First-order kinetics were observed for the degradation of 2,4-D, lindane, paraquat, and glyphosate in sandy loam and muck soils, with the exception of glyphosate degradation in an anaerobic muck. Short half-lives were observed for 2,4-D in aerobic (3.4 days) and anaerobic (9.3 days) muck soils, while longer half-lives were found for glyphosate (19.2 days) and 2,4-D (35.9 days) in the sandy loam. Long half-lives were observed for lindane (1.0−1.7 years) and paraquat (1.4−7.2 years) in the soils. The results of the laboratory studies on the degradation of the pesticides in the Malaysian soils showed little difference from the results reported in soils from other parts of the world. Keywords: 2,4-D; lindane; paraquat; glyphosate; degradation

Working with Malaysian agricultural soils, high Freundlich adsorption distribution coefficients (Kads(f)) were observed for paraquat (28·7 and 1419) and glyphosate (83·8 and 417) and lower values for 2,4‐D (0·57 and 5·26) and lindane (2·65 and 14·1) in a sandy loam and a muck soil, respectively. Desorption of 2,4‐D and lindane from the muck soil occurred. The adsorption of the pesticides was not affected by temperature (20°C/30°C), pH or addition of the pesticides as a mixture. Leaching of 2,4‐D and lindane was evident under a high water influx (200 mm). Comparable results in the leaching of 2,4‐D were observed between laboratory studies and a VARLEACH model prediction. © 1997 SCI.

Laboratory studies utilizing radioisotopic techniques were conducted to determine the adsorption, desorption, and mobility of endosulfan (6,7,8,9,10,10-hexachloro-1,5,5a,6,9,9a-hexahydro-6,9-methano-2,4,3-benzodioxanthiepin3-oxide) and methamidophos (O,S-dimethyl phosphorothioate) in sandy loam and clay soils of the Cameron Highlands and the Muda rice-growing area, respectively. High Freundlich adsorption distribution coefficients [Kads(f)] for endosulfan (6.74 and 18.75) and low values for methamidophos (0.40 and 0.98) were obtained in the sandy loam and clay soils, respectively. The observed Koc values for endosulfan were 350.85 (sandy loam) and 1143.19 (clay) while Koc values of 20.92 (sandy loam) and 59.63 (clay) were obtained for methamidophos. Log Kow of 0.40 and 1.25 were calculated for endosulfan as well as -1.96 and -1.21 for methamidophos in the sandy loam and clay soils, respectively. Desorption was common to both pesticides but the desorption capacity of methamidophos from each soil type far exceeded that of endosulfan. Soil thin layer chromatography (TLC) and column studies showed that while methamidophos was very mobile in both soils, endosulfan displayed zero mobility in clay soil.

The Beyond Compliance project, which began in July 2011 with funding from the Standards and Trade Development Facility for 2 years, aims to enhance competency and confidence in the South East Asian sub‐region by applying a Systems Approach for pest risk management. The Systems Approach involves the use of integrated measures, at least two of which are independent, that cumulatively reduce the risk of introducing exotic pests through trade. Although useful in circumstances where single measures are inappropriate or unavailable, the Systems Approach is inherently more complicated than single‐measure approaches, which may inhibit its uptake. The project methodology is to take prototype decision‐support tools, such as Control Point‐Bayesian Networks (CP‐BN), developed in recent plant health initiatives in other regions, including the European PRATIQUE project, and to refine them within this sub‐regional context. Case studies of high‐priority potential agricultural trade will be conducted by National Plant Protection Organizations of participating South East Asian countries in trials of the tools, before further modifications. Longer term outcomes may include: more robust pest risk management in the region (for exports and imports); greater inclusion of stakeholders in development of pest risk management plans; increased confidence in trade negotiations; and new opportunities for trade.

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