Posted: 13/09/2015 at 11:21
Amelanchiers are pretty robust so they shrug off most things Jo. That said, mildew can spread from one plant to another. It's mainly caused by dry conditions and poor air circulation, so improving the growing conditions can help prevent that. Honeysuckles need moisture at the roots so if they don't have that, they can be prone to mildew, especially after the summer.
I'm sure there will be a chemical way of solving the issue , but the best solution is prevention.You can prune off any damaged branches of your shrub and keep it well watered in long, dry spells. Make sure there aren't too many other plants or shrubs crowding it and you should see an improvement. Nothing you can do about the neighbouring honeysuckle, except pruning off any material that falls into your property. Perhaps you could have a word with the owners too