Not a Natural Disaster

It's over, it's all over! This year should have been the best harvest ever, and I could smell the sweet scent of my grapes ripening. I still can't accept what happened. Last night, every bunch of grapes on the vine near the gate were a tender green! Now, they all have an eerie blue color. If a rainstorm floods my vineyards, I understand that's nature's way. Natural disasters are inevitable, but what the hell could make these grapes grow blue spots overnight?!