Submitted to: American Phytopathological Society
Publication Type: Proceedings
Publication Acceptance Date: 7/23/2002
Publication Date: 12/1/2002
Citation: AJWA, H.A., TROUT, T.J., MUELLER, J., WILHELM, S., NELSON, S., SOPPE, R., SHATLEY, D. APPLICATION OF ALTERNATIVE FUMIGANTS THROUGH DRIP IRRIGATION SYSTEMS.. AMERICAN PHYTOPATHOLOGICAL SOCIETY. 2002. Vol. 92(12): 1349-1355. Interpretive Summary: Although the alternative fumigants can be applied to soil by shank injection, these fumigants have relatively lower vapor pressures and higher boiling points than MeBr, and their efficacy to control soil pathogens and weeds is more dependent on the application method, soil type and condition, and ambient conditions. Drip irrigation systems can serve as a vehicle to deliver water-soluble formulations of fumigants to the target soil volume and may provide a more uniform distribution of chemicals in the soil than shank injection. However, the physico-chemical properties of the applied fumigant, soil properties and condition, and the method of water application to the soil profile determine soil water dsitribution. Drip fumigation is still in its infancy. Further research is needed to optimize parameters for drip fumigation, including determining minimum application rates, best mulching to reduce emissions and maximize efficacy, best soil conditions, optimum water carrier amounts, and most efficacious combinations of chemicals.
Technical Abstract: Strawberry fields in California (9,500 ha annually) are pre-plant fumigated with methyl bromide and chloropicrin to prevent serious soil pest and disease problems. Although soil fumigation with methyl bromide has ensured stability of strawberry production, its use is being discontinued because of its effect on stratospheric ozone. The likely short-term alternatives such as 1,3-dichloropropene, chloropicrin, and metam sodium, although not ozone depleters, are potentially hazardous to the environment and humans if applied improperly. Water-soluble formulations of alternative fumigants can be applied through drip irrigation systems established to irrigate crops. In comparison to conventional shank methods of injection, application of soluble formulations through drip irrigation systems would be economical and environmentally friendly, reduce worker exposure, and allow for simultaneous or sequential application of a combination of fumigants. This paper discusses techniques developed to apply alternative fumigants through drip irrigation systems, and reviews ongoing studies to determine optimum application rates, soil conditions, plastic mulches, and amount of irrigation water used to apply these alternative fumigants.