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United States Department of Agriculture

Agricultural Research Service

Title: Entomopathogenic Nematodes for Control of Overwintering Navel Orangeworm

Authors
item Siegel, Joel
item Lacey, Lawrence
item Higbee, Bradley - S&J RANCH
item Bettiga, James - PARAMOUNT FARMING CO.
item Fritts, Robert Jr. - CERTIS USA

Submitted to: International Conference on Methyl Bromide Alternatives and Emissions Reductions
Publication Type: Proceedings
Publication Acceptance Date: September 7, 2004
Publication Date: October 31, 2004
Citation: Siegel, J.P., Lacey, L.A., Higbee, B.S., Bettiga, J., Fritts, R. 2004. Entomopathogenic nematodes for control of overwintering navel orangeworm. International Conference on Methyl Bromide Alternatives and Emissions Reductions, October 31-November 3, 2004, Orlando, Florida. p. 72:1-4.

Interpretive Summary: This study evaluated the effect of both application rate and soil temperature on the success of the insect pathogenic nematode Steinernema carpocapsae, for use against navel orangeworm (NOW) larvae infesting fallen pistachios on the berm. This insect is the principal pest of California pistachios and the use of nematodes to kill NOW larvae inside fallen nuts because there is no chemical that can target these insects once they have entered the nut. Mortality ranged from 44% - 65%. Further research is needed to determine the minimum amount of water necessary for successful treatment. Soil temperature from the surface to a depth of one inch played a major role in determining the success of our treatments. The data from 2004 clearly demonstrate that high soil temperatures (>90° F) are deleterious to insect pathogenic nematodes. Two applications were made in March at two locations. In the first location soil temperature exceeded 90° F within 3 hours after application, even though the soil was moist, while at the second location soil temperature remained below 90°F. Nematodes only caused 9.65% mortality at the first location and although this was significantly greater (P < 0.0001) than the 1.5% Control mortality. In contrast, mortality in the nematode treatments was 65% at the second location. Future research will concentrate on further quantifying the impact of temperature on treatment as well as determining the best time to apply EPNs after harvest.

Technical Abstract: This study evaluated the effect of both application rate and soil temperature on the success of the entomopathogenic nematode (EPN) Steinernema carpocapsae, for use against navel orangeworm (NOW) larvae in pistachios on the berm. In most trials, the berm was moistened for two hours using microsprinklers (6 gal/hour) before the nematodes were applied, and after application, water was applied at the same rate as the nematodes to facilitate EPN penetration. Four trials employing 1-m2 plots were conducted between November 2003 and April 2004 in Madera and Kern County, California utilizing nematodes applied at a concentration of 400 million IJs per acre and application rates of 400 and 200 gallons of water per acre followed by wetting the nematodes at the same rate. S. carpocapsae was equally effective when applied at 200 or 400 gallons per acre followed by wetting at 200 and 400 gallons per acre, respectively). Mortality ranged from 44% - 65% and it did not matter whether the nematodes were applied before the nuts were moistened. Further research is needed to determine the minimum amount of water necessary for successful treatment. Abiotic factors played a major role in determining the success of our treatments. The data from 2004 clearly demonstrate that high soil temperatures (>90° F from one inch below the surface to the surface) are deleterious to EPNs. Two applications were made in March at two locations in California. Soil temperature at the first location exceeded 90° F within 3 hours after application, even though the soil was moist, while at the second location soil temperature remained below 90°F. EPNs only caused 9.65% mortality at the first location and although this was significantly greater (P < 0.0001) than the 1.5% Control mortality. In contrast, at the second location mortality in the nematode treatments was 65%. Future research will concentrate on further quantifying the impact of temperature on treatment as well as determining the best time to apply EPNs after harvest.

Last Modified: 8/22/2014
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