engleski

Inhibitory potential of olive leaf extract on plant pathogenic fungus Verticillium dahliae Kleb.

Olive is one of the most important Mediterranean fruit and oil crops but its sustained cultivation is endangered by various abiotic and biotic stressors, highlighted by plant pathogenic bacteria and fungi causing serious diseases which can even result in dieback of olive orchards. Verticillium wilt, caused by fungus Verticillium dahliae is considered the most important fungal disease of olive with increasing incidence in Europe. V. dahliae population infecting olive comprises of highly pathogenic “defoliating” (D) type and less pathogenic, but still dangerous, “non-defoliating” (ND) type, with only latter being identified in Croatia recently. Olive leaves, an important byproduct of olive cultivation and also recently recognized as a source of important natural compounds with antibiotic and antimycotic properties, are used for production of olive leaf extract (OLE). The aim of this study was to screen potential of water solutions of commercially available OLE (Magdis, Zagreb, Croatia) to inhibit growth in vitro of two V. dahliae (ND) isolates, obtained from Spain and Croatia. The fungal isolates were grown on PDA medium amended with water solution of OLE in four concentrations, with water only for control. Growth of V. dahliae was inhibited by 2, 2, 12, 45 % (Spanish isolates) and 9, 36, 70, 81 % (Croatian isolates) at OLE concentrations of 5, 50, 500, 5000 mg/L, respectively. Results suggest variable susceptibility of isolates of V. dahliae to OLE with high susceptibility of Croatian isolate to even low concentrations of OLE. In addition to growth rate, OLE reduced fungal colony density and microsclerotia formation. These results suggest future prospect of using OLE in novel methods of biological control of Verticillium wilt of olive.

Olea europaea, leaf extract, Verticillium wilt, biological control, non defoliating

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