I planted a willow tree last fall. This spring it seemed to be doing beautifully. Beautiful color, lots of new leaves and it seems to have grown quite a bit taller. Now it has dark brown spots developing on the leaves and then they turn yellow and drop off. Can you identify from these pictures what might be the problem? Am I not watering enough? Is it getting too much water? Or is this some kind of disease? It seems to be widespread on the tree but must have started at the bottom because that's where most of the leaf loss is. The tree is planted in a clay soil. When I planted, I did amend the soil with some black dirt.