Abstract
The present study was undertaken to assess the in vitro antifungal activity of petroleum ether, chlo-roform, methanol and aqueous extracts of Datura metel L. leaves and flowers, against two Trichoderma species (Trichoderma harzianum and Trichoderma viride) and three formae speciales of Fusarium oxysporum, that is, Fusarium oxysporum f. sp. melonis, Fusarium oxysporum f. sp. lycopersici and Fusarium oxysporum f. sp. tuberosi. Radial growth of the pathogen on PDA plates was recorded after 3 to 7 days of incubation at 25°C. Results revealed an important antifungal activity of D. metel leaf and flower aqueous extracts at all concentrations tested (1, 2, 3 and 4%) against pathogenic fungus.How-ever, the extent of response to extracts was species specific. In fact, the highest inhibition (69%) of T. viride mycelial growth was observed with flower aqueous extracts. Indeed, F. oxysporum f. sp. melonis was found to be more susceptible than the other fungal species to organic extract; radial growth inhibition varied from 24 to 76% and from 31 to 76% in the presence of leaf and flower organic extracts, respectively. In addition, the radial growth of F. oxysporum f. sp. Lycopersici was reduced by all organic extracts. The fungicidal activity of leaf extracts was more effective against F. oxysporum f. sp. tuberosias compared to flower extracts. Both Trichoderma species were less sensitive to D. metel organic extracts than Fusarium species. Our findings showed that D. metel extracts can be used as potential source of fungicides to control the phytopathogenic fungi tested. Key words: Antifungal activity, aqueous and organic extracts, Datura metel, Fusarium, Trichoderma, radial growth.
Highlights
The development of biopesticides has been focused on as a viable pest control strategy
The highest radial growth inhibition of about 32% was obtained with leaf aqueous extracts applied at 1% against F. oxysporum f. sp. tuberosi (Figure 1)
F. oxysporumf. sp. lycopersici exhibited important sensitivity to D. metel organic extract than F. oxysporum f. sp.tuberosi; the highest radial growth inhibition (67.5%, in average) was obtained with leaf and flower petroleum ether fractions applied at 9000 and 6000 ppm, respectively
Summary
The development of biopesticides has been focused on as a viable pest control strategy. Many of them such as Euphorbia macroclada, Euphorbia bougheii, Euphorbia striatella, Euphorbia serrata, Euphorbia virgata, Euphorbia fortissimo and Euphorbia cooperi are used to control root infecting fungi including Fusarium oxysporum, Rhizoctonia solani, Alternaria solani and Verticillium dahliae (Gundidza et al, 1992; Gundidza and Kufa, 1993; Shaudat and Siddiqui, 2002; Al-Mughrabi, 2003) Another plant such as Datura metel L., a Solanaceous species, is a sub-glabrous shrubby herb that exists throughout the world (Rajesh, 2002) and is widely distributed in Tunisia. The aim of this investigation was to assess the in vitro antifungal activity of aqueous and organic extracts of D. metel leaves and flowers This allelopathic plant species was tested, as potential source of natural biologically active substances, against three phytopathogenic and two antagonistic fungi
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