Soil enrichment cultures were prepared by giving repeated applications of metalaxyl to three different soils, i.e. sandy loam soil from Hessaraghatta, Bangalore (Typic Haplustalt); organic matter rich soil from Ooty, Tamilnadu (Cumulic Hapludolls) and black clay soil from Bellary, Karnataka (Typic Chromusterts) and incubating them in the glasshouse for 6 months and 1 year after the last application. The enrichment cultures obtained from soil with longer period of incubation were more effective in enhancing metalaxyl degradation in a mineral salts medium compared to that from soil with shorter incubation period and this factor was more pronounced in case of organic soil. Cultures from sandy loam and organic matter rich soil were more effective than that of black clay soil and could degrade all applied fungicide within 20 days whereas during the same period cultures from 6 months incubation in the glasshouse could degrade 50 and 21.6 per cent metalaxyl, respectively. During this period loss of metalaxyl from uninoculated control was only 13.05 per cent.
Metalaxyl, fungicide, enrichment cultures, microbial degradation
