Apple tree - leaf browning

I planted a couple of fruit trees in my front garden about 6 months ago, the leaves have started to brown and im not sure why. Its been theres been rain most days here for a while so I dont think its underwatering and doesnt feel waterlogged or anything either. The PH meter is reading ~7 which I think is ok for apple trees? 

Any ideas what the issue is? Im a complete novice when it comes to gardening so not sure what to do.