Bacteria Linked to Mystery Spud Disease

The culprit behind the mystery disease that struck potato fields in western United States has been identified by researchers at the U.S.Department of Agriculture's Agriculture Research Service (ARS). The researchers found genetic evidence suggesting that a new species of Candidatus Liberibacter bacterium causes the disease. The disease was dubbed Zebra chip (ZC) because afflicted tubers form dark, unsightly stripes when they're cut and fried to make chips or fries. ZC was first reported in Mexican potato fields in 1994 and in U.S. spuds in 2000.

Potato growers had been spraying their crops with insecticides to prevent psyllids (Bactericera cockerelli) 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.

The scientists are conducting further research to better understand the psyllid-Candidatus connection. It is an enigma why some psyllid populations transmit ZC and others don't. The researchers are also studying how altered planting dates may affect the severity of ZC.

Read the original article at http://www.ars.usda.gov/is/AR/archive/oct09/zebra1009.htm