Plant Doctor Archive

Yew who

MY variegated yew tree has dead patches appearing in it. The rest of the tree seems healthy and there are no obvious insect pests. Can you help?

DIEBACK on yews is usually caused by problems with the root system. Yews are notoriously susceptible to root damage, which can be caused by a variety of factors including poor drainage, excessive summer drought, soil too acid or too alkaline, root injury by insect pests, too much fertiliser and damage from digging or cultivation. The dieback symptoms usually start off with an occasional shoot turning yellow and eventually going brown. If you cut out the dead piece the tree may look fine for a while, then another shoot may die off and this sequence of events can go on for years.

Unfortunately, the tree will probably eventually decline and die. If you can't improve the soil conditions, you could try spraying it with the fungicide No Root Rot which may help, but probably only temporarily.

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