Newswise — Witchweed, a parasitic weed that can strangle crops, has been nearly extinguished in the United States. but in Africa and Asia, it still grows rampantly, posing a threat to crops and forests. One estimate places agricultural losses due to a single variety of witchweed at $1 billion per year. A published symposium in the journal Weed Science discusses several species of parasitic weeds, including witchweeds,...