Orchard People

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Autumn Walk and the Beauty of Leaves
After a long, hot summer, autumn has finally arrived. So the other day I went for a walk in my local ravine. It was so breathtaking, one of those special days when the leaves on the trees are vibrant shades of red, yellow, and orange.
The sugar maples are always the trees I love best in the fall. Their multicolored autumn leaves remind me of a yummy scoop of lemon, orange, and raspberry sorbet.
Understanding Tree Leaves and Their Health Indicators
But leaves aren't just beautiful, they're educational too. You can learn so much from your tree just by looking at its leaves at any time of year.
You can learn if the tree has nutritional deficiencies. You can see if it's experiencing drought stress. And you can learn lots more. Now, while this is useful information for anyone who has a tree, It's even more useful if you grow fruit trees, because fruit trees can be a bit [00:01:00] temperamental. And it's our job to understand their needs so that we can support them.
So in the first part of the show today, we'll talk about tree leaves and what we can learn from them.
Cherry Tree Rootstock and Expert Insights
Then part two is about cherry tree rootstock. Now if you're ordering a new cherry tree to plant this coming spring, your rootstock choice is just as important as the cherry cultivar you choose to grow.
I'll talk to Lynn Long, a professor at Oregon State University and a cherry specialist. He'll tell us about the different types of cherry rootstock that are available and why we should really take a few moments to learn about them.
/ But first, let's learn about leaves.
Interview with Linda Chalker Scott: How Plants Work
On the line is Linda Chalker Scott, an associate professor and horticulturalist at Washington State University, and the author of a book I really enjoyed called How Plants Work.[00:02:00]
The Science Behind the Amazing Things That Plants Do. Linda, how are you today? I'm fine, Susan, and thanks so much for having me. thanks for being on the show. Before we dig in, do tell me about your book. What was your goal in writing How Plants Work? as someone who started out her career, in marine biology and then late on switched to plants, it was interesting to find out how much I knew about how animals and, humans as animals work in terms of their physiology, but how plants were so much different.
And I think a lot of times we as gardeners make some assumptions about, what plants don't like. And a lot of those assumptions are based on how we would react to something. And the more I got into my program in plant physiology, the more I understood that plants are nothing like people or animals.
And so my goal was to help explain a lot of [00:03:00] plant physiology to gardeners in terms that weren't terribly scientific, not dumbing it down, but just making it more understandable and translating the science. so let's talk, about fall leaves then. right now it's such beautiful color here.
I don't know, do you guys have beautiful colors there where you live as well? It depends on the plants and the weather. We don't, I lived in Buffalo for 8 years and the colors there were just amazing. And it's because you get those huge temperature shifts, in the fall when it's very cold at night and very warm during the day.
And we don't have that as much here, so our colors aren't as vibrant. But there are some things that, I have a cat, Sarah, for instance, that doesn't ever turn red, but has the most amazing yellow and, orange colors as it starts to, go to sleep. so that's a good question with regards to the colors.
The Science Behind Leaf Colors
Like, how does, how, what does it mean when a tree [00:04:00] goes, has red leaves in the fall and another tree has yellow leaves? What's going on exactly when the leaves turn colors before they fall off? what the plant's doing is busy scavenging all the nutrients out of the leaves and storing them away before the leaves die.
So with our deciduous trees, they're, Those tissues just can't survive cold weather, and so the tree just, sloughs them off. or what's called senescence. And what the tree does is want to salvage as much as it can, from those leaves before they go. And so it starts, breaking them down into different components.
And so when you see the color change, one of the first things that gets taken out and saved is nitrogen. and the chlorophyll. So the chlorophyll goes away, so the green color goes away, and then other colors start to appear. Now, the red color isn't something that was hiding there all along, unlike the yellow and orange, but the red color is from anthocyanins, and it's part of the process [00:05:00] of the tree scavenging, nutrients that the anthocyanins are made, and also probably helps it survive.
The leaves survive, cold temperatures as this process is going on. So, that's the red's function, and what about yellow and orange? Were they there underneath the green already? and what do they represent? Yeah, the orange pigments are carotenoids. the word carrot, is, where carotenoid is, linked to.
And then the yellow ones, are xanthophyll. So the yellow and orange are part of the photosynthetic system along with the chlorophyll. So if you were to look at chloroplasts, up close and personal, you would see green pigments, orange pigments, and yellow pigments. It's the red pigments that are not photosynthetic, and those are the ones that are involved in other processes.
So, for instance, if you have a beautiful tree out in your local ravine or your local park, and it's got very red leaves, and you don't see a bit of yellow and orange, does that mean it sucked out the other, [00:06:00] nutrients? It's related to those colors and it just has gone straight to red saying, okay, this is the process, whereas others take out the colors more slowly.
How would you describe that? the green always goes first because it's high nitrogen. So the green goes away and then, the red will show up if, there's anthocyanins in the leaves. and then those will go away because they're transient and then the orange and yellow start to show up. So the orange and yellow are a little bit harder to break down.
They're not as valuable. nutrient wise as, the chlorophyll is, and that's why you see them last. And, a lot of the yellow just stays there, because it's pretty tightly bound. So you have yellow and brown left at the end. yeah, so it's, I forget this image as you're talking of a package of M& M's.
So let's say the M& M's are, like, all these different nutrients, your, yellow is your, or your orange is your beta carotene, or your yellow is your something else, and So it just [00:07:00] helps us to understand that each color actually represents a different type of nutrient. I love that analogy.
I'm going to start suggesting people eat their M& M's in that order. Haha, that's a great idea. Now, fruit trees are interesting and I work a lot with fruit trees obviously. They are beautiful in the spring and summer. Then the fall comes and boom, you just get like depressing looking, maybe a little yellowish leaves.
Why don't they get any of the fun colors? At least, lots of them don't. yeah. That's a really good question, and I guess the simplest answer would be it's genetics, So some species just don't have the red pigments as part of their senescing process. And it doesn't mean that they're not as cold hardy or something like that.
It's just they have a different grouping of pigments that are all called flavonoids. So some of those are, Some of them are red and some are blue, and some are purple, and some are actually white. And it's the ones we see. Of course, the ones that [00:08:00] are most visible to us, the red ones. So we see those, we focus on those.
a lot of times we'll, cultivate plants that have those, but. With fruit trees, we're not really looking for beautiful foliage. We're looking for really delicious fruit. So the traits that get selected for have more to do with fruit production rather than how beautiful leaves are. That's interesting.
Actually, if there's any listeners that know of fruit trees that do have beautiful fall colors, I'd love to get an email from you guys. to hear about them because that is interesting. There must be some that have lovely, fall leaf colors. /So let's talk about why are leaves important in general when it comes to considering the health of our trees.
we're talking not about fall colors and the beauty we're talking about all, season long during the growing season, why should we be looking at the leaves of our trees? it's, the longer I've done this, more of I've learned from leaves myself, just partially from science and partially just observational.
And [00:09:00] you can really tell a lot what's going on, especially with, water relations in your plant, just by paying attention to the leaves. for instance, and this isn't true with deciduous plants, and so I, I'll beg forgiveness, that I'm not going to be talking right now about fruit trees.
But, for instance, if you have some evergreen shrubs and you notice that, the current, The roots are working, how much water is available, by looking at leaves and, damage patterns. You can, tell what happened maybe last year in terms of temperature and water. you start linking all this together and then you're able to, do a health assessment of your tree, just by looking at, leaves.
[00:10:00] it's interesting.
Drought Stress and Leaf Health
You talk about the size of the leaves because and drought this summer here in Ontario, we really had a very, dry summer. and I don't know if it can happen this quickly, but I do notice that some of the apple trees have smaller leaves than they used to, and the color is just not as.
and so the drought has happened and the leaves are not as glossy as before. So I wonder if that might be something to do with whether it's drought this year or last year. maybe they didn't get enough water. What would you think? we're seeing a lot of that too, and with both evergreens and deciduous, we saw this year much poorer leaf production, either not as many leaves or leaves were smaller.
And what that is telling us is that a year before that, I think most of, a lot of the, a lot of the continent had some pretty serious drought issues. And if you have a drought during that season, of course, your fine roots die back. And then when the next spring rolls [00:11:00] along, you don't have as many fine roots to take up the water for good leaf expansion, so you get smaller leaves the following year.
keeping that in mind, if you have a particularly droughty year or hot year, And you haven't been able to irrigate, that you're going to have smaller and fewer leaves the following year. You know what, it makes sense in a way, because you think about it, like you, if you don't eat well and you don't have enough good food and you need to run a race, you're not going to run as far as if you've eaten well and had, you're well hydrated and stuff like that.
So it's similar.
Listener Questions and Restoration Horticulture
I have an interesting email here actually, from a listener called Eamon. And, interesting question. I don't know the answer to this, but we'll find out if you do. Hi, Susan. Great show. A question for your guest. What is meant by restoration horticulture? Thank you. Have you heard that term before?
Restoration horticulture. Restoration horticulture, I'm wondering if that, if it means ecological restoration, in which [00:12:00] case I'm really well familiar with that. my previous position at the University of Washington, I was involved in a, an urban horticulture program there that had restoration, ecology as part of that, and I was the horticulturist that kind of helped with a lot of these projects.
yes, what it is, It's looking at degraded environments, usually ones that we've created and trying to get them back into, a functional system using native plants. huh. for instance, if you have an area that was, industrial area, or perhaps it was, old, landfill or something like that.
You try to get, get rid of the weeds, the invasive weeds, and then try to get back into, native plants. And you can never get right back to where you were, but at least you can get it with enough, structural and habitat diversity with your plants so that it becomes functional again.
that's interesting. Eamon, I hope that answers your question. [00:13:00] we were talking about, oh, Eamon says thank you. That answers my question. Thank you, Eamon. Oh, good. That's great. now we were talking about drought stress and, I've noticed that in different types of trees and it seems to look different.
Sometimes some trees seem to go brown around the edges. on their leaves, like certain types of maples or, do, does it look the same in every tree? Are there different, does every tree have its own way of expressing its stress when it comes to drought stress? the nice thing about drought stress is that it's a pretty good signature when you have it.
So if you have, what we'll ostensibly call tip and marginal necrosis, so you have, browning around the edges and at the tip, that's from leaf drought. Now, exactly What's causing the drought is the question. Is it that you don't have a good enough root system? Not enough water? Water's too salty?
Too hot so that you're more evaporation than water [00:14:00] uptake? there's a whole bunch of reasons that leaves will show drought stress and have that, browning around the tips and margins. but it's because there's not enough water in the leaf. And so the water is lost initially from the tips and margins.
Okay. So that's me. That makes sense. So basically what we're saying is dread stress, it'll give you some more clues that the different symptom will give you a clue as to what is the cause of this problem.
Nutrient Deficiencies and Leaf Analysis
So let's move on to nutrient deficiency. I have, a colleague who is like a magician when it comes to fruit trees in particular, but we're talking about all types of trees today.
but he can look at the leaf and he can tell me exactly what nutrients are lacking in, in the tree. is that some, is that real? Can we really find out, nutrient deficiencies? Do we need to, soil testing anymore? How much can you tell from the leaf? Yeah, you can tell what the leaf doesn't have, but what the leaf doesn't [00:15:00] have and what the soil doesn't have can be two completely different things.
So yes, you can, diagnose, if you have overall leaf chlorosis, especially in the older leaves, you can pretty much say, there's not enough nitrogen there. Or if you have interveinal chlorosis, where the veins are green, but the tissues in between are yellow, you could say, it's probably iron or maybe it's manganese that's not in the leaf.
But you don't know if that's what the soil problem is. And what we're seeing a lot with, home gardens and landscapes is an overuse of phosphorus and that overuse of phosphorus can cause a deficiency in iron or manganese in the leaves. So it looks like you have an iron deficiency, but actually what you have is phosphate toxicity.
So I, I would say that soil tests are even more important now. So that we can see what we have too much of, not just what we have too little of. Okay, so you talked about two types of chlorosis, and just for our listeners who may not know, what will that look like? The leaf will be completely yellow, or you [00:16:00] describe that a little bit.
Yeah, so if you have, total chlorosis, like you might if you have no nitrogen, then the leaves, they look like they do right now, they're just, they're yellow, without any green markings at all. On the other hand, if you can see the veins, is being green. and they're, really very beautiful, so it's an interesting disorder.
very fine, tracings of, green and yellow in between. And that is generally iron, although it can also be manganese that's deficient. And we, when you're intensively producing crops, whether it's fruit or something else, you can run out of these nutrients in the soil.
But for people that just have one or two trees at home, it's usually not from a deficiency, it's oftentimes from a toxicity of some other nutrient. Okay, what about disease? Is that something that we'll ever see in the leaves of our trees? I'm sorry, I missed the first part. What about disease? [00:17:00] Will we ever see disease on the leaves?
sometimes you see canker oozing stuff from the trunk and things like that. Does it ever manifest itself on the leaves? Sure, and that's also a good clue about what's going on, too. A lot of times, you'll see things, especially as leaves start to become stressed. And when they become stressed, they lose a lot of defenses, and so then the opportunistic, pests and pathogens come in.
So as leaves start finessing, you'll see more leaf spot and, bacterial types of issues on leaves, but it's not, a disease so much that's causing that, it's just that the tissue is busy dying and other things are starting to grow on it. And that's what you see a lot, especially with drought stress, is you'll see as, leaves, in a hot summer, they'll start turning colors early, as a way of, saving water, but they're also starting to senesce, and because they're dying early, then those opportunistic [00:18:00] things appear earlier.
What I'm trying to say is these aren't things you can treat, it's just, kind of natural progression. what you want to be looking for, of course, is diseases that appear on otherwise really healthy, robust leaves. And those are the things you'd want to try to treat. Okay, so what about, the last question I have here is, curling of the leaves.
Is that something, I know, again, you see it in fruit trees, but sometimes the leaves curl up at the side. Does that mean anything at all? it can, and again, it's one of those things where you have to pay attention to what's been going on, especially weather wise. there are, the problem is that a lot of times, we try to go to these nutritional deficiency tables, and they'll have all kinds of pictures of, twisted, distorted, cupped leaves as being a deficiency of calcium or something like that.
And oftentimes it's actually not a deficiency, it's something else going on. it could be something as simple as a pest, one of these leaf rollers that's causing it. And you can, look closely to see if [00:19:00] there's signs of insects. But sometimes it's because of what's happened while the leaf is expanding.
And so this is something that's really interesting about leaves. once they get to their full size, they get this nice waxy cuticle and it helps keep Water in and keep pests and other things out, but while they're expanding, they can't have that covering. And as leaves are expanding, they're very sensitive and vulnerable to different pests and diseases, and environmental conditions.
if you have a late, frost, When leaves are expanding, then you'll end up getting some brown areas in the leaf, which will cause cupping and distortion, and it's actually because of that temperature difference. It's not because of some kind of nutritional deficiency or pest or disease. Oh, so it seems like leaves really do have a lot to say, but it sounds like it could be an entire book just on leaves and what they tell us.
That's your next book. Oh, yeah, really. Yeah, [00:20:00] it's, it may also be like human skin. There's some people who say that if you have skin problems that it's a sign of other things inside that maybe aren't quite right. and we can't see our trees roots either. So maybe that the leaves help us.
That's right, absolutely. I can tell you what's going on, at least with, roots and water uptake, if nothing else.
Commercial Break and Marine Biology Anecdotes
Okay, /I have a very interesting email from a listener called Janice. Don't know where Janice is, but Janice says, Hi Linda, I'm a sport diver.
Any great stories about you being a marine biologist? It's funny, not quite on the topic, but I would love to hear a little story if you have one. Okay. let's see. Unfortunately, I wasn't the, The deep sea type of marine biologist, I worked in what was called the superliteral zone, which is up in the splash zone.
So I worked with little tiny tide pools, way up, that rarely get [00:21:00] covered with water. They just get splashed from the ocean and rainwater, which is a very stressful environment. And I worked with a little tiny orange copepod that lived in those tide pools. That's about as exciting as it got for me. Oh, that's great.
Analyzing Tree Leaves: Practical Examples
Linda, we've talked in general about tree leaves and what they teach us. Let's look at some examples. Were you able to find the Orchard People Facebook page? I did, and unfortunately, when I looked at them, a lot of them had to do with insect damage, and I'm not an entomologist, so I can't help with that, and I'm not a pathologist, so I can't help with that either.
That's okay. We do have a few pictures, though. We've got the first one is the hickory. That's great. with chlorosis, I think. Can you see that first picture? let me go to that because I closed on my Facebook page. Sorry about that. That's okay. I have, I'm quite new to Facebook and I get quite confused most of the time.[00:22:00]
I totally understand. But, yeah, have a look. But yeah, there's just a few pictures up here I'd love to discuss before, we sign off for this particular interview on the show today. This first picture that once you log in, you'll find I took during a walk, and it's, I think it's a hickory tree, and I thought these leaves were so beautiful.
They're green with yellow, and I thought this is lovely. But sadly, it's not a good thing to have these. I think that's their first picture. Is that correct? It is.
Identifying Interveinal Chlorosis
Yes. Yeah. Yes. It's so pretty. gorgeous patterns. You can see the veins on the leaves. you can see the yellow. but this is not the way they're supposed to look.
No, and this is a really great example of the interveinal chlorosis that I was talking about. So you can see that there's, the yellow tissue in between is [00:23:00] the interveinal part and then the veins, oddly enough, the major veins themselves are not green, but the area right around the veins is green, but it's the same, it's the same problem.
Possible Causes and Solutions
So this could be, one of a few things. It's definitely not, It's not a virus. It's not anything alive. It's either from a nutritional deficiency, a nutritional toxicity, or a pH problem. you'd want to, you'd want to be able to test your soil pH to see if it was too alkaline because that can be a problem.
My guess is it's probably not that because you normally can grow hickories just fine around there. It's either from too little iron in the leaf or too little manganese. Now my guess would be manganese, just because of the pattern, and that can be because there's too much phosphate in the soil.
Soil Testing and Nutrient Management
So this would be a great, example of when it would be good to do a soil test and to find out exactly how much iron, how much manganese, and how much phosphate you've got.
[00:24:00] Because the more phosphate you have, the harder it is for the tree to take up iron and manganese. So what would the correction be? Like, could you correct a problem like that? this is one of those great questions that I have not figured out a wonderful answer to yet. I'm going to, let's take the easiest thing first.
If it's a pH issue, it's too alkaline, then yes, there's ways to make the soil more acidic. You can add sulfur, on an ongoing basis to bring the pH down. my guess is probably not that. It's probably from, either iron or manganese. So looking at the soil test, finding out if you've got a lack of one of those two things, and that could be added if you do have that problem, but let's take the most common occurrence, which is too much phosphate, and there isn't a an easy way to fix that quickly.
the trick is to draw down the phosphate levels like you would with any, like any kind of [00:25:00] crop would do. if you were able to plant something fast growing, that would suck down all the nutrients, not just phosphorus, but, grow quickly, take the nutrients down. You could draw down the phosphorus that way and then add back the things that you were going to be missing now, like nitrogen, because you'd be drawing that down too.
But that's a way of drawing it down, relatively quickly. The other way would be to add, like a, good, wood chip mulch, which is going to get your, microbial population up and running. And that can also draw the phosphate down. But it takes longer. It's interesting because one of the things in the fruit tree care workshops that I teach is the importance of understanding nutrition and what each of the nutrients gives your tree and I guess the biggest problem that people have is if they incorrectly apply amendments because once you get the soil out of balance, it's really hard to get it back into balance.
So it's like you've got to [00:26:00] be so careful. You do. And what I, try to, suggest to people is and this is one of the times where I do use a human analogy. if, we aren't feeling great, we don't go to, the nutrient supplement store and buy everything, on the shelves and take everything.
we, go in and we have lab tests done to find out what exactly is going on so we know how to treat it. And that's the same thing that soil tests will do. it'll give you a baseline. from which to work, and that'll help you figure out how to, how to correct deficiencies easily, and then the balance, as you say, it's going to be tricky, but just getting, nothing else than a really healthy microbial population there, busy chomping down on, wood chip mulch.
It's going to help correct things. Interesting.
Practical Advice for Tree Health
I guess we'll wrap up with this question. What would you suggest? listeners across North America and they may have, [00:27:00] a native tree in their front yard, whether it's a fruit tree, a native tree, an ornamental tree. What should they do if they see something strange happening in the leaves of their tree?
as I said before, the very first thing I would do, just as a baseline for your entire landscape, is just to have a soil test done, so you know what you're working with. with a lot of our soils, especially if we're in more urbanized areas, we don't know, where they came from, because they're certainly not what was there in the first place.
We don't know if there's, Any contamination there, possibly from lead or, from house paint or something like that. all these things can have an impact on, tree health. So just getting a soil test done and then really paying attention to, Water issues, looking at differences in leaf sizes from year to year, especially With what I've seen a lot now with perched water tables.
And this is a common thing when you [00:28:00] have improperly amended landscapes. And that's not to say that a gardener may have not had to have done this themselves, but when a house is built, for instance, like our house, they dug all the clay out from where the foundation went, and then they threw it in the front yard and covered it up with topsoil.
Which we didn't discover. Until years later when our dogwood failed and could not figure out why in the world, the leaves were getting smaller and smaller every year, dug it up and it was Basically rotted, and it turned out we had this, perched water table. And it, no drainage, so we took it out and moved it.
It actually recovered, and it's doing fine now. and everything we have growing there now is very shallowly rooted. Because you just don't know, what your soil looks like unless you get a an auger or something and take a big core out to see what kind of, interesting patterns you have with, fill.
Yeah, I think that's good advice. also what I do is, I've learned the hard way that if you're thinking of planting a tree, something that needs, lots of root space. [00:29:00] dig a hole before you buy the tree, because sometimes you do see really like hard subsoil and not good soil or construction garbage in the soil and you just think, maybe I should build a raised bed or something.
Yeah, absolutely. And if, even before you decide to plant a tree and, you think you've got really crummy soil, the best way to prepare your soil is if you can let it just rest with a nice thick cover of wood chips on the top, but a lot of the compaction and drainage issues solve themselves when you finally, get it covered up and protected from, compaction from foot traffic and, rainwater and everything else.
You just get it covered up and let the underground processes start to repair the tilth. Linda, thank you so much for coming on the show today. I really appreciate it and I hope you'll come back again one day when you write your book on leaves. I'll be waiting for that one. Okay, you take care.
Goodbye for now. Thanks, Susan. Bye bye. Bye. [00:30:00] That was Linda Chalker Scott, an associate professor and horticulturalist at the Washington State University, and she's the author of How Plants Work, The Science Behind the Amazing Things That Plants Do. Coming up, /we'll talk about cherry trees and cherry tree rootstock, and why it's good to learn more about it before you buy your trees.
Introduction to Cherry Tree Rootstocks

/I learned that it's essential to choose the cultivar for your own unique conditions. And then I learned about rootstock. when you buy a fruit tree, you're really buying two trees. that have been fused into one. Fruit trees are made up of rootstock, the root system from a tree that has great qualities like vigor or disease resistance.
And the rootstock has been grafted together with tree number two, the scion. The scion is a branch from a tree with a fruit that you want to grow, like Macintosh apples or Bartlett pears. [00:31:00] your choice of rootstock will also determine the size of your tree once it's fully mature. These days you can get dwarf trees that'll be a maximum of maybe 8 feet tall when they're fully grown, or semi dwarf trees, which are a little larger, or full sized trees.
But here's the rub. Until recently, or relatively recently, when it came to cherry trees, there were not a lot of rootstock choices. you could get a full size cherry tree, or you could choose a full size cherry tree. It was one size fits all, even if you wanted to plant your cherry tree in a small urban yard where you didn't have a lot of space.
Now all this has changed, and so on the line I have Lynn Long, a professor of horticulture at Oregon State University, and an extension expert who specializes in cherry trees. Hi Lynn, how are you today? Good, how are you doing, Susan? I'm doing very [00:32:00] well.
History and Development of Cherry Rootstocks
Can you tell me a little bit about the history of cherry rootstock?
Am I right to say that it used to be more one size fits all, and now we've got more selection? Absolutely, that's exactly right. In fact, If you look at the history of the cherry industry over the years, it was basically one or two rootstocks and that was all that the growers had to choose from. And all the homeowners had to choose from as well.
And both of those rootstocks, or all those rootstocks, were full sized trees. And so there wasn't a whole lot of flexibility if you needed to grow a small tree in a small space. And then, sometime in the 1970s, I believe, there's a program that started in Germany called the, Giessen program. And they started to breed cherry rootstocks.
And from that, we had some of the first dwarfing cherry rootstocks that were produced at Oregon State [00:33:00] University and Washington State University. We were testing those rootstocks for years through the 70s and into the 80s and even into the 90s and Nobody was really talking about making these things commercial and so then I went to Europe in 1994 and I saw that in Europe in places like Germany and France they were growers were using these dwarfing rootstocks in a commercial planting and So I came back and talked to our growers and said hey these rootstocks are really working for commercial growers somewhere in this world and we need to be trying these rootstocks as well.
And that was really the beginning of using commercial, or dwarfing rootstocks, rather, in commercial settings here in the United States.
Choosing the Right Rootstock
So if we used to have a selection of, let's say, two different types of rootstocks, both of them full size trees, how much of a selection do we have today? Like four different kind of rootstocks, or are there [00:34:00] many more?
there's many more. we've got rootstocks that will grow trees that, for example, the GiSelA 3 rootstock can grow a tree that you can keep six feet tall. It's a very dwarfing rootstock. We don't use it much here in the United States, for a number of different reasons, but it is being used in, in, Europe, and it's an extremely dwarfing tree.
we also have some other rootstocks called geese with five that also produce very small trees. And then we get up to some of the larger rootstocks. most of these, the Gisler rootstocks were bred in Germany, as I had mentioned earlier. And then we've got a new set of rootstocks called the Kremsk rootstocks that were actually bred in Russia.
And those are some of the more popular rootstocks now in Oregon that our growers are using at this time. And there's, advantages and [00:35:00] disadvantages to all of these various rootstocks. And so growers usually decide on the rootstock based upon the science, the variety that they choose and also their soils and their climatic conditions.
And so there's a lot of factors going into choosing which rootstock you want, based upon the, those, factors. it's funny because I think in terms of customizing, when you, I don't know, what do we have customized in life, You're saying, I want my tree to be a certain height.
So I'll customize it by choosing this type of rootstock, or I want my tree to be disease resistant. maybe some of them give those types of benefits. What are the various benefits that we might be looking for when choosing a rootstock? so yeah, there are. Certainly some benefits you can gain from some of these dwarfing rootstocks.
One is that they come into production a lot faster than these full size [00:36:00] rootstocks. So with a full size rootstock, it may take five or six years for you to get your first cherries off of the tree. With the dwarfing rootstocks, you can expect fruit in the second year or maybe the third year after you plant the tree.
So that, that's a huge benefit, not only for the commercial grower, but also for the homeowner as well. Nobody wants to wait around and see their distribution. Big old tree growing and growing and not producing any fruit. So that's certainly a benefit the other benefit for homeowners is that you can put a Tree in your backyard without taking up a lot of space And, that is not only a function of the rootstock, but also the way you prune the tree and the training system that you choose as well.
And so now we have the ability between the, rootstock that we choose and the training system that we choose to grow trees that are no more than eight feet [00:37:00] tall and we can harvest all the fruit from the ground without use of, ladders. And that's a huge step forward for, cherry trees. That's what it used to be.
Anywhere from 20 up to 50 feet tall in the past. Wow. we've made some real strides when it comes to, cherry production. Both for the homeowner and for, the commercial grower. We, have an interesting question from a listener, Nan. She doesn't say where she's from.
Health Benefits of Sweet Cherries
But she says here, Lynn, what are the health benefits from eating sweet cherries on an ongoing basis?
And I think that's interesting because who, knows, maybe some varieties are even more nutritious than other varieties. Do you, have a comment on that? yeah, just a brief comment. Yeah, certainly. Certainly cherries are, are one of the fruits that are high in anthocyanins.
And so the, health benefits from those that we've heard from the medical, [00:38:00] side of things are, clear that anthocyanins can, help reduce the potential for cancer and, and, keep the, individual, healthy. But my understanding, and I'm not a medical doctor or anything close to that.
But my understanding is that cherries also can help reduce the potential for gout as well. And beyond that, I really don't have any more comments, because that's outside of my area of expertise.
Modern Cherry Tree Cultivars
it's interesting, because again, there are, in addition to being lots of different types of rootstocks, there are also lots of different types of, of cultivars that you can choose.
There are either yellow cherries. I think there are. There are cherries of different colors, that kind of thing. so let's talk about that as well. So we've been talking [00:39:00] about root stocks and I know the listeners. If they're anything like me, they're going to want to know this secret. You're a guy who works with fruit trees, with cherry trees all the time.
Do you have favorite varieties, cultivars, that you love, that you think taste amazing? Oh yeah, you always have your favorites, don't you? yeah, I think, I think one of the favorite, varieties that I always enjoy every year is, Bing. And that's a variety that, was bred in Oregon, I think, back in the 1850s or something like that.
So it's been around forever and yet it is probably, the cherry that people most identify with sweet cherries. it's, got great flavor, it's got a, great, tart, sweet acid balance. And, and, it's, the cherry that, that people think about when they think about sweet cherries.[00:40:00]
But you're right, there are other varieties out there. Up until about the mid 1990s, most of the cherry production industry in the United States in particular focused on just the Bing Sweet Cherry. But now, we've got, as you mentioned, yellow cherries, such as the Rainier cherry. It has a totally different flavor to it.
It's got a very, sweet subacid flavor to it, and, it, it stands out, as a premium cherry that, that, tastes, different than, most other cherries. And because of that, it's, highly sought after by the consumer. So I think those are probably my two favorite cherries, Bing and Rainier.
They've both been around for a long time. We've got newer cherries that are available out there. There's been a very good [00:41:00] breeding program out of British Columbia, Canada, that has bred a lot of new varieties. Varieties such as Lapens and Sweetheart and Skeena. and then there's some other varieties in other parts of the world, but Really, Bing and Rainier still are my favorite, varieties that, I think a lot of people would recognize.
Dwarf Cherry Trees and High-Density Planting
we were talking about dwarf, rootstock and dwarf cherry trees, which is relatively new compared to dwarf apple trees. These days, apples, in my travels around, I'm seeing more and more apple trees are grown like grapes and vineyard. They're planted really close together.
They're dwarf trees. They're supported on trellises. And, I'm just wondering, does that happen now with, cherry trees? Do you get orchards of these dwarf trees that are grown in almost, espalier form? [00:42:00] is that what things are going to look like in the future? I think so. We've got, we're seeing more and more of that now with cherries as well.
We are, growing some cherries on trellises just like apples. It's taken a long time for that to happen, but we are slowly moving in that direction. There's a new training system that was in, northern Italy called the Super Slender Axe. That is a super high density, system. We're planting trees anywhere from, let's see here, two feet apart, 80 centimeters.
And lots of times using that geese with three rootstock that I mentioned earlier. So it's super dwarfing rootstock and we're planting them very close together. And we're pruning them in such a way that the fruit stays very near the trunk. And so it looks more like a cornfield than it does a cherry orchard, [00:43:00] when, these, trees are at maturity.
And so the, there's been a, literally a revolution that has taken place in cherry production in the last 20 years. and it's amazing to be a part of that. It does. It sounds amazing. I can't wait to see this. I have never seen it.
Challenges and Disease Management
Is there, are there any dangers? a lot of, I have heard from a number of experts concerned that some of the problems that we have with apples, like fire blight that rips through orchards and neighbourhoods and communities and kills so many trees, and is absolutely not curable.
could something like that happen with these dwarf cherries? the theory is that the reason that fire blade is killing these, smaller trees is because they're so small that the disease gets straight from the tips of the branches into the trunk very quickly. Whereas if it was a full size tree, it would take a long time for the disease to work its way right down [00:44:00] into the dead.
the base of the tree, the trunk and the roots. Do you have any concerns or any fears about smaller trees and dwarf trees, cherry trees that is? Sure. we don't have any diseases that spread as quickly as fire blight in cherry trees. Probably the, disease that we deal with on a worldwide basis more than any other disease is bacterial canker.
That's a disease that causes, as the name implies, a canker or, a lesion, a wound on the, on a branch or a trunk and girdles that, that branch or trunk and eventually can kill the, tree. it doesn't develop as quickly, doesn't, it doesn't move through an orchard as quickly as fire blight.
So in that respect, the danger is not as high as it is with apple trees or pear trees with, fire blight. but yeah, certainly [00:45:00] if you have small trees, there is that potential that, that there can be infections and they're planted close together that, a disease starting in one tree can, move, quickly to neighboring trees.
so that's just a part of growing. fruit trees. especially with cherries, that there's always something that can happen that, is going to affect. the yield or the quality of the fruit And you have to, you just have to learn to deal with those things. So you've got to be aware these things are possible and you've got to, you've got to be a smart grower, whether a homeowner or a commercial grower.
Yeah, I totally agree. I always say that the best time to learn about the potential fruit tree diseases that may [00:46:00] affect your fruit tree is while your tree is still healthy, especially if you grow your fruit tree organically or in a community context in your backyard, where you're not using sprays.
If you can learn what to recognize, then you can usually stop the progress of any disease early on. So I'm big on that kind of thing. But, yeah, and with regards to bacterial canker, we do have a problem with that here. Everywhere I've visited, whenever I see a cherry tree, I can always find some canker.
Other problems we have are rotting sort of little mummy cherries. I don't know what that is. Have you seen that? there's, a number of diseases that can affect the, cherry, especially, as, cherries approach, harvest time, they, start turning red. And at that point. They are susceptible to, to rain cracking.
So if you get a, if you get a rain at the wrong time, cherries can split open from the rain and that allows diseases to get in. [00:47:00] diseases such as brown rot, can be, can be, an important, disease in trees just prior to harvest. And then after harvest as well, it can spread through, Bunch of fruit that's stored in your refrigerator or that are being shipped commercially.
And so some of these diseases can cause problems either pre harvest or post harvest when it comes to cherries. Especially if there's an opening in the skin that's caused by rain cracking or some other type of factor That, causes the protection of the, cherry fruit to break down. And that brings us back full circle to rootstock, because there are some rootstocks that do protect against the cracking.
Am I correct in saying that? no, not [00:48:00] Against rain cracking, there, there are rootstocks that you can use that will, that will produce, as we've been talking about, smaller trees that you can, more easily protect from the rain by putting a plastic cover over. So if you've got a big cherry tree growing on, for example, a mazard rootstock, and this tree is 30 feet tall or something, it's going to be pretty hard to protect that tree from, rain cracking by, covering it with plastic, but now if you've got a tree that's only eight feet tall, then you've got a chance of protecting it from rain by covering it with plastic and keeping the rain off of off the fruit.
But the rootstock itself won't have an effect on rain cracking. Aha. Okay.
Conclusion and Final Thoughts
I don't believe this, but the show is almost over. I don't know where it went. It disappeared. but I want to thank you so much for being on the show today with me, Lynn, and I hope you'll come back again sometime. We can talk about more [00:49:00] cherry issues.
Sounds good. It's been my pleasure. Okay. thanks so much and goodbye for now. Bye bye. that's all for the show today. It was really great to speak to my special guests, Linda, Chalker Scott, an associate professor and horticulturalist at Washington State University, and Lynn Long, a professor of horticulture at Oregon State University.