Ed, the one thing we have in great abundance around here is cheat. When cheat goes to seed with good moisture, it can produce upwards of 1000lbs of seed per acre. The rule of thumb here in Nevada is that one year's worth of cheat seed is usually viable for the next seven years, in wave after wave after wave of the stuff.

In our fallow areas, I've quit using glyphosate to kill it, and am starting to use light doses of diuron, about 1lb/ac.

We get foxtail barley too. We pull it by hand out of hay fields. Sounds absurd, but that's what it takes, so that's what we do.