I'm sorry, new here, but I can't find out how to get to the answer! I have spots and dying leaves, and I'm watching helplessly as the stuff spreads across my yard. Help! Thank you...

Nancy, the patterning looks to me like it might be mold. The plant otherwise looks healthy. Have you examined the roots for any signs of rot? Tracy

The label should tell you if you need to wait a certain number of days to harvest. IIRC, Daconil has no wait time to harvest when used on tomatoes. It would be almost impossible to avoid spraying your fruit if you're spraying correctly. Remember that you have to spray all stems, foliage (both top and underside), and preferably also all developing fruit as well. If you can do that and avoid getting anything on mature fruit, you are very talented.

The color also looks too yellow to be right. From the photo, it looks like it may have been planted too deep since I cannot see the root flare, the part of the trunk where the base of a tree broadens slightly, though it might be just hidden by mulch. Or it may have come from the supplier planted too deep. IME pin oaks are reasonably happy with OH soil. Mulch shouldn’t be against the trunk, so pull that back. Ideally mulch will start a few inches from the trunk and go out to the drip line of the tree on a small tree such as this to reduce competition from grass. I would pull aside the mulch and soil until you find the root flare to see how deeply it is planted compared to the flare. Have you done a pH test? What has the weather, particularly rain, been like this year compared to usual?