By Marcuspayne
United Kingdom 
Hi
In April of this year we planted four x 6 foot Yew cones into our lawn (attached photos).
We planted in large holes with plenty of organic compost and mindful of the lawn being on clay and (not wanting the roots to sit in water) put agricultural grit and holes in the bottom of our excavations. All was well initially and all the yews put on a few inches of lovely new green growth.
However, upon returning from a week's holiday taken in the first week of July (a wet & not particularly hot week for our garden), one of the yew had dramatically turned a horrible brown, whilst all the other 3 Yews were still pretty much a picture of health. Fearing it had been scorched and lacking water we have assiduously watered and whilst there is a small amount of green growth the rest of the tree leaves are now brown underneath with white supple tips (not mildewed though). Having done some web search on yew problems I cannot find any mention of white colouration of yew - is this new growth and why is it white? (as in human beings, has it gone white from shock?!) Would you expect the white tips eventually to turn green or will the yew depressingly eventually die?
I find this all particularly perplexing as all the other 3 yews have been treated exactly the same, are in much the same aspect as the sickly one and are doing very well?
Any ideas gratefully received on how to revive this yew?
Marcus Payne
15 Aug, 2016
Answers
It's the location. An ever so slight pitch in the geography may cause water to collect around the roots. Is the ground mostly clay? Adding grit to the planting will not do much if all the rain is pooling in that location. This yew is done.
15 Aug, 2016
Couldn't say why this has happened, but fear it is too late to revive it. have to say what a lovely formal design your garden is and its so disappointing that this has happened.
I agree with Jimmy, go back to the supplier - he might have suggestions and might well give you a replacement.
Its incredible that all this damage occurred in a single week.
15 Aug, 2016
Before you replace, find out what killed this once healthy tree. You don't want to repeat this scenario again.
15 Aug, 2016
Just thought - the lawn is looking extremely dry as its been cut a bit short - if the ground was wet enough to kill a newly planted tree which hasn't had time to put its roots down a long way the grass would surely be greener?
15 Aug, 2016
Even though you have used grit in the bottom of the hole, it is still possible that the hole could be draining off water underground especially in heavy clay. I must admit that I have never seen the foliage go brown and then white before. Having said, if you bought them from a reputable supplier, i.e. a garden centre, I would call them in as good centres do guarantee their hardy shrubs for as long as 5 years.
15 Aug, 2016