Efficacy of Sweep-Shank Fumigation with 1,3-Dichloropropene Against Pratylenchus penetrans and Subsequent Groundwater Contamination. R. Loria, Department of Plant Pathology, Cornell University, Long Island Horticultural Research Laboratory, Riverhead, NY 11901. R. E. Eplee, Whiteville Methods Development Center, P.O. Box 279, Whiteville, NC 28472; J. H. Baier and T. M. Martin, Suffolk County Health Department, Hauppauge, NY 11788; and D. D. Moyer, Suffolk County Cooperative Extension, Riverhead, NY 11901. Plant Dis. 70:42-45. Accepted for publication 12 June 1985. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-42.

Populations of Pratylenchus penetrans in plots treated with a 92% solution of 1,3-dichloropropene (1,3-D) at 47, 70, 94, 117, or 140 L/ha of formulated material increased less than in control plots when this fumigant was injected under an untilled winter cover crop with a sweep-shank injector. Linear regressions of posttreatment P. penetrans populations or population changes against 1,3-D rates were significant (P ≤0.01) at one of two locations. Fumigation at 140 but not 94 L/ha resulted in contamination of groundwater by cis and trans 1,3-dichloropropene within 68 days of application. Water samples taken 83 days after fumigation also contained 1,2-dichloropropane. Peak concentrations of these chlorinated hydrocarbons in groundwater occurred 83 days after fumigation. Abnormally heavy rainfall (11 cm) that occurred within 6 days of fumigant application probably reduced fumigant efficacy and enhanced pesticide leaching. The need for research to evaluate the potential for groundwater contamination by soil-applied pesticides is discussed.