Control of Silverleaf Whitefly on Commercial Eggplant, 1997

Abstract

Abstract A commercial field of staked eggplant was used ap-proximately 45 days after transplanting for this trial in the Culican Valley of Sinaloa, Mexico. The field was 100 m wide and approximately 2 km in length, located between 2 fields of corn. The crop had recently been sprayed with endosulfan (Thiodan®). Consequently, relatively few adult whiteflies could be observed although the presence of eggs and young nymphs indicated the likelihood of increasing infestation, and no further applications were made by the grower for the duration of the trial. Experimental design was completely randomized block with 5 treatments and 4 replicates. Beds were 100 m in length running north and south with 1.5 m between centers and 2 rows per bed. Plots were 4 beds wide and 15 m long with 1.5 m between plots (90m2). Three weekly applications were made beginning on 12 Feb with 2 Maruyama™ motorized backpack sprayers equipped with a hand-held boom carrying 2 bronze T-Jet™ D2 hollow cone nozzles containing #45 spinner plates. Each bed was sprayed from both sides with 5 liters per replicate of each treatment, delivering a volume of 60.5 gpa. Each plot was sampled for whitefly adults and immature stages prior to application. A beat pan made of an aluminum cake pan 22.5cm X 32.5 cm painted black and covered with a film of vegetable oil and liquid detergent (9:1) was used to sample adults. Three samples were taken in each plot by beating the pan 10 times against the foliage in the middle 2 rows and counting the whiteflies trapped in the oil mixture. Immatures were sampled by counting all whitefly eggs, small nymphs, large nymphs, and pupae in 4 lensfields of 1.77 cm2 per leaf (3 leaves per plot). Additional samples were taken 3 days after each successive treatment. Small nymphs, large nymphs, and pupae were combined as “immatures” for analysis.