In Season Control of Navel Orangeworm, Assessment of Application Coverage
Commodity Protection and Quality
2012 Annual Report
1a.Objectives (from AD-416):
Investigate the length of persistence of the new soft insecticides in pistachios that target navel orangeworm (Amyelois transitella), using bioassay and analytical chemistry,and assess spray coverage.
1b.Approach (from AD-416):
Pistachios will be sprayed by commercial cooperators and collected at intervals over a 30-60 day period. These pistachios will be challenged in the lab by infesting them with known numbers of eggs and assessing adult emergence. Samples will be taken from the hull and environment and analyzed to determine insecticide residue, which will be linked to the success of the bioassays. Additional experiments conducted in the field will assess insecticide coverage using sentinel eggs and spray cards.
This agreement was established to support objective 2. B of the in house project. We investigated the persistence and coverage of the two newly registered insecticides Lambda Cy (lambda cyhalothrin) and Voliam Xpress (lambda cyhalothron + rynaxapyr) in order to enhance navel orangeworm (Amyelois transitella) control in pistachios. A 500 gallon PTO-driven Air-O-Fan airblast sprayer filled with water applied at either 70 or 100 gallons/acre, tractor speed 2 mph, was used in these trials. Droplet deposition decreased in a nonlinear manner as the height increased. The dropoff in coverage began by 12 feet and was quite noticeable by 16 feet. Using two nozzles per vane improved coverage but dropoff still occurred. Coverage increased at 18-20 feet because the targets were above the canopy and the leaves did not block the spray. In conclusion, these coverage trials revealed a substantial breakdown in coverage between 14 and 16 feet, despite the use of two nozzles per vane. Based on other studies, this loss of coverage is exacerbated at higher speeds.