In vitro evaluation of Penicillium digitatum Sacc strains sensitivity to various fungicides from Jordan

This investigation is the first report in Jordan, aimed for in vitro evaluation of six fungicides and their combinations, to control the post harvest green mold (Penicillium digitatum) of citrus fruits. Thirty one different concentrations (0.01-3000 microg mL(-1)) of each fungicide, in addition to 6 combined concentrations from each of 7 fungicide mixtures, were tested using Agar well diffusion method against four fungal strains. Regression analysis, one way ANOVA and Post Hoc Multiple comparisons were carried out to test the significance of these treatments. Results of regression analysis indicated significant correlation (p < 0.01) between fungicide concentration (microg mL(-1)) and inhibition zone (mm) of tested strains. All applied fungicides have resulted in complete inhibition of fungal growth in the four tested strains with MIC values ranging from 5 to 2700 microg mL(-1). Canvil and Ranvil of the DMI family were the most effective against tested strains (except strain dg6) where an MIC in the range of 5 to 150 microg mL(-1) was required. Benomyl has worked effectively with the least MIC values against the four tested strains. The obtained Benomyl's MIC values were: 20, 40, 300 and 40 microg ml(-1) against strains dg2, dg4, dg5 and dg6, respectively. One way analysis of variance indicated that the following fungicide mixtures: Benomyl/Canvil; Topsin/Vydan; Blin/Canvil; Topsin/Blin and Topsin/Canvil had significantly (p < 0.001) affected the sizes of inhibition zones, in strains dg2, dg2 and dg5, dg2 and dg4, dg2 and dg4, respectively. Scheffe multiple comparisons analysis showed that there were significant differences (p < 0.001) between the combined concentrations of 50:50 microg mL(-1) or 100:100 microg mL(-1) of Benomyl/Canvil mixture and the rest of tested concentrations where complete inhibition of growth was achieved at a combination of 100:500 microg mL(-1). The mixtures of Benomyl/Canvil and Blin/Canvil were the most effective against strains where, wither complete inhibition or the largest inhibition zones were obtained at the least (50:50 microg mL(-1)) combined concentrations.