Thiram residue estimation by fungal bioassay and its evaluation in paddy and its milled products

K.A. Anu Appaiah, Md. Mastan Pasha, N.G.K. Karanth


Six fungi, Altemaria altemata, Aspergillus flavus, Colletotrichum dematium, Drechslera oryzae, Fusarium moniliforme, and Trichoderma harzianum, were tested for their effectiveness in the bioassay of thiram. Reduction in the growth of A. flavus, T. harzianum, C. dematium, and F. moniliforme was not proportional to thiram concentration, and D. oryzae was very sensitive to the fungicide. Altemaria altemata growth showed a linear relationship with thiram concentration, and spore germination decreased proportionally with increase in the concentration of thiram in the range of 0 to 50 ppm. Therefore the spore germination method was selected for routine estimation of thiram residues in paddy and its milled products and gave results similar to a colorimetric method. Thiram residues up to 50 ppm could be estimated using this bioassay method.


Alternaria alternate; Bioassay; Thiram residue; Paddy; Milled products

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