By JOHN O'CONNELL

Capital Press

Too often this season, George Parker III took flight with chemical mixtures provided by potato growers to control zebra chip and other crop problems, only to discover they'd congealed to a mayonnaise consistency.

University of Idaho researchers seeking to control zebra chip, a crop disease that first arrived in the Pacific Northwest in 2011 and returned this summer, have begun soliciting input from aerial applicators such as Parker, owner of Crop Jet Aviation in Gooding, Idaho.

Zebra chip, caused by the Liberibacter bacteria and spread by aphid-like insects called psyllids, reduces yields and leaves bands in tubers that darken when fried.

Parker hopes pilots will give the potato industry a more realistic picture of the limitations of aerial application. He advises growers to plant crops that require less spraying than spuds near residential areas and to test chemical mixtures in a jar. Parker invited U of I Extension storage specialist Nora Olsen to witness a recent spray pattern test clinic hosted in Gooding.

"It's unrealistic to think in all conditions that we will be able to spray that last row of potatoes. That's where I think (Olsen) learned a lot," Parker said.

At Olsen's invitation, Idaho Agricultural Aviation Association members Tim Schamblin and John Cooper will discuss zebra chip and tank mixing from an aerial applicator's point of view during the Idaho Potato Conference, scheduled for Jan. 22-24 in Pocatello.

Olsen also invited association president Bruce Hubler to a new 30-member state zebra chip advisory committee, formed in collaboration with Rupert-based Miller Research to provide input on prioritizing extension efforts. The first meeting was hosted Nov. 8 in Jerome.

"I think that's something about zebra chip is you're constantly having to look outside of the box to see what's going on," Olsen said.

U of I Extension economist Paul Patterson calculated the fiscal impact of zebra chip on Idaho growers for a production cost study he's compiling. He estimates southwestern growers increased foliar spraying from three to seven applications, paying $125 to $175 per acre more this season. He calculated southcentral growers who had used two or three foliar applications increased to six, increasing costs by $85 to $125 per acre. Eastern Idaho growers paid $35 to $85 more per acre, stepping up from a single foliar pesticide application to two or three.

However, zebra chip brought business to crop dusters.

Hubler, with Valley Air LLC in Caldwell, said he's glad his company upgraded a plane from part-time to full-time status prior to the season. He's uncertain the increased business will continue as added costs of fighting zebra chip and low spud prices could lead growers to shift toward crops that require less chemicals.

Based on talks with growers, Rod Weeks, a manager with Ken-Spray in Twin Falls, expects his contracted spud acres will drop 15 percent next season.

This year, thanks to zebra chip, his company topped a record 2011, treating an additional 13,000 acres.

"We had to hit it hard, from daylight to dark," Weeks said.