Hi, I'm trying to diagnose an issue with my apple tree. The leaves are turning yellow with brown spots and curling. They are also falling off relatively easily when pulled. There doesn't seem to be any mass of insects on the plant. Could it be to do with a lack of nutrients or a fungal infection? Any advice would be greatly appreciated.

How heavy is the leaf-drop? If it's just a few, don't worry about it. I have an Asian Pear that is dropping 50-100 leaves every day, but the tree is very healthy otherwise.

Thanks. The tree is relatively young so there aren't many leaves on it. It just seems to be a few leaves at the moment that have turned yellow, but the majority are curling. I've attached another photo to see if that changes thoughts?

It looks healthy. A lot of deciduous plants drop a lot of leaves right now. Those are the first leaves that popped out to get the growing season started and have been replaced by stronger leaves that will last most of the summer. When I worked in retail nurseries, years ago, this is when new gardeners would come in in droves about now, panicked that their roses were dying. If you haven't fed it yet this year, now is a good time to do it.

It looks like the apple scab fungus to me. My apple tree does the same thing. It starts out with dull brown spots on the leaves and petioles, the leaves turn yellow (sometimes mottled) and then drop. You should gather up the fallen leaves and dispose of them so the fungus in them can not continue to infect the tree. Some apple varieties are fairly resistant to scab. Mine is not, and if I didn't cover all the little baby apples with plastic bags, most of them would be all gnarly with scab infection.

Thanks for the advice. Having looked at my other apple trees, some that are definitely resistant to Scab such as the Pearmain, they all seem to have started to show yellow leaves and curling. Could it be to do with the lack of rainfall we're currently experiencing in the uk, putting stress on the trees?

Yes, that will do it.

kreemoweet is right: it's just apple scab, and follow his/her advice. I've never heard of the paper bag thing for this, but one can't argue if it works!

You may be get leaves turning yellow without those dark spots. These would be due to the drought.