Because it sounds like we're going to need the ones we've already got and more:

Just as the heavy use of antibiotics contributed to the rise of drug-resistant supergerms, American farmers’ near-ubiquitous use of the weedkiller Roundup has led to the rapid growth of tenacious new superweeds. To fight them, Mr. Anderson and farmers throughout the East, Midwest and South are being forced to spray fields with more toxic herbicides, pull weeds by hand and return to more labor-intensive methods like regular plowing.... Farm experts say that such efforts could lead to higher food prices, lower crop yields, rising farm costs and more pollution of land and water.

“It is the single largest threat to production agriculture that we have ever seen,” said Andrew Wargo III, the president of the Arkansas Association of Conservation Districts.

The first resistant species to pose a serious threat to agriculture was spotted in a Delaware soybean field in 2000. Since then, the problem has spread, with 10 resistant species in at least 22 states infesting millions of acres, predominantly soybeans, cotton and corn. The superweeds could temper American agriculture’s enthusiasm for some genetically modified crops. Soybeans, corn and cotton that are engineered to survive spraying with Roundup have become standard in American fields. However, if Roundup doesn’t kill the weeds, farmers have little incentive to spend the extra money for the special seeds.

First, it looks like might need all those illegal immigrants for the weeding and plowing in our very near agricultural future, huh?

Second, as we live in a country where only four out of ten adults believe in evolution—and the natural selection, mutation, and adaptation stuff that goes along with it—politeness dictates that we feign shock when it turns out that weeds can adapt to the pressures of an environment laced with Roundup, develop resistance to that poison, mutate, evolve, etc., and then go all Audrey II on our asses. Folks in rural areas—folks in farm country—are more likely to be devout and less likely believe in that evolution stuff. The emergence of superweeds presents us with an opportunity to point out to the rural and the devout that condemning evolution doesn't make it any less true and that we ignore Darwin at our peril.

Third, and this is only vaguely related, but is anyone else wondering how all those Southern states are reconciling their hatred of the federal government and their fear of socialism with their calls for federal assistance in the wake of the oil spill in the Gulf of Mexico? Perhaps this might be a time to point out that we actually need a federal government for all sorts of things. And making sure all Americans have access to health care is at least as important as protecting the livelihoods of fishing boat captains.