Yellow leaves/brown spots during flowering

[Rusty Trichome]

Which MG potting mix?
How long since their last transplant? If you just transplanted, you are overdosing the ladies, and will need to flush well. You have to let the plant eat-up the existing (MG) nutrients before adding your bloom ferts.

13) Specific brand and N-P-K ratio for each bottle. List dosages (quantity per gallon) and current feeding schedule. Gro-Fine Bloom (10-54-10) 1/4 tsp/gal weekly

Sounds like Schultz rose food. But I couldn't find the Grow-fine Bloom. I found their lawn products, but no Bloom formula. Some rose foods are low in micro's, but you use molasses, so doubtful that's an issue.
If it's a powder, are you dissolving it COMPLETELY (for a few minutes) before adding it to the plants?

14) How often are you watering between feedings, and how much per watering? I water 3-4 times a week, 6-8 cups at a time
15) Any additives or tea's? (Superthrive, CalMag, molasses, Mother's Earth...) I use molasses at 1 tsp/gal

How much runoff do you have when watering?
Before watering...if you squeeze opposite sides of the pot a little, (at the same time) does the soil have any 'give' to it? (does it squish, or is it a solid, unmovable brick?)
After watering...same question.