Management of Insects on Fresh Market Tomatoes, Spring 1996B

Abstract

Abstract On 1 Mar, transplants were set 18 inches apart on raised beds of EauGallie fine sand covered with black polyethylene mulch. Plots were 3-21 ft long rows on 5 ft centers and were irrigated by a seepage subirrigation system. Insecticidal sprays were replicated 4 times in a RCB design and were applied with a high clearance, self-propelled sprayer on 15, 22 Apr, 1,8, 16, 24, 31 May, 5 and 12 Jun. The sprayer was operated at 200 psi and 3.4 mph and was fitted with Albuz orange nozzles. The number of nozzles per row was increased from 4 to 8 to increase gallonage as the plants grew. Thus, 60 gpa were applied the first two sprays (four nozzles), 90 gpa the next spray (six nozzles) and 120 gpa for the remaining five sprays (eight nozzles). The Admire treatment was applied in 4 oz water/plant on 4 Mar. Because of a very heavy population of southern armyworm larvae, weekly applications of Bacillus thuringiensis (Javeline and Xentari alternated biweekly) were initiated on 13 May. All control and yield data were collected on the middle 10 plants of the middle row of each plot. The terminal leaflet was collected from a leaf from the upper third of each of ten plants on 22 May and from two leaves from each of ten plants on 18 Jun. The numbers of crawlers, sessile nymphs and pupae (red eye nymphs) of the silverleaf whitefly (SLWF) were counted. The plants in the outside two rows of each plot were examined weekly for the presence of virus-like symptoms. There are two viruses present which have nearly indistinguishable symptoms: tomato mottle virus (ToMoV), a geminivirus vectored by the SLWF, and potato virus Y (PVY), a potyvirus vectored by several species of aphids. On 13 May and 18 Jun, a 3—4 leaf terminal was collected from each plant with virus symptoms from the outer two rows of the checks. The samples were frozen and a single leaflet was used later for determining the presence of ToMoV using nucleic acid spot hybridization and the presence of PVY using ELISA. All fruit of marketable size were harvested on 29 May and 14 Jun and the fruit were separated by the presence of southern armyworm, thrips (fruit with five or more oviposition dimples on blossom end) and stink bug damage and were counted and weighed.