Evaluating insecticide coverage in almond and pistachio for control of navel orangeworm (Amyelois transitella) (Lepidoptera: Pyralidae)

Abstract

BACKGROUND: Insecticide application is essential to control navel orangeworm (Amyelois transitella) in California almond and pistachios. Coverage is difficult because of tree height and applicator practices. Studies were conducted to characterize insecticide deposition by both ground and air, and to develop alternatives to the use of water-sensitive cards to assess spray coverage. RESULTS:We used almond challenge bioassays to demonstrate that insecticide application failed first in the upper canopy (5.2-6.1 m) when application speed exceeded 2.9 kph. In pistachios, we used filter paper and insecticide extraction from hulls to demonstrate that deposition increased with application volume. Typically, in ground applications, coverage decreased with height, whereas for application by air, coverage was greatest at the top of the canopy (6 m) and decreased as the spray penetrated the canopy. In the best ground applications there was no loss over height. We were able to demonstrate a dose-response relationship for methoxyfenozide using contact toxicity bioassays. CONCLUSION: Coverage was best at or below the recommended speed of 3.2 kph and improved when water volume increased.There was a 50% loss in insecticide efficacy at the height of 4-4.8 m; we suggest that future monitoring concentrate on this portion of the canopy. The best ground application provided uniform deposition throughout the canopy, whereas the applications by air were most effective in the upper canopy. The use of filter paper can provide information for chemical deposition and enable contact toxicity bioassays, whereas water-sensitive paper cannot do this. Published 2018. This article is a U.S. Government work and is in the public domain in the USA.

Evaluation of an unmanned aerial vehicle as a new method of pesticide application for almond crop protection

“…Insect pests can attack shoots (peach twig borer), foliage (mites, leafrollers) and the almond nut (navel orangeworm, peach twig bower, leaf footed bug, oriental fruit moth). Of all the pests mentioned above, the navel orangeworm (NOW ‐ Amyelois transitella , Lepidoptera: Pyralidae) is the primary pest of almond in California 15 . Its control requires precise timing and targeted insecticide delivery at the early hull split stage to protect the newly exposed nut from NOW egg‐laying and subsequent larval damage.…”

Canopy spray deposition and related mortality impacts of commonly used insecticides on Drosophila suzukii Matsumura (Diptera: Drosophilidae) populations in blueberry

“…Air-blast sprayers always resulted in higher deposition levels compared with electrostatic and cannon sprayers. 21,53 In the current study, spray deposition quantity differed between seasons in some cases. It was not possible to determine which of these factors resulted in the recorded differences between seasons, because no significant differences in environmental conditions were recorded during either growing season.…”

“…The deposition patterns recorded in this study were relatively consistent with those in other published studies, with lower deposition rates in more sheltered portions of the canopy and at greater distances. Air‐blast sprayers always resulted in higher deposition levels compared with electrostatic and cannon sprayers . In the current study, spray deposition quantity differed between seasons in some cases.…”

Spray drift mitigation using opposing synchronized air‐blast sprayers

“…1). Twelve to 13 filter papers were clipped to a plastic strand with small binder clips and placed at each location in each replicate (100 total filter papers per treatment) 13 . The filter papers were collected after the insecticide residue was dry.…”

“…Percentage mortality was determined after the petri dishes were incubated at 30 °C at 16 h:8 h, light:dark photoperiod, for 18 days. The NOW eggs used in this study came from a laboratory colony reared at 30°C, 16 h:8 h, light:dark photoperiod, on a modified bran‐wheat germ diet in Parlier, CA 13 …”