My cherry blossom tree was just purchased in April, and it's about 2-3 years old. It gets decent sun for at least 4 hours a day on sunny days but not every day, and lots of rain (I live in Ireland). I have been watering it with a hose when it doesn't rain, to keep the soil moist.
It is growing a lot (about a 3/4 foot in the past few months) and putting out new leaves. The problem is the brown streaks on many of the leaves, some of which lead to jagged holes in the middle of the leaves, and this can be seen on nearly all of the leaves except the brand new ones, but I fear it will happen to them eventually. The leaves don't fall off for the most part, but a few have turned yellow and fallen off.
What could be causing this, and how can I help it out?
It doesn't seem to be shot hole disease because the holes are not circular or quite as concentric, but it definitely wasn't doing this 6 weeks ago so maybe it could be? Nearly all of the leaves have a small hole. I have tried a reverse image search of the leaves on Google but nothing is cropping up.
I have a north-facing garden, and I did check the bottoms of the leaves for pests but no bugs. There are black flies and magpies in my garden (and the occasional cat) but it's far too tall for anything to be nibbling and the brown lines that seem to follow the leaf veins make me think it could be a fungus?