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.
Thanks for taking the time to ask a Master Gardener.
This looks like bacterial leaf spot on your willow tree, I have attached a link to our University site to check out. This like will give you management suggestions and explain your disease problem. With our wet season this year we are seeing many of these leaf diseases appear.
The one thing I would stress is that you clean up your dead leaves on the site as the spores will get into the soil and the disease will come back next year.