Growing & Winemaking

 

A CONVERSATION WITH Michael Pierce

June 2015
 
by Laurie Daniels
 
 
Michael Pierce
 
Michael Pierce is the director of enology at Arizona's Yavapai College.

Winemaker Michael Pierce grew up far from vineyards in Phoenix, Ariz. He studied electronic media and visual communication at Northern Arizona University, and after graduating in 2004 he went to work doing print and web design.

But while he was in college, Pierce had taken up brewing and winemaking as hobbies, and after graduation he decided to take online viticulture and enology courses through the University of California, Davis, extension. He switched to Washington State University’s program in 2007.

After working harvest jobs in New Zealand, Oregon and Tasmania (Australia), Pierce took a winemaking job in 2010 at Arizona Stronghold Vineyards. In 2014, he became director of enology at Yavapai College in Clarkdale, Ariz.

Meanwhile, his wine-loving parents, who were in their 50s and looking for a new adventure, bought land in Willcox, Ariz. The property had a neglected 8-acre vineyard, which they’ve renovated and expanded to 27 acres. The family now has two wine labels, Saeculum Cellars and Bodega Pierce, and Michael Pierce handles the winemaking.

Wines & Vines: The Arizona wine industry is still relatively young. Where do things stand in regards to finding the best sites, best grape varieties and most appropriate viticultural techniques?

Michael Pierce: The first post-Prohibition commercial plantings of Vitis vinifera in Arizona were done with the help of a grant sponsored by the Four Corners Commission, meant to study the viability of wine grapes as an economy-stimulating crop in the Southwest. The grant was written by a University of Arizona soil scientist named Dr. Gordon Dutt in 1976. Dr. Dutt had previous experience with table and wine grape vineyards in Tucson and Yuma (Ariz.) areas. Based on lessons learned from those projects, he looked for a site with good air drainage, a higher elevation and acidic soils. He chose the Sonoita (Ariz.) area, 60 miles southeast of Tucson, which sits at an elevation of 5,000 feet. The soil in that region has a top layer referred to as terra rossa, which consists of a clay-rich acid soil, with iron giving it a distinctive rusty color. Below this layer is a more basic limestone.

The first cultivars were primarily chosen based on what was popular at the time—Cabernet Sauvignon, Chenin Blanc, Sauvignon Blanc. All of Dr. Dutt’s original plantings succumbed to Pierce’s disease in the early 1990s and had to be replaced. Today, the majority of vineyards in Arizona are free of PD, but the threat remains on the minds of growers. Establishing a vegetation-free zone around your vineyard and having IPM (integrated pest management) in place are the lessons that have been learned by any grower who has been hit.

Sonoita is currently Arizona’s only AVA, although there are two other established growing regions in Arizona: Willcox in the southeastern part of the state and the Verde Valley an hour and half north of Phoenix. As of 2012, approximately three-quarters of the state’s wine grapes come from the Willcox area, and a petition is pending to establish Willcox as an AVA.

Region-specific wine characteristics are slowly starting to show themselves as farming practices become more uniform. Both vineyard yields and grape quality have surged in the past few years. Varietal selection in Arizona has not yet been refined down to a certain few. There is a large list of cultivars that will grow well here and a short list of bad cultivars. Some of the cultivars that have proven themselves in Arizona are things like Malvasia Bianca, Tempranillo, Grenache, Mourvedre, Graciano, Petit Verdot, Sangiovese and Tannat—cultivars that thrive on full sunlight and the large temperature swings we see at the higher elevations where most vineyards are planted. These varieties require a less invasive management approach from growers and create wines with good concentration and balance. Cultivars that are resistant to bunch rot and can hold up against the high humidity brought on by our late summer rains are certainly favored here. Kent Callaghan, one of the longest standing winegrowers in the state, tried to make Zinfandel work for 15 years. Kent said, “That was mostly a disaster due to rot. I grafted/replanted that plot to Graciano in 2009, and the result is some of our best wine in the cellar since then.” It’s the sharing of experiences like these that has lessened the learning curve for new potential growers in the state.

There are some other vineyard-management experiments going on in the state where growers are trying to develop some best practices for our climate. For example, Merkin Vineyards is purposefully setting a smaller structure on their new vines through water and nutrient management. 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.

W&V: What are your biggest viticultural challenges 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 ripening. When people think of Arizona, they assume 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 afternoon 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 majority of vineyards are set up on VSP trellising. The fungicides that most growers use are Kocide, 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 experience 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 moisture 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.

 

W&V: How do grape physiology and wine chemistry differ in Arizona, compared 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 cultivars planted statewide. In general, Arizona does not have trouble producing adequate sugar levels in grapes. The acid-to-sugar balance is typically more of the challenge in Arizona. 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 ripeness without any unneeded hang time. A midseason shoot-thinning pass can make the world of difference. Vineyard yields of 2-4 tons per acre tend to come off healthy and with respectable 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 elevated 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 challenge 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 approach 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 acidulation 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 definitely 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 adequate shade to avoid sunburn. Some vineyards 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 shading 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 desert flowers in many of the wines.

W&V: Winemakers and growers in well-established areas have easy access to equipment, supplies, lab services and other necessities. What’s the situation in Arizona?

Pierce: Nearly all equipment must come from out of state—California suppliers for the most part. There are also no established wine grape nurseries yet, so all new plant material has to be ordered from out of state. With the small size of many of the producers and costs associated with trucking, it has been beneficial for wineries and vineyards to partner up on orders and reduce shipping costs. We generally do this by sending out emails.

It is not only more expensive to bring in things like barrels on our own, it is logistically more of a pain. If you ship your small order by common carrier, it will make its way through Phoenix and be passed off to different regional carriers before it makes its way to wine country a few days later. Filling a truck with orders from the local wineries and having direct delivery has been the better way to go. Today, for example, a 53-foot truck full of glass arrived in the Verde Valley from Diablo Valley Packaging in Fairfield, Calif., to deliver glass to three wineries before heading to wineries in Willcox.

Slowly the industry is making its way into Arizona. Higher education has helped bring instructional resources in the last few years. Yavapai College in the Verde Valley has 8 acres planted (a total of 17 acres are planned by 2021) and a full-scale teaching winery with a 3,000-case capacity. (See “See Arizona to Build a Teaching Winery” in the September 2012 issue of Wines & Vines.) One-year certificates in viticulture or enology and two-year degrees in viticulture and enology are offered. The college’s facility, which is referred to as the Southwest Wine Center, has a well-equipped lab for wine analysis. Wineries’ lab samples are commonly sent to California, but there are plans for the Southwest Wine Center lab to offer services, with revenues going to support the program.

The college is also partnering with the University of Arizona& rsquo;s College of Agriculture and Life Sciences to create a data repository. The purpose is to create a community resource for state-specific information pertaining to grapegrowing and winemaking. The university has also hired a cooperative extension agent in the southern part of the state to provide educational assistance to growers. Plans are in place to hire a second cooperative extension agent to be stationed in the Verde Valley whose focus will be viticulture.


A resident of the Santa Cruz Mountains, Laurie Daniel has been a journalist for more than 35 years. She has been writing about wine for publications for more than 21 years and has been a Wines & Vines contributor since 2000.
 

 
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