We've have heave rain, and unfortunately poor draining soil. Thought leaves were yellowing and blossoms rotting because of too much water. Now yellowing leaves are developing black spots. Is this also from too much water or is something else going on? Thanks in advance!

Blossoms rotting, only two zucchini from four plants and no new fruit starting. Yellowing leaves, black spots on leaves. Only two plants affected so far with yellowing of leaves but no fruit on other plants.