摘要：

A survey of common and uncommon weed species usually showing Verticillium wilt symptoms was carried out during 1992–2000 in Crete, Greece. Verticillium dahliae was isolated in 48 out of 182 sampled fields, in which several weed species were grown, from several locations in Oropedio, Lasithi. Altogether, 124 isolates of V. dahliae were recovered from the vascular stem-tissue of 19 weed species, belonging to ten botanical families. Pathogenicity trials with 13 out of 19 weed species that have never been reported as hosts of the fungus, using for inoculation isolates which originated from the same weed species, resulted in infection of all of them, showing various disease symptoms. Seven weed species ( Anthemis melanolepis, Cardaria draba, Convolvulus arvensis, Erodium sp., Euphorbia helioscopia, Helminthotheca echioides and Sinapis alba ) are new hosts worldwide, and six additional species ( Euphorbia sp., Lactuca serriola, Raphanus raphanistrum, Sinapis arvensis, Sonchus oleraceus and Trifolium sp.) are new hosts for Greece. The most susceptible (isolation frequency: 27.9–52.8%, moderate disease severity) species were: Capsella bursa-pastoris, C. draba, Chenopodium album, Senecio vulgaris and Solanum nigrum . Less susceptible (isolation frequency: 4.8–17.8%, slight disease severity) were: Amaranthus sp., A. melanolepis, C. arvensis, Erodium sp., Euphorbia sp., E. helioscopia, H. echioides, L. serriola, Malva sylvestris, R. raphanistrum, S. alba, S. arvensis, S. oleraceus and Trifolium sp. Some species — C. draba, C. album, L. serriola and S. nigrum L. — that usually showed external and vascular wilt symptoms, occasionally exhibited only reduced growth. Visible symptoms under natural field conditions in all 13 weed species that had never been reported as hosts of V. dahliae were similar to those observed after their artificial inoculation. The fungus was not isolated from Foeniculum vulgare ssp. piperitum, Oxalis corniculata and Stellaria media , among other species.

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