Biodegradation of fungicide Thiram (TMTD) in soil under laboratory conditions

In vitro studies were carried out, using four selective media, to determine the effect of the main groups of soil microorganisms on the degradation of fungicide Thiram in soil. Soil from El Geraif (East Khartoum) that had no history of pesticide exposition was chosen to conduct this experiment. In general, Thiram have a fluctuating effect on the growth of organic nitrogen using bacteria up to 13 weeks of incubation after which a steady increase in the numbers of these microorganisms was observed. This was found to coincide with the lack of the fungicide residue in soil. Soil fungi were the most affected by the addition of the fungicide Thiram compared to other major groups of soil microorganisms. Although to a lesser extent Thiram have negatively affected the growth of inorganic nitrogen using bacteria and actinomycetes .On the other hand the fungicide has stimulated the growth of soil microorganisms capable of growing on poor media (Nitrate Agar). Microbial degradation of the fungicide Thiram in soil was assessed under laboratory conditions. Fungicide residues in soil were determined in synchronization with microbial counts. Under laboratory conditions, soil microorganisms degraded Thiram in a period ranging from two to eight weeks depending on its concentration. Maximum degradation percentage (97.36%) was recorded after eight weeks of incubation. The half – life of fungicide Thiram in soil determined in this study is 10 days at pH 7.8 at room temperature.