Characterisation and pathogenicity of Fusarium taxa isolated from ragwort (Jacobaea vulgaris) roots

We characterised the fungi isolated from necrotic lesions observed on roots of the noxious weed Jacobaea vulgaris and assessed their host range. ITS-rDNA sequence data identified twenty-one isolates of Fusarium and TEF-1α sequencing separated these isolates into four clades namely Fusarium avenaceum/Fusarium acuminatum, Fusarium redolens, Fusarium culmorum/Fusarium cerealis and Fusarium solani. Representatives of each clade were tested for virulence against ragwort seedlings. All isolates in the F. avenaceum/F. acuminatum clade caused visible disease symptoms. Host range of three isolates was tested using six pasture grass species along with Trifolium pratense and Trifolium repens. No disease symptoms were detected on the grasses. All three isolates, however, caused disease symptoms on T. repens, and two isolates also attacked T. pratense. The results demonstrate that several species of Fusarium can colonise ragwort roots but only isolates from one clade cause significant disease symptoms on ragwort seedlings.