Marcus Buchanan strolled between vine rows, auger in hand, digging out samples as he searched for clues to a mystery that has stymied the operators of Quail Run Vineyard.

Marcus Buchanan strolled between vine rows, auger in hand, digging out samples as he searched for clues to a mystery that has stymied the operators of Quail Run Vineyard.

He repeated the process about 20 times Tuesday, collecting samples. The answers the new Southern Oregon Extension viticulturist seeks can be elusive, but his eyes on the region's vineyards figure to help the area's burgeoning wine grape industry.

For the past 15 years, Buchanan has dealt with fertilizer and irrigation management, emerging crop production technologies and practices, watershed and water quality assessment, solid waste and wastewater management in California. Since 1996, he's run a consulting firm in Scotts Valley near Santa Cruz. He continues handling 50 clients, alternating weeks in the Golden State and Southern Oregon.

"We lucked out," said Phil Van Buskirk, administrator for Oregon State University's Southern Oregon Research and Extension Center in Central Point. "The maturity of the (Southern Oregon) viticulture industry is to the point that they're not asking the simple questions any more."

State figures show Oregon's viticulture produced $21.3 million in revenue, excluding retail sales, with $7.6 million of that in Jackson and Josephine counties. While agriculture revenue has grown at a 5 percent clip in Jackson, Josephine and Douglas counties over the past three years, the wine-related industry has seen 7 percent growth.

Buchanan, a New York native who earned his doctorate in soil science from North Carolina State University, admits he's not your typical viticulturist.

"I don't have the traditional academic degree in viticulture from UC-Davis," he said. "Much of my work is directly with growers and not in a research environment. I've worked either with specific problems or extending technical or academic information."

Given the region's tricky soil make-up, Buchanan might be a better fit.

"A year ago, we conducted a statewide survey and the two items that topped the list were soil nutrition and irrigation and how that relates to wine quality," Van Buskirk said. "Everyone thinks you can get all your answers off the Internet or down at the library, but that's not true."

"He's a real field man," said Chris Hubert, vineyard manager and partner who is now in his fifth season at Quail Run Vineyard, which now covers 250 acres on nine sites. "We've had some potassium issues in our soil. We haven't come up with a plan yet, but we'll continue with some experimenting and take a little more scientific, professional approach. With Marcus' help, we're going to be able to do some follow-up with statistical analysis that will hopefully be useful for other farmers in the valley."

Interviews with several growers and a look at their soils have given Buchanan a list of projects already.

Dick Ellis, another south Jackson County vintner, had his own set of soil issues for Buchanan to pry into. Ellis Vineyards encompasses 16 acres of plantings off Camp Baker Road. Some of his seven varieties struggle.

"My Syrah was an issue," said Ellis, whose own label is Pebblestone Cellars. "I'm in the middle of an old riverbed with rocky, sandy soil. Some parts are rockier than others and the amount of water available varies. I've got some grasses in the middle of a vine row that are robbing the vine of nutrients, too."

After Buchanan visited last month, Ellis had some ideas for improving his temperamental Syrah grapes.

"I have a plan now how to deal with the vine as it starts shutting down, and that will help next season," he said.

Some Josephine County growers are battling crown gall, a bacterium present in the soil.

"It can lay in wait in grapevines until there is an injury," Buchanan said. "In the Illinois Valley, you occasionally get a number of evenings below 10 degrees and that causes injury in the trunk itself. That sets off a series of events that activate the bacteria. They multiply in the wound and start interfering with the tissues that conduct water, nutrients and sugar, and then the vines start to decline. It can be a minor impact or cause the vine to die."

Reach reporter Greg Stiles at 776-4463 or at business@mailtribune.com