THIRAM RESIDUE ESTIMATION BY FUNGAL BIOASSAY AND ITS EVALUATION IN PADDY AND ITS MILLED PRODUCTS

Six fungi, Alternaria alternata, Aspergillus flavus, Colletotrichum de matium, Drechslera oryzae, Fusarium moniliforme, and Trichoderma harzi anum, were tested for their effectiveness in the bioassay of thiram. R eduction in the growth of A. flavus, T. harzianum, C. dematium, and F. moniliforme was not proportional to thiram concentration, and D. oryz ae was very sensitive to the fungicide. Alternaria alternata growth sh owed a linear relationship with thiram concentration, and spore germin ation decreased proportionally with increase in the concentration of t hiram in the range of 0 to 50 ppm. Therefore the spore germination met hod was selected for routine estimation of thiram residues in paddy an d its milled products and gave results similar to a colorimetric metho d. Thiram residues up to 50 ppm could be estimated using this bioassay method.