Synthesis and fungicidal activity of some 5-aryl/aryloxymethyl-2-[5-aryl-3-methyl-1,2,4-triazol-2-yl]-1,3,4-thiadiazoles and 5-aryl/aryloxymethyl-2[5-aryl-2-phenylimino-1,3,4- thiadiazolin-3-yl]-1,3,4-thiadiazoles.

5-Aryl/aryloxymethyl-2-[5-aryl-2-methyl-1,2,4-triazol-2-yl]- 1,3,4-thiadiaxoles 4 and 5-Aryl/aryloxymethyl-2-[5-aryl-2-phenylimino-1,3,4- thiadiazolin-3-yl]-1,3,4-thiadiazoles 5 have been obtained from the cyclocondensation of 5-aryl/aryloxymethyl-2-arylidene hydrazino-1,3,4-thiadiazoles 3 with methyl cyanide and phenyl isothiocyanate respectively. Compounds 4 & 5 have been screened for their fungicidal activity against R. solani, F. oxysporum and P. oryzae. Based on screening data some structure-activity relationship is given.