Synergistic effect of fungicides on resistant strains of Penicillium italicum and Penicillium digitatum.

In vitro and in vivo tests were carried out to study the inhibitory effect of mixtures of sodium orthophenylphenate, methyl-1-(butyl-carbamoyl)-2-benzimidazole ('Benomyl') and sodium orthophenylphenate, 2-(4-thiazolil)-benzimidazole ('Thiabendazole') on growth of strains of Penicillium italicum and P. digitatum resistant to sodium orthophenylphenate, 'Benomyl' and 'Thiabendazole'. 'In vitro' tests showed a synergistic effect of the mixtures; 10 ppm of sodium orthophenylphenate and 10 ppm of the benzimidazolic compound in most cases resulted in complete growth inhibition. Navel oranges inoculated with P. italicum spores showed no damage after 7 days of incubation at 25 degrees C and 80-90% relative humidity when treated with a mixture of 100 ppm of sodium orthophenylphenate and 100 ppm of Thiabendazole.