IN VITRO DIFFERENTIAL SENSITIVITY OF PENCILLIUM ITALICUM CAUSING POSTHARVEST ROT TO CITRUS FRUITS IN JORDAN TO CHEMICAL FUNGICIDES AND THEIR COMBINATIONS

摘要

In this study we evaluated "in vitro" the efficacy of six chemical fungicides and their mixtures as a strategy for the control of Penicillium italicum. The antifungal efficacy against four P. italicum isolates of thirty-one concentrations (0.01-3000 mu g/ml) of each of the tested fungicides (Vydan, Blin exa, Canvil, Ranvil, Benomyl and Topsin M), in addition to six combined concentrations from each of ten fungicide mixtures were tested using agar well diffusion method. Regression analysis, one way ANOVA, and Post Hoc Multiple comparisons were carried out to test the significance of these treatments. Our results showed that benomyl completely inhibited the growth of tested isolates (Pi.1; Pi.3; Pi.5; and Pi.6) with MIC values of: 1000; 300; 150 and 40 mu g/ml respectively. Canvil as compared to Blin exa, Ranvil and Vydan (no complete inhibition) showed high efficacy against isolates Pi.1 and Pi.5 (MIC values of 5 and 25 mu g/ml respectively). The mixtures of Blin exa/Vydan and Topsin M/Canvil were the only mixtures that generated synergistic effects against tested isolates at all tested concentrations. The above mentioned mixtures showed at the first four tested combined concentrations (50:50, 100:100, 100:500 and 500: 1000 mu g/ml) either the largest inhibition zones (in the range of 47 +/- 1.40 mm to 51 +/- 1.49 mm) or complete inhibition of fungal growth at the last two (1000:1000 and 1000:2000 mu g/ml) combined concentrations. The mixtures of Blin exa/Canvil and Blin exa/Ranvil as compared to the effect of each as singles showed additive effects against tested isolates. The mixtures of Benomyl/Vydan; Benomyl/Ranvil; Benomyl/Blin exa; Topsin/Vydan and Topsin/Blin exa (i.e. mixture of benzimidazole and DMI members) all generated antagonistic effects against tested isolates.