How Viticulture Practice Influences Wine Quality at Pride Mountain Vineyards
Steve Pride
August 21, 2023
Farming is likely the most underappreciated of the leading-order influences on wine quality. Most wine consumers and even wine professionals, including winemakers, are not aware of the way that specific farming practices influence and even create specific characteristics of the resulting wine. The only way to obtain such insight is to form hypotheses as you keenly observe your vines over decades, perform experiments in the field that test your ideas and then monitor the wines made in the same way from vineyard blocks that are farmed in different ways. Not everybody making fine wine goes through such time-consuming efforts. I'd like to share here some of what I have learned over the 20 years that I have been directing our farming operations here at Pride Mountain Vineyards.
The present 2023 vintage represents the 34th vintage that the Pride family has been farming grape vines on our mountain-top property. For the first two vintages (1990 and 1991), my Dad contracted John Arns to farm for him and John would bring in his own crew and equipment to perform each required task. But starting in 1992, John Arns allowed my Dad to hire one of his best workers, David Orozco, who became our vineyard manager for the next 31 years until he retired in 2022. Several members of the Alcantar family were also hired in 1992 to form Pride Mountain Vineyard's first full-time year-round vineyard crew, which for context was five workers in 1992 and is presently seventeen workers in 2023. Also in 1991 and 1992, Dad bought the needed tractors, spray equipment and backhoes so that we could remove old under-performing vineyards, plant new ones and tend to the grapevines ourselves. We have done all our own farming with our own equipment and year-round full-time vineyard crew for these last 32 years.
In 2004, Dad died after a bout with cancer and I took over as the general manager of the winery. I spent most of my time in 2004 and 2005 learning all aspects of our farming and viticultural peculiarities at the top of the Mayacamas Mountains. Much of my technical understanding of vine growth and vine health I learned from Dr. Paul Skinner, who has been our viticultural consultant and friend from 1990 to present. In those first years of my tenure, I observed a gap between our actual farming practices and the important viticultural objectives that Paul Skinner had in mind. This was fairly easy to fix by simply spending a lot of time with David out in the vineyards explaining the ideas until they became our practice. But the lesson was an important one: it is essential that your vineyard manager is not just given tasks to perform but also knows the reasons for each of your farming practices so that you get buy-in and follow through. From that point in 2005 to present, I have investigated many viticultural hypotheses at our property as our farming has evolved, all while keenly observing the resulting wines. What makes our property that straddles the rolling hill crests of the Mayacamas Mountains particularly educational is the wide range of expositions to the sun, wide range of soil types and different microclimates.
There is a school of thought among some grape-growing academics that says terroir, which is the vineyard-specific influence of climate, sunlight and soil on the wine, is a faulty concept because viticultural decisions can at times have an even greater influence. I am not a part of this school. It is an objective fact that wine is strongly affected by the location where the vines are growing even if farming practice is also important. I have planted identically the same clone of cabernet sauvignon on the same rootstock on both north-facing (less sunlight) and south-facing (more sunlight) vineyard blocks and farmed those blocks and made the wines in identically the same way and the resulting wines are quite distinct. More sun results in more density, richness and fruit intensity, while less sun results in a lighter-bodied wine.
Wine quality is influenced by the totality of terroir, farming decisions, the timing of harvest and the myriad of winemaking decisions from fermentation through to bottling. Although we are only exploring farming effects in this article, you must master each of these major influences in order to understand why your wines taste the way they do and, more importantly, to know how to make desired changes. That wine is affected by so many variables is what makes winemaking so endlessly fascinating.
When you have an empty field that you want to plant with wine grapes, you are faced with your first major farming decision that you almost certainly will get wrong unless you have decades of experience at the site: what grape variety, and specific clone of that variety, to plant and, equally important, what rootstock to use. When we began 34 years ago, there were only 45 vine acres on the property, while today we have 85 vine acres of which only 5 acres are original from 1990. These 85 acres are broken into 54 distinct vineyard blocks on which we grow nine grape varieties. We have replanted about 50 acres of these vines two times due to both early mistakes and disease and a few vineyard blocks have been replanted three times. Here are a few high-level takeaways from my planting and replanting experience:
Merlot has to be on our south-facing warmer blocks that receive the most sunshine for it to acquire the round phenolic richness and assertive black cherry flavors that makes this varietal so distinctive. Our soils in these blocks tend to be surprisingly deep and it is essential to use a lower vigor rootstock in such soils because merlot tends to be growthy and if the clusters are hidden inside overgrown canopies they do not acquire the depth, fruitfulness and savory-spice nuance that is required of world-class merlot.
Similar comments hold for cabernet franc. Where merlot thrives, so does cabernet franc. This is similar to the right bank of Bordeaux where merlot and cabernet franc are the dominant grape varieties. The right bank is warmer during the growing season compared to the marine-influenced left bank of Bordeaux where cabernet sauvignon is dominant. Cabernet franc grows less vigorously than merlot and should be on slightly more vigorous rootstocks compared to merlot. When cabernet franc does not get enough sunlight, the dried-herb and dried-flower aromatics and lighter phenolics that make this varietal so appealing are not balanced by enough pretty fruit and the wines are just not as interesting.
Cabernet sauvignon, in contrast, can be grown on any of our 54 blocks. When in doubt, plant cabernet sauvignon. To be sure, the wine character is different from blocks having either cooler or warmer microclimates or more or less sunshine, but each wine is interesting as a stand-alone and when combined across all blocks makes for a more complex savory wine that has, for example, cedar, menthol and oily underbrush aromatics in addition to the dark-fruit flavors and bold tannins that come from our south-facing blocks.
For our Rhone varieties, syrah, grenache and viognier, which are more aromatic than the Bordeaux varieties, I have learned that you get a more interesting finished wine when the time between veraison and harvest is as long as possible without sugar becoming elevated. As such, these Rhone varieties need to be in blocks that receive less sunshine and have cooler temperatures. Where merlot and cabernet franc thrive, syrah makes a monolithic wine having a wall of black impenetrable fruit intensity. To get more open-knit savory, meaty, herbal and spicey qualities that are what make syrah so great, you have to slow down the ripening by planting it on cooler, less-sunny sites.
In addition to choosing the right grape variety and rootstock, it is essential to test your soil and add soil amendments to the block prior to planting. Our mountain soils tend to be depleted in many of the major nutrients such as phosphorous, potassium, calcium and zinc that grape vines (and indeed any plant) need to thrive but such mineral concentrations can vary significantly from one of our blocks to the next. Mixing the right amount of lime, gypsum and potash into your soils prior to planting is essential to support young vines as they start to produce fruit. With proper nutrients, young vines between three and six years old can begin making beautiful fruit-forward wines that get more complex with each passing year. Without adding nutrients, the canopies of young vines tend to shut down at fruit set, compromising fruit quality and, even worse, delaying the development of a strong root structure. On the couple times I have ever skipped adding amendments prior to planting, I have regretted it once the vines were three to six years old. In addition to the minerals, I also like to add to the soil a good fungus called mycorrhizae that derives from ground-up crab shells and that helps the hairs of the roots with the uptake of water and minerals. Young vines supplied with mycorrhizae get off to a healthier start. Further, as the climate is changing, I am observing an increasing presence of several types of bad fungi on our property that get onto the roots of grapevines and harm the root hairs. Although only a small number of vines are showing this problem, adding good fungus to the soil is an important and proven effective counter to this new trend over the last few years.
So now that vines are growing, what ongoing farming practices influence the quality of the finished wines? Nearly all of them! In a perfect vineyard in a perfect growing season, each of the main shoots would grow to the desired length of say five feet, while the secondary shoots called "laterals" would only grow to say six inches. Ideally, this new growth would stop a couple of weeks prior to veraison. The two clusters hanging at the bottom of each main shoot would be bathed in dappled sunlight from fruit set through to harvest. A vine that has this shoot behavior is said to be "in balance". Unfortunately, a balanced vine is rarely attained without considerable intervention on the part of your vineyard crew even if you were lucky or skilled enough to select the perfect rootstock. This is because some spring times are wetter and some are drier, especially when you are on a mountaintop that gets so much rain.
The main farming task for making beautiful, rich, fruit-forward, complex red wine is to get plenty of sunlight onto the clusters between fruit set and veraison and then from veraison through to harvest making sure the clusters have protection from direct sun and are not damaged. Veraison is the moment in the growing season, typically in the middle of August for us, when the grape clusters stop accumulating acid and begin accumulating sugar. For red wine grapes, it is also when the clusters change color from green to dark purple. When the months of April and May see a lot of rain, the main shoots and laterals will grow dramatically more compared to a drought year. After a wet spring, the laterals can grow to several feet in length and the clusters become completely enclosed within the dark interior of the canopy. To counter that, we pass through the vineyards and remove the laterals near the clusters that are blocking the sunlight. A mechanical hedger cannot reach in and remove these laterals, so I insist this work be done by hand. Higher up the main shoots, especially as climate change is increasing the number and intensity of heat waves, we do not remove the laterals so that we can come back after veraison and allow these higher shoots to flop out of the trellis wires to create needed shade throughout the ripening season. We also use shade cloth to protect the clusters after veraison in those blocks that receive strong afternoon sun.
Further, if shoots are growing at veraison, which is not desired and corresponds to a vine that is not in balance, the Bordeaux red varieties acquire a big increase in the concentration of pyrazine compared to when the shoots have stopped growing for the few weeks leading up to veraison. Pyrazine concentration in red grapes peaks at veraison and falls steadily to harvest. If pyrazine levels shoot up too high due to too much growth at veraison, Bordeaux-variety wines can acquire a green flavor of bell pepper that is unpleasant. Further, any shoot that is growing after veraison consumes photosynthates and vine energy that should be going to the clusters. This often happens if a shoot is growing horizontally at the top of the canopy. As such, it is important to go through all the blocks prior to veraison and arrange the shoots as vertically as possible, topping the main shoots and laterals that are still growing. When a shoot tip is clipped, it sends a hormonal signal to slow down and even stop growth.
We choose to do all of this "canopy work" by hand because machine trimmers cannot entirely remove the laterals in the fruit zone and cannot reposition shoots vertically nor top horizontally-growing shoots. This represents a huge amount of work each year and can involve four or five passes through the blocks on wet growthy years. To prove to my vineyard crew and myself that such an effort makes a better wine, I have done experiments where we leave some rows of a block "untouched" (i.e., the growth of the shoots is allowed to do whatever it wants to do), while managing the canopies of the other rows in that block in our usual meticulous way. The clusters on the untouched vines do not receive as much light but, interestingly, get to the desired sugar level at about the same time as the more exposed clusters. We then harvest and ferment the grapes separately so that we have two wine lots we can compare: (1) a lot made from grapes that have had no canopy management and (2) a lot made from the identical grape variety, rootstock and terroir but that has received a huge amount of canopy management. The two lots have entirely different wine character, with the cared-for grapes producing a richer, more fruit-forward and flavorful wine than the "untouched" lot, which did not receive any canopy management.
Another big decision with your young vines is to choose a trellis system for how your canopy grows each growing season. We have used and experimented with the two dominant approaches:
Cordon-trained and "spur-pruned" vines mean that you lay a shoot horizontally on a wire typically in a vine's first year of growth and this shoot becomes a woody "cane" that is never removed. The next year, shoots grow from nodes on this cane, which is now called "the cordon", and each winter you prune the canes that grew from the cordon back to one or two nodes. The two nodes of a cane that remain after pruning is called a "spur" and new shoots will grow from spurs spaced every 5 inches or so along the cordon at positions called "arms" that get a bit longer each year.
Head-trained and "cane-pruned" vines mean you do not form a horizontal cordon but allow shoots to grow from the "head" of the vine (the top of the trunk) each year. In the winter, you typically select two canes called "fruiting canes" to lay onto the wire from which the shoots and fruit will grow in the upcoming season and you remove all the other canes from the previous growing season leaving some spurs near the head from which "replacement canes" will grow that will become the next year's fruiting canes.
We have used and had success with both approaches but each has its advantages and disadvantages that can lead to considerably different wines.
The main drawback with cane pruning is that shoot growth from the nodes along each cane can be nonuniform, especially if you use canes that are too long. Shoots at the end and start of a cane tend to be longer and those in the middle of a cane can be shorter. Even more important than getting sunlight onto clusters, the main way that canopy design influences wine quality is through shoot length. If a shoot is not long enough, there are not enough leaves and photosynthesis on that shoot to ripen the clusters properly. The clusters on shorter shoots will not make the same high-quality wine as clusters on longer shoots (so long as those shoots stop growing prior to veraison). If there is enough springtime water in the soil and if you have the right rootstock and do not make your canes too long, you can get uniform shoot growth and cane pruning is just great. The main advantage of cordon-trained vines is that the shoot growth from each spur along the cordon tends to be uniform. A goal when you look down any vine row is to see vertically oriented shoots of the same length that are spread out uniformly along the length of the row. If shoots are concentrated more toward the trunk of each vine or if some shoots have variable length, the quality of the wine will suffer because not all clusters are ripening in the same way. Early on, we did only cordon training and then I switched to only cane pruning on our replanted vineyards between 2013 and say 2020. I am now drifting back toward cordon training due to its more consistent "uniform-shoot-length" and "uniform-distribution" advantages. When retraining some blocks from cane pruning to cordons, I noted an immediate increase in wine quality. When thinking about such viticultural decisions, I like to remember that we see huge differences in a finished wine if we tweak a blend by only 1%. So if a row of 100 vines has 4000 clusters in it, if even just 40 clusters in that row are underflavored due to being on short shoots, this will have a noticeable impact on wine quality.
A downside of cordon training is that when a vine becomes 20 years old and older, the path for water and nutrients to get from the soil to the growing shoots becomes quite tortuous. The water must make a sharp 90-degree turn from the trunk into the old cordon and then another sharp 90-degree turn into the old vertical arm that develops where the spur is located. In one of my very best cordon-trained cabernet blocks that was 24 years old in 2016, I began to notice a decrease in fruit intensity in the wines between 2016 and 2019. I decided to retrain to cane pruning by removing the cordon and leaving canes that grow from arms left near the head of the vine. So in 2021, I did an experiment where we cane pruned 12 rows of this block and left the other 24 rows as cordons. The wine made from the cane-pruned rows was significantly better with more fruit forwardness and greater overall complexity compared to the wine made from the cordon-trained vines. In 2022, we got an identical result and so now in 2023 the entire block is being cane pruned. This is yet another example where we observe a big change in wine quality by simply changing a single viticultural practice in a controlled experimentally-verifiable way. Overall, I now like the idea of using cordons through the first 15 to 20 years and then switching to canes if wine quality ever falls off.
Another key part of canopy management, at least here in California where it does not rain in the summer, is irrigation strategy. Some vineyards have gone to electronic sensors that measure the electrical conductivity of the soils which is influenced by water content and which tells you when it is time to water your vines. I prefer the old-fashioned approach of simply looking at each of your vineyard blocks each day during the growing season. The vine tells you what it needs. If shoot tips are growing and tendrils are green and upturned, a vine does not need water. You need to water only once growth has stopped with the goal being to maintain a roughly static green canopy through to harvest. A big challenge is that most vineyard managers including my own do not want to see any yellow leaves anywhere and tend to over water. As stated, too much water can lead to shoot growth at veraison which can create undesired bell-pepper flavors in your red wines. And vines that are growing from too much watering after veraison are putting photosynthates into growing tips and not into ripening clusters. Providing the right amount of water throughout the growing and ripening season has a direct impact on wine quality and is another essential task to get right.
We also water when we add fertilizers to particular blocks that need nutrients such as nitrogen, phosphorous or potassium. The nutritional need of a block is determined both through direct observation of the leaves and by annual mineral analyses of leaves that are collected and tested for their mineral concentration at an outside laboratory. Such mineral testing is important so that you do not add too much of any one mineral, like potassium that can increase the pH of your wine if excessive in the vine, and so that a vine has the minerals, in particular potassium, that helps it get through heat waves. Providing proper mineral nutrition to the vines is essential for combating heating stress and getting the fruit optimally ripe at low sugar and is another important example of how careful farming practice leads to better wine.
About water use at our vineyards, I want to emphasize that we only irrigate with water that is collected in our three ponds each winter. No groundwater has ever been used on our vines. Even in drought years, these ponds fill and spill into the local creeks by December or January at the latest. Every drop of water we put on our vines each summer is water collected in the ponds from winter runoff that otherwise would have flowed to the Pacific Ocean. Irrigating vines using water from rain-filled ponds in no way impacts negatively our creeks or aquifers that always need more water. Indeed, I contend that putting this winter water from our ponds back into the watershed each summer is a net benefit to the watershed.
In addition to canopy management, another key part of each growing season is keeping fungus and rot under control in the vineyard. Our 2000' elevation and mild temperatures create ideal conditions for mildew growth on our vines. Mildew on the leaves reduces photosynthesis, while mildew and rot (e.g., botrytis) on the grape clusters at harvest produce nasty flavors of dirt in the wine. An effective fungicide program is essential to the making of quality wine. The traditional centuries-old approach is to use sulfur and copper solutions in the spring when growth begins and then use sulfur dust later in the growing season. These treatments are "organic" but come with the downside that sulfur kills beneficial insects and if copper is used multiple times per year over decades, soil toxicity can become a problem. We indeed use a limited one-time application of organic sulfur, organic copper and organic "good fungus" fungicide sprays as part of the early season program. But I prefer never to use any one type of fungicide more than once per growing season and to use fungicides that target specific types of fungi in ways that cannot create fungal resistance and that do not in any way harm our beneficial insect community. A fungicide spray is typically effective for two to four weeks depending on the rainfall. Our approach of never using the same treatment twice and using the fewest sprays as possible each year (typically five sprays from April through July but the number depends on both rain and temperatures during the growing season) provides the most sustainable way, in my opinion, to keep our vineyards and overall environment at optimal health over many decades. We do not use insecticides as part of our annual spray program. Our approach for controlling the few insects that harm grapevines at our property is to maintain a year-round cover crop for beneficial insects that eat the harmful insects and to not kill those beneficial insects through sulfur use, which is the main downside of mid-season sulfur dust.
What are the impacts we are seeing at our vineyards due to climate change? The main difference compared to 20 years ago is the frequency and intensity of summer heat waves. Where we are located at 2000' elevation, the afternoon temperatures during a heat wave is now typically in the upper 90s to low 100s, while it is between 110 and 120F in the surrounding valleys. Vines are not terribly affected by the occasional heat wave from May through July. But the stronger heat waves of August and September can do considerable damage to the ripening fruit. The damage is twofold: (1) grapes that are exposed to the sun during heat waves can shrivel, acquire skin damage and not ripen properly; and (2) at least in the surrounding valleys, the acidity in the grapes can drop as high temperatures climb into the 100s. A high-quality wine needs a sufficient level of organic acid (both tartaric and malic) in the grapes at harvest. Acidity in grapes peaks at veraison and steadily declines until harvest. It is generally thought that acidity goes down faster with increasing high temperatures but this is not quite true. Scientific studies have shown that the daily acidity drop is proportional to the difference in temperature between the high and low temperature each day. On our property, during an extreme heat wave when our high temperature is say 100 F, our low temperature might be 90 or 92 F. This daily "delta" in temperature, if anything, goes down for us during heat waves and we have no problem retaining acid during heat waves. This is a distinction between our mountaintop setting and the surrounding valleys where the daily "temperature delta" goes up during heat waves which drives the acid down. A defining signature of our wines compared to similarly ripe valley wines is that our wines have more acid and this is because our property has warm nights and cool afternoons and smaller daily temperature swings. As to the other concern of grapes becoming shriveled and damaged during heat waves in the ripening season, we use shade cloth for the grapes exposed to the hottest afternoon sun and allow our main shoots and laterals to flop out from the trellis wires, which provides more dappled sunlight on the clusters and less direct sunlight. So far, we are adapting well to climate change at least from a viticultural and wine-quality perspective.
A final topic where vineyard practice has an enormous influence on wine quality is in a grower's response to the arrival of viruses and other pathogens that reduce the quality of fruit at harvest. Let me tell you one such story as an example. Starting in 2012, we began observing reddish-purple blotches on some of the leaves in a couple of our blocks. These leaves were also distinctive in that they had veins that were red, something I had never seen before. In 2013, these symptoms, which only appeared after veraison, had spread to some other blocks and was a bit more pronounced in those blocks that had symptoms in 2012. My alarm bells went off and I systematically mapped each symptomatic vine in each block. There was a clear pattern where the symptoms were more pronounced on the margins of blocks that were in contact with other blocks showing symptoms or in contact with our surrounding chaparral. It was irrefutable to me that we had a new virus on the property that was being spread by an insect (or "vector") and I began reading all that was known. Fortunately, a handful of UC Davis professors and scientists, whom I later got to know and collaborate with, had just written a paper describing that the virus was being spread by an insect called a "three-cornered alfalfa hopper" (a particular type of "treehopper") and I caught some of those treehoppers in some of our blocks. The virus was called "red blotch" and over the last decade, it has become a big issue for high-end wineries throughout California, Oregon and Washington because the virus prevents wine grapes from ripening properly and is so widespread. A qPCR test for red blotch had just become available in 2013 and I confirmed through 100 or more such tests that the symptoms I was seeing was indeed due to the red-blotch virus.
Instead of waiting for advice that did not exist from those handful of scientists studying this virus, I began doing my own studies at our vineyards about how the virus spread via treehoppers, which taught me a lot and led to effective prevention strategies. But the single most important thing I did was to begin replanting in 2014 those vineyard blocks that had the highest concentration of symptomatic vines. I knew through my own calculations based on observations of the vector distribution across our property that the disease had been spreading for a number of years and that the spread was not extremely rapid because there were not a lot of treehoppers present. I continued to replant about 5 to 8 acres of blocks with significant red-blotch each year while waiting to learn more. If in a newly replanted block I found a symptomatic vine that tested positive for red blotch, I would remove it. My friends at UC Davis determined the lifecycle of this treehopper. It turned out that it loves to overwinter in most of the cover crops we were using at the time. Its favorite host is a plant called "purple vetch" that our property was loaded with at the time. So I changed our cover crops and removed the purple vetch from around the edges of the vineyards. The good news is that by replanting about 40 of our 85 acres in this way and taking away the habitat of this treehopper, there is essentially no red-blotch virus left on our property and almost no remaining three-cornered alfalfa hoppers. The vines from these replanted blocks are now reaching maturity and the fruit quality is terrific. So the disaster of watching the quality of wine from our 85 acres gradually go down over time was averted by being assertive in our response to red blotch.
That red blotch negatively affects wine quality is something I began to quantify in 2014 by harvesting our green healthy vines separately from the red vines in an infected block. Even if l let the red vines continue ripening up to the rainy season, the color, density and flavor of the wines made from the red vines was hugely inferior to that made from the green vines. We never used the wine from those separately-harvested red-blotch vines and this practice has had a huge benefit to our wine quality over the last decade as we went through the process of eliminating the red-blotch virus from our property.
Last, a final aspect of how farming influences wine quality and indeed our quality of life is how growers treat and respect their vineyard workers. Our seventeen full-time year-round vineyard workers put in 60-hour weeks throughout the seven to eight months of the growing and ripening season. They work incredibly hard and they never complain about it. On the rare occasion that I work a 10-hour day in the vineyards, I am exhausted. Without their dedicated professionalism, we simply would not be able to make high-quality wine. Just as you want to make the wisest decisions for how to take care of the land so that the local environment is as healthy as it can possibly be, so must you treat with respect and dignity these workers that are the backbone of any successful winery. As such, I have always paid our workers a living wage, roughly 30% more than other growers in our area, and I have always paid them overtime even though that was not required for farm workers until recently. I provide them with full medical and dental benefits, provide them with a matching 401k program to which most contribute, send them home with pay whenever temperatures rise above 95 F, give them a significant bonus after harvest and pay them when they are home with medical problems, such as when some people became sick during the Covid crisis. I know these workers feel cared about and, as a result, they give back to the vineyards, winery and wine quality through their careful hard work. We would not have a successful long-term business without them.
