Season 3, Episode 12 | Behind the Scenes with Tissue Labs (Part 2)

00:00 Patty Skinkis

This is the Hi-Res Vineyard Nutrition Podcast, devoted to helping the grape and wine industry understand more about how to monitor and manage vineyard health through grapevine nutrition research. I am your host, Dr. Patty Skinkis, Professor and Viticulture Extension Specialist at Oregon State University.

00:26 Patty Skinkis

Many growers submit plant tissue samples to labs each summer for nutrient analysis. There are labs based throughout the United States that provide the service ranging from land grant institutions that do these analyses to private sector labs.

Today, we're focusing on what actually happens in the tissue analysis lab from the standpoint of how interpretations are made from your reports and what is done with that. To help us talk about this, I have two agronomists with me today, very accomplished agronomists. We have Alan Meijer, senior agronomist with Waypoint Analytical in Virginia, and Danyal Kasapligil, Vice President and Senior Agronomist of Dellavalle Lab in California. Both have been working with growers for decades and are with companies who have long served growers in their region. Both Alan and Danyal were invited to join us today because of one main reason. They provide support to the Hi-Res Vineyard Nutrition Project by way of analytical services for the tissues that are part of our research for plant nutrient analysis.

So, I want to hand it over to our guests today to introduce themselves and tell us a little bit more about, not only themselves, but the company they work for.

All right, I'll have you start, Danyal.

01:46 Danyal Kasapligil

I'm Danyal Kasapligil with Dellavalle Laboratory. We are headquartered in Fresno, California, and have been in business serving California agriculture since 1978, specializing in soil, plant, water analysis, primarily for crop production. Not only are we an ELAP certified laboratory, we are also a crop consulting company.

02:12 Patty Skinkis

All right, Danyal, and Alan, welcome.

02:16 Alan Meijer

Yeah, thank you for having me. As you said, I'm a senior agronomist for Waypoint Analytical. I pretty much cover the East Coast. So that's three of our labs. We have one in Pennsylvania, one in Richmond, and one in Wilson, North Carolina. I live in eastern North Carolina. Our company is based in Memphis, where our main lab is. And we have two other agricultural labs, or three, I should say: a new one going into Nebraska, as well as Champaign, Illinois and Atlantic, Iowa. In addition to these seven labs, which consist of our agricultural labs where we handle soil and plant tissue and other types of testing like fertilizer and manure, we also have ten environmental labs, but I pretty much deal with the agricultural side.

03:05 Patty Skinkis

All right. Well, we have lots of expertise with us today because not only do they analyze vineyard samples, but they cover many agricultural crops. So, I'm going to start with some questions, and these questions came from the Hi-Res Vineyard Nutrition Project team. They were interested in knowing what happens once we get samples, and just – what does the world look like outside of research, in terms of what analyses are done and who's doing them.

What type of analyses do you recommend for grape growers?

I'll have Danyal start first.

03:43 Danyal Kasapligil

That starts with, are you a leaf or a petiole centric person? In California, most of the interpretive guidelines for tissue analysis for grapevines has focused on petiole analysis. I lean heavily towards the petiole analysis largely because I think we have a more robust interpretive data to support our analytical data. So data from the land grant universities for interpreting the results. Most of those are for petioles more so than leaves.

There is also a publication out of the Pacific Northwest where they have interpretive ranges for what they call whole leaves, which is the leaf lamina plus the petiole. I am not a fan of that because I've found the optimal ranges are rather wide. And I prefer the petiole analysis because your optimal ranges tend to be a little more narrow and also more well-defined than for the leaf analysis. However, as a crop advisor, when I am called in to diagnose a problem, I like doing both leaf and petiole analysis because I don't want to overlook anything. And I would say probably when I do that, nine out of 10 times, I learn what I need to learn from the petiole analysis. It's that 10% of the time where I really do get something from additional leaf analysis that I would have missed had I only focused on the petiole analysis. My job as a crop advisor is to really look at all the possibilities of what could be an issue. I don't want to overlook anything. That's why it's important to do both in a problem diagnosis situation. But for routine monitoring of nutrients, I'm very, very comfortable just focusing on the petiole analysis.

06:01 Patty Skinkis

Alan, how about you?

06:03 Alan Meijer

I was interested to hear Danyal's answer because I follow kind of the same thought. We have crop codes in our system for both leaf and petiole, and I wouldn't be surprised if we actually sampled more leaves than petioles when it comes to grapes.

When I started investigating, trying to look at some of these numbers. I was surprised at the number of crop codes that we have for leaves as well as petioles. It depends if you're petiole-centric or focused, he said. You have to understand the interpretation. What are you trying to get out of it? When you get those results back, it's important to know what to expect. This also pairs up with the time of sampling and things like that. One reason we have so many crop codes is just because of the variety of clients that we have from a large geographic area. Danyal may have the same experience on his end. Part of it is demand, what our clients are asking for.

07:11 Patty Skinkis

In terms of timing, a lot of times we're talking bloom time or veraison, so start of ripening. If those are the two main time points for grapes, are those the timeframes? Do you see one or the other for your samples, or do you see something completely outside of those two typical timeframes for analysis or sampling?

07:34 Danyal Kasapligil

I would say in California, 90% of the industry really focuses their tissue analysis, which is largely petiole, at bloom time.

Personally, I think it's probably more important to look at what the tissue nutrient levels are veraison. And the reason for that is during the early season crop protection sprays, growers are typically throwing in some foliar nutrients into their spray tank. All your micronutrient levels look good and they might throw in a little extra potassium. But at veraison, the onset of ripening, we're always sampling the leaf or the petiole from the leaf of the recently fully mature leaf.

At veraison, that's six to 10 positions from the shoot tip. And those leaves weren't around prior to bloom, receiving all those sprays that had some extra foliar nutrients. And so they haven't received the foliar zinc and foliar boron that typically goes on at or just prior to bloom. The onset of ripening is when you have the greatest nutrient demand. Are you an optimist or a pessimist? Do you want to see the best-case scenario or do you want to see the worst-case scenario? Personally, I’m an optimist, but I want to see the worst-case scenario so I can make sure that we cover bases and don't miss anything. I do think it's important to do veraison samples because you can definitely miss important things if you only are doing analysis of bloom time. I must say, the vast majority of the industry does just bloom-time petioles one time a season. We have other crops where we do multiple samples per season to track the nutrient dynamics. I always joke, our favorite clients are the ones that do it at bloom time and veraison.

But I really do think it is very important to do it at veraison to make sure that nothing is overlooked. I have seen cases and confirmed boron deficiencies that looked fine at bloom, but because foliar-applied boron does not translocate from older growth to newer growth, you can have a boron deficiency later in the season, and boron is involved in more than just pollination and fruit set. It is also involved in sugar translocation dynamics.

10:24 Patty Skinkis

Great. Alan, what do you see on the east coast?

11:37 Alan Meijer

Unfortunately, when I query our system, I can't query the numbers by the two crop codes. It's hard for me to know exactly. But I'm a fan of veraison for the stability that you see then, versus at flowering. I don't think it's improper for me, this is a business, to say it would be better to do more than one sample.

Maybe wrongfully, I see grapes as almost a specialty crop. That’s a specialty product that we're getting from them. It's a high value crop. Maybe you'd be surprised to know how many times farmers are tissue sampling in corn and soybeans now to try to really go for top yields. That could be weekly, for five to 10 weeks. It depends if they're really aggressive. To me, I see it as, you got value in getting an idea of what's going on in that plant earlier, at bloom. Then either, have we seen an improvement? Or, as Danyal mentioned, enough has changed in that plant that you're dealing with a whole new set of levels that need to be addressed. You can't assume that you took care of everything at bloom. If it were me, and I do come from a university background where you might be sampling every week anyway, I certainly don't see two samples a year, at least, as being unreasonable.

12:03 Patty Skinkis

The multiple time point sampling definitely is much more indicative of issues or a pattern that can emerge. What makes it challenging for growers is that now you've got multiple tissues, multiple time points, which patterns? I know as a researcher too, we run both time points, both tissues, and it gets really to be a lot of data and which one, you know, there'll be a pattern this way with petioles and not with leaf blades. It's pulling all of that together. So I see, Alan, you want to chime in. Let's hear what you have to say.

12:43 Alan Meijer

Danyal mentioned something about this subject earlier in the talk, there's also diagnostic sampling if you see an issue. The good time to address that is probably even before you see the deficiency. But unfortunately, in general, we have to wait until we see it. And then there's methods that you should follow to ensure that we can figure out what's going on.

13:12 Patty Skinkis

The next question I have comes to what a sample represents. We've got whether it's maintenance or getting that baseline nutrition or if you're going to do a diagnostic. What size of a sample would you recommend for a unit area of land?

13:32 Alan Meijer

Man, you like asking questions that I want to say ‘it depends.’

13:36 Patty Skinkis

Let me start out, I'll give you a little carrot, because this was a question I had too. I have no idea how big of a sample growers are pulling from when they get one sample to submit to a lab. We asked this question in a national survey in 2021 at the outset of the Hi-Res Vineyard Nutrition Project, and the answer was that each sample was between one and five acres. That was the size of what they were sending in samples. That was the average. Now there are some as high as 20 acres represented by one sample. And really one acre was about the smallest, but the majority were saying that was what they were doing. I don't know if you have any insights as to what you would recommend. If it's situationally based, that's fine. What would you recommend, for a sample size relative to an average vineyard that you might work with in your area?

14:37 Alan Meijer

I'll just start for a second by saying I don't mind continuing with the ‘it depends’ because what I'm getting at is: what are you trying to manage? Are you trying to manage some level of variability you might have in the field? Even if we go to a finer scale, a one acre or a five acre, do you have plans or the ability to address the differences through GPS or precision agriculture, something like that. Again, I like to know more. I like to have the detail. So that's where I'm coming from when I say it depends. What we're after is, is it representative? And then even if we say we're going to do one at, let's say every acre in a vineyard, what's representative within that acre. So we could go on. Danyal, feel free.

15:26 Danyal Kasapligil

It should be representative of a management unit. In a good management unit, you would not have two different rootstocks. It would all be the same rootstock and same scion because rootstocks have a huge influence on the nutrient uptake. If it's a large block, say it's—even with large vineyards in the north coast of California, you don't really see 40-acre blocks. It might be a 40-acre vineyard with many varieties. But even if it were a 40-acre vineyard, of one variety rootstock combination, I prefer to limit the sample area to about an acre. And have a designated sampling area that is representative of the field. Now, if you have a lot of field variability, you might have to have a couple of different sampling locations with separate samples. Because as the founder of our company, Nat Dellavalle, would say, ‘well, you just take a large composite average sample. That's kind of like having one foot in boiling water and one foot in ice water.’ But on average, you ought to be comfortable, which is not the case.

It's really best to focus on extremes, weak areas and strong areas to find out, is it a nutritional factor that is causing that difference? And if your analytical results come back the same, well, then you know it's not nutritional, it's something else. Could be disease, could be water, et cetera. I do like the sampling zones and designating them so you can go back year after year or even throughout the year to attempt to minimize the issues of spatial variability, to minimize it.

17:32 Patty Skinkis

We just talked about the tissue samples. How about soil samples? Do you have any recommendations for depth, timing, frequency that you recommend growers look at soil samples?

17:46 Danyal Kasapligil

The soil analysis is most important at the development stage, prior to planting a new vineyard. At that point, it should be very thorough. Unless there are issues, problems, there isn't a lot of need for periodic soil testing. I mean, it's not a bad idea to do it every five years or so, but it's not necessary on an annual basis, unless you have an issue. For example, poor quality irrigation water, salinity issue. Then you would want to monitor the soil salinity levels and be very precise about it.

There are many instances where somebody has a problem in the vineyard, and maybe it's even this time of year, and I ask about baseline soil analysis: ‘oh, we don't have any’ or ‘we can't find it.’ Well, at that point, it's better late than never to get some soil analysis. At that point, in an existing vineyard, I strongly recommend collecting samples from outside the vine row. Oftentimes, you know especially in drip irrigated vineyards, the fertilizer is applied through the drip system, and we don't want to have a sample skewed by the fertilizer placement. ‘Oh, we have high soil potassium levels.’ You can't rely on that because it might be a very small portion of the crop root zone, maybe it's only less than 5%.

So I like taking the samples from in between the vine rows too, because that's where the majority of your roots are. Even in a drip irrigated vineyard where we rely heavily on winter rainfall and have a lot of roots everywhere and it's only later in the summer season that we even need to begin irrigating in the north coast, there's many, many roots outside the drip zone. For that reason it's very important to collect samples from outside the drip zone. Then, if there's a problem, you can compare those to soil samples in the drip zone. Especially if there's a salinity issue and see if there is salinity buildup within the drip zone compared to outside the drip zone. As far as depth goes, although vine roots can go deep, the majority of the roots are in the top half of the root zone.

Say you have a hypothetical four-foot root zone, 70% of those roots are in the top half, which is the top two feet, which is where one should really be focusing. However, if there is an issue, you definitely want to go deeper. We like digging backhoe pits five feet deep, collecting soils from the various horizons that we find. It's preferable to just using an auger where we can't see the soil and we just have to take samples at one-foot increments, depending on how deep we can go. We will do all types of approaches, everything depending on individual situations.

21:06 Patty Skinkis

Being thorough with soils, I like it. Especially with the development, that's the time to get the most extensive. Then coming back every so many years, especially if you have diagnostics. One of the interesting things is a lot of people I see will usually want to focus on soils rather than on the plants. As they get more educated in nutrition management, they try to transition over. It's good to hear that aligns with what we have been saying in extension and even in the Hi-Res Project, our focus is mainly on tissue sampling, not on soils.

I want to hear from you, Alan, do you have any soils recommendations, sampling frequency, depth?

21:55 Alan Meijer

Danyal's covered a lot of it. In parts of the east, we would have a shallower root zone, I would think, or at least it would be very difficult to sample outside of it with a backhoe. To expect our roots to get too deep, in some areas that could be quite difficult. Speaking with this vineyard association recently, guys weren't even able to sample. We've been in such a drought the last few years. It does lead to a point that I was wanted to make: when sampling, be consistent in your depth. When you get into droughty conditions or just tough sampling conditions, it can be so easy not to. If your sampler, if it's not you, a person might not understand the need to be consistent. Often in agriculture in general, we're dealing with a zero-to-six-inch sample. A lot can happen in those top six inches. It's important to be to be consistent and to submit an adequate, good quality soil sample.

23:15 Patty Skinkis

That reminded me of the consistency. How about timing? When is the best timing to get the soil sample? That's where I see people grab the soil samples when they think of it, but it might be at vastly different times of year and the results for some analyses can come out quite different. Do you have a preferred timing or just stay consistent?

23:38 Danyal Kasapligil

After I answer that, I would like you to explain what differences you see. I like to joke that you want to sample when it's easiest. It's very true. The easier it is for somebody to sample, the more thorough they're going to be. When soils are moist in the winter and spring, you can get composite samples, not just from one spot, but you can go to multiple spots and then combine them. I do prefer a composite sample in a small area. You can go deeper. Anything to make it easier to get a good sample, you're more likely to have a good representative sample.

As far as depth goes, Alan had mentioned a zero-to-six-inch sample, which is very standard for the agronomic corn and soybean industry. With grapevines, oftentimes they have very few roots in the top six inches and we really need to focus on that six-to-18-inch depth for the for the first foot. We'll typically do a zero to one foot, one to two foot, two to three foot, if we can. Probably more important is a zero to 18 [inch] and an 18 to a 36, or just a zero to 12, 12 to 24. Kind of breaking it up and separating it out so you have different depths so you can look at nutrient stratification. Are there textural changes as you go down? Again, that's where it's so important to do that prior to planting very thoroughly.

Back to your comment, Patty, what do you see changing by the timing of the sampling in a soil sample?

25:33 Patty Skinkis

My context is coming from western Oregon, specifically the Willamette Valley, where a lot of people want to sample in February because it's easy. It might be rainy, but it's easy. Then they see low nitrogen, which is not surprising. We have cold soils, they've just been rained on since November. They're getting a sample and then they think, oh my gosh, I need to add nitrogen. If you would wait a couple months till it's warmer, we don't need nitrogen in our soils. That's what we see mostly as the big difference.

26:10 Danyal Kasapligil

And those soils should be low in nitrogen most of the year. You might have a little organic matter mineralization as it warms up, but you should never have high soil nitrogen in a vineyard.

26:22 Patty Skinkis

Yeah. We have high organic matter too. They're looking at interpretations coming back from the labs to say, oh, you're low in nitrogen. Then they think they have to add nitrogen. But we don't need (typically, in our region) to add nitrogen to the soil.

Another question along the line of what we're getting into when you come up with recommendations. You like to see a certain type of tissue sample or a soil sample, and you like to see different data points. That's all coming to the analyses. The report that's given to the grower, what do you recommend or what comes out of that recommendation? How are you coming up with this? Is it experience? Is it a complex of different sources of information?

How do you come to that interpretive report that's handed off to the growers?

27:18 Alan Meijer

I'll start because Danyal's role, if I understood it correctly, takes on more of a crop consulting role. We do less of that at Waypoint. I mean, I'm here to help anybody, but I think our role is different. Our tissue reports in contrast to our soil reports, we don't provide any recommendations when it comes to tissue. There may be some crop notes about timing and some suggested fertilizers. Especially when it comes to vegetables and lawns for our clients like that. We provide the results and the sufficiency ratings, as well as some nutrient ratios, but we don't provide, as we would with soil specific recommendations, for every crop that we do when it comes to a tissue test.

28:13 Patty Skinkis

You said you use some thresholds. Can you talk about where those thresholds come from?

28:18 Alan Meijer

I've been with Waypoint for just under two years, so they didn't come from me. Dr. Large, one of the founders of Waypoint, when it used to be known as A&L—He's the L in A and L. He and agronomists work to develop our sufficiency ratings in both tissues and soil, and then we also use other sources like university research and whatnot, because we have thousands of crop codes. We don't run a whole internal research program doing test plots to come up with new ones. We use the best sources we can find to develop these sufficiency ranges.

29:01 Patty Skinkis

Danyal, how about you?

29:02 Danyal Kasapligil

When we issue a tissue analysis report, we color code the results and try to provide our clients with a user-friendly interpretive guide, but not dumbing it down, which is very important. We use the University of California critical levels for deficiency ratings. As far as an optimal rating, a lot of that is building in a comfort factor as well as incorporating some of our experience in the field where one needs to be. With some nutrients it's easier than others. For example, with nitrogen on a tissue analysis, I like to run both the nitrate nitrogen and the total nitrogen to look at what the plant is assimilating and also what it has assimilated.

I always emphasize that it is the evaluation of the canopy visually that is far more important than the actual nitrogen level. The nitrogen level that we report is really secondary to that visual evaluation. If the analysis shows low nitrogen and you have a vigorous canopy, well, don't be applying more nitrogen because then all you're going to have to do is hedge. However, if you have a weak canopy and the nitrogen level is low, well, no wonder, you need to add more nitrogen. You have to use it with some common sense.

We've got ranges for deficient, ranges for low normal and also what is high and excessive. Just to help us to see when we look at a page of results. We have a format where you can look at 20 different samples on one page, so you don't have to flip through a lot of tabs on a spreadsheet or pages of paper. You can see a lot of results. They're color coded. You can hone in on what's important and what needs attention. The critical levels were based on university research and some of the optimal ranges are based experientially.

31:33 Patty Skinkis

Do you have any differences in how you interpret the data relative to region or state or area within your state? Or are the critical values and the overall comfort level generalized for all of wine grapes or all of table grapes?

31:56 Danyal Kasapligil

They are. They're for all varieties, first of all. This is wine grape specific, not table grapes. But as far as regions go, there are some differences. A lot of that has to do with average yields, tonnage goals. The nutrient concentrations you may need in Napa Valley, where the average yield is slightly under four tons per acre, is quite a bit different than, say, in the San Joaquin Valley where yields might be four or five times that.

32:36 Patty Skinkis

That makes complete sense; nutrient demand follows yield goals.

32:42 Danyal Kasapligil

Yes. Also, as far as what the optimal value or normal value is for potassium. For example, with potassium, the two major forms of crop uptake by the roots are diffusion and mass flow, in that order. Both diffusion and mass flow are strongly affected by soil water content. As the soil gets drier, both mass flow and diffusion decrease. For example, in Napa Valley, there tends to be a lot more deficit irrigation than, say, in the central coast of California. We like to see those potassium levels at bloom time a little bit higher in the Napa Valley, then we may need to see them in the Central Coast where they tend to irrigate more to get slightly higher yields.

33:41 Patty Skinkis

Adjusting it based on either precipitation or irrigation, that makes complete sense. How about organic matter? Maybe there's not enough difference in organic matter, but looking at organic matter in soils general to a region and doing nutrient recommendations. Adding to that would be pH. What are soil pH and organic matter considerations?

34:07 Danyal Kasapligil

We definitely see less nitrogen fertilization in the north coast than we do in other areas. And it's higher rainfall. The soils tend to have higher organic matter, but organic matter mineralization is so unpredictable. I wouldn't want to predict what it's going to be. I know of some vineyards that never need to be fertilized with nitrogen. When you have six, seven percent organic matter in a higher rainfall area, that could even be providing more nitrogen than you really need, but that's an unusual case.

34:49 Patty Skinkis

Around the recommendations that come out, whether they're interpretations and you're just handing it off to growers, out of the years that you've been working with grapes, are there commonly deficient or excessive nutrients that you see in your respective regions?

35:08 Alan Meijer

I'll start, and I’ll be brief. From my perspective, I haven't worked with many grape growers personally, but looking at the numbers, I would say it's boron and zinc that I tend to see in our low to deficient category. Those ranked high or very high would be manganese and magnesium. Still, the bulk is sufficient or on either side. But if I had to look at the nutrients that tend to show up low, it's boron and zinc. This is only in the last year or two, the query I did. That's what I'm going to offer.

35:56 Danyal Kasapligil

I would say that in California, the two nutrients that are most often deficient are potassium and boron. Potassium because that is the nutrient that is removed the most in the harvest, approximately eight pounds of potassium per ton of fruit. And boron, with the exception of areas that have high boron in their groundwater. A lot of times growers, they're afraid to apply too much boron. It's not uncommon to see low boron levels because people are worried of, oh, well, I don't want to put on too much. They heard some of the horror stories of somebody over applying boron. They're always at that low end of the range.

What's funny is in some of the older UC literature for example, Pete Christensen, heavily focused on zinc. That was from back in the day when all those vineyards ever got was sulfur dust as a fungicide. There were no foliar sprays. I suppose that if you were only dusting, you could have zinc deficiencies, but I have never seen zinc deficiency in a commercial vineyard. The only time I've seen a zinc deficiency was in a vine grown on someone's backyard fence that never got fertilized and saw the classic zigzag shoot tip. But it's largely potassium.

Coming back to the Hi-Res Vineyard Project, we did the tissue analysis for Matt Fidelibus at UC Davis for one of his projects. It was a great project. He explained it in really user-friendly, simple terms, as far as budgeting for nutrients. It was very important. Grapes remove a fairly wide range of nitrogen per ton of crop harvested, but it averages around three pounds of nitrogen per ton of fruit. One of the published values is 2.8, let's call it three pounds, but it can vary. We've had a few clients that send us harvest samples. We've seen anything between two and a half and six and a half, depending on how they were fertilized. Some of the higher values were from vineyards irrigated with reclaimed water that had a higher nitrogen content.

If you use that three pounds of nitrogen per ton of fruit, what Matt came up with, you really need to be applying two and a half times that to supply the grape vine for what it's going to need for its vegetative and reproductive growth. You take that three pounds of nitrogen per ton of fruit, multiply by two and a half, comes out to seven and a half pounds of nitrogen per ton of fruit and if you multiply that by an average crop of four tons per acre as we would see in high quality vineyards that's 30 pounds of nitrogen which is really what a lot of growers are applying.

Matt's research showed that you cannot count on nutrient cycling. Now in California, we have a lot of regulations regarding nitrogen usage and nitrogen contamination of groundwater and regulators who think that everything can be budgeted. When you look at what is in those prunings and in the leaves, it's all high carbon to nitrogen plant tissue that is not going to readily decompose and mineralize nitrogen. It's going to add to the long-term organic matter pool, but that nitrogen is not going to be available next year, nor the year after. That's why Matt's research showed that you really need to budget two and a half times the crop removal for vineyards. I thought that was fabulous research because it was so practical.

40:33 Patty Skinkis

It's interesting to hear your comments about the budget. It's really difficult because that's one of the things that we're challenged with is the request for growers to have a fertilizer recommendation, which is not the goal of our research project, the Hi-Res Project. That's not what the scope of the work is about, but we recognize that's what people want. How many growers do you encounter that – or perhaps this is the goal of the fertilization recommendations that you develop – how many are based on that goal of nutrient replacement?

41:09 Danyal Kasapligil

Very few.

41:10 Patty Skinkis

Okay, very few.

41:12 Danyal Kasapligil

Because there's plenty of soils that release enough nitrogen, and then there's others that don't. It's so site-specific, you can't make a blanket recommendation.

41:21 Patty Skinkis

Okay, that's good, because that matches what I understood from our national survey, when we asked how they come up with a fertilization budget. A lot of them just said ‘I work with my consultant.’ Some of them said nutrient replacement value, but very, very few said that. So that was interesting.

Last question I want to ask is, and some of this comes into the interpretation of the analytics, you can do your soil analysis, you do your tissue analysis, and that really helps you come up with the fertilization plan, or at least the nutrient management plan. Even if you're not applying fertilizers, it helps to see what the plants are doing.

A big part of the Hi-Res vineyard nutrition project is to come up with new methods or new technologies to sense the canopy. The two goals are: one, can we detect the variability and be able to equate that to a tissue sample? We're very heavily rooted in the tradition of doing ground truth testing of plant tissue analysis. The second goal would be, can we come up with a sensor that could make our sampling much more robust or be able to equate to ground truth samples? What that's looking like at the moment is a sensor that can look at hyperspectral images and be able to help correlate to a nutrient sample. Building a baseline is still critical there. If a sensor were to come out, how do you see this fitting into the work you do as a plant nutrient analysis lab or as an agronomist?

43:05 Danyal Kasapligil

Where it would really help the most is to fine-tune smart sampling locations. The hyper hyperspectral imaging might be able to correlate to some macronutrient levels. That would be good, but I don't see it getting down to the micronutrient levels because we are measuring these important micronutrients in parts per million. We're not going to have a sensor that's going to tell us from the air what the percent boron is in our vines. It might be able to sense the nitrogen status or the potassium status. If it can differentiate, like the NDVI images, and even do a better job, it can help us pinpoint where we need to take our ground truth tissue samples and take them from those specific locations and track changes over time.

46:16 Patty Skinkis

Tracking the variability and the changes over time and adding another element of technology so we're not shooting in the dark. Choosing a spot that now you can take your nutrient analysis budget and say, okay, we're gonna focus it over here instead of all these other places that we randomly went to traditionally, because that's what we always did. Here's where we need to focus now. That's great to hear that would fit into that plan.

Alan, you work with a lot of other crops as well. Do you have any other examples of crops that are already using this and grapevines are slow adopters?

44:59 Alan Meijer

When I was a research technician at NC State on my knees counting wheat tillers for days on end, and then we were conducting a study with infrared aerial photography and, man, you should have seen the results – fantastic paper! And the next year I'm back on my knees counting tillers. And I said, can't we use an airplane? You guys said it works. Oh no, we have to still… [etc.]. So I'm a big fan of trying to find ways to use multispectral imagery and whatnot. I agree. It's not magic. You're not going to find and be able to detect everything.

Sulfur deficiency might show up too, even though your nitrogen might be fine. I would venture to say the multispectral will help you find spots that you're not going to see with the naked eye, or you'll see them sooner. How does it change what we do? I don't know. I would say it's more how it's going to change from the management, the crop consultants. The problem is, you could get too much data, right? How do you pore through it? I would imagine it does need to be ground truth at this point. You’ve got to be careful when you start using it to know what you're getting into.

46:18 Patty Skinkis

It's part of the suite of tools that's available to us and that's how we're looking at it. It’s not going to be the easy button, and now we can do away with everything else we've done. I know many of us viticulturists still want to see the ground truth data. We've generated a lot from the project and it's helping develop the tool, but it's not perfect. Certainly, as Danyal said, we can't do the micronutrients. It's too difficult.

Even in the project, we had to focus, so we did the macronutrients. Nitrogen, potassium, and magnesium are the three we focused on. Really difficult to do much else. We were working within in the confines of the plants that were available regionally across the U.S. too. Over 17 field-based studies were done, and of all those samples we collected, not all of the 17 were scanned, but all of the 17 had some level of tissue analyses done, mostly petiole and leaf blade during bloom and veraison. We generated a lot more information for grapevines that we hope to include for improving the interpretations, those critical values.

I'm very glad to hear that you're focusing mostly on just grape, not specific cultivars. The interpretation is based on what you know about the region, rather than trying to come up with a critical value for each region. That was good to hear because as a team, we're trying to come up with these critical values. Everybody wants to be everything to everybody. We just can't. We still need that agronomist, that extension agent, that farm advisor, who's going to work with the growers to pull it all together, whether it's a new tool or an old school analytical method.

Do you have one last thing you want to summarize that you think growers or maybe even researchers should know about what you do? The crop evaluation or nutrient evaluation part of what you do.

48:24 Danyal Kasapligil

I would say: ask questions. It was an eye opener to me, Patty, to hear you talk about the growers in Oregon thinking they needed to add nitrogen because they had low soil nitrogen from their wintertime samples. I thought, let me pull up a typical soil analysis in case we're going to talk about it. I'm looking at one and, believe it or not, it's from Oregon. All of the nitrate N values are listed as non-detect and they're color-coded as low because it's below the normal range of two to five parts per million. I'm thinking like an agronomist that, yes, that's normal for this time of year. It's a high rainfall area; it's a low nitrogen input. I'm not worried about it, but somebody else might look at that report and go, ‘oh it's low.’

I always encourage users of any laboratory’s analytical services to ask the questions and make sure that you understand the reports. I would feel much better if somebody contacted us and asked us about those results so we can assure them that, yes, that's normal and there's nothing to worry about. No, you're not deficient. That's just normally low for the season. That's what it's supposed to be. I'd be worried that if it were 10 parts per million in the wintertime.

50:04 Alan Meijer

I would say, be thorough when filling out a submission form. If you have questions, please call the lab. If the lab staff there needs further assistance, they would have me call our client, for sure.

If you're not the one doing the sampling, make sure that your sampler knows how to take a sample. I have looked at reports when the person told me, this isn't matching up with what the private consultant is getting. And I said, are you submitting petioles or leaves? Oh, we're submitting petioles. And I'm like, what do you say? And then they come back and call later, said, oops, they were submitting the whole leaf, petiole and leaf. I'm just saying, cover the basics, it is still important for getting the right answer.

50:51 Patty Skinkis

So that reminds me, I said this was going to be like my last question, but you reminded me of an important one. You kind of hit at it, what is the biggest mistake you see when samples are submitted to the lab? Incomplete information is one, it sounds like.

51:07 Alan Meijer

Right. Wrong plant part would be another. Maybe growth stage or something like that for other crops. I think in general, I know this is a grape centric.

51:18 Patty Skinkis

This can be in general. I'm sure you see similar in grape submissions that you would see in other crop submissions.

51:24 Alan Meijer

Sure. Incomplete submittal and maybe improper plant part at times. Those would be the two biggest.

51:32 Danyal Kasapligil

I think those are good. It's always good to have thorough documentation of sample descriptions. The other thing is it all starts with proper sampling. If you do not have a good representative sample, it doesn't matter how good we are as an analytical laboratory, or how astute we are as crop advisors. It all starts with getting a good representative sample.

If you're looking at strong areas, weak areas, it all starts with a sample. Having enough sample volume, going to a number of different places. Make sure you've got that minimum of 60 to 80 petioles from different vines. If it's a soil sample, different laboratories have different analytical techniques. Alan's laboratory on the east coast and our laboratory on the west coast we have different analytical methods that have been developed for the soils in our respective regions.

Now, the tissue analysis is going to be the same, but the soil analysis is very different in different regions of the country. On the west coast, the saturated paste that we use for pH and soluble salts requires a fair amount of soil. Our sample bags are larger than typically on the east coast. We like to have a quart of soil to work with. We don't necessarily need all of it, but we do need to start with about 250 grams of dried ground soil, so we like to receive two pounds of fresh moist soil. Periodically, we get these little teeny tiny bags that have, at best, a half a cup or a cup of soil and it's just not enough to work with.

Then, either the client has to resample or we do not do a comprehensive analysis. There's many tests that can be done on a very small amount of soil, but also how representative is that small amount of soil? And then again, we’ve got the people who bring us a gallon bag full of soil. That's also a bit much.

Having the right sample volume is important. No such thing as a dumb question; check with the laboratory first.

54:13 Alan Meijer

We do saturated pastes, especially in Texas, Arizona, California. Also, we like to have extra soil in case a client calls for a rerun and for our own system of checks. 15% of our samples are lab check samples. It's a high percentage. We run a lot of checks through each of our runs. That's in soils, it's 15%. In our own system, all the data is being checked. There are flags that pop up and we say, we're going to run that whole run again, or between this check to that check gets rerun. Then we need additional soil. If someone's knowledgeable about how little soil it actually takes to run the sample, they'd say, I don't have to submit that much. But it's better to submit what we ask than for us to say we don't have enough soil to run that additional test you want or that rerun. That's another reason to make sure you submit what's requested of you.

55:23 Patty Skinkis

That brings up a good point of the sampling protocols. I'm assuming that both of your labs have sampling protocols for your growers. I see you both nodding your heads. That's what I get asked a lot. How do I sample? Go to the lab that you're planning to submit it to and read their protocol, because you want to make sure you're sending in the appropriate amount of soil, of plant tissues. You can go to their websites and find that.

Thank you both for coming and joining in the discussion today.

We have Alan Meijer from Waypoint Analytical on the east coast and Danyal Kasapligil of Dellavalle Labs in California – both very experienced agronomists within their regions. Thank you for sharing your knowledge with us today.

I'll have some links to their labs in the show notes. If you're interested in learning more about the High-Resolution Vineyard Nutrition Project, we have a website and we're on social media.

If you've been enjoying this podcast, please take a moment to complete the listener survey. The link will be in the episode information.

Show notes and links:

Learn more about the Hi-Res Vineyard Nutrition Project

Learn more about the two labs represented:

• Waypoint Analytical
• Delavalle Laboratory Inc.

Related podcast episodes:

Season 1, Episode 3 | The Grapevine “Blood Test” (Paul Schreiner)

Season 1, Episode 8 | Honoring the Past, Building the Future (Matt Fidelibus)

Season 2, Episode 11 | Virginia Nitrogen Trials – A Tale of Two Cultivars (Dana Acimovic)

Season 3, Episode 5 | Tailoring Vineyard Nutrition from Soil to Wine (Anji Perry)

Season 3, Episode 8 | Rethinking Critical Values for Grapevine Nutrition (Matt Fidelibus)

Season 3, Episode 9 | Digging Deeper to Decode Vine Tissue Results (Cain Hickey)

Season 3, Episode 10 | Unlocking Healthy Vines with Practical Nutrition Strategies

Season 3, Episode 11 | Behind the Scenes with Tissue Labs (Part 1)

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This podcast was funded through the National Institute of Food and Agriculture’s (NIFA) Specialty Crop Research Initiative Coordinated Agricultural Projects (CAP) grant. Project Award Number: 2020-51181-32159. The continued efforts of the podcast are funded by the Viticulture Extension Program at Oregon State University.

Audio mixed by John Adams.