Fed 3 days ago..

gave my plants less than a cup of 4-8-4 top dressing feeding 3 days ago. Some spots have shown up.. cal mag?

I would think damage from the elements or maybe some burn from an oil spray that pooled up a bit on those spots.

I wouldn't worry about any of that. Daily wear-n-tear.

Feck. I got some cal mag 1-0-0 from general hydro. Will it kill my micro herd?