7.62 m long, arranged in a randomized complete block design with 4 replications. Three border rows were left unsprayed between eaeh plot. Treatments were applied with a hand-held CO2, sprayer, 3-nozzle boom, 1/row (D-1 orifice disk, 45 core, slotted strainer, hollow-cone nozzle, Teejet), at 2.81 kg/cm2 and 374 1/ha. Treatment application dates were 15, 22, and 27 Jul and 5, 11, and 23 Aug ’88. On 12 Jul, 16 randomly selected plots were sampled prior to treatment. A random sample of plants (20/plot) was pulled from the center row of each plot and the leaf bases of pulled plants were rinsed with 70% ethanol. The rinsate (with thrips) was collected in a cup and returned to the laboratory for analysis. Samples were filtered through a Buchner funnel onto filter paper and the adult and immature thrips were counted under a binocular microscope (10 X). All plots were sampled (20 plants/plot) on 18 Jul, 26 Jul, and 3 Aug. On 14 Sep, one 4.57-m section of an outside row was harvested from each plot. The total weight and number of onions/sample were recorded.