A survey of damage caused by the Sirex woodwasp in the radiata pine plantations at Delatite, North-eastern Victoria, between 1972 and 1979.  R. J. McKimm and J. W. Walls.  July 1980.  14 pp. (unpubl.)

SUMMARY

This report describes the results of a survey of the damage caused by Sirex noctilio between 1972 and 1979 in 1 960 ha of Pinus radiata plantation at Delatite, in north-eastern Victoria.

Up to 1979, in unthinned stands aged between 12 and 15 years, an average of 77% of trees were killed on 25 ha of plantation, 63% on 79 ha, 35% on 379 ha and 5% on 701 ha; approximately 390 ha of the 10 and 11-year-old stands remained uninfested. In the thinned stands, aged 16 to 18 years, 26% of trees were killed on 78 ha and 5% on 256 ha after 1975. The peak of the S. noctilio-induced tree mortality occurred in 1977.

Within the seven years following the discovery of S. noctilio in the plantation, merchantable timber volume (to 10 cm small-end diameter) was reduced by an estimated 38 000 m³ or approximately 12% of the total 1979 standing, merchantable volume.

The mean DBHOB of killed trees was found to be significantly less than that for healthy trees in each damage class and in each year, irrespective of the damage level or the silvicultural treatment. At the higher damage levels, the main DBHOB of killed trees was found to be greater than at the lower damage levels for stands of similar size.

Also published:

McKimm, R.J. and Walls, J.W. (1980)  A survey of damage caused by the Sirex woodwasp in the radiata pine plantation at Delatite, North-eastern Victoria, between 1972 and 1979.  For. Comm. Vic., For. Tech. Pap. 28: 3-11.