I have a Chamaecyparis hedge which was planted in 1930 approx.In June we noticed some of the leaves dying back on three of the trees in one corner. They are continuing to get worse and one now looks fully dead. The trees beside them are now changing colour and I am worried it is going to spread and kill the complete line of trees.Early last year we had a burst oil pipe from a tipping trailer which sprayed oil all over one of the trees, and the branches died off fairly fast. This might be the root cause of whatever the infection is.Is there a fungicide we should apply to stop the spread or should we cut out the trees which appear infected (LAST RESORT)?
If a lot of oil soaked into the soil, it could be the cause. Soil with oil should have been taken off and not allowed to soak in.
Nothing much can be done in any case. The affected trees are very unlikely to recover.