171: How to Farm Wine Grapes for Climate Change

Amid extreme weather events, many grape growers ask themselves what they can do to adapt their vineyard for climate change. Chris Chen, Integrated Vineyard Systems Advisor in Sonoma, Mendocino, and Lake Counties at the University of California Cooperative Extension is exploring solutions to this question. Mediterranean climates like California, with hot and dry summers and cold wet winters, are particularly sensitive. Researchers expect temperature maximums will be higher and the minims will be lower in years to come. Chris explains a few tactics growers can use to continue farming successfully amid climate changes including rootstocks, canopy management, new scions, and most importantly trialing.


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Craig Macmillan  0:00 

My guest today is Chris Chen. He's integrated vineyard systems advisor for Sonoma Mendocino and Lake counties with the University of California Cooperative Extension. And I think we're gonna have a very interesting conversation today, Chris has done some pretty interesting work and some pretty interesting ideas. So welcome to the podcast, Chris.


Chris Chen  0:14 

Thanks, Craig. Appreciate it. Looking forward to it.


Craig Macmillan  0:16 

Doing a little bit of background on you. Would you say that there's a particular thread or what the thread is that runs through your research and extension work? Because it seems like there is one to me.


Chris Chen  0:25 

A lot of my work is focused on adaptation to climate change and vineyards. And it's something that goes back to when I was in grad school, you know, the, the whole climate change thing became really big and something to focus on when I entered grad school. And as I went through grad school, it became what I did. The thread here is kind of how do we adapt viticulture, to changing climates? How do we predict what a climate today is going to be in 510 years, the thread is to see how can we adapt to these changing conditions, and still keep viticulture, thriving and successful.


Craig Macmillan  0:57 

What is the prediction right now, in terms of let's start with California, but we can talk about the West Coast, we can also talk about New York, and we can talk about Europe. But you work in California, what is the current picture in terms of long term climate change that might affect grapes?


Unknown Speaker  1:15 

It's not really easy to say this will happen that will happen. But what we expect to see in California, it's a Mediterranean climate right now, these are very sensitive climate types, typically classified as regions with really hot, dry summers, cold, wet winters, right. And they're kind of fringe ecosystems, fringe climates. So they're on the border of, of an inland climate in a coastal climate, that means they're the most sensitive to climate change. So what we're expecting to see in California, and what a lot of researchers, climate researchers are planning on is, you know, increased temperatures, the maximums are going to be higher, the minimums are going to be lower, and those swings are going to be more drastic in between. So the diurnal temperature shift is going to be huge. You know, that is something that everyone kind of expects with climate change. It gets hotter, it gets colder, the extremes are more extreme, but what we're not really sure about is how precipitation is going to change. And in California, rainfall is such a huge thing. It's variable year to year, we have droughts for three years at a time and then one relief year, what we're really confused about is how is the rain pattern gonna change where we are today are we going to get the same rainfall and we're going to be able to support viticulture here anymore?


Craig Macmillan  2:33 

Now that brings up an interesting question. I'm going to bring up Andy Walker here, Dr. Andy Walker, the very famous plant breeder and I attended a seminar that he did on rootstocks, which he's done a ton of work and many rootstocks are out as a result of his lab. And he started off the whole thing by saying, you can dry farm winegrapes anywhere in the world. And the room just went silent, like I don't think anybody was breathing. And then he says, Now you might get two clusters, providing but the plant itself is going to do what it does. It's an amazing plant. It's incredible. And then he went on and talked about being in the Andes and seeing things in different parts of the world. And I found that really inspiring because when we talk about what we're doing right now, water, obviously is probably the biggest knob. If you have all these knobs, you can twist fertilizer, whatever water is probably the biggest one. Yeah, California, you have done some work with a number of people, but also with Kaan Kutural who I love on drought tolerance, drought resistance, I would say and what kinds of things? Are you finding out what you mean? Where is it kind of leading you? Where is it? What's kind of the thought process?


Chris Chen  3:38 

Andy, he was also my doctoral advisor. So I've heard his Spiel once or twice about dry farming. You know, you can do that can grow grapes in most almost all places without water there. There are grapes on islands that are irrigated with fog drip, so it's possible, but he's also right in saying that you're not going to get the yields that make you profitable. So that's concerning. And what we want to avoid, because we still need a certain tonnes per acre to reach profit margin that matters in terms of what can we do and how we're going for drought adaptation. There's the old approach of using rootstocks. And it's a very useful approach, right, these rootstocks from Andy Walker's perspective, and if you're looking at it from his lens, they have different rooting patterns. They have different water demands, and that translates to what we're growing on top. Whether it's Cab, Chardonnay, Sauvignon Blanc, whatever you want to grow on top of it, it's going to be impacted by what it's grafted to that is actually a very reasonable strategy to address drought that has its limits, you know, you still need water to grow grapes. Almost all grape vines in the wild, are only found near perennial water sources. So it's not like we can get rid of water altogether. We can't just leave them alone and expect to have any crop on them. But there's other things we can do. One of the huge management strategies that we can look at is canopy management. So canopy management in vineyards have really impacts how much water transpires and how much water evaporates from the surface of the soil. With a bigger canopy, you get less evaporation. But you also get more transpiration because there's more leaves, right. And vice versa. If you have a small canopy, you have the opposite problem that actually really impacts your fruit, your crop load, you know the quality of your fruit, the characteristics of the berries. So it's not something that everybody's going to play around with, because they want us to in the end, they want a certain kind of fruit with certain characteristics for their winery. But canopy management is a huge one as well, as rootstocks, there's also the interest in precision agriculture. So there is the spoon feeding approach where instead of irrigating large quantities at once, we can irrigate small portions at a time.


Craig Macmillan  5:43 

Irrigate strategicly. I mean, I've seen some pretty interesting work from the past where it was like a 10, Vine irrigation block. And you were able to control this and that little bit in that little bit. And you could use NDVI to figure out where you want to do it. Interesting work. I'd never was convinced how practical that might be for most growers, especially if you're retrofitting their orchards.


Chris Chen  6:05 

In Australia that irrigate on a tree to tree basis. So it's very doable. You know, the question is, how much water would you actually save doing that? And how much energy are you using to pump that every time?


Craig Macmillan  6:18 

Exactly. Now, we're talking about rootstocks rootstock breeding back in the day, 100 years ago, or whenever it was all about phylloxera. And it was about salt. I know that Dr. Walker has done a lot of work on salt resistance. n=Nematode resistance is turned out to be a big one. If I remember that's the GRM series are specifically for nematode. Is that right?


Chris Chen  6:38 

Correct. Yes. Those are anti Walker's.


Craig Macmillan  6:40 

Crowning achievements. Brilliant stuff. You know, we're talking about genetic differences and rootstocks that have been bred for different conditions, including things like drought tolerance. What about what's on top, you make a point one of your articles that the landscape of wine growing is dominated by Cabernet Sauvignon and Chardonnay, which means we have a very limited genome, essentially, of what's above ground. And we've learned from other crops that might not be such a great idea. We're talking about maybe trying to rootstock our way out of some of this. Can we variety, some of our way out of this.


Chris Chen  7:11 

So the short answer to that is yes. The long answer is a bit more complex. You know, overall, all of the scions we put on are all one species Vitus vinifera, there's a few others like Vitesse labrusca, which is Concorde. And there's a there's a couple others that we use, but the majority of what we consider winegrapes is Vitus vinifera. So the genetic differences in the scions are not huge. The real differences are in the phenotyping. Right, you look at a Cabernet Sauvignon vine. And you compare that to a Tempranillo or Zinfandel, you'll see that the latter, they actually have quite larger canopies, even though they're the same species. The weird thing is they're more heat tolerant. Part of that might be their transpiration and might be for several reasons, these small changes in how they look change how they interact with their environment. So the real concern in you know, changing the scions from place to place site to site is that some places actually have latched on to a variety or two. If you think about Napa Napa, you think Chardonnay and Cabernet Sauvignon, where I work in the north coast, it's Pinot Noir, a little bit of Chardonnay, some Sauvignon Blanc and Lake County, right? It's very possible to say, you know, if we have a one, one site that increases temperatures by, you know, temperature accumulation by 20%, in 10 years, it might behoove them to go from a cold climate grapes like Pinot Noir and switch over to something like Zinfandel. The problem is, well, the market that purchases their wine actually still keep buying their wines. If they go to Zinfandel, it would be a smart move. If you're thinking about, you know, the physiology of the plant of the difficulty of managing the vineyard, all the extra things you have to do if you want to stick with that cold climate grew up in a hot climate, not to say that people don't do that we do have Pinot Noir grown in San Joaquin Valley, for instance, just not as much as up here. So it's possible one of the problems is actually picking those varieties, picking the right varieties because just because it gets hotter here doesn't mean you know, Santa Rosa has the same climate as Bakersfield. There's differences in humidity and light incidents. There's differences in just cultural practices, what people do to manage the soils what they do for fertilizing. So overall, yeah, it's possible but there's other barriers besides just switching the plant.


Craig Macmillan  9:29 

It sounds like some of those barriers are the ability to make accurate predictions about what might happen if I'm planting Zinfandel in an area where it's never really had Zinfandel. I don't know exactly what's gonna go on. But then also it sounds like acceptance of the marketplace is gonna play a big role. That's that's a different conversation. Unless you have a feeling about it. I think part of what goes on is we do have information from the marketplace. We do have research, but a lot of what goes on here is growers themselves as individuals are making decisions out what's gonna happen? Right? It's not necessarily that we're getting handed down this necessarily the trend, but like, I think this is where we're gonna go. When you talk to people about this kind of thing. What kind of response do you get from growers?


Chris Chen  10:10 

Yeah, you know, it depends. There are growers that are all about trying new cultivars, and they usually inhabit kind of niche markets, a lot of these growers will grow varieties that are useful for blending. So if you need some more color, if you need some more acids, they'll grow these varieties that impart that to wines that otherwise wouldn't have them. And you know, there's only so much of a market for that. I think there's also growers on the other side where they say, Well, no, in order for us to make our ends meet, we have to stick with so and so variety, we have to stay with Pinot Noir because our entire consumer base wants it. And you know, there's trends in viticulture in California as a whole that have followed these, you know, this chain of events Muscats Muscats, used to be very popular along with making a rose out of Zinfandel. Riesling was another one, people planted a bunch of these things, and then the consumer market dropped out. And they were stuck with fines that take, you know, five years to hit any kind of good crop. And within those five years, it fell out of favor. So they're selling their grapes for pennies, compared to what they would have been if had they had them at the peak of the popularity, we can't change our varieties just based on popularity, and we can't keep them just based on popularity. But there are these constants right 40% of the grapes planted in California are Cabernet Sauvignon Chardonnay, which is not a bad thing. It just means that people want it.


Craig Macmillan  11:31 

use the term asynchronous or asynchrony, and viticulture. What What do you mean when you refer to that?


Chris Chen  11:37 

so that's a term that I thought would be very applicable to the situation. So vineyards as a whole run on a schedule, they run on timing, and part of that is their biological timing, right? So their biological timing is based off of heat accumulation. So the hotter it is for the longer the quicker we have budbreak, the quicker we have chute growth and fruit set, and so on. So that as the climates are changing, and we know we're going to see higher temperatures in some places, then we're seeing a shift in that timing. And a shift in that timing changes a lot of things, it changes how the plants interact with insects and pests and beneficial insects, because they're also changing their timing, we're seeing, you know, some insect pests are increasing their generations. So they instead of two generations a year, they'll have three in some really hot places, for instance. But also these these beneficial insects that control the pests are switching their timing of hatching and switching their timing of maturity. And we're seeing that more and more, and we're afraid we're gonna start seeing that in agriculture relatively soon. So what all of that together means is that when you look at a vineyard, the events that you would have had for the past 100 years are not happening at the same times as they would have been in the next 10 years than they did previously. And that's a challenge actually, for you know, management as well, because labor resources are, especially in agriculture are often you know, made more available during timeframes where they're needed. And if that timeframe changes, there's gonna be a year or two where that's a problem.


Craig Macmillan  13:09 

If we don't change anything, let's say we don't change varieties, we don't change the root stocks or anything, I'll get vineyards that are 10 years old now and hopefully get another decade or two out of it, or I'm making decisions 20 years from now for a variety like Cabernet Sauvignon you're in and we will talk about Pinot Noir as well that I think that's an important one. But I want to start with Cab, in your experience, let's say things get warmer and colder. And then we don't know what's going to happen with weather. So let's just leave rainfall out of it for now. But just the swings in the higher the highs and lower lows, what impact do you think that's gonna have on wine quality or yield? How are these things going to change? Do you think as a viticulturalist?


Chris Chen  13:45 

Especially wine grapes really need that big swing in temperature, so they need that diurnal shift that's really hot summer days and really cold summer nights. That really helps them develop their flavonol profiles, their tannins, their anthocyanins, anthocyanins more so about, light, you know, incidents light exposure, but that's beside the point. So it's actually kind of a good thing. The problem is when we hit these limits, right? So when we hit these limits of it's too hot. So now instead of accumulation of these compounds, what we're seeing is a degradation of them. So they're accumulating in the grapes faster throughout the year. So again, this is that asynchrony, right. So as you get closer toward the traditional historic harvest time, you think, okay, these grapes are still accumulating their tannins, or they're still accumulating their flavonols or their their anthocyanins are not degrading it. But what we're seeing is that increase in the growing degree days or heat accumulation is actually decreasing the amount of stable compounds in the grape that we want. So we're seeing especially with color, we're seeing a degradation in color. anthocyanins are degrading, much sooner and to higher degrees in these really hot summers, especially when We have these heat waves that we had last year. These heat waves are terrible for these things. But we don't know which varieties are going to be tolerant to this and can can withstand these changes in extremes. So the increases in high temperatures, the decreases in low temperatures, the low temperatures aren't really a problem unless we get freezing temperatures which we shouldn't in summer, but it's not impossible.


Craig Macmillan  15:23 

Not impossible could happen. What about Pinot Noir, famously very sensitive, very narrow range that it likes. Right. I got you on the spot here.


Chris Chen  15:32 

Yeah, I can't speak to that too much. Because all of the trials that I've done and I've seen have been with Cabernet Sauvignon, one of the most popular red varieties in the world, I can't say that it's more or less sensitive to these changes Pinot Noir. But based on its classification, as a region, one region two cold climate grape, it's likely to be more sensitive to these extreme highs in summer and degrade faster. We do know that Pinot Noir ripens sooner than Cabernet Sauvignon does, on average, you know, put them in the same spot and your Pinot is going to be done. I don't know spitballing number here two weeks before the Cabernet is so you harvest the two weeks ahead of time. That means if you're harvesting it at the same time as Cabernet, you're getting more degradation in those anthocyanin. So that would be the theory behind why Pinot Noir might be more affected by these high temperatures. But I don't have anything to cite for you at the moment.


Craig Macmillan  16:25 

Sure, sure. But I think that your insight there is useful in that. Okay, maybe we don't know what's gonna happen. We can kind of guess at some things that might happen. But if we know kind of where things might end up, or how the vine might repond, I might change my winemaking, I might change my canopy management style, right? I knew a guy who was an old school farmer, and he refused to put in drip irrigation even in new vineyards. And I asked him about it. And he said salts, that's the way to go. That's it only way to do it. And I was like, well, that's 1974 It's not 1974 anymore. And he goes looks listen in the middle of a day, it's 105 I can turn on those sprinklers. And I can cool that canopy and I can avoid stress. I said we're gonna overwater, you're gonna do it, because you just gotta know what you're doing son, like just, I can put it out there. And I can manage this a more effective tool for me. I watched him over the years and saw what he did. He had it really dialed in. But he had a totally different approach to what tool he wanted to use to deal with whatever the environmental condition was. And I thought that was really interesting and very clever. Are there things that we can learn from other parts of the world? Because obviously, there's differences in climate different places to Australia, you know, very different interestes and very warm areas there, if I understand correctly, are we gaining knowledge, we gained some guidance from other parts of the world on this topic?


Chris Chen  17:42 

If we're not we should be there's this popular topic that England United Kingdom can grow grapes now, and they can grow good grapes now. And that's new. That never used to be the case. And you know the story of I don't know if this is true. But the story of why Brut champagne or Brut sparkling wines called Brut is because the French made it for the English and they didn't like them. No, I mean, we do have things to learn. Yeah, we do have things to learn from other people, especially places that are really hot. South Africa, Australia, these, you know, these locations are, a lot of them are dealing with conditions that, you know, we see here as well, but they're dealing with it on a much larger scale. So we see, you know, really hot temperatures in the San Joaquin Valley, Sacramento Valley. But we grow grapes there. And we're good at it. You know, in Australia, that's a huge swath of land that's in those kinds of conditions. But then the one where it gets really sensitive is when we get to the coast when we get to colder climates, like where I work where I operate. So it's going to be, you know, the coastal regions that really are impacted more, because they don't have the infrastructure, they don't have the cultivars to really tolerate that heat. And what we need to do is look at places that are experiencing this change before we're experiencing it. And often these are Mediterranean climates, also, right, New Zealand, Australia, South America, Chile, and see what they're doing, see how they're adapting to it and what cultivars they're planting. You know, I'm not saying that all of Mendocino County should be planting Sheraz or Sahra. But you know, it might be good for some growers to try it out and see what's going on. I've been advocating for a lot of growers that, you know, if you're replanting, and vineyard, plant a few other cultivars somewhere and just see how they do, you know, it's not really great for if you're harvesting with the machine, because you end up knocking those into the same bin as all the other grapes. But if you could, you know, find an area where it's isolated and far enough away that you're not going to mix them up might be good to plant five, five to 10 vines of something else and see how it does because each each region is going to be different. Each region is going to have to have a different response because climate change is very regional.


Craig Macmillan  19:53 

But the good news is that we are pretty clever. As an industry we've come up with all kinds of solutions to all kinds of problems over the years. without the folks like you have made that possible. We're running out of time. But I want to ask you one very simple and very short question. And that is based on everything that we've kind of talked about what one piece of advice or what one takeaway would you give a grape grower?


Chris Chen  20:16 

I would say the most important thing is to do really good monitoring practices to really get out there and see how your vines are changing, and how your site is changing. You can you can try new cultivars, you can try, you know, different root stocks, you can try different canopy management practices. But if you don't keep track of how things are changing in response to that, then there's no point, right? There's a lot of really good tools out there. There's a lot of new things coming out that you can you can, you know, remotely sense and identify diseases, changes in stomatal conductance in different physiological measurements that are really important to developing a grapevine. Just look at these new monitoring solutions. Be wary of ones that may or may not work, you know, don't don't put all of your your eggs in one basket, that kind of thing. But get out there and monitor.


Craig Macmillan  21:06 

I think that's great advice. And I think that applies to a lot of things. Where can people find out more about you?


Chris Chen  21:10 

I have a website. If you go to Google, and you type in UC AND Chris Chen, it should bring up my bio, and there's a link to my lab page there, has a bunch of resources has a bunch of links and papers. And I think you know, especially if you're in the North Coast region and the counties I work in, you can just give me a call. You know, most people can just call me anyways, I work for University of California. So it's, you know, quasi public domain. Yeah, please feel free to reach out.


Craig Macmillan  21:38 

Fantastic. So our guest today has been Chris Chen. He's an integrated vineyard systems advisor for Sonoma, Mendocino and Lake counties with the University of California Cooperative Extension. Thanks for being on the podcast. Chris. This is really fun.


Chris Chen  21:50 

Thanks for having me. Craig. Enjoyed it.


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