Can virtually impermeable films reduce the amount of fumigant required forpest-pathogen management in high value crops?

Methyl bromide (MeBr) is scheduled to be phased out as a preplant soil fumi gant by 2005 because it has been identified as a chemical that is alleged t o contribute to stratospheric ozone depletion. Potential replacement chemic als such as 1,3-dichloropropene (1,3-D) products might also face future use restrictions due to health risks and environmental hazards unless greater efforts are made to prevent losses from treated fields. One approach to red uce risks of volatilization and plume drift is to apply 1,3-D under virtual ly impermeable films (VIFs). Our objectives were to determine efficacy of V IF and standard polyethylene (PE) films for pest and pathogen management un der raised-bed plasticulture and quantify chemical efflux through the films . MeBr under VIF film was applied at full (400 kg ha(-1)) and half the labe led rate. MeBr under VIF film at half-rate performed equivalent to all full -rate MeBr treatments. In plots where the pesticide was applied with no-fil m cover, plant growth and fruit yields were reduced by one-half due to poor pest-pathogen control. In 1,PD trials, the VIFs reduced substantially the amount of 1,3D emission to the atmosphere and enhanced residence time withi n the soil for potential degradation. Because of potential volatilization a nd plume drift, VIF use should be considered more often in research dealing -with alternative chemical replacements for MeBr. Decreased atmospheric rel ease and lowered chemical use may prevent other agricultural fumigants from also being phased out or limited further in their uses.