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 Trust Agreement was established to support Objective 2.B of the in-house project, and by evaluating the persistence of these newly registered insecticides will improve control. In 2010 spray coverage, ovicidal and neonate activity, and the persistence of the insecticides Altacor, Belt, Bifenture, Brigade, Intrepid, Lambda-Cy, Warrior II, and Voliam Xpress were evaluated in Madera and Tulare counties by an ARS scientist in Parlier. In these assays, insecticides containing bifenthrin were the most toxic to eggs while insecticides containing Altacor, Belt, and Intrepid provided the longest duration of control. Insecticides containing bifenthrin (Bifenture, Brigade) broke down after 3 weeks while Belt retained its activity for 64 days. When Intrepid and Altacor were applied post harvest on October 1, Intrepid (24 oz) was more toxic than Altacor (4.5 oz) although both reduced the adult emergence by more than 85%. Experiments evaluating application coverage demonstrated that spray deposition decreased by 50% at a height of 12 feet at 2 mph, and that spray deposition decreased by 30% when tractor speed increased from 1.8 to 2.2 mph. There was a 50% dropoff in penetration after the first foot going into the canopy.