2011 Annual Report
Objective 1a. Conduct Laboratory Experiments and Modeling Studies to Test Accuracy of Simplified Approaches for Estimating Fumigant Emissions. Objective 1b. Determine the Effect of Fumigant Exposure and Soil Temperature on Survival of Nematodes, Fungi, and Weed Seeds. Objective 1c. Develop and Test a Model to Predict Fumigant Fate and Transport and Survival of Nematodes, Fungi, and Weed Seeds after Soil Fumigation.
Objective 2: Develop and test new management practices to reduce contamination while controlling plant pests in strawberry and vegetable production.
For Objective 1b, experiments have been conducted to determine the survival of plant pests and diseases when exposed to various levels of soil fumigants. Other experiments have been conducted to determine survival of pests when exposed to high temperatures. A database has been created to organize the response of plant pests to chemical and temperature stresses. The survival data has been analyzed using concentration-time and temperature threshold-time approaches.
For Objective 1c, an experiment has been conducted to provide quantitative information on fumigant movement (methyl iodide), emissions and pest control efficacy for a citrus nematode, a weed seed and a fungus using a 2-D laboratory chamber system. The experimental conditions were simulated using a 2-D soil diffusion model coupled to a concentration-time plant-pest mortality model. Comparing experimental and predicted pest control provided a demonstration of the accuracy and viability of this approach to obtain simultaneous pest control and fumigant emissions information.
For Objective 2, an experiment was conducted to determine the effectiveness of combining soil solarization (including active solarization) and reduced application of soil fumigants (Telone Inline). This study included a bare-soil control, covering the surface with high-density polyethylene film, a thermic film or a virtually impermeable film. Fumigant application rates included the standard rate (i.e., 100% application rate); a 70% and 40% reduced application rates. Each of these treatments was replicated 3 times. The experiment was conducted in September to determine if solarization could be used after the warm summer months. Preliminary results demonstrate that soil heating coupled with reduced application rate of fumigant (70%) may be an effective method to control plant pests, especially when a virtually impermeable film is used to cover the soil beds which limits fumigant losses to the atmosphere. A future experiment will be conducted during the summer to determine if warmer conditions improve the efficacy for the non-virtually impermeable film treatments.
Luo, L., Yates, S.R., Ashworth, D.J. 2011. Predicting methyl iodide emission, soil concentration, and pest control in a two-dimensional chamber system. Journal of Environmental Quality. 40(1):109-117.
Chellemi, D.O., Ajwa, H.A., Sullivan, D.A., Alessandro, R.T., Gilreath, J.A., Yates, S.R. 2011. Soil Fate of Agricultural Fumigants in Raised-Bed, Plastic-Mulch Crop Production Systems. Journal of Environmental Quality. 40:(no page).
Xuan, R., Ashworth, D.J., Luo, L., Yates, S.R. 2011. Reactive films for mitigating methyl bromide emissions from fumigated soil. Environmental Science and Technology. 45(6):2317-2322.
Ashworth, D.J., Luo, L., Xuan, R., Yates, S.R. 2011. Irrigation, organic matter addition, and tarping as methods of reducing emissions of methyl iodide from agricultural soil. Environmental Science and Technology. 45(4):1384-1390.
Gao, S., Hanson, B.D., Wang, D., Browne, G.T., Qin, R., Ajwa, H., Yates, S.R. 2011. Methods evaluated to minmize emissions from preplant soil fumigation. California Agriculture. 65(1):41-46.
Yates, S.R., Ashworth, D.J., Yates, M.D., Luo, L. 2011. Active solarization as a nonchemical alternative to soil fumigation for controlling pests. Soil Science Society of America Journal. 75(1):9-16.
Xuan, R., Ashworth, D.J., Luo, L., Wang, H., Yates, S.R. 2010. Depleting methyl bromide residues in soil by reaction with bases. Environmental Science and Technology. 44(23):9080-9085.
Luo, L., Ashworth, D.J., Dungan, R.S., Xuan, R., Yates, S.R. 2010. Transport and fate of methyl iodide a its pest control in soils. Environmental Science and Technology. 44(16):6275-6280.
Ashworth, D.J., Luo, L., Xuan, R., Yates, S.R. 2010. 1,3-dichloropropene and chloropicrin emissions following simulated drip irrigation to raised beds under plastic films. Environmental Science and Technology. 44(15):5793-5798.
Reichman, R., Rolston, D.E., Yates, S.R., Skaggs, T.H. 2011. Diurnal variation of diazinon volatilization: Soil moisture effects. Environmental Science and Technology. 45(6):2144-2149.