Neighbor poisoning my plants
Can my plants be tested for poison? Any advice for dealing with this problem?
Plants can be tested for herbicide residues in most cases. There are several private labs in OR that can do this, but the tests are not inexpensive. I suggest you contact the Oregon Department of Ag Pesticides Division (link below) to see what your options might be. They can advise you on making a claim/following up with an investigation if you desire.