Plant Doctor Archive

Conifer dying

A TREE in my garden, about 3m tall, was perfectly healthy until a couple of weeks ago when it suddenly turned brown. I think it is a conifer of some kind. I'd appreciate any help you can give me.

FROM the sample you sent it looks like your tree is a variety of cedar. However, it was too far gone to more accurately identify. The symptoms you describe sound like it has succumbed to phytophthora root rot. Conifers with root rot often show few obvious symptoms until it's too late to do anything to save them.

Root rot is usually caused by some sort of damage to the roots allowing the fungus to invade the normally healthy tissue which in good conditions can resist the fungus attack. Waterlogging in winter, severe drought in summer, root disturbance by digging or soil compaction can all contribute to the problem. Damage to the base of the trunk through mowing too close or piling mulch too deeply around the trunk could cause collar rot, which can also lead to similar symptoms.

Reproduced with permission from the former Weekend Gardener magazine. The views expressed here are not necessarily those of the RNZIH.