Late blight found in northern Utah; zebra chip discovered in lower Columbia Basin
The big news coming from the Columbia Basin is the discovery of zebra chip in the southern area of the basin.
According to a press release issued by Silvia Rondon, Extension entomologist specialist, and Phil Hamm, plant pathologist at Oregon State University's Hermiston Agricultural R & E Center, a number of fields and cultivars, including Russet Norkotah, Umatilla Russet, Alturas, Russet Ranger, a red cultivar and Pike, have been infected.
The bacteria causing zebra chip, Candidatus liberibacter, is vectored by the potato psyllid. The insect picks up the bacterium when feeding on an infected plant and transmits the bacterium to other plants. Eggs laid by an adult with the bacterium pass it on to later generations.
Hamm said that his early assessment is that the amount of psyllid infestation is minimal. The infestation has been found in the southern part of the Columbia Basin, southern Washington and northern Oregon.
"It's in a number of fields but in no one field is it a catastrophic issue," Hamm said. "Some fields might have 1 percent to 3 percent infestation."
He said that he knows of maybe 15 fields that have been affected.
"Some of these spots are individual plants or are three to five feet in diameter," Hamm said. "They're very confined areas of infection and that's what we've seen in all the fields."
Growers who were treating their fields with insecticides for other reasons may have unknowingly prevented the psyllids activity in their own fields.
Hamm said that it is believed that psyllids cannot winter in the Columbia Basin, but that could change with a mild winter.
Phil Nolte, University of Idaho seed pathology specialist, said that it's difficult to say if the discovery will be a huge problem but you have to treat it as such.
"I think we're foolish if we don't take this seriously. We're done for the season but we need to get some traps next year," he said.
"Management of the vector is straight forward. If you haven't done in furrow application, you have to be timely in your insecticide application," Nolte said.
With this announcement that they've actually found the disease in the Columbia Basin then I think that Idaho should be taking some steps to see if there's a potential for a problem," Nolte said.
For more information on zebra chip visit http://oregonstate.edu/dept/hermiston/announcement/zebra-chip-potato-psyllid.
Southeast of the Columbia Basin in northern Utah there has been confirmation of late blight infestation, close enough to be of concern to Idaho growers. The University of Idaho recommends that growers spray protective fungicide on a seven-day schedule for green growing potato crops.
Jeff Miller, of Miller Research in Rupert, Idaho, believes that most growers' crops are either dead, dying or within that range that the late blight infestation should not be a problem here in Idaho.
"I would think at this point in time, with the conditions of the crop in the middle of September, we've dodged the late blight bullet," Miller said.
Photo courtesy of Gary Secor and Viviana Rivera, North Dakota State University.