bethel heights

Ted Casteel and Patricia Skinkis at Bethel Heights Vineyard.

(Katherine Cole/Special to The Oregonian)

Jack harvests his pinot noir grapes at 3 tons per acre. Jill harvests her pinot noir at just 2 tons per acre. Who earns the most money?

You might say Jack. But most wine experts would say Jill.

It's a head-scratcher for anyone with a basic grasp of economics.

Say you want to grow your winery business to meet an increasing demand for pinot noir. Try explaining to a banker that you want a loan so that you can buy a piece of expensive vineyard land, plant grapevines, wait four years for them to mature, then pay a team of vinetenders to carefully clip and compost 40 percent of your crop. Every year.

In theory, the fruit that remains on the vine should be higher quality. It should ripen more uniformly, and taste more flavorful. And it should command a higher price.

In practice, no one has ever really put this presumption to test. Previous examinations of crop load have been conducted by horticulturists, in small research plots, not in working vineyards and wineries.

The fashion for dropping fruit, also known as "green harvesting," appears to have coincided with the publication of the first edition of "Parker's Wine Buyer's Guide" in 1995. In it, prominent wine pundit Robert M. Parker, Jr. quotes the winemaking maxim, "The smaller the yield, the better the wine," railing against "flagrant abuses of overproduction" and praising the "handful of fanatics who continue, at some financial sacrifice, to reject a significant proportion of their harvest in order to ensure that only the finest-quality wine is sold under their name."

And so, for the past couple of decades, Oregon vineyard managers have regularly discarded up to half of the precious clusters off their vines so that their surviving siblings can, the thinking goes, soak up more of the plant's limited resources.

But the practice is expensive, not only in lost fruit, but also in terms of ever-rising labor costs, as cluster thinning cannot be mechanized.

In 2008, Patricia Skinkis, an associate professor of horticulture at Oregon State University, decided to check out this supposition. After completing a successful experimental study, she has now launched a comprehensive 10-year crop-load study as part of her work as an extension specialist and researcher with the Oregon Wine Research Institute. Her goal: to definitively determine just how effective cluster thinning is in enhancing fruit and wine quality.

So far, 14 working vineyards in the Willamette Valley have signed on to collaborate with Skinkis. The vineyard managers take care of the day-to-day farming and basic data-gathering; and Skinkis' team of scientists from OSU carries out more complicated investigations and analyses.

Bethel Heights Vineyard in Salem was the first to fully commit to the study, in 2011. Vineyard manager and co-owner Ted Casteel has been an eager proponent of vine research since the early 1980s, when vintages were frighteningly weather-dependent.

"I remember the year we had a very late bloom in July, and then it started raining in November and never stopped. Most of the the pinot noir in the valley became pink wine," Casteel recalls. "I thought, 'We have got to get a handle on this.'"

Since then, viticulture has come a long way. Vines are grafted onto hardy rootstock, which deters certain pests, lowers yields and generates more uniform fruit clusters. Vineyard managers have become expert in the arts of trellising, leaf-and-shoot pruning, soil health and the sparing use of sprays and irrigation. Today, says Casteel, "We are starting to ask more sophisticated questions about vine balance that we were not asking back then."

At Bethel Heights, Casteel set aside 2.5 acres of vines for the OSU experiment, marking alternating end posts with a dot of either yellow or orange paint to identify which rows to crop-thin and which to leave alone. Bethel Heights donates fruit, labor and finished wine to the study, and pays for some lab analysis. "The benefit for me is a serious, high-quality experiment guided by excellent scientists taking place in my vineyard, and being a participating member of the collaborative team of people advancing our understanding of viticulture in the Willamette Valley," Casteel explains.

So far, Casteel has been comparing the thinned and non-thinned rows for four vintages. As far as he can tell, the fruit tastes the same. The vines seem equally healthy. And the wine from the vines that haven't been thinned might actually taste better than the wine from less fruitful vines. Likewise, Skinkis and her team report that they haven't yet found any discernible differences; they will begin sensory evaluation comparisons of finished wines this autumn.

While the study currently only encompasses Willamette Valley pinot noir, Skinkis hopes to add other grape varieties and Oregon growing regions to her study in the future. For now, she's cautiously optimistic about her still very early findings: Vine health and fruit quality do not seem to be affected by increased crop load. "We're not advocating for doing nothing," she warns. "Some sites will probably require some crop thinning on high-yielding years. But it's really about focusing on good management rather than yield."

Casteel is less guarded in his enthusiasm. "If I could leave one half-ton of fruit per acre more on my 100 acres, that's 50 more tons of grapes," he marvels. "Times $3,000 a ton, that is three new tractors. That is money that we can use to build our business."

-- Katherine Cole has been writing about wine for The Oregonian since 2002. She's the creator of Oregon Wine, the App, for iPhone, iPad and Android. She's also the author of "Complete Wine Selector" and "Voodoo Vintners."

