Leaves Dying

Question

i thought it was due to having my roof spayed for moss, but that was 18mths ago, and the 3 plants are still suffering this problem of brown dead patches on leaves. flowers seem to be ok. i will add photos

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Answer 1

Are those rhododendrons? Here is some info that should help:

https://www.gardeningknowhow.com/ornamental/shrubs/rhododendron/brown-rhododendron-leaves.htm