Wines & Vines

June 2015 Enology & Viticulture Issue

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WINEMAKER INTERVIEW 48 WINES&VINES June 2015 ment. The hope is that these smaller vines will naturally want to carry a smaller fruit load that will result in higher quality from the lower yield. The idea is to follow more of a European model of cropping. Also, perhaps this smaller crop can mature faster to avoid longer hang times and higher pHs. Q What are your biggest viticultural chal- lenges in Arizona? Pierce: We have a couple of key viticultural challenges in the state, though growers are learning to manage their inputs to better to mitigate the results of these threats. The two larger threats we face are late spring frosts and heavy monsoon rains around the time of ripen- ing. When people think of Arizona, they as- sume it's too hot and too dry to grow grapes, but the fact is that cold and wet weather at the wrong times are what we are faced with. The 2013 and 2014 vintages were both defined by the monsoon rains, which hit us hard during the middle of our harvest period, which runs mid-August to late September. If these after- noon rains come early enough in the season, they can provide a welcome break from the warm summer. However, it's proving to be a good practice to manage your vineyard with the expectation for potential heavy rains or hail later in the season. Growers are starting to get their canopies up and open and being careful not to set too much fruit. The vast ma- jority of vineyards are set up on VSP trellising. The fungicides that most growers use are Ko- cide, Serenade and elemental sulfur. Regardless of the region you are in, picking a site with decent air drainage is imperative to avoid winter kill and spring frost. Even a couple of feet of elevation can make the difference from a great site to an impossible one. Both the Willcox and Sonoita areas experi- ence windy conditions throughout most of the summer. Hardy VSP trellising with adequate catch wires and canopy management to avoid shoot damage is critical. Because of the sandier, lower nutrient soils, we don't naturally have issues with overly vigorous canopies. We can have the opposite issue, with shoots shutting down due to high temperature and low mois- ture levels. The wind can likewise decrease moisture levels in the vines and increase the need for irrigation. Making sure soil moisture levels stay up is important throughout the growing season. We have to be careful how or if we deficit irrigate. We can't really follow the same irrigation model as California in that regard. Any water stress during flowering coupled with the wind can wreak havoc on your fruit set. Q How do grape physiology and wine chemistry differ in Arizona, com- pared with other viticultural areas like California? What are winemakers and viticulturists doing to mitigate problems or deficiencies? Pierce: It's difficult to speak in broad terms about Arizona wine grapes with three distinct growing regions and a large selection of culti- vars planted statewide. In general, Arizona does not have trouble producing adequate sugar levels in grapes. The acid-to-sugar bal- ance is typically more of the challenge in Ari- zona. Certain sites with high-pH soils, which affects nutrient availability, coupled with a warm growing season and a high rate of vine respiration tend to produce higher pH grapes. Growers are trying to mitigate this with a healthy canopy-to-fruit ratio to provide ripe- ness without any unneeded hang time. A mid- season shoot-thinning pass can make the world of difference. Vineyard yields of 2-4 tons per acre tend to come off healthy and with respect- able pHs. Common vine densities are at about 900 to 1,000 per acre, but there are a few growers who are experimenting with higher density and a lower fruit load per vine. This is in response to our lower vigor soils and the desire to ripen before rains and to retain acidity. To compound the issue, we tend to see el- evated potassium levels in our musts. This creates a twofold effect where the potassium binds with tartaric acid and also reduces the vine's respiration of malic acid, leading to fruit with high TA and high pH. This can be a chal- lenge to address in the winery. There are a couple of techniques growers are using to try to manage the final potassium levels in the fruit—either by applying micronized gypsum through drip irrigation to supply extra calcium that will displace some of the potassium in the vines, or through foliar calcium applications for the same purpose. They're trying this ap- proach at Merkin Vineyards. By supplying the vines with applications other than potassium (calcium, magnesium, etc.) from flowering through véraison, the hope is to reduce total potassium in the leaves and stems. While acid- ulation in the winery is fairly common in red wine, some wineries are choosing to live with higher pHs in the 3.9-4.0 range. The higher elevations (generally 4,000- 5,000 feet) provide large diurnal temperature swings, which help with tannin development. This allows for good aging potential despite elevated pHs. Acid levels in grapes are defi- nitely a factor in the discussion about which cultivars do well here. With intense sunlight during the summer days, sun exposure also needs to be managed. Delicate white cultivars like Viognier need ad- equate shade to avoid sunburn. Some vine- yards are opting to modify their VSP system using cross arms to open up the canopy. This increases canopy efficiency by providing some shade to the fruit zone yet reducing leaf shad- ing and promoting photosynthesis. It also opens the canopy to more airflow. Another thought is that by creating open canopies with high photosynthetic efficiency, we can limit potassium movement from the foliage to the fruit during ripening. In terms of flavor profile, the wines are tasting more like Arizona every year as vineyards mature. I tend to pick up bright fruits with notes of dried herbs and des- ert flowers in many of the wines. Q Winemakers and growers in well-estab- lished areas have easy access to equip- ment, supplies, lab services and other necessities. What's the situation in Arizona? HIGH-ELEVATION ARIZONA VINEYARDS Arizona viticulture is concentrated in Willcox, Sonoita and the Verde Valley, but there are isolated vineyards in other parts of the state. Some of them have been developed by Michael Pierce's stu- dents at Yavapai College. For example, students helped plant a vineyard in Williams, Ariz., the gateway to the Grand Canyon. The area is at about 7,500 feet elevation and very cold, and Pierce says they've planted hybrids because of the conditions. "I still question their longevity," he adds. Pierce knows of another high-elevation vineyard in the White Mountains, northeast of Phoenix, Ariz.; a couple of vineyards around Kingman, Ariz., where it's much warmer; and one outside Prescott. "All of those areas are completely untested," Pierce says. Ultimately, Pierce says, debates over water rights will probably limit some of the planting in new places. ARIZONA Grand Canyon Phoenix Tucson VERDE VALLEY WILLCOX SONOITA

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