We have many Hills yews and they are all doing well except one. They were planted 4 years ago and where about 12 inches at the time and in pots. They are in the Danforth area of Toronto on the north side of a wood fence. The yew in question has been doing well over the years but about 2 weeks ago (early May) it started to go brownish. They are all on planted in the same soil and bed. Any idea what is going on? Should we remove it? Cut it back? Add something to the soil? Help!
May 23, 2021
Thank you for contacting the Toronto Master Gardeners. This is an interesting situation when only one of your many Hill’s yews (Taxus x media ‘Hillii’) suddenly has a problem. The top reason for yellowing yews is wet or waterlogged soil which can lead to root rot and death. Yews cannot survive standing water. I see that your yew that is yellowing is in a corner at the end of a line of shrubs against a fence and with some kind of a wall on the its other side. If water is draining to and being trapped in this corner that could be the problem, and additional drainage could be the solution.
Your yew might also be under attack by insects that have not (yet) spread to your other plants. Black vine weevils, scales and mealy bugs are the primary pests that affect yews. In your case because the plant is yellowing it could be either of the last two. Check your plants carefully for insects, damage to the leaves, sooty black and/or sticky deposits, any webbing. Here are a couple of links with information about scale and mealy bugs. Please be aware that any reference to insecticides may not apply in Ontario where insecticide use is very restricted.
Here is another website that might be helpful in helping to determine why your yew is yellowing :
http://www2.ca.uky.edu/agcomm/pubs/ID/ID52/ID52.pdf
Good luck with your ailing yew !