Since 2000, a mystery disease has struck some potato fields in Texas, Arizona, California, Nevada, and other western states, reducing tuber yields and quality. Losses have been estimated in the millions of dollars.
In response, scientists from ARS laboratories in Washington State, California, and Texas joined their state university colleagues to track down the cause of the disease, dubbed “zebra chip” (ZC). In 2007, an ARS-led team completed studies implicating the potato psyllid (Bactericera cockerelli) as an insect accomplice. In January 2008, New Zealand scientists—followed 7 months later by a University of California-Riverside team—announced their discovery of DNA evidence, coupled with investigative fieldwork, tying a new species of Candidatus Liberibacter bacterium to ZC in potatoes.
Throughout, growers had been spraying their crops with insecticides to prevent psyllids from transmitting ZC. But they didn’t know what actually caused the disease—only that it correlated to psyllid feeding. Now, with researchers building their case against the new C. Liberibacter species, growers have more information to go on. Confirmation of the bacterium’s ZC crimes will also create new opportunities for managing it.
