h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Number one thing I fear with vegetables is a yellow rot that comes especially with green leaf vegetables, especially lettuce and represents a serious food poisoning problem which can extreme cases cause hair and fingernails to fall out as well as bleeding problems.

If you've ever seen cattle with hair falling out in patches in spring, its due to this getting to them in spoiled silage. Safety; if the vegetable has turned to yellow mush, throw it out.

For a considerable time this was frequent problem with bagged, precut salad vegetables at the stores. Recently, they've apparently gotten the problem under better control and the bagged precuts stay stable a week or more, so long as the seal isn't broken. Sometimes a convenience for me since that entire bag becomes a standalone meal, ready to eat with a toss into a salad bowl and a dash of salad dressing, maybe few peanuts, soda crackers on the side.