Fusarium spp. as a cause of crown and root rot of asparagus in Greece

Specimens of diseased asparagus (108) were selected from 17 fields in northern Greece. The asparagus crowns showed limited or widespread brown discoloration or extensive internal rot with fibrous tissues. A red-brown discoloration was also observed on the roots and, in a serious infection, most of the roots were totally destroyed and only their epidermis and ribbon-like central axis remained. 68 strains of Fusarium proliferatum , 25 of F. oxysporum , 19 of F. solani , and 1 strain of Rhizoctonia solani were isolated from crowns and roots. Single-spore isolates were subcultured from 50 strains of F. proliferatum , 21 of F. oxysporum and 7 of F. solani. These isolates were evaluated for pathogenicity by inoculating cultivar UC157F₁ of asparagus in an in vitro agar test-tube assay for 21 days at 29–32°C, with a light period of 16 h. Isolates of F. proliferatum and F. oxysporum were found to be the most pathogenic. The pathogenic F. oxysporum isolates were characterized as f.sp. asparagi.