Submitted to: Canadian Journal of Forest Research
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/24/2005
Publication Date: 6/16/2005
Citation: Wang, D., Spokas, K., Zhang, Y., Juzwik, J., Fraedrich, S.W., Koskinen, W.C. 2005. Atmospheric emissions of methyl isothiocyanate and chloropicrin following soil fumigation and surface containment treatment in bare-root forest nurseries. Canadian Journal of Forest Research. 35:1202-1212. Interpretive Summary: Production of tree seedlings in forest nurseries has relied on soil fumigation with methyl bromide (MeBr) to control soilborne plant pathogens, weeds, parasitic nematodes and insects. Since the announcement of the scheduled MeBr phase-out, a number of nurseries throughout the United States have participated in research programs on MeBr alternatives. There does not appear to be any information on the environmental fate and emission of these potential alternative fumigants when applied in forest tree nurseries. The objective of this study was to evaluate atmospheric emissions of fumigants, methyl isothiocyanate (MITC) and chloropicrin (CP), for four alternative fumigation methods as combinations of two fumigants and two surface cover treatments. Among all treatments, a very small percentage (< 3%) of MITC was lost through atmospheric emission, most immediately after application. Less MITC emission was found in the water seal than in the tarp plots. Final cumulative emission accounted for about 10 to 22% of the CP injected in the soil. Because of higher air and soil temperatures, emission losses in the Georgia plots were about twice that of the respective losses in Wisconsin experiment. These data will help scientists determine effective replacements for MeBr by providing important information on MITC and CP emissions during soil fumigation management in forest tree nurseries.
Technical Abstract: Field experiments were conducted at a Wisconsin tree nursery and a Georgia nursery to measure emissions of methyl isothiocyanate (MITC) and chloropicrin (CP) in soil fumigation. Four treatments were tested as combinations of two fumigants (Basamid or a co-application of Vapam and CP) and two surface cover methods (tarp or water seal). Among all treatments, a very small percentage (< 3%) of the equivalent MITC, applied as either Basamid or Vapam, was lost through atmospheric emission. Less MITC emission was found in the water seal than in the tarp plots. Final cumulative emission accounted for about 10 to 22% of the CP injected in the soil. Because of higher air and soil temperatures, the cumulative MITC or CP emission losses in the Georgia tarp plots were about twice that of the respective values from the Wisconsin experiment. Regardless surface cover methods, over 70% of total cumulative emission of either MITC or CP occurred within one week after fumigation. These characteristics in MITC and CP emission provide important information for soil fumigation management in forest tree nurseries.