title: Accelerated degradation of metam-sodium in soil and consequences for root-disease management.
abstract: We studied the development of accelerated degradation (AD) of methyl isothiocyanate (MITC) following repeated applications of its parent compound, metam-sodium (MS). Laboratory studies and four sets of field experiments were conducted during 2002-04 in three commercial fields in Israel. Repeated applications of MS to the three soils in the laboratory under controlled conditions demonstrated AD of MITC in some soils. In a peanut field, MS significantly reduced the incidence of Pythium pod rot and improved pod quality after a single application but its effectiveness was greatly reduced after two applications. In a second experiment, MS was significantly effective after a single application in controlling Verticillium wilt in potato but its efficacy diminished after three consecutive applications. In an additional experiment, fumigation with MS following single or double applications was more effective in reducing Verticillium wilt severity of potato compared with triple applications. Soils which did not develop AD of MITC were also recorded. Preplant MS fumigation of melon fields was effective at reducing sudden wilt following a single and two consecutive applications. Our study shows that development of AD of MITC might occur following repeated applications of MS in commercial fields. The data on MITC dissipation in soil following repeated MS applications under controlled conditions indicate the chemical's potential loss of activity under regular agricultural practices and the need for a management strategy to prevent such a development.
authors.affiliation: Laboratory for Pest Management Research, Institute of Agricultural Engineering, ARO, The Volcani Center, P.O. Box 6, Bet Dagan 50250, Israel.
authors.forename: Shachaf
authors.initials: S
authors.lastname: Triky-Dotan
authors.forename: Miriam
authors.initials: M
authors.lastname: Austerweil
authors.forename: Bracha
authors.initials: B
authors.lastname: Steiner
authors.forename: Yitzhak
authors.initials: Y
authors.lastname: Peretz-Alon
authors.forename: Jaacov
authors.initials: J
authors.lastname: Katan
authors.forename: Abraham
authors.initials: A
authors.lastname: Gamliel
mesh_terms: D010367:Arachis / Q000254:growth & development / Q000382:microbiology; D018533:Biomass; D019662:Cucurbitaceae / Q000254:growth & development / Q000382:microbiology; D054884:Host-Pathogen Interactions; D017879:Isothiocyanates / Q000737:chemistry*; D010575:Pesticides / Q000737:chemistry*; D010935:Plant Diseases; D011775:Pythium / Q000502:physiology; D012987:Soil / Q000032:analysis*; D011198:Solanum tuberosum / Q000254:growth & development / Q000382:microbiology; D013859:Thiocarbamates / Q000737:chemistry*; D020172:Verticillium / Q000502:physiology
chemical_list: D017879:Isothiocyanates; D010575:Pesticides; D012987:Soil; D013859:Thiocarbamates; C008435:methyldithiocarbamate; C005227:methyl isothiocyanate