Onion Thrips Control, 1993

Abstract

‘Spartan Banner 80’ onions were direct seeded on 13 May at the Michigan State University Muck Research Farm, Laingsburg, MI. Plots were 3 ft long non-adjacent sections of single rows (16 inch spacing between rows), separated by 8 untreated rows, with five replications in a randomized complete block arrangement. A natural population of thrips present in the field was augmented with thrips introduced on onion tops from a heavily infested commercial field. For each plot, five onion tops were inverted and placed in close contact with the hearts of the onions for 3 days and removed just prior to spray application. Treatments were applied with a hand-held CO2 sprayer with a flat fan nozzle at 40 psi and 50 gal per acre on 18 Aug. Due to a rain, heavy winds and the stage of the onions, plants had begun to lay down by 26 Aug when post-treatment sampling was done. Five standing plants were randomly selected in each plot and thrips were counted. Data were log transformed before analysis.