Page Banner

United States Department of Agriculture

Agricultural Research Service

Title: Use of nematodes and insecticides for postharvest control of navel orangeworm (Amyelois transitella)

Authors
item Siegel, Joel
item Kuenen, Lodewyk
item Higbee, Bradley - PARAMOUNT FARMING COMPANY
item Bettiga, James - S&J RANCH

Submitted to: California Pistachio Commission Production Research Report
Publication Type: Trade Journal
Publication Acceptance Date: January 15, 2007
Publication Date: March 1, 2007
Citation: Siegel, J.P., Kuenen, L.P., Higbee, B.S., Bettiga, J. 2007. Use of nematodes and insecticides for postharvest control of navel orangeworm (Amyelois transitella). California Pistachio Commission Production Research Report. p.193-198.

Interpretive Summary: In previous research the feasibility of two different large scale nematode application methods were evaluated, application by herbicide sprayer and application through the irrigation system. Application through the irrigation system, chemigation, was chosen for follow up experiments because this method was more flexible and drastically reduced the cost of labor. In 2006 742 acres were treated by chemigation and 200 of these acres were monitored intensely to assess treatment efficacy. Unfortunately, the heavy rains in March adversely affected the treatments, which were often put out 2-4 hours before a downpour. Nonetheless, when the data were combined for the 200 acres adult emergence was reduced by 28.6%. This reduction indicated that the nematodes did produce some mortality but their efficacy was lower than in previous trials. A different treatment to reduce the overwintering population was also evaluated, the use of the chemical insecticide Intrepid. This chemical targets Lepiodptera (moths) and is considered to have less broad spectrum activity than the organophosphate and pyrethroid insecticides used in pistachios. Applications were made to the pistachio canopy on October 6 at two ranches in Madera County. Adult emergence was reduced by 82% at one location and by 56% at the second location. These results are promising and followup studies are underway.

Technical Abstract: In previous research the feasibility of two different large scale nematode (Steinernema carpoapsae) application methods were evaluated, application by herbicide sprayer and application through the irrigation system. Application through the irrigation system, chemigation, was chosen for follow up experiments because this method was more flexible and drastically reduced the cost of labor. On march 24, 27, and 30, 742 acres were treated by chemigation and 200 of these acres were monitored intensely to assess treatment efficacy. The dose used was 500 million infective juveniles per treated acre. Efficacy was assessed by collecting unharvested (mummy) nuts immediately before treatment and 10 days after application. Unfortunately, the heavy rains in March adversely affected the treatments, which were often put out 2-4 hours before a downpour. When the data were combined for the 200 acres sampled, adult emergence was reduced by 28.6%. This reduction indicated that the nematodes did produce some mortality but their efficacy was lower than in previous trials. A different treatment to reduce the overwintering population was also evaluated, the use of the chemical insecticide Intrepid combined with Permethrin. Intrepid targets Lepiodptera (moths) and is considered to have less broad spectrum activity than the organophosphate and pyrethroid insecticides used in pistachios. Permethrin is relatively short acting and was applied because it also is toxic to lepidopteran eggs and larvae. Applications were made to the pistachio canopy on October 6 at two ranches in Madera County, using Intrepid at 16-22 ounces per acre and Permethrin at 14 ounces per acre and the tractor speed was 3 mph. In one ranch, adult emergence was reduced by 55.8% (38,607 control nuts and 31,478 treated nuts) and at the second ranch adult emergence was reduced by 81.4% (48,152 control nuts and 52,941 treated nuts). These two ranches differed in the population density of navel orangeworm (2.47 fold difference) and the treatment worked best with the lower density population. Our results demonstrate that it is possible to augment sanitation in pistachios by use of a carefully timed chemical application based on the development rate of the navel orangeworm. The timing of the postharvest application is dependent on degree day accumulation and will vary among counties and between years. Followup studies will continue on the use of entomopathogenic nematodes as well.

Last Modified: 7/25/2014
Footer Content Back to Top of Page