The soil ecotoxicology of 1,3-dichloropropene under commercial growing conditions

Soil fumigants are used extensively in the protection of crops against parasitic nematodes and other soil borne pests. The active ingredient in Telone II soil fumigant is 1,3-Dichloropropene (1,3-D) which has a wide range of uses in Europe as a pre-plant nematocide. During the use of soil fumigants such as 1,3-D a range of non-target soil dwelling organisms has the potential to be exposed and impacted. We report here the results of a field study conducted in Italy to assess the impact of 1,3-D applications to soil-dwelling non-target organisms. This study was conducted under conditions of commercial tomato growing either without (untreated control) or with an application of 1,3-D at 224 kg a.i./hectare. Samples of arthropods and earthworms were taken before and up to 12 months after application to measure season long effects. A soil sample was taken at 4.5 months and a soil function test performed. By evaluating the effects of 1,3-D both in the Laboratory and under field conditions equivalent to commercial practices it was concluded that applications of 1,3-D would not adversely effect soil arthropods, but may have an effect on earthworms and soil microflora. These effects were, however, transient as full recovery was observed within six months of application for earthworms and 4.5 months for soil microflora. Consequently, the risk to non-target soil micro- and macro-organisms was considered acceptable according to current risk assessment guidelines within the European Union.