Above Soil Surface Treatment Following

Concentrations of methyl isothiocyanate (MITC) and chloropicrin (CP) in air spaces of nursery soil and in air at the soil surface following fumigation were deter-mined in field trials in a Wisconsin and a Georgia nurs-ery. MITC was measured in plots receiving either dazomet or co-application of metam sodium and chloropicrin; CP was measured in the latter plots. Soil surfaces were sealed with either a high density polyeth-ylene tarp or by surface compaction and maintenance of a water seal following fumigation. Findings from the Wisconsin trial are highlighted. A very small percentage (< 3%) of the applied MITC was lost to the atmosphere, either through the plastic or water-sealed surfaces dur-ing the 14 days following treatment. For CP, 10 % an