Human pathogens make homes on plants
Jeri Barak's tomato plants have a weird disease breaking out on them. Not the biggest surprise, perhaps, since she's a bona fide U.S. Department of Agriculture plant pathologist. But what's afflicting Barak's tomatoes isn't some everyday farm ailment—their leaves are colonized with Salmonella enterica, more famous as an animal pathogen. This bacterium leads to about 600 deaths in people each year, along with 40,000 reported cases of illness.