Die-back in the mixed hardwood forests of eastern Victoria – a preliminary report.  G.C. Marks, F.Y. Kassaby and S.T. Reynolds.  August 1971.  27 pp. (unpubl.)

SUMMARY

The distribution of die-back and the symptoms in the mixed species hardwood eucalypt forests of eastern Victoria are described. The disease began in 1952 in small patches of eucalypt forests situated in the flat, badly drained sandy coastal soils and has spread rapidly into the better drained low foothills. Disease spread was associated with above average rainfall during warm, spring, summer and autumn seasons.

Chee and Newhooks lupin bait was used to isolate Phytophthora cinnamomi from the diseased areas and the field symptoms seen on susceptible eucalypts of sub-genus Renantherae were similar to those observed on young saplings inoculated with P. cinnamomi in the greenhouse . Species of the sub-genus Macrantherae observed in the forests and tested in the greenhouse are tolerant to the disease. Estimates of population density indices (PDI) of the fungus gave highest values in areas where the disease was most active. The fungus was not isolated from adjacent healthy forests.

Improvements in the baiting and identification of P. cinnamomi using excised lupin radicles floated over a small sample of soil in a Petri dish is described. Several bio-types of the fungus with differing growth rates were isolated.

Also published:

Marks, G.C., Kassaby, F.Y. and Reynolds, S.T. (1972)  Dieback in the mixed hardwood forests of eastern Victoria : a preliminary report.  Aust. J. Bot. 20(2): 141-54.