Spots on outdoor leaves

Please, need help with major leaf trouble. Experienced outdoor grower, never seen this problem. No obvious insect trouble. Inspected with magnifying glass – no spider mites. Outside plants in 25-gallon holes; filled holes three years ago with Miracle-Gro potting mix. Each spring, amend with Osmoscote Time-Release Fertilizer and half-cup Dolomite lime. Also, mixed 1 cup dried blood with soil halfway down the holes. Plants looked fine until 7/22, then noticed BB-sized white spots on leaves that became necrotic spots. Leaves then turned yellow, began falling off. All plants affected, but planted many yards apart. Began watering early summer with 1 tbsp Miracle-Gro 20-20-20 per gallon H2O, but don’t think it’s over-fertilization, which I’ve experienced before. Any help is greatly appreciated! First 2 photos in beginning stages, second 2 in advanced stages.

That breaks my heart to see that. I have two outside with major leaf problems also and I can't figure if it's bugs or over-nute. I'd post pix, but have to get 'em off the camera, etc. and am way too medicated. I'm hoping someone has advice if it turns out to be bugs.

The first pic looks similar to thrip damage. The other pics, not so much, except for maybe the last one.

If you haven't already, there is no reason not to start treating it with Neem oil. Best of luck to you.