These studies investigated the persistence of molinate (a selective herbicide registered for use in rice culture to control watergrass, or barnyardgrass) in flood and seepage waters, residues, and extent and speed of chemical movement. Results from these and earlier experiments show that water management and circulation in flooded rice fields are important considerations. Regardless of how uniformly a chemical is applied, downstream movement of water tends to redistribute it. Gusty winds can also modify chemical distribution. The redistribution of chemicals can be minimized by holding flood waters for a few days after application. Soil incorporation gives less residue in flood waters and drains than does water application.

D. T. Bradley, Superintendent of Cultivations, M. Ashkar and M. Iqbal, Staff Research Associates, and J. Martin and J. Corry, Jr., Laboratory Helpers also assisted in this investigation. The project was supported by the California Rice Research Foundation.