My 30 year old Yew Hedge is showing large brown patches - there are a number of other hedges in the village showing the same - is this treatable? - am I likely to lose the hedge - if i do nothing will I make it worse, or might it recover? Richard Polebrook, Northants, England
Fear that it may be Phytophthora ramorum. http://www.fera.defra.gov.uk/plants/publications/documents/pRamorumPoster.pdf Yew pictured at bottom right; possibly useful email address and phone number below it. Could be other problems---root rot, or other stress factors: http://www.ashridgetrees.co.uk/blog/dead-and-dying-yew-trees-and-hedges/ And here is the address for the Royal Horticultural Society, to which you can send a sample for diagnosis, or correspond with via computer: http://www.rhs.org.uk/Gardening/Help-advice/RHS-Advisory-Service Please give us photo(s) if you can do so. Also tell us if you find insects or evidence of them, oozing sap, or any other symptoms.
We also had a drought in Northamptonshire this year, which may be a contributing factor, (although Yews are considered fairly drought tolerant). My parents and many of their neighbours have Yew hedges, I will check to see if there is any sign of blight or dieback on those.
Yews are sensitive to impeded drainage, prone to root rot. However, if the problem is general there maybe it is due to drought.
(I am 15 miles away from Polebrook where the OP lives) I checked the ones here (70+ year old hedge) and they are a little tatty looking, especially the areas that have been sheared this summer where many brown leaves can be seen. I cannot see any evidence of dieback or blight, but they are definitely much less lush looking than they would normally be. Here it just looks like a reaction to the drought, but the OP may have more serious problems.
