Eucalypt crown dieback associated with Phytophthora cinnamomi, following the September 1973 wildfire near Cann River, East Gippsland.  P. C. Fagg, B. K. Ward and G. R. Featherston.  December 1982.  15 pp. (unpubl.)

SUMMARY

In late September 1973, an intense wildfire burnt about 8500 ha of mature eucalypt forest south-east of Cann River, in eastern Victoria. Some trees of Eucalyptus sieberi L. Johnson (silvertop) and E. globoidea Blakely (white stringybark) were killed outright, and many others, which had sprouted epicormic shoots, were observed to be dying in January 1975.

An observation plot containing ten mature trees and six seedlings was established in July 1975, and aerial photographs taken in 1941, 1961, 1973 and 1975 were examined to determine the history of dieback in this forest. The aerial photographs showed a substantial increase in the area of dead trees between 1973 (pre-fire) and 1975. Epicormic development, diameter and height growth, which were measured on the observation plot at intervals up to February 1981, were poor, and most of the surviving trees had not regained normal crown volume 7.4 years after the fire. Examination of sequential photographs of tree crowns showed a rather slow rate of disintegration, some fine twigs (< 0.5 cm diameter) being retained for up to four years after death.

In July 1975, Phytophthora cinnamomi Rands (phytophthora root rot) was found in soil at the base of 56% of trees sampled on the observation plot, and it appears that weather conditions following the fire favoured build-up of this fungus on roots of the fire-weakened trees so that many of these trees were killed. A salvage harvesting of most trees before they dried out, would have been desirable.

Although there have been a few seedling deaths, the dense natural eucalypt regeneration beneath the dead and moribund mature trees should result in an excellent regrowth forest.