I have 2 coronet apple trees. They were fine until about 2/3 weeks ago. They had brown/black spots on leaves which then developed into the the leaf becoming almost scorched or burned looking and crumbles away. They have been kept well watered and were fed potash some time back. One of them has no fruit developing now, the other still has a couple, any ideas what I should do?
It is likely that there might have been some apple scab disease present that caused blackening of the foliage but the potash might have been a bit too salty for them and may have aggravated the scorching ogf the leaves.
Coronet trees are grafted on a very dwarfing rootstock, which means they have a small root system which can be upset relatively easily, so caution about watering and feeding.
And control apple scab disease … more at: https://gardenie.wpengine.com/gerrycategory/apple-scab/?id=5705