Differential enhanced degradation of cis- and trans-1,3-D in soil with a history of repeated field applications of 1,3-D

The fumigant 1,3-dichloropropene (1,3-D) is considered to be a potential al ternative to methyl bromide. The degradation rates of cis- and trans-1,3-D in soil from a treated site during three successive annual applications of 1,3-D progressively increased with an increase in the number of annual appl ications. The enhancement was greater for trans-1,3-D degradation than cis- 1,3-D. In untreated soil, the degradation rates of the two isomers were sim ilar. The enhancement lasted slightly longer than 2 years after annual fiel d application of 1,3-D had ceased. A single field reapplication of 1,3-D to the treated site that had not been treated for 2 years resulted in resumed differential enhanced degradation of cis- and trans-1,3-D. Microorganisms were responsible for the enhanced degradation.