Effect of formulation and repeated applications on the enantioselectivity of metalaxyl dissipation and leaching in soil. Issue 11 (19th January 2015)

• Record Type: Journal Article
• Authors: Celis, Rafael; Gámiz, Beatriz; Adelino, María A; Cornejo, Juan; Hermosín, María C
• Is Part Of: Pest management science. Volume 71:Issue 11(2015:Nov.)
• Page Start: 1572
• Page End: 1581
• Publication Date: 2015-01-19
• Subjects: Pests -- Control -- Periodicals; Pesticides -- Periodicals; 632.9
• DOI: 10.1002/ps.3963
• Languages: English
• ISSNs: 1526-498X

Abstract

<abstract abstract-type="main" id="ps3963-abs-0001"> <title>Abstract</title> <sec id="ps3963-sec-0001" sec-type="section"> <title>BACKGROUND</title> <p id="ps3963-para-0001">Soil incubation and column leaching experiments were conducted to address the question of whether the type of formulation (unsupported versus clay supported) and repeated applications of the chiral fungicide (<italic>RS</italic>)‐metalaxyl affected the enantioselectivity of its dissipation and leaching in a slightly alkaline, loamy sand agricultural soil.</p> </sec> <sec id="ps3963-sec-0002" sec-type="section"> <title>RESULTS</title> <p id="ps3963-para-0002">Regardless of the type of formulation and the number of fungicide applications, the <italic>R</italic>‐enantiomer of metalaxyl was degraded faster than the <italic>S</italic>‐enantiomer, but the individual degradation rates of <italic>R</italic>‐ and <italic>S</italic>‐metalaxyl were highly affected by the different application regimes assayed (<bold><italic>t</italic></bold><sub><bold>1</bold>/<bold>2</bold></sub> = 2–104 days). Repeated applications accelerated the degradation of the biologically active <italic>R</italic>‐metalaxyl enantiomer, whereas they led to slower degradation of the non‐active <italic>S</italic>‐metalaxyl enantiomer. The type of formulation had less influence on the dissipation rates of the enantiomers. For all formulations tested, soil column leachates became increasingly enriched in <italic>S</italic>‐enantiomer as the number of fungicide applications was increased, and application of metalaxyl to soil columns as clay‐based formulations reduced the leaching of both enantiomers.</p> </sec> <sec id="ps3963-sec-0003" sec-type="section"> <title>CONCLUSION</title> <p id="ps3963-para-0003">Pesticide application conditions can greatly influence the enantioselective dissipation of chiral pesticides in soil, and hence are expected to exert a great impact on both the biological efficacy and the environmental chiral signatures of pesticides applied as mixtures of enantiomers or racemates to agricultural soils. © 2014 Society of Chemical Industry</p> </sec> </abstract>