Identification of the fungi associated with damping-off in the regeneration of Eucalyptus obliqua and E. radiata in a central Victorian forest.
Soil baiting techniques revealed species of 5 genera (Cylindrocarpon, Fusarium, Penicillium, Pythium and Rhizopus) in forest soils in Victoria, Australia. Eight species were found associated with post-emergence damping-off under field conditions (Pythium mamillatum, P. ultimum, P. paroecandrum, P. irregulare, P. perplexum, F. avenaceum [Gibberella avenacea], F. longipes and C. destructans [Nectria radicicola]). Pathogenicity tests showed that these species also caused pre-emergence damping-off. Identification of seedborne fungi revealed 9 species contaminating <10% of Eucalyptus seeds. Of these, Penicillium olsonii and Aspergillus terreus were pathogenic. In the field, post-emergence damping-off caused fewer losses than germination failure. Results suggest that this failure is partly due to pre-emergence damping-off caused by fungi present in soil and on seed surfaces.