Root rot, symptom development and disease escape in Eucalyptus obliqua growing in soils infected with Phytophthora cinnamomi.  G. C. Marks and J. T. Tippett.  November 1977.  14 pp. (unpubl.)

SUMMARY

Eucalyptus obliqua seedlings were grown in lightly steamed soil contained in 60 cm deep, wedge-shaped, glass fronted root boxes, standing in shallow permanent water tables. When seedlings were 6½ to 7 months old and at least 20 cm tall, the soil was inoculated with Phytophthora cinnamomi and the resultant root rot recorded. Damage was most severe in the well aerated, moist soil above the water table and erratic in the surface layers due possibly to variations in the microenvironment. Roots were able to grow into the permanent water table under the semi-sterile experimental conditions and they escaped infection for the duration of the experiment.

Shoot growth continued during the initial stages of root rot and acute wilting appeared in the shoot only after most of the roots were severely rotted. Tyloses formed in the vessels of inoculated seedlings and were most abundant in the region of intense root rot. Tyloses were also found in E. obliqua saplings growing in infected forest soil. P. cinnamomi infection also produced a false annual growth ring in the stem of the root box seedlings at surface level. False annual rings were also found in E. obliqua and E. sieberi growing on infected sites but they may not have been produced by fungal root rot.

Also published:

Marks, G.C. and Tippett, J.T. (1978)  Symptom development and disease escape in Eucalyptus obliqua growing in soils infected with Phytophthora cinnamomi.  Aust. For. Res. 8: 47-56.