Infection of Eucalyptus obliqua and Eucalyptus globulus ssp. bicostata by Armillaria spp.  G. C. Marks, C. A. Almond and J. G. Edgar.  July 1976.  7 pp. (unpubl.)

SUMMARY

In Australia Armillaria spp. have been associated with die-back and mortality in eucalypt forest in central Victoria and southern Tasmania. Although it is uncertain if Armillaria is the primary cause, it appears to be a significant factor in accelerating tree decline.

This report deals with the spread of Armillaria spp. in the stems and bark of Eucalyptus obliqua L’Herit, a stringybark eucalypt, and E. globulus subsp. bicostata Maiden, Blakely and Simmonds, a smooth-barked gum species, in the dry sclerophyll forest on the slopes of Mount Cole, 180 km north-east of Melbourne. There was considerable uncertainty about the identity of the species of Armillaria present and the fungus under observation is referred to as Armillaria spp.

Armillaria spp. is traditionally associated with collar rot at the base of the tree. In this study seventy-four infected trees were selected at random, felled and measurements were made of the circumference of infection in the sapwood and inner bark of the stump at 30 cm above ground level, and at the height of infection in the outer bark.

Armillaria spp. was recovered at a maximum height of 7 m, more than twice the height recorded elsewhere in living forest trees. Vertical spread of the disease was directly proportional to the circumference of infection in the butt. Vertical spread in the bark was less in E. globulus subsp. bicostata than in E. obliqua, and the difference between the two species is possibly related to the differences in bark structures.

Also published:

Marks, G.C., Almond, C.A., Edgar, J.G. and Kile, G.A. (1976)  Spread of Armillaria spp. on the bark of Eucalyptus obliqua and bicostata.  Aust. For. Res. 7: 115-19.