Sweetpotato Whitefly Control on Cantaloupe, 1991

Abstract

The study was conducted at the USDA-ARS Irrigated Desert Research Station at Brawley, California, in a randomized complete block design with four replications. Seed was planted 20 Aug at the rate of three seeds/hill with hills spaced 30 inches within a row. Missing hills were replanted on 9 Sep. Each plot consisted of two rows spaced 40 inches wide. Rows were 20 ft long. Plots were partially isolated by 7-ft wide corridors of fallow ground between plots and 7-ft fallow alleys separating experimental blocks. Treatments were (1) cantaloupe seeds treated with NTN 33893 at 0.10 lb Al/lb of seed, (2) NTN 33893 treated seeds followed, after plant emergency, by a foliar spray of 1% liquid detergent, (3) a foliar spray of NTN 33893 at 0.13 lb Al/acre, (4) a foliar spray of Monitor at 0.5 lb Al/acre and (5) untreated plots. Foliar sprays of each material were made in 27 gal of water/acre on 10 Sep with a high clearance sprayer with a modified spray boom having two nozzles at the top of plants and four nozzles at the bottom of plants per row. Bottom nozzles were oriented at 30° angles to improve underleaf coverage. Five leaves numbered 2 or 3 from the apical bud were sampled from each hill in each plot on days 6 and 13 after foliar sprays. Large third and fourth instar nymphs were counted on each side of one 1.55-inch2 leaf disk/leaf and recorded separately for each surface. The effect of the treatments and SPW infestations on plant stand establishment were determined by counting the number of seed hill replants from the two 20 ft rows in each plot.