Studies on the interaction between Heterodera daverti, Fusarium avenaceum and F. oxysporum on Trifolium subterraneum

Abstract

The interaction between Heterodera daverti, Fusariurn avenaceum and F. oxysporum on two clones of subterranean clover was studied. Simultaneous inoculation of H . daverti with F. avenaceum or F. oxysporum did not reduce the yield of the two clones of subterranean clover more than the additive losses caused by inoculation of each pathogen separately. When the nematode was inoculated one or two weeks after either fungus, plant dry weight was reduced synergistically. Nematode penetration and development was generally increased when the nematode was inoculated after the fungus. Increasing the interval between F. avenaceum and H . daverti inoculations decreased the number of cysts produced. Leaf reddening, a symptom often observed under field conditions, was developed only on plants inoculated with both H . daverti and F. avenaceum. The root-rot-tolerant ecotype 48G formed lesions after penetration of H . daverti.