Thank you, gigim, for the info. about alfafa meal being moldy. Someone dump alfafa meal on her roses and noticed more BS, since the leaves got wet. Wet, acidic stuff breeds fungal growth, so I don't put alfalfa on top any more.

I always put my alfalfa meal on top of the soil. The mold that could develop doesn't cause blackspot, but I have never had mold develop.

The question was about mold on top of alfalfa TEA.

If it was my alfalfa tea (I don't bother), I would discard the mold, give the brew a stir, and use what is left all over the garden. But that's me.