Antifungal Effect of Different Plant Extracts against Phytopathogenic Fungi Alternaria alternata and Fusarium oxysporum Isolated from Tomato Plant

The antifungal activity of 10 plant extracts was tested against the phytopathogenic fungi, Alternaria alternata and Fusarium oxysporum, the pathogens of early blight and wilt diseases of tomato. Plants tested related to different families. Three doses (10, 50 and 100 mg/ml) of plant extracts were assayed on A. alternata and F. oxysporum by measuring the inhibition zone of mycelial growth of fungi by disc-diffusion method on the Potato dextrose agar (PDA). The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of plant extracts were determined. The inhibitory effect of plant extracts ranged from 10-29 and 12-31 mm against A. alternata and F. oxysporum, respectively. The extracts of Pulicaria crispa and Olea chrysophylla were the most effective antifungal followed by Citrullus colocynthis, Psiadia arabica and Otostegia fruticosa. These plant extracts contain biologically active major compounds such as alkaloids, flavonoids, saponins, tannins and terpenoids. The remaining plant extracts did not emerge any inhibitive effect on tested fungi. The MIC and MFC of plant extracts ranged 6–38, 7-34 and 28-56, 22-50 mg/ml for A. alternata and F. oxysporum, respectively. Therefore, these plant extracts have biologically active compounds and have a potential to control fungal phytopathogens in agricultural crops.