I purchased a 12 acre tract of planted black walnut trees. They are...
I purchased a 12 acre tract of planted black walnut trees. They are approximately 15 years old. Who do I call to come inspect them and advise me on what care they need. I was told by a neighbor that someone had tested for disease
I would suggest that you call a certified arborist to look at the trees.
The link below will help you find one in your area.
Also, here is an extension bulletin on Black Walnuts that you might find helpful.