Temperature-Dependent Antimicrobial Activity of Hydrogen Peroxide-Nitric Oxide Mixture on Strawberry Pathogens

Hydrogen peroxide (H2O2) and sodium nitroprusside (SNP) have shown different in vitro antimicrobial activities against strawberry pathogens Colletotrichum fructicola, Phytophthora cactorum and Neopestalotiopsis clavispora. The antimicrobial activities were evaluated by measuring colony diameters on half-strength potato dextrose agar supplemented with different H2O2 and/or SNP concentrations at 20°C, 25°C, and 30°C. Mycelial growth of C. fructicola and P. cactorum decreased in the presence of H2O2 and SNP individually across all three temperatures, and the two compounds showed synergistic antimicrobial activities. N. clavispora growth was arrested by H2O2 at three temperatures, but the SNP-limited growth was only found at 30°C. Synergistic antifungal activity of H2O2 and SNP against N. clavispora was found at 30°C, but not at 20°C and 25°C. These results suggest that the antimicrobial efficacies of H2O2 and SNP against these strawberry pathogens are temperature-dependent and can be significantly enhanced by combining the two compounds.