Tiny gray aphids or mites got hold of them and pretty much destroyed all the tender new growth on the inside of the plants. I might have been able to save them, but I don't like brussel sprouts enough to deal with it, and I have serious problems with leafy-type plants that get consumed by teeny weeny bugs. It's the heebie-geebie factor.
Plus, I discovered after planting them that brussel sprouts are a little bigger pain than just planting and letting them go. Apparently, you've got to top them to encourage the side shoots and all kinds of things I'm not really interested in.
So, when it comes to brussel sprouts, Bugs-1 Lori-0