One year, it's the potato tuber worm; another year, it's the beet leafhopper. This year's public enemy insect is the potato psyllid. At both the Idaho Potato Conference and Washington/Oregon potato conference, the psyllid was foremost on the agenda of everyone attending. Last fall's discovery of potato psyllids and zebra chip disease transmitted by psyllids in the Columbia Basin, Hermiston, Ore., and across the Columbia River in McNary, Wash., has grabbed the undivided attention of growers throughout the Pacific Northwest.