Volatilization, Leaching, and Adsorption of Prometryne in Relation to Selectivity in Cotton

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Abstract
In leaching studies utilizing slotted columns of soil and redroot pigweed (Amaranthus retroflexusL.) bioassay, 2,4-bis(isopropylamino)-6-methylmercapto-s-triazine(prometryne was leached to a greater depth in the coarse-textured sandy soils than in the fine-textured clay soils. There was little correlation between the depths of leaching and the amount of water used to leach the herbicide. Prometryne formulated as an emulsifiable concentrate was leached to a greater depth than the wettable powder and the granules. The14C-pro-metryne was much more strongly adsorbed to a clay soil than to loam and silt loam soils. Volatility studies, using cotton (Gossypium hirsutumL.) plants to assay for vapor injury, showed the vapor loss of prometryne was greater from a metal surface than from a soil surface. Injury from prometryne vapors was greater with silt loam and sandy loam soils than clay soils. Cotton plants exposed 1 week after emergence were more severely injured by prometryne vapors than cotton plants exposed at emergence or 2 and 3 weeks after emergence. The vapor injury from prometryne formulated as a wettable powder or an emulsifiable concentrate was greater from granules. Prometryne vapor injury was increased as soil moisture and temperature was increased. Vapor injury to leaves of cotton was characterized by interveinal chlorosis while injury from root uptake was characterized by veinal chlorosis.