MOBILITY AND DISSIPATION OF METALAXYL IN TOBACCO SOILS

Soil thin layer chromatography studies showed that metalaxyl (methyl-N-(2,6-dimethylphenyl)-N-(2-methoxyacetyl)alaninate) was similar to 2,4-D and more mobile than pyrazone > permethrin. Soil column studies indicated that approximately 0, 9, 73 and 83% of the applied fungicide leached through a 25-cm soil column after being subjected to 5, 10, 15 and 20 cm of simulated rainfall, respectively. A study on the effects of sequential periods of rain and dry spells on movement of metalaxyl showed that the fungicide was leached with each 5 cm simulated rainfall but moved upward during the dry cycle. There was no leachate from soil columns that received four increments of 5 cm of simulated rainfall alternated with a 48-h drying cycle. However, approximately 32% of the applied metalaxyl was leached through soil columns that received similar rainfall treatment alternated with a 24-h drying cycle. Field plot studies indicated that most of the soil-incorporated metalaxyl remained in the upper 0–30 cm, with approximat...