Published online: Jul 26, 2012 Insecticide, Fungicide
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A new potato alert was posted to PNWPestAlert.net:

"The single potato plant observed on July 17 at the Kimberly R&E Center with zebra chip symptoms has tested positive for liberibacter, the bacterium that causes zebra chip. Several other plants with suspicious wilting symptoms were tested as well, and two of them also tested positive for liberibacter. Since these samples were taken, at least two additional plants were found at the Kimberly R&E Center with zebra chip symptoms; these also will be tested for liberibacter.

"Also on July 17, several plants with suspicious symptoms from a grower field from which liberibacter-positive psyllids had been collected were tested for liberibacter. These plants all tested positive for liberibacter.

"Two of the four psyllids collected from last week's U-Idaho scouting program (week of July 9) tested positive for liberibacter. Both positive psyllids were in Twin Falls County; the psyllid found in Jerome County was negative.

"The number of potato psyllids collected by our scouting program is now increasing, though numbers are still much smaller than what has been found in the Columbia basin. This past week, the U-Idaho sampling program collected potato psyllids from three grower fields (all in Twin Falls County) and from the Kimberly R&E Center. From the three grower fields, we collected 8, 6, and 4 potato psyllids, all but one of which was collected on yellow sticky cards (one was from a vacuum sample). We collected 8 psyllids at the Kimberly R&E Center.

"Additionally, last week several potato psyllids were found on sticky cards taken into the Kimberly or Parma R&E Centers by crop consultants. Three potato psyllids were found across two potato fields in Canyon County, and on July 15 a single potato psyllid was collected from the Sand Hollow area of Canyon County from potatoes in a non-commercial setting. All samples will be sent to the University of Idaho campus to test for liberibacter.

"We have now confirmed what is to our knowledge the first finding of ZC potato plants from this year's planting in the Pacific Northwest this season. However, we continue to encourage scouting in order to make the most sound and appropriate management decisions for a given field.

"Refer to the sites below for guidance on scouting and IPM programs for potato psyllids.