Abstract

The effect of increased concentrations of potassium bicarbonate (KHCO₃) as a possible alternative to synthetic fungicides for controlling Rhizoctonia solani AG 4 HG-I and Sclerotinia sclerotiorum was evaluated in vitro, in this study. In addition, the effect of potassium bicarbonate on Trichoderma sp., a natural antagonist on R. solani AG 4 HG-I and S. sclerotiorum was determined. Potassium bicarbonate substantially inhibited (P<0.05) the growth of the three fungal strains. Mycelial growth of R. solani AG 4 HG-I significantly decreased as the concentration of bicarbonate increased, especially at concentrations greater than 200 mM. Similarly, mycelial growth of both S. sclerotiorum and Trichoderma sp. dramatically reduced in increasing concentrations of KHCO₃. Mycelial growth of either fungi was completely inhibited when exposed to 100 mM bicarbonate. In addition, KHCO₃concentrations higher than 10 mM caused significant (P<0.05) reduction of the sclerotium formation of S. sclerotiorum. Also, sclerotium germination and de novosclerotium formation were significantly inhibited as the concentrations of KHCO₃increased. As a result, it was concluded that potassium bicarbonate was an alternative chemical agent for controlling R. solani AG 4 HG-I and S. sclerotiorum.Also, KHCO₃ was found to have negative effects on Trichoderma sp.

Key words: Antifungal effect, KHCO₃, soil borne pathogens, sclerotium germination.