Onion growers in Eastern Oregon and southwestern Idaho are dealing with a new plant disease that can damage the inside of onions but they so far don’t know what’s causing it or how to prevent it. Oregon State University researchers are conducting field trials to try to answer those questions. “We know what the problem is real well but we don’t know what’s causing it or how to manage it,” said Clint Shock, director of OSU’s Malheur County experiment station.