It is a hybrid, not a Satsuki.
Petal blight, not leaf blight, it attacks the flowers, turns them to jelly quick. The fungicide did not cause it, just did not prevent in, it got washed off by a late night shower. I usually use daconil, but was out. I had used this one before with success, I just think it rained too soon after it was applied.
Petal blight may not be a problem for you, it likes cool, damp weather, typical of Mobile this time of year. I don't know what it is like for you. On colored flowers, it starts as white spots on the flower. On white flowers it starts as brown spots