VIEW ARTICLE

Disease Control and Pest Management

Response of Phytoparasitic and Free-Living Nematodes to Soil Solarization and 1,3-Dichloropropene in California. J. J. Stapleton, Department of Plant Pathology, University of California, Davis 95616; J. E. DeVay, Department of Plant Pathology, University of California, Davis 95616. Phytopathology 73:1429-1436. Accepted for publication 4 May 1983. Copyright 1983 The American Phytopathological Society. DOI: 10.1094/Phyto-73-1429.

Ten field sites in the California counties of Merced, Napa, Sonoma, and Yolo were preplant or postplant treated for 4- 6 wk with soil solarization and/or 56- 150 L of Telone II (50- 100% label dosage of 92% 1,3-dichloropropene [=1,3-D]) per hectare. Results of soil assays immediately following treatment by solarization and solarization plus 1,3-D included significant population density reductions of 42- 100% of Meloidogyne, Heterodera, Pratylenchus, Paratrichodorus, Criconemella, Xiphinema, and Paratylenchus spp., total phytoparasitic nematodes, and total phytoparasitic plus free-living nematodes, compared to nontreated control soil. Nematode population density reductions following treatment by 1,3-D alone were usually significantly less. At two of the sites, moist soil covered by polyethylene film was shaded from solar heating by sheets of gypsum board (sheetrock building construction wallboard). Subsequent soil assays from the shaded treatments showed significant population density reductions that were approximately half of those attained following solarization, indicating partial control directly or indirectly due to the polyethylene film cover and/or maintaining high soil moisture during the treatment. Several months after solarization, population density reductions were usually greater than those found immediately following treatment, even when susceptible crops were planted in the soil during the interim period. At one site, significant population density reductions of Helicotylenchus digonicus were found in solarized plots 3 mo after, but not immediately after treatment. Soil was assayed to a maximum depth of 91 cm. Field and greenhouse-grown plants usually showed significant increased growth responses in solarized (32- 128%) or solarized plus 1,3-D-treated (43- 152%) soil, as compared to nontreated control soil; but not by 1,3-D alone, or from orchard trees at postplant-treated sites.