Inhibitory Effect of Selected Medicinal Plant Extracts on Phytopathogenic Fungus Fusarium oxysporum (Nectriaceae) Schlecht. Emend. Snyder and Hansen

Aims: The study was aimed to screen antifungal activity of some medicinal plant extracts against F. oxysporum by screening fungistatic, fungicidal activities and minimum inhibitory dilution (MID).
Study Design: All the data were subjected to analysis of variance followed by mean separation through Duncan’s multiple range tests using computer software.
Place and Duration of Study: Faculty of Agricultural Sciences, Sabaragamuwa University of Sri Lanka between June 2012 and May 2013.
Methodology: In vitro studies were carried out to test the antifungal activity of 6 plant extracts; Oxalis corniculata L. (creeping wood sorrel), Ocimum gratissimum L. (wild basil), Tithonia diversifolia (Hemsl.) A.Gray (wild sunflower), Azadirachta indica A.Juss. (neem), Kaempferia galangal L.(aromatic ginger) and Zingiber officinale Roscoe (ginger). All plant extract were screened for their fungistatic, fungicidal activities and minimum inhibitory dilution (MID) against F. oxysporum.
Results: Results showed that radial growth of F. oxysporum was significantly impaired (P = .05) by all extracts except wild sunflower and creeping wood sorrel. F. oxysporum differed in their reaction to the different extracts but on the whole, growth inhibition increased with the concentration of each extract. At 25 %, the most active extracts were aromatic ginger, wild basil and neem, which are shows inhibition values of 91%, 89% and 83% for F. oxysporum respectively. The minimal inhibitory dilution (MID) were 3.125 % (v/v) for aromatic ginger and wild basil and 6.25% (v/v) for ginger. Out of six plants extract screened, wild basil, aromatic ginger and neem showed more than 80% fungal inhibition after 6 hour immersion and other extracts could not exceed 60% inhibition after any exposure time.
Conclusion: The study revealed that methanol crude extract of aromatic ginger, wild basil and neem exhibit strong fungistatic and fungicidal activities against F. oxysporum, whereas aromatic ginger and wild basil could be used as an effective antifungal agent.