281: How Rootstock Impacts Vine Drought Tolerance and Longevity

Originally developed to combat phylloxera, rootstocks are now being researched as a solution to one of viticulture’s challenges: drought. Dr. Suraj Kar, Assistant Professor of Viticulture at Cal Poly San Luis Obispo, explores the 150-year history of rootstocks and their evolving purpose. He explains the complex influence rootstocks have on drought tolerance, vine vigor, and fruit set—and how long-term research is identifying those best suited to support vine longevity in a changing climate.

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Transcript

[00:00:04] Beth Vukmanic: originally used to combat phylloxera root stocks are now being researched as a solution to one of viticulture's latest challenges, drought.

[00:00:13] Welcome to Sustainable Wine Growing with Vineyard Team, where we bring you the latest in science and research for the wine industry. I'm Beth Vukmanic, executive director

[00:00:22] In today's podcast, Craig Macmillan critical resource manager at Niner Wine Estates with longtime SIP certified vineyard in the first ever SIP certified winery speaks with Suraj Kar, assistant Professor a viticulture at Cal Poly San Luis Obispo.

[00:00:40] He explores the 150 year history of root stocks and their evolving purpose. He explains the complex influence root stocks have on drought tolerance, vine vigor, and fruit set, and how long-term research is identifying those best suited to support vine longevity in a challenging climate.

[00:00:59] Are you looking for more about the latest viticulture and technology from the world's top experts? Then you won't wanna miss our Sustainable Ag Expo where we bring together researchers and growers so you can earn continuing education hours and improve your business all while connecting with peers and agricultural companies. It all takes place. November 10th through 12th 2025 at the Madonna Inn Expo Center in San Luis Obispo, California. As a listener to this podcast, take $25 off of your ticket when you use Code Podcast 25 at checkout. Get registered today at sustainableagexpo.org.

[00:01:37] Now, let's listen in.

[00:01:42] Craig Macmillan: Our guest today is Suraj Kar. He is assistant professor in the Department of Wine and Viticulture at Cal Poly San Luis Obispo. And today we're gonna talk about drought resistant root stocks. Thanks for being on the podcast.

[00:01:55] Suraj Kar: Thank you, Craig. I have been a fan of this podcast for the last two and a half years, so it's a great honor.

[00:02:02] Craig Macmillan: That's awesome. Yes. Well, it's an honor to have you on here. You're doing some really interesting stuff. So let's just get right into it. We're talking about drought tolerance with root stocks. What is the key physiological mechanisms that certain root stocks have that make them more drought tolerant than others?

[00:02:18] Suraj Kar: Yeah. , So before we get into that, like for your, , listeners, we should probably give some introduction to why, you know, we use Rootstocks in the first place,

[00:02:28] Craig Macmillan: Perfect.

[00:02:29] Suraj Kar: You know, root stocks, they have been around for like 150 years. They have been developed in the late 1800s, principally because of phylloxera.

[00:02:39] So phylloxera was this, , root born afid that was quite devastating during that time for both American as well as French wine industry. Only the American root stocks that were developed at that time. They saved, most of the wine industry, you know, in both continents. at that time, these three, uh, species of Native American grapevines that were used and their hybrids that were used as rootstocks, these species were Vitis riparia, Vitis Rupestris and Vitis berlandieri.

[00:03:13] So their hybrids and their hybrids with, uh, vivera, which is quality wine grapes and table grapes that we, we use. And these species, they have co-evolved with phylloxera Phylloxera. They're native to North America, so they have co-evolved with phylloxera. So they show some degree of resistance or tolerance against phylloxera.

[00:03:36] So since they have been used as root stocks, they were more resistant or tolerant against phylloxera. So like you can see, you know, most of the root stocks that we are using. Currently they were not developed for drought tolerance, like keeping drought tolerance in mind. So they were developed for phylloxera tolerance.

[00:04:00] So now, because you know you have the root stock and root stock, it is determining all the soil related traits of the vine. So drought becomes a very obvious like trait that you should look and select for. So this is why there is now a lot of interest being, you know, lot of emphasis is being paid for selection of drought tolerance, root stocks. yeah. Now if you think about the physiological mechanisms by which, you know root stocks sort of can influence drought tolerance of a fine, some of the obvious ones are, you know, higher root volume. More surface contact, more access to water and nutrient. So those are pretty obvious. , They influence water uptake.

[00:04:46] You know, they also have some indirect influence on the vines as well. Like roots. They synthesize different hormones. They also synthesize different signaling compounds that go throughout the vine and can tell the vine like what type of drought that the the vine is sort of experiencing.

[00:05:05] One of those I think, has been researched quite a lot. Abic acid. That is synthesized in the roots. And abic acid is a signaling molecule that tells stroma, when to close. So if there is more abic acid in stroma the stroma would close and the vine would stop transpiring water out of the, of the vine.

[00:05:25] So there are certain root stocks that synthesize more abic acid, some that synthesize less abic acid. So, so one example is the one of the M series root stocks M four that produces less abic acid under drought conditions. Because of that, the stroma can remain open for longer period of time so the vine can extract more water even when, you know, there is like depleting water in the soil. They can still extract water, they can still go on with photosynthesis. So M Series root strokes are considered as drought tolerant.

[00:06:01] Craig Macmillan: So having stomata open for longer is beneficial because there's having the EVA transpiration, which is pulling water from the soil, the rest of the plant up into the plant, as opposed to having it just shut down. Is that the idea?

[00:06:12] Suraj Kar: Yes, so that's a very good question because now that, you know, begs the question, what do you mean by drought tolerance, right? Because, for a grower it would , make more sense if a, if a vine can maintain photosynthesis, maintains stroma activity and produce a larger crop, like more vegetative growth, larger crop, and.

[00:06:33] Yeah, that would mean the vines are, uh, vines are more drought tolerant. But then from a physiological standpoint, if a vine can conserve more water that would, you know, make the vine less susceptible to like cavitation damage. It can go on longer under, you know, depleting moisture stress, depleting water stress.

[00:06:52] So, yeah, it's, it's kind of a complicated question. I, I would say that, what do you mean by drought tolerance?

[00:06:59] Craig Macmillan: So you mentioned ab cystic acid. That's obviously, obviously an important one. What are some other signaling compounds or hormones that are involved in this? The communication between the rootstock and the scion.

[00:07:11] Suraj Kar: So Abic acid is the main one. , Aquaporin, they also play some important role. . Also like xylem Suberization is another important aspect, physiological aspect. Some drought sensitive root stocks, they tend to, um, Suberization their xylem like pretty quickly compared to, , some of the drought tolerant ones.

[00:07:32] So these are some of the mechanisms, you know, that are involved with drought tolerance.

[00:07:38] Craig Macmillan: Just real, real quick, what is , Suberization.

[00:07:41] Suraj Kar: I believe Suberin is a lipid-based molecule, , in the xylem vessels. If there is more suberin deposition, that means there is more resistance for water movement within the Xylem vessels. It's harder for the vines to like translocate water from the, from the roots to the above round part.

[00:07:59] Craig Macmillan: All right, good. Thank you. , How do you go about doing this work? How do you go about comparing things? And I'm really interested in the actual, like, the setup, literally, how do you do this kind of research?

[00:08:11] Suraj Kar: Yeah, that's, that's interesting. So my research here at Cal Poly, I just began, , this is my first growing season. Here at Cal Poly, but before this I was doing research in, , Alec Levin's lab in Oregon State, there we were testing 10 different root stocks, two different scions under, you know, drought and well watered conditions.

[00:08:34] So there are many things we are looking for. Of course, the physiology part is very important for us because we are a group of physiologists, so we have been. You know, monitoring physio, phenology, we have been monitoring physiology like gas exchange, photosynthesis, , stromal conductance you know, stem water potential. And interestingly we were also collecting , tissue samples for carbon 13 analysis.

[00:08:59] So these are some of the things that we were looking for and we were comparing between different root stocks and scions. So I'm doing similar things here at Cal Poly as well.

[00:09:08] Some of the interesting things that we found, like in some of the initial results that we got, , from the, uh, Oregon study, that under even well watered conditions, we have seen quite a degree of variability between rootstock behavior under the same scion. we have seen some root stocks. They can how to say that like. they induce earlier, verasion on than later. Some, some induce later varies on. So there is a significant effect on verasion on dates that we have found. We have also seen quite, uh, a range of, , variability between, , strm conductance values, stem order potential values.

[00:09:49] Also the amount of fruit that they produce. The quality of the fruit quality, I would say is not that strongly correlated, but, the amount of fruit that yield was one of the more strongly influenced like variables that we found in that study. And that is under well watered conditions. So the idea was that since we have this you know, high variability between different root stocks, , we can capitalize on this, like this variability and. The hypothesis is that under drought stress conditions, , this variability would even be, even be larger. So the the traits sort of that, that would be interesting for us to determine which root stocks are, to find out which root stocks are, , drought tolerant would be accentuated under, , under drought conditions.

[00:10:43] That was the idea. And I'm pretty much continuing that in at Cal Poly.

[00:10:48] Craig Macmillan: And were you doing this in the field? Were you doing with potted wine in a greenhouse?

[00:10:52] Suraj Kar: No, these are all field experiments.

[00:10:54] Craig Macmillan: All fuel experiments. Okay, fantastic. What root stocks and what signs did you work with?

[00:10:59] Suraj Kar: So at Cal Poly I'm working with six different root stocks. These are 16, 16 C one 10 one 10 R, 1 0 1, 14 4 20 A five C and 1103 yeah, some of the very common, you know, root stocks that you find in this area in Oregon, we, , we did 10 root stocks, so all of those, and plus we had sg, rg, and I think we had SO four.

[00:11:29] Craig Macmillan: Okay. What were the scions you were working with?

[00:11:32] Suraj Kar: Oh yeah. So in Oregon we, we worked with Pinot Noir and Cabernet Sauvignon.

[00:11:37] Craig Macmillan: We've touched on this a little bit, but I would like to know more about the influence of the rootstock on the scion. You said there's fruit, there's water efficiency.

[00:11:46] can you really get into the detail of, of what happens with that scion? You get certain signals and then it does different. Things, I guess is what I'm asking.

[00:11:58] Suraj Kar: So root stock's influence on Scion is a complex concept. the direct impact of a root stock on Scion is of course the water and nutrient absorption. And by that it is influencing the vigor of the Scion, um, and the fruit quality and wine quality that comes, you know, later That is like a indirect impact of root stock.

[00:12:22] So since grapevines are perineal plants, rootstocks impact on grapevines or the interaction of rootstock and drought on grapevines is not like a short term sort of an impact. It's like a long-term impact. If, if the vine is going through drought this season, it's not only affecting the vine this season, but it is also impacting the vine in constitutive seasons to come.

[00:12:46] So, the rootstocks effect on Scion, it's like somewhat negating that effect of drought. So it is influencing the vine long term, like over multiple growing seasons. One of my goals with this experiment that I'm doing at Cal Poly is like, do this experiment for like 10 years, 15 years, and see what we find.

[00:13:08] Like not only that. We are, we are comparing between like different levels of drought, but also the time is a factor there as well. So like if this influence of drought and the effect of, you know, root stocks on mitigating the effects of drought, if that can sustain long-term, which of these root stocks would be effective long-term in like mitigating the stress, the drought stress.

[00:13:36] Craig Macmillan: My experience has been that when you have a repeated drought situation, and I had one of these where the, the buyer did not want irrigation on his block. That was selling grapes too. It becomes this downward spiral and the vines just get weaker and weaker year after year,

[00:13:51] Suraj Kar: Mm-hmm.

[00:13:52] Craig Macmillan: there's less crop year after year after year. Is that a fair assessment?

[00:13:57] Suraj Kar: Absolutely. Yeah. So, you know, like I was saying, grapevines are perineal plants. So they have an annual growth cycle, but they are a perineal plant. So if a grapevine is going through drought, let's say in one season, that means it's producing less vegetative growth in that season. Less vegetative growth would mean less green area, green surface area, leaf area.

[00:14:19] Less leaf area means it would produce less photosynthesis for that season. Less photosynthesis would mean it would have the capability of ripening less amount of fruit, as well as sending less amount of carbohydrate in its storage if it sends less amount of carbohydrate in its storage.

[00:14:38] When it comes back next growing season, it has less amount of storage to grow from. So that means it would produce even less shoots in the next growing season. I mean, I'm generalizing here, but that is the common trend. Like if you are having perennial drought, like every year you are having drought, the vine would have less and less vegetative growth, less and less fruit, and the fruit quality would go down as well.

[00:15:03] And that is the reason.

[00:15:04] Craig Macmillan: Yeah, that's my opinion from experience. We've had a lot of people on the, the podcast talking about soil microbiota, the, the life and the soil. And one thing that keeps coming up is our muscular microrisal fungi do they play a role in this? Are there some stocks that seem to be more friendly to

[00:15:24] Suraj Kar: Yeah, so I'm not an expert on this because I have not done research on microrisal fungi, but what I can tell you that there had been certain, some work done on this. And of course, you know, some things are quite obvious that Microrisal fungi, they increase the root surface area. So that means they make the. Grapevine root access, a lot more water and nutrients. So in that way Microrisal fungi can help grapevine mitigate some of the drought impacts.

[00:15:57] Craig Macmillan: And another related thing I think is water quality. So we're talking about basically inputs to the roots and then what they do with it. I think that probably in areas that are experiencing severe dry, we probably will see higher salt content in those waters. What role does that play and are there root stocks that have better salt tolerance? And that helps also with drought resistance.

[00:16:18] Suraj Kar: Yeah. Salinity, of course, they exist a bit. The problem, they make drought problems worse because, you know, if, the water has high ute concentration. That would mean the, the water would have more negative osmotic potential and the vine would have to work harder. The vine roots would have to work harder to extract that, that water from the soil.

[00:16:40] And in some cases, if the salt concentration is too high, like higher than what the root, the root cells have. So that means water would come out of the root rather than going into the root. in that way, um, water quality influences, how much drought the vine is experiencing.

[00:16:57] So there are some very strong well, I, I don't know if they're strong because I have not done research on them, but there are some C series root stocks developed in Australia, like C 20 C 113, C 114.

[00:17:12] These are fairly salt tolerant. And they have I think they're derived from Champinii. So rupestris, riparia, they have some scenario, they have some berlandieri in their ancestry. So these also play a role in like their, their soil tolerance.

[00:17:30] Craig Macmillan: Another issue here is the timing. Because there's definitely a philosophy that vines should be somewhat drought stressed at different times of year. And I'm wondering, so this is controlled drought stress. This would be me turning off the irrigation. And what I have seen is vines that were under watered early and they were fine, and then they get to full canopy later in the summer and they just collapse.

[00:17:56] If I have the ability to control it? How does the timing of of drought stress affect what happens on the top of if.

[00:18:04] Suraj Kar: Generally earlier in the season, the vines are more susceptible to drought because they're actively growing. Shoot growth rate is very high earlier in the growing season. We see like reduction in vegetative growth. So that is why you use, you know, RDFA regulated deficit litigation to control some of the vegetative growth early in the season.

[00:18:26] Um, severe drought. Yeah, like early in the season can impact, , fruit set berry size. But later in the season, grapevines tend to be more, resistant against, um, drought stress. So you can have even like with. Moderate degree of stress. Later in the season, you can actually improve the quality of fruit.

[00:18:47] We have done some research on that. we have submitted a paper. It should come out pretty soon, that post verasion on water stress, moderate amount of water stress post variation. Increases the phenolic concentration in red grapes. Later in the season, it probably is helpful.

[00:19:03] Earlier in the season, it's probably not as helpful. It's probably more you know harmful for the vine. Earlier in the season,

[00:19:10] Craig Macmillan: That makes a lot of sense. So let's say I have a drought year and I'm not able to put on as much water as I might like and I'm worried about it. Can I rescue vines? If I can give them water the following year? Can I turn this process around? Basically.

[00:19:25] Suraj Kar: Ah, that's interesting. Well, like I was saying, you know, One season's worth of drought, depending, of course, the extent and, , the duration of that drought would have some impact next year. Especially fruit set vegetative growth. But if the drought is not. How to say, um, not acute. Like it's not a severe drought in one season, , it would probably not influence next year's growth too much.

[00:19:54] But of course next year with better management, you can recover part of that the impact after drought.

[00:20:01] Craig Macmillan: You've mentioned a number of root stocks that I personally have never heard of. Can you tell us a little bit more about like these Australian ones, the Cs series, I think you mentioned. And a couple of others that you mentioned earlier. I'm, I'm old school, so I know one 110R and I know 3309. But tell me more about these new ones.

[00:20:19] Suraj Kar: I also have very limited understanding of these root stocks. I have not done research on them. I have read about these root stocks. They're of course, newly developed root stocks. They have been, they have been mentioned in a few papers that I have read. I have not done research on them.

[00:20:34] There are some root stocks that were newly developed root stocks that were developed in the United States, like the GRN Series, root stocks. Those are focused on nematode resistance some RS Series root stocks. Some USD has developed some, some of those root stocks as well that are resistant against, against nematodes.

[00:20:53] So these are some of the newer root stocks that are developed that I have not had a chance to, you know, really do research on. We have some GRN series root stocks here at Cal Poly, and going forward I would like to do some research on them, but right now, yeah, I have very limited understanding of those as well.

[00:21:10] Craig Macmillan: So are some of these root stocks, are they available in the US yet? Have they gone through foundation plant services?

[00:21:17] Suraj Kar: I am not sure. Yeah,

[00:21:20] Craig Macmillan: Neither am I, but I'm gonna look, I gotta tell you, I'm super curious about this now,

[00:21:27] Suraj Kar: Uhhuh.

[00:21:27] Craig Macmillan: Again, getting into detail how did you set it up in the field? I assume you had, you got mature plants, and then I assume that they're on drip, and then you must have a different irrigation schedule for each treatment.

[00:21:40] Suraj Kar: Right.

[00:21:41] Craig Macmillan: So tell me more about that, how you set it up, what the treatments were, et cetera.

[00:21:45] Suraj Kar: Yeah. So the way that experiment is, the experiment was designed here at Cal Poly. We have. Okay, so let's talk about just one block. So if we have one block, the one block consists of three grapevine rows. And these three grapevine rows have six root stalks, like along the row.

[00:22:05] So there are 10 vines along the row. Six, six roof trucks, or 60 total vines along the row. And this pattern is repeated. Along those three rows that, that consist of one block. And of course, you know, each row has its own irrigation system. Irrigation line. So we can just turn that irrigation line on or off. Based on when we want to irrigate them and, you know, that would determine our, our irrigation and drought treatment.

[00:22:33] So right now what I'm testing is a short term deficit earlier in the season. So the vines are not getting any water until bloom, and then they're getting water post bloom. And then another one I'm testing is slightly longer. The vines are not getting water until veraison and then getting.

[00:22:52] Getting water post very soon. And then we have a control to compare them with, which is like the vines are getting water throughout the whole season. So, yeah, this is how, you know the, the experiment is laid currently.

[00:23:05] Craig Macmillan: I know that you're in the middle of this project and have been for several years. Do you have any preliminary findings as to what rootstocks seem to be better suited for tolerating drought than others?

[00:23:18] Suraj Kar: Yeah, so right now I really don't have an answer for you on that. Like, which root stocks would do better, which root stocks would not do better. There are of course general recommendations like under drought. There are, you know, 1103 P one 10 R, one 40 RU. These are like, you know, go to root stocks. Under drought conditions.

[00:23:37] But then again what do you mean by drought? Drought tolerance. Like do you want the vine to survive for a longer period of time with maybe producing lower fruit or do you want the vine to produce a lot of fruit and then risk, it risk more embolism depending on what the extent of drought stress is.

[00:23:54] Interesting thing would be that would come out of this research, I, I hope would be, you know, the impact of long-term drought, long-term, you know, deficit irrigation on these root stocks. And root stock research, from what I have read is extremely localized. So you have to test out root stocks in certain regions, like your vineyard might be, behaving in a different way or be behaving in a way that is not representative of what the literature says or what I say from my own research. So it would be best to like test out certain root stocks in specific vineyards under certain soil conditions, certain, you know environmental conditions.

[00:24:34] Craig Macmillan: That's an interesting question. So, as far as vineyard development goes, could I plant some test plants, like a, a little mini block of different root stocks, just the root stock and see how they perform? Or do I need to have a sign on top?

[00:24:47] Suraj Kar: That's a very good question. I mean at Cal Poly we have a dedicated root stock block where we have these, like dozens of root stocks that we have planted, and they are trained as full vines. So, I am gathering quite a bit of data on those root stocks. How they behave as vines, like fully grown vines.

[00:25:06] So I don't know how important or interesting that would be, like when we select for, select them as root stocks. But then of course, I would suggest any grower like to do a planting, like a small block of like multiple root stocks. Maybe plant a few scions on top, like the scions that you would. Generally grow in your vineyard and test like which rootstocks perform well.

[00:25:29] Craig Macmillan: That is fascinating. I think that'd be very interesting to do. I didn't realize how, local, these conditions were. And that has to do with soil type, I'm imagining?

[00:25:37] Suraj Kar: Mm-hmm. Yeah.

[00:25:38] Craig Macmillan: Yeah.

[00:25:39] What environmental factors are gonna also impact drought resist or drought tolerance? Because I'm thinking, you know, if I have control of how much water I put on, I can manipulate this somewhat. But are there other things like high heat, wind or cold? Are there other ambiotic factors that might affect this?

[00:25:58] Suraj Kar: Yeah. Yeah. Most important would be the soil related factors, like, you know, the depth of the soil, the soil structure. Texture, the water level, if there is an impervious layer underneath or something. Some root stocks tend to, you know, Produce roots that are more spread out horizontally rather than deep rooted.

[00:26:17] One example I can give you generally riparia area derived root stocks. They send roots more horizontally and then rupestris derived root stocks, they're more deep rooted. They tend to be more deep rooted. So yeah, I mean, depending on the, so soil conditions, you know you would see. Uh, quite variable, like rooting patterns, uh, from these root stocks above ground factors like you know, anything that influences the, uh, transportation of the roots, uh, transportation of the scion, that means water is being lost.

[00:26:51] Roots need to absorb a lot more water. Would influence, you know the behavior of like. How much the rootstock can extract from the soil. but yeah, soil factors I would say are more important in terms of like how rootstocks influence a Scion.

[00:27:05] Craig Macmillan: As far as root architecture goes, I would imagine that we want deeper, straighter, more narrow angles than something that's gonna be shallow and spread out. Is that true?

[00:27:16] Suraj Kar: Yeah. In terms of drought tolerance, yes. But if you are growing, vines in a very shallow soil like conditions, then you, you probably don't want your root stocks to be sending more root downwards because that would mean they would have very small root volume and most, you know, irrigated vineyards We see. High density of roots, like on the surface soil rather than deep in, in the soil. So yeah, I think again, it would depend on the specific site.

[00:27:50] Craig Macmillan: Is there one thing that you would tell growers on this topic? Is there one takeaway message that you would give people?

[00:27:57] Suraj Kar: So, if you are interested in selecting suitable root stock for your vineyard, I would recommend, you know. your own research, like put a small block, plant some, some vines on different root stocks and make measurements on those root stocks. Like by measurements, I mean, see how well, you know, the vegetative growth is how much food that they're producing.

[00:28:25] And, like collect some soil-based information and see, you know, over five years, six years, which ones are doing consistently better. So those root stocks are probably going to be best for your, your vineyard.

[00:28:39] Craig Macmillan: I can see that as part of vineyard development where I, I pick a root stack I think is gonna be a good choice. But then I also plant my trial rows because I'm either gonna be replacing blocks in the future, or maybe I'm gonna be expanding. So I don't necessarily have to wait six years to find the perfect one, but I will in five years find, oh, hey, this worked much better in the next planting. Let's use this.

[00:29:00] Suraj Kar: Yeah, absolutely. Yeah.

[00:29:02] Craig Macmillan: Where can people find out more about you?

[00:29:05] Suraj Kar: Well you can reach me on my email at Cal Poly. Uh, my email is surajkar@calpoly.edu. Okay, my publications are available in my Google Scholar account. I have a LinkedIn account as well.

[00:29:18] Craig Macmillan: And I wanna make sure I get the email correct. It's S-U-R-A-J-K-A-R, Sarraj Car at Cal Poly.

[00:29:28] Suraj Kar: yes.

[00:29:28] Craig Macmillan: Fantastic. Well, our guest today has been Suraj Kar Assistant Professor in the Department of Wine at Poly San Luis Obispo, and thank you being on the podcast.

[00:29:39] This has been really interesting to this, a constant problem, and it's probably only going to get worse.

[00:29:45] Suraj Kar: Well, thank you Craig for inviting me. This has been a lot of fun.

[00:29:54] Beth Vukmanic: Thank you for listening.

[00:29:55] Today's podcast was brought to you by Helena Agri Enterprises. Founded in 1957, Helena Agri Enterprises has grown to become one of the nation's foremost agricultural and specialty formulators and distributors. In the United States, products and services offered include crop protection products, fertilizer specialized nutrients, seeds and precision ag services and software. Helena's overriding goal is to help its customers succeed. This is achieved with a unique combination of dedicated and knowledgeable people, unique and useful products, and the latest technical knowledge. The company defines its own success through the success of its customers.

[00:30:36] Make sure you check out the show notes for links to Suraj Kar, a number of different research articles on grapevine root stocks. And sustainable Wine Growing podcast, episodes 110. How to develop a new vineyard site and 171. How to Farm Wine Grapes for Climate Change.

[00:30:55] If you liked this show, do us a big favor by sharing it with a friend, subscribing and leaving us a review. You can find all of the podcasts at vineyardteam.org/podcast and you can reach us at podcast@vineyardteam.org.

[00:31:08] Until next time, this is Sustainable Wine Growing with the Vineyard team.

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