In vitro antifungal evaluation of various plant extracts against early blight disease (Alternaria solani) of potato

Antifungal activities of 27 plant extracts were tested against Alternaria solani (E. & M.) Jones and Grout using radial growth technique. While all tested plant extracts produced some antifungal activities, the results revealed that Circium arvense, Humulus lupulus, Lauris nobilis and Salvia officinalis showed significant antifungal activities. The leaf extract of L. nobilis was most effective in inhibiting the mycelial growth of A. solani (79.35%) at 4% concentration, followed by S. officinalis, H. lupulus, and C. arvense with 76.50, 61.50 and 55.83% inhibition, respectively. The other tested plant extracts exhibited modarate activity and average mycelial growth inhibition of fungus varied from 9.15 to 50.58%. The lowest antifungal activity was observed on Hypericum perforatum extract. The antifungal activity of extracts of C. arvense, H. lupulus, L. nobilis and S. officinalis were further evaluated at different concentrations (0.2, 0.4, 2, 4 and 8% (w/v)) against A. solani. Inhibitory effects of these extracts were increased with increasing concentration. The minimum inhibitory concentration (MIC) of H. lupulus, L. nobilis and S. officinalis were 8% (w/v). Further studies on isolation and characterization of the active (antifungal) compound is needed before the possible use of the tested extracts in control strategies of this fungus.