Assessment of Application Coverage to Control Navel Orangeworm
Commodity Protection and Quality
2013 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).
1b.Approach (from AD-416):
Pistachios will be sprayed by commercial cooperators and collected at intervals over a 4-8 week period. These pistachios will be challenged in the lab by infesting them with known numbers of eggs and assessing adult emergence. Additional experiments conducted in the field will assess insecticide efficacy against sentinel eggs and adults. Bioassays will be conducted evaluating contact toxicity as well.
This trust agreement supports Objective 2 B of the parent project, reducing insect pest populations to reduce the need for post harvest treatment as well as promoting the use of selective rather than broad spectrum insecticides to control navel orangeworm. The navel orangeworm is the primary lepidopteran pest of pistachios and its control can be challenging. Growers need to know the relative strengths and weaknesses of the insecticides on the market so that they can be used to maximize control of this pest. An ARS scientist at Parlier investigated the duration of control by bioassay (as long as 30 days) of several newly registered classes of insecticides used to control navel orangeworm in pistachios. Split pistachios (early split or hull tear) were collected at intervals after insecticide application and placed in glass jars (half gallon or full gallon),challenged with navel orangeworm eggs and incubated at 80°F. These results indicate that narrow spectrum insecticides can provide protection for as long as 30 days and that the growers can choose from several classes of these new insecticides. This flexibility will enable growers to rotate among classes of insecticides and delay the onset of resistance, as well as increase nut quality, resulting in greater sales.