someone told me that if you cut off the top of sprouts they grow better sprouts. SO I tried this with the one plant that seemed to be affected by some kind of aphid. I didn't see any difference with the sprouts but what i did get was a load of small sprouty growth growing out the top of the plant!! Brassicas seem to be indestructible sometimes!!! I have lots of regrowth on my smooth head cabbages where I cut them off too!