Potato vascular Fusarium wilt in Tunisia: Incidence and biocontrol by Trichoderma spp.

Abstract

Pathogen isolations from potato tubers showing dry rot symptoms revealed the presence of Fusarium oxysporum f. sp. tuberosi in different Tunisian regions. Pathogenicity tests of different isolates were realized on potato plants. Typical symptoms of vascular wilt disease were observed and noted. After wilting, inoculated plants were totally damaged. Trichoderma spp. were evaluated for their antagonistic potential against F. oxysporum f. sp. tuberosi in vitro and in vivo. Trichoderma harzianum, T. viride and T. virens inhibited the mycelial growth of F. oxysporum f. sp. tuberosi. The antagonism included lysis and dissolution of the host cytoplasm and/or transformation into cords and/or coiling around pathogen hyphae. Moreover, substrate application of Trichoderma species (108 spores per mL) before inoculation by F. oxysporum f. sp. tuberosi controlled Fusarium wilt of potato plants compared with non-inoculated plants and untreated-inoculated plants. This approach may be beneficial for biological control in F. oxysporum f. sp. tuberosi and could allow protecting plants from this pathogen. © 2006 Asian network for Scientific Information.