Sources of Petite Sirah’s
Regional Diversity

In our Best-of-Appellation™ evaluation of Petite Sirahs from eighteen different AVA’s, it was quite evident that the variety is capable of great regional variability. In retrospect, the reasons seem obvious. Aromatics, color and tannin. All abound in the grape, and the development of each appears strongly influenced by place.

by Clark Smith
November 10, 2008

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n wine competitions where the standard is to hand out five percent Gold Medals, judges commonly award 50 percent Gold to the Petite Sirahs. Why is it that this grape consistently passes muster? Petite Sirah seems regularly to surpass its supposedly more noble parent. Ever since I sat on a panel at the West Coast Wine Competition, which gave paltry scores to 70 Syrahs, and then immediately turned around and bestowed 8 Golds and 9 Double Golds on 42 Petite Sirahs, I have wondered just what made the difference. It occurred to me to pin it on scientific versus traditional winemaking - that Syrah was made by Davis grads and the less noble grape by the old farts.

The Nose Knows

But perhaps something more innate is at work. “Whatever else it may be doing, there’s just something delicious about it,” opines Robert Brittan (formerly winemaker at Stags’ Leap Winery), who proposes an interesting theory: aromatic sulfur compounds. Although early interest in vegetal aromas centered on nitrogen compounds called pyrazines, which are responsible for the bell pepper aroma of Cabernet Sauvignon and the English pea aromas of Chenin Blanc, in Brittan’s view, the sulfur compounds found in New Zealand SB are at least as important.

These compounds have split personalities. University of Bordeaux-based guru Denis Dubourdieu led Kiwi Sauvignon Blanc to world dominance by studying and perfecting the management of the oddball compound 4-mercapto-pentanone, which normally smells like grapefruit but in high doses can come off like kitty pee, and has become the region’s signature aromatic. Could it be that this aromatic is part of the contribution of Durif’s other parent?

Apparently so. DNA tests at Carole Meredith’s UC Davis lab confirmed that David Coffaro Vineyards of Dry Creek has pure Peloursin in their Block 4, and David reports that it “makes a very floral spicy wine with a long finish.” Like its aromatic fellow traveler Roussanne, Peloursin was first grown in the mountainous French Department of Isère in the Rhône-Alpes. It must have charmed somebody enough to bring it down the hill, but its tight, rot-prone clusters did not fare well in the Rhône lowlands, where it is now almost extinct.

Aromatics are the most obvious way in which regional typicity manifests. In my view, this is what Petite Sirah has in spades but which its more vaunted father Syrah lacks as a primary attribute. One can always find fruit in a Syrah at close inspection, but Petites fairly ooze with blueberries, cherries, blackberries or even oranges.

Who knows the sources of aromatic diversity? One aspect seems obvious: the transfer of aromatic substances from native vegetation to the wax cuticle which surrounds every berry. It isn’t surprising to pick up sagebrush aromas on Howell Mountain or menthol proximate to the profuse eucalyptus windbreaks in Monterey.

The wildflowers and garrigue of Provence are evident in the air to anyone who has hiked in the South of France, and unsurprisingly they also show up in the wines of the region. Duh! It stands to reason that wines grown in our own more drought prone areas offer thyme, rosemary and bay, while wetter climes are laced with juniper and pine nuances, particularly in areas like the Santa Cruz Mountains where tiny vineyards are surrounded by local forestation. In grape monocultures, this factor plays less of a role. Gotcha!

Less clear are the sources of variation in fruit aromatics. Why do we consistently find maraschino cherries in, not just the Zinfandels, but the Cabernets and, yes, the Petite Sirahs of Mendocino? What gives high altitude Petite from so many regions the bright red pomegranate/cranberry fruit which is replaced in lower sites by cassis and blackberry? Beats me.

When Robert Brittan headed up winemaking at Stags’ Leap Wine Cellars, he was often pointed to as a pre-eminent Petite Sirah expert. A vineyard-savvy winemaker, he has made wines from a broad spectrum of sources in the Napa Valley, as well as Mendocino hillside and Valley, Lodi, Green Valley, and Lake County. He is now owner/winemaker at Brittan Vineyards in Willamette Valley, Oregon.)

According to Brittan, fruit expression has to do with not just regional high temperatures (the UC Davis Degree-Day system), but with the way it gets hot. “The characteristically austere, black fruit one finds throughout Napa comes from big diurnal temperature swings - even in Calistoga. In Oregon, I have a Van Duzer-contiguous site with southern and western exposures, but it has huge diurnal shifts, which drives phenolic buildup in grapes, particularly Petite Sirah, and if it stays hot at night, you get very different fruit flavor development. Valley floor Mendocino gets maraschino, light color and tannin, as does Lodi. Not so for Mendocino hillsides.”

Color Me Happy

Color is the key to wine structure. In the philosophy of my guru Patrick Ducournau, the importance of the variety’s propensity to produce lavish anthocyanin content cannot be overstated. Based from work on many thousands of wines, Ducournau’s theories, still awaiting confirmation from a recalcitrant academic sphere, have proven extremely useful and powerfully predictive to me in a decade of consulting work, and seem valuable to share here to shed some light on how Petite Sirah behaves. Ducournau, the father of micro-oxygenation and a whole postmodern school of winemaking, tamed the manly monster grape Tannat in his native Madiran by understanding that wine quality is linked to its structure.

In Ducournau’s system, monomeric anthocyanins are held in high esteem. These unique flavonoid phenolics are favored targets for polymerization-happy tannin monomers, which like samurai nano-bots, are eager to build structures. The red pigment molecules have only one addition site, so they cannot themselves continue the daisy chain, and are thus the bookends of tannin polymers. The more color, the shorter the chains. Shorter chains form finer colloidal beads, and plusher texture and greater aromatic integration are the result. Color isn’t just pretty - it leads to wines with more finesse.

Some varieties seem to require cool areas to produce good color. If the Sonoma Coast and Oregon’s Willamette Valley are any indication, cool foggy areas bring out the color in Pinot Noir. So it seems with Syrah, as witness the inky Bien Nacido and Margaret River Shirazes. Only the cool Northern Rhône reds base their color on this varietal, while in the warmer Southern Rhône, it is lighter.

Other varieties seem to need more heat to color up, and something else. Partial drought causes Grenache to be the ink of the southern Rhône, apparently stimulated by some struggle with the earth. Like Cabernet Franc, irrigated Grenache will not color up. These varieties are vigorous weeds, and excessive vigor produces shading canopies. Not so with our less vigorous subject at hand. Water stress certainly affects its tannins, but the irrigated dense deep clays of Suisun give us remarkably dark wines. Based on our observations during the Best-of-Appellation™ tastings, I do not find that Petite Sirah’s color responds positively to cool conditions – the Russian River Valley wines were the lightest.

What, then, do the highly colored Petite Sirah sites have in common? My hypothesis is this: high incident light. Not only did all our high altitude wines color up well, but also one lowland region: Suisun’s fogless conditions give all day light exposure, and here we found some of our darkest wines, though color on these deep clays is not guaranteed, and canopy management seems critical to success.

There are three possible influences here. To begin with, it seems plain that some combination of warm conditions and incident light persuades the PS genome to manufacture color in the berries. But then two other factors come into play. The first involves the variety’s rot susceptibility. Absent the suppressing power of UV light, Botrytis mold manufactures the enzyme laccase, which destroys color.

Also important to wine color is the ability to extract color. In extracting anthocyanins, winemakers have got two problems. One, they aren’t water soluble. Two, they have a slight positive charge, so they repel each other and thus won’t aggregate into extractive globs called colloids. Saving the day, other uncharged phenolics will inter-stack with the pigment molecules, together making a big Dagwood sandwich called a co-pigmentation colloid.

The co-pigmentation phenomenon, elucidated through two decades of research by Dr. Roger Boulton of UC Davis, has turned much standard winemaking practice on its head, including the hangtime craze and the gold standard of varietal purity. High alcohol destabilizes these colloids, and all the punching down in the world won’t extract color deficient in cofactors. Boulton’s work validates the traditional practice of co-fermenting of mixed varietals, such as the uncolored but highly phenolic Viognier in the Syrah fermentations of Côte Rôtie. By contrast, Durif doesn’t need help, it IS the helper. In fact, Ridge Vineyards’ master Zinfandel guru Paul Draper has been principally interested in Petite for its field blend extraction capabilities in the fermenter, only bottling pure varietal PS as excess production once the Zins are taken care of.

Since Syrah can be deficient in cofactor, one cannot help but look to PS’s other parent as a source of this difference. Perhaps Peloursin’s mountain lineage disposed it as a good producer (either through natural adaptation or human selection) of the super-cofactor quercetin, a kind of suntan which is stimulated by and also protects against UV radiation. If so, high quercetin levels could be one reason incident light seems to give us such dark wines.

High incident light has a downside. Lake County’s Red Hills obsidian perhaps offers the most extreme example of high incident light, for, in addition to fog-free, smog-free, thin air 1,000-foot conditions, the decomposed granite soils limit vigor and prevent shading, and the ground is strewn with fractured volcanic obsidian glass, reflecting under the canopy so that the clusters are bathed in light from all directions. “You always get great color and a solid big mid-palate,” explains Brittan, “but sunburn can damage the intense delicious character.”

Easy to be Hard

In Ducournau’s picture of wine, flavors are not dissolved into a water/alcohol solution, but mostly retained within colloidal beads formed by tannins and pigment. The aromas of herbs, oak and microbial activity can be integrated into a harmonious single voice by wines that have piles of refined, dense tannins. Thus, in discussing tannin, it’s important to talk about both content and structure - how much building material is present, and also how it’s put together.

As for tannin content, it seems that adequate warmth and moderate yield are the main influences. The lightest wines (on a scale of big to huge) were the cool Region I Russian River and the hot Region IV Lodi products.

But the character of those tannins appears to be controlled by soil type. “In exactly the same climate conditions, well-drained gravelly soils give wines which are highly structured, aggressively tannic and closed,” offers Brittan. “On clay soils in the same climate, the wine is much fleshier and rounder.”

Paul Draper concurs. “Our arid York Creek site has big firm structure that requires a lot of cellar time, whereas the Lytton Springs site, which has much more water availability, is always much more supple and round.”

The most extreme contrast in tannin character that our panel observed lay between Howell Mountain’s remorselessly hard textures and the almost equally dense Suisun wines, whose heavy clays yielded fine, voluptuous, sweet tannins. Howell Mountain’s hot west face has much more potential for field oxidation and sunburn than the otherwise equal east-facing slopes of Spring Mountain, producing much more angular presentation.

In my view, this influence of water availability has to do with controlling the degree of field oxidation. Angular tannins result from pigments that are fried on the vine. How can you make a tannin soufflé when the egg’s already scrambled? In more temperate conditions, pigments are still raw, available as those special end-cap building blocks to protect a refined structure.

High and Mighty

When we say high altitude is where Petite Sirah is currently grown, so the main common themes are absence of fog and good drainage. Climatologist Greg Jones of the University of Southern Oregon has elucidated the sources of variability in high altitude terroir that make each site unique: daily and seasonal temperature curves, fog, air flow, precipitation, drainage and water holding capacity, weather hazards like frost and hail, and topology. Altitude tends to impart coolness, dryness, good drainage, and enhanced incident light, especially UV. Reduced CO₂O₂ ratios stunt growth and may retard canopy and berry size, loosening clusters and reducing rot.

Consulting viticulturalists Daniel Richards and Theo Csavas utilized 30 weather stations installed throughout the North Coast by Kendall Jackson to elucidate the effects of altitude. Their pooled findings showed that, in general, vineyards above 1000 feet in this Region (up to around 2200 feet) have smaller daily swings in summer temperatures - lower highs and higher lows. They cited two reasons for this: absence of fog and average temperature decrease due to lower air pressure, around 4 degrees per thousand feet.

Though each area showed its own distinct characteristics, there were obvious common threads: very dark color, minerality, and hard, angular tannins. It would seem that Petite is well suited to return to its mother’s mountain roots. But there are also many fine lowland wines, especially for those who like the grape’s feminine side.

The sea level Suisun Valley wines were also very deeply colored, leading us to believe that incident light is the driving factor here, but their tannins were supple and fine. The pinnacle of refinement was to be found in the Russian River wines, whose age worthiness set them apart.

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For a full account of the regional diversity observed in the Petite Sirah Evaluation, check out
PS, How Do I Love Thee? Let Me Count The Ways.

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Photos by Jo Diaz