African cowpea farmers have long known their worst enemy. They call it “witchweed,” a parasite so virulent that it threatens to decimate what is a food staple for millions of people. Crop rotation isn’t effective. And the growers, mostly subsistence farmers, can’t afford herbicides or fertilizers. Enter U.Va. biology professor Michael Timko, who is working with growers in west and central Africa to attack the problem at the molecular level. In applying research from his lab to the field, he is helping a region that provides 80 percent of the world’s supply of cowpeas (better known in the U.S. as black-eyed peas).

Timko and other scientists have sequenced the cowpea genome and have identified all the possible genes resistant to witchweed. In identifying genes that control key characteristics, Timko can selectively breed cowpeas that emphasize those traits using associated genetic markers. “We may even eventually breed a more drought-resistant plant and varieties that have higher levels and a better balance of nutrients,” he says. “We’ve reached a point where we can manipulate the plant for the good of millions of people.”

Modern molecular techniques speed up a breeding process that farmers have done for centuries through trial and error. The work is successful but ongoing, however, because there are at least seven different strains of witchweed, each capable of adapting to changing varieties of cowpea. As Timko’s research continues, his lab has become a locus for international collaboration. In recent years, more than 20 African graduate students and postdoctoral fellows have studied in his lab, and Timko is now trying to send U.Va. students to west Africa to learn their agricultural practices firsthand.

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