FUSARIUM SPECIES ASSOCIATED WITH ASPARAGUS CROWNS AND SOIL IN AUSTRALIA AND NEW-ZEALAND

Crown and root rot, a destructive disease of asparagus caused by Fusar ium oxysporum and F. proliferatum occurs in many countries, but has be en reported only once in Australia. This may be because the pathogens are absent from most fields or because their densities are too low to incite significant disease. Asparagus crowns were sampled from eight a sparagus-growing regions in Australia and one in New Zealand. Ten spec ies of Fusarium were associated with the crowns. F. oxysporum, F. prol iferatum and F. solani comprised 85% of the 374 isolates and were reco vered from each site. F. semitectum, F. equiseti, F. moniliforme, F. s ubglutinans, F. scirpi, F. compactum and F. nygamai were also isolated . Most isolates (88%) of F. proliferatum could be assigned to making p opulation ''D'' in Gibberella fujikuroi, but all other members of the Liseola section could not be aligned with a known mating group. Eight species of Fusarium were found among the 228 isolates from asparagus f ield soils, and F. oxysporum, F. equiseti, F. solani and F. semitectum comprised over 90% of the isolates. F. compactum, F. scirpi and F. ny gamai were recovered infrequently and only from tropical and subtropic al areas. The species composition found in Australia was similar to th at observed on asparagus in other countries where the disease caused b y F. oxysporum and F. proliferatum is severe. The reason for the low s everity of the disease in many of Australia's asparagus-producing area s is not known.