Increasing the efficacy of difluoromethylornithine to inhibit the growth of three phytopathogenic fungi by membrane modifying agents

The selective inhibition of fungal polyamine biosynthesis using difluoromet hylornithine (DFMO) has been a promising approach for plant chemotherapy. H owever, some plant pathogenic fungi have been found to be resistant to high concentrations of DFMO. Therefore, an attempt was made to increase the eff icacy of DFMO to inhibit the growth of three phytopathogenic fungi (Pythium aphanidermatum, Helminthosporium oryzae and Rhizoctonia solani) by using C aCl2 and polyethylene glycol (PEG). The growth inhibition was increased by 12-30% for all the fungi tested with adjuvant concentrations in a selected range (5 mM CaCl2 and 5% PEG), which were otherwise not inhibitory for norm al growth of fungi. These results suggest that the effective control of pla nt pathogenic fungi mag be achieved by the use of DFMO in conjunction with CaCl2 or PEG.