Hello, I planted seven cornus nuttallii from bareroot seedlings and am also growing from seed. I am applying neem oil every week because I have an aphid/sawfly problem in my yard. Is this sufficient to also prevent athracnose? Are these trees too young to worry about dogwood diseases at this time? Should I apply copper/sulfur anti-fungal spray to the plants, and when should I start? I mean do I need to start in their first year? Thanks very much!