My impressive golden leylandii hedge is now looking very sorry for itself. It has black mildewy stuff all over it - I'm presuming it's pretty much the end of the hedge but thought I'd check with the experts first to see if it's treatable in anyway. has anyone any experience of this ?
I would check underneath the leaves it could be that you have scale insect and the black is the honeydew from them. With so many insecticides being taken off the market I am not sure what will contro; it but a good nurseryman should be able to recommend something.
Laurie
IM,
Could it be 'Cypress Canker'?
Caused by Seiridium cardinale - a microscopic fungal parasite.
Please google this, it may be your problem - but not only yours. It's spreading & will be spread by the use of hedge cutting equipment I'm afraid.