An armillaria root rot control experiment in Mount Cole State Forest, Victoria.  I. Establishment and progress report.  G. A. Kile, R. O. Squire and J. G. Edgar.  May 1982.  30 pp. (unpubl.)

SUMMARY

Armillaria root rot caused by Armillaria luteobubalina Watling & Kyle is an important disease in mixed eucalypt forests in the Central Highlands of Victoria. An experiment to evaluate the effectiveness of various site preparation treatments to reduce inoculum levels and limit disease development in new stands, was established in 1978 on each of three high and three low-hazard sites. The operational feasibility and costs of the different site preparation treatments were determined.

Site preparation treatments, viz: (1) clearfelling, with stumps retained, (2) clearfelling, stumps retained, and ripping, (3) whole tree pushing, and (4) whole tree pushing, and ripping, were carried out on 26 m x 78 m plots; these plots were subdivided into three 26 m by 26 m subplots, which were planted with either Eucalyptus obliqua L’Hérit. (messmate stringybark), E. globulus Labill. subsp. bicostata (Maid. et al.) Kirkp. (Gippsland blue gum) or Pinus radiata D. Don (radiata pine) at 182 trees per subplot. Prior to site treatment the positions of all standing trees or stumps on the plots or influencing them were mapped and the proportion of their circumference infected by A. luteobubalina determined. On high-hazard sites the proportion of the pretreatment basal area infected ranged from 11.6% to 73%, although 9 of the 12 plots had more than 40% of the basal area infected by A. luteobubalina.

From financial records kept during establishment for the major operations of pushing trees and stumps, heaping, burning and deep ripping, the cost ($ 1978) of Armillaria control in an interim operational sequence for regenerating infected sites was estimated at $266 ha^-1 or $1.55 m³ of sawlog from diseased areas.

Total mortality of planted stock in the first two years was 6.7% and was greater for E. obliqua than for E. globulus ssp. bicostata or P. radiata. Most mortality was attributable to establishment losses or insect attack and only 6.6% of total mortality to A. luteobubalina. Average heights were 1.7, 2.1 and 0.6 m for E. obliqua, E. globulus ssp. bicostata and P. radiata respectively, after two years.