Len Webb Ecological Images Collection

Image No. 9-69

Field Experiments Chlorosis, blackening, and deaths of Silky Oak seedlings in pots watered with leachates from Silky Oak seedlings in pots Grimstone Plantation, Yarraman district, Queensland Early 1960s Larger image (112K)

Glasshouse experiments in which leachates from Silky Oak saplings were used to water Silky Oak seedlings in pots confirmed the field observations and experiments - that the seedlings became chlorotic, blackened and died. No pathogens could be identified. However, "unfavourable" micro-organisms in the rhizosphere of seedling regeneration in the pots treated with leachates, and in the field close to Silky Oak trees with deleterious root exudates, may be involved. Microbiological studies under suitable sterile conditions would be necessary to follow through these preliminary experiments.
For details, see Webb, L.J., Tracey, J.G. and Haydock, K.P. (1967) " A factor toxic to seedlings of the same species associated with living roots of the non-gregarious subtropical rain forest tree Grevillea robusta." Journal of Applied Ecology 4: 13-25.
See also Images 9-65, 9-67 and 9-68.

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