I WOULD fret over it. if its not fixed it will spread horribly fast. within 36hrs it did twice for me.
As said 1 TBSP / gal should be good. If you have Grandma Unsulphured molasses , that has 2% calcium and mag in it which is nice.
Foliar may help fix it quicker as said, but im partial to foliar feeding as light can always burn the leaves when wet. Ive been taugh that way with my garden center that i run as my fulltime job so i dont do any foliar. Only soil feeding, but it will work as said as a foliar.