Biodegradation and persistence of several acetamide,acylanilide, azide,carbamate, and organophosphate pesticide combinations

The effect of potassium azide (KN₃), O,O-diethyl O-(2-isopropyl-6-methyl-4-pyrimidinyl) phosphorothioate (diazinon), O,O-diethyl S-(ethylthio)- methyl] phosphorodithioate (phorate), 1-naphthyl methylcarbamate (carbaryl), and p-chlorophenyl methylcarbamate (PCMC) on the biodegradation and persistence of several amide, carbamate, and urea herbicides in soil and microbial culture systems was examined. KN₃ inhibited the biodegration of isopropyi m-chlorocarbanilate (chlorpropham) in both soil perfusion and microbial culture system, but was limited in increasing chlorpropham persistence in soil under greenhouse conditions. PCMC and diazinon, inhibited the metabolism of chlorpropham by isolated cultures of soil bacteria (Pseudonwnas striata Chester and Achromobacter sp). Phorate inhibited chlorpropham metabolism by P. striata, but did not inhibit chlorpropham metabolism by Achromobacter sp. Carbaryl, PCMC, and diazinon increased the persistence of chlorpropham in soil under greenhouse conditions. PCMC also inhibited the microbial metabolism of isopropyl carbanilate (propham), 3',4'-dichloropropionanilide (propanil), 2-chloro-N,N-diallylacetamide (CDAA), 1,1-dimethyl-3 (α,ga,α-trifluoro-m-tolyl)urea (fluometuron) and 3-(3,4-dichlorophenyl)-1,1-dimethylurea (diuron), but not that of 2-chloro-N-isopropylacetanilide (propachlor) in isolated culture systems.