We have a large Holly tree in the garden about 12 feet tall and about 35 years old. It has always been healthy and happy with little help from us. Last year we built decking with holes cut to accomodate the trees and this year over the past 6 - 8 weeks the Holly is dropping its leaves in vast numbers. We're unsure if the decking has had anything to do with it or if it has just been coincidental. The leaves all seem to have black raised areas and most turn yellow before they fall so I wonder if it could be a blight or pest. When the leaves fall they are being being replaced with new leaves but we are becoming really concerned about this lovely old tree and would hate it to come to harm. We are in west central Scotland with a mild damp climate and we're not experienced gardeners. ANY advice would be really appreciated. Many thanks.
Have you read this thread on holly leaf drop? Check your situation against some of the other ones occurring in that thread.