HERMISTON, Ore.-Volunteer potato plants growing from seed infected with zebra chip are likely too few in number and survive too briefly to contribute to the spread of the crop disease, according to new Oregon State University research findings.
OSU plant pathology laboratory manager Jordan Eggers, OSU Extension entomologist Silvia Rondon, Hermiston Agricultural Research and Extension station director Phil Hamm and OSU postdoctoral entomology scholar Alexzandra Murphy studied volunteers in fields hard hit by zebra chip in 2011.
Eggers said they also planted infected tubers in a screened facility in 2011 to study emergence. He said 53 percent of infected seed produced plants, but only 10 percent of those sprouts showed any symptoms of zebra chip. Furthermore, only half of the symptomatic volunteer plants tested positive for the Liberibacter bacterium that causes zebra chip.
The researchers also found healthy plants survived throughout the entire season, while symptomatic plants lived 45 days on average. Zebra chip, which first arrived in the Pacific Northwest in 2011, causes bands in tuber flesh that darken when fried.
Eggers said most volunteers surface in corn or wheat fields, where it's unlikely they could survive herbicide applications.
"It looks like volunteers won't be a source of the bacterium for in-season spread. The biggest source is migrating psyllids that have the bacterium," Eggers said.
They'll be publishing their findings in a research paper, which they'll present at the August meeting of the American Phytopathological Society in Austin, Texas.
SOURCE: John O'Connell, Capital Press