APPLICATION OF INSECTICIDES FOLLOWING IMIDACLOPRID FOR MANAGING THE SILVERLEAF WHITEFLY ON FRESH MARKET TOMATOES, SPRING 1999

On 8 Mar, transplants were set 18 inches apart on raised beds of EauGallie fine sand covered with black polyethylene mulch. Plots were three, 21 ft long rows on 5-ft centers and were irrigated by a seepage subirrigation system. Treatments were replicated four times in an RCB design. Admire and Platinum were applied on 11 Mar to each plant in 4 oz of water. Naturalis, Neemix, Sunspray Ultrafine Oil, Mycotrol, and the insect growth regulators, Applaud and Knack, were first applied 30 Apr at the predetermined density of > 0.5 whitefly sessile nymph and/or pupa/leaflet. Subsequent treatments were made on a weekly schedule except during the week of May 17. Applications were made with a high clearance, self-propelled sprayer operated at 200 psi and 3.4 mph. It was fitted with eight Albuz orange nozzles per row and delivered 90 (six nozzles open) or 120 (eight nozzles open) gpa depending on plant height. Because of a heavy population of southern armyworm larvae, Mattch (2 qt/acre), SpinTor at 6 oz/acre, or Lannate LV (2 pt/acre) were applied weekly. The numbers of sessile nymphs (second and third instars) and pupae (fourth instar or red eye nymphs) of the silverleaf whitefly were counted on the terminal leaflet from the seventh-eighth leaf counting from the top of each of 10 plants in the center row of each plot on 5, 12, 19, 28 Apr, 3, 10, 17, 24 May, and 1 and 7 Jun. Red ripe fruit were harvested from the middle ten plants of the center row of each plot on 26 May, 1 and 7 Jun and were separated as to cull or marketable on the basis of fruit size and shape and the presence of zippers and excessive blossom end scars. Each marketable fruit was rated on 1-5 scale for increasing severity of external symptoms of irregular ripening. This disorder is caused by the feeding of the silverleaf whitefly and is characterized by incomplete ripening of longitudinal sections of fruit and an increase in internal white tissue. A rating of 1 had a small, faint "star" at the blossom end, 2 had a distinct star at the blossom end, 3 had a distinct star at the blossom end with points radiating up the fruit, 4 had < 30% of the fruit surface affected, and 5 had >30% of the fruit surface affected. Fruit with ratings of 3-5 were considered unmarketable.