Gardening Q&A: What is happening to my black-leafed elder?

The experts at the RHS answer your gardening questions...
Question: The pride and joy in the front garden is a black-leafed elder, Sambucus nigra Black Lace, which looks lovely by my front door, against the red brick wall of our house. To my horror, though, I have just noticed that all the foliage, on both sides of the leaves, is covered with small silvery brown blotches that seem to have appeared overnight, unless I just hadn't noticed them before. Can you tell me what is going on, please?

Answer: It may well be that slugs and snails have been at work. They tend to rasp at leaves, taking off the very top surface of the leaf, where the colour is, leaving translucent patches. Now that there is more humidity and cooler condtions, these night-time emerging creatures thrive. This would be my best guess, since there are no particular diseases that would cause this damage to your elder plant. 

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