'Soft wood' in Canterbury hill country radiata
From Forest Health News No. 42, May 1995.
In the Canterbury hill country there appears to be an increasing incidence (probably due to increased planting) of radiata pine suffering from what could best be described as 'soft wood' in the leader and branches. Trees affected are usually in the 6 to 10 year age class and are commonly found to have severely bent and often split leaders and branches. The lack of rigidity is also often associated with needle yellowing, similar to either magnesium or potassium deficiency symptoms. Dieback and/or breakage frequently occurs.
One line of thought is that the damage results from cold injury such as that associated with unseasonal frosts (always possible in the high country). The weak pathogen Sclerophoma pithyophila has been isolated from affected tissue but its role in the damage is unknown and may well only be a secondary agent.
If anyone has seen similar damage or 'soft wood' I would be interested to hear.