In vitro antifungal effects of potassium bicarbonate on Trichoderma sp. and Sclerotinia sclerotiorum

Bicarbonates are often utilized in the food industry to avoid fermentation and to improve pH, flavor, and texture. In the same manner, bicarbonates have been demonstrated to control postharvest phytopathogens; however, there are no reports describing the effects of these chemical compounds either on soil-borne pathogens such as Sclerotinia sclerotiorum or on antagonist fungi such as Trichoderma species. This study evaluated the antifungal effect of increasing concentrations (0, 2, 4, 6, 8, 10, 25, and 50 mM) of potassium bicarbonate (KHCO3) on the growth of Trichoderma sp. strain R39 and S. sclerotiorum under in vitro systems. Applications of KHCO3 greater than 8 mM significantly inhibited (P < 0.001) the growth of both fungi. Concentrations of KHCO3 lower than 25 mM did not affect the antagonistic effect of Trichoderma on the growth of S. sclerotiorum; however, this fungal interaction was not observed when exposed to 50 mM KHCO3 because of its strong inhibition of fungal growth. In addition, KHCO3 concentrations higher than 8 mM caused significant (P < 0.001) reduction of the sclerotium formation of S. sclerotiorum. Sclerotium germination and de novo sclerotium formation were significantly (P < 0.001) inhibited as the concentrations of KHCO3 increased. Results show the potential benefits of potassium bicarbonate for controlling both growth and development of S. sclerotiorum, although it also exerts negative effects on the Trichoderma strain that is a natural antagonist to S. sclerotiorum.