R.D. DAVIS

Plant Pathology Branch, QDPI, Queensland, Australia.

Abstract

Following a wildfire which caused patchy damage to a Stylosanthes spp. pasture in north Queensland, anthracnose development was monitored in the subsequent plant generation in unburned, partially burned and completely burned areas. The disease, caused by Colletotrichum gloeosporioides, appeared within four days after seedling emergence in unburned areas but not until after 14 days in both burned treatments, indicating that seedborne inocula did not establish an anthracnose epidemic. Although disease incidence increased rapidly in the unburned areas and had affected 70% of the plant population in the first 14 days, at the conclusion of the experiment (52 days after commencement) only 6.6% of the population in the completely burned area showed symptoms. There was no difference in anthracnose development between the two burning treatments. Laboratory isolations indicated that the fungus was unable to survive in sub-epidermal lesions remaining in plant debris exposed to the fire, and trap plants exposed daily during rainfall indicated very little inoculum was present in these areas. The bulk of the inoculum appeared to be that of a single, simple race of C. gloeosporioides. Provided other effects are considered, managing anthracnose in Stylosanthes spp. pastures and seed crops by fire is worthy of consideration.