Studies on Fusarium species associated with 'pathogen-tested' seed potatoes in Victoria

Abstract

Fusarium populations were assessed in newly-cleared and previously-cropped areas which had been used for planting 'pathogen-tested' potatoes at the Potato Research Station, Toolangi. Fusarium propagules were fewer in newly-cleared than in previously-cropped land; in fumigated than in nonfumigated land; and at 10 cm than at 1 cm below the soil surface. However, numbers of infected tubers from pathogen-tested plants were similar in newly-cleared and previously-cropped land; and in fumigated and untreated land. Five species were isolated from tubers, F. oxysporum being the commonest. Three species, F. avenaceum, F. culmorum and a weakly-pathogenic species, which is morphologically close to F. arthrosporioides, had not been recorded on potatoes in Victoria previously. The remaining species was F. solani. Laboratory and field studies indicated that infection of pathogen-tested plants usually occurred through injuries and that approximately three per cent of cuttings were infected before planting.