A small batch (thankfully) of my pyracanthas had what I thought was a fungal leaf spot, which they can be prone to. On closer inspection it turned out to be Pyracantha Leaf Miner. Into the wheelie bin they went – bonfires being a thing of the past in this country.
I had never seen this before as it a fairly new pest to here and to Britain. I found it the following day on pyracanthas in a shopping centre, so it is quickly getting around. Pyracanthas will still flower and berry even with the leal miner present as, but it is very disfiguring, and ruins the appearance of the plant.
The usual remedies for leaf miner can be used, but not much point on most plantings, where what goes for maintenance is at best minimal.
But gardeners should be aware of it, particularly for pyracantha groups which are not yet infested, so it can be stopped before it gets out of hand.
Source: John Lord