I have a pieris and euonymus next to each other. a couple of years ago the pieris leaves started to go mottled and the plant looked very tired. This year it is much worse. the new leaves open green but in a short while they also go mottled and the tips turn brown as if scorched. This year too the euonymus which has been thriving has suddenly lost most of its colour and the leaves are drooping as if it is dry which it isn't. Any ideas what has gone wrong? I have fed the pieris with ericaceous feed.

• 16 Aug, 2013