Orchard People

[00:00:00] Introduction and Disclaimer
The following program does not necessarily represent the views and opinions of Reality Radio 101, its advertisers and sponsors, or its listening audience. Listener discretion is advised.
[00:00:33] Welcome to the Urban Forestry Radio Show
Welcome to the Urban Forestry Radio Show, here on Reality Radio 101. In this radio show and podcast, we learn about fruit trees, permaculture, aboriculture, and so much more. So if you love trees, and especially fruit trees, or if you're interested in living a more sustainable life, then this is the place for you.
I'm your host, Susan Poizner, of the fruit tree care training website, OrchardPeople. com. Thanks for tuning in, and enjoy the show.
Welcome to the Urban Forestry Radio Show with your host, Susan Poizner. To contact Susan live right now, send her an email. InStudio101@gmail. com.
And now right to your host of the urban forestry radio show, Susan Poizner.
[00:01:37] Challenges in Growing Fruit Trees
Sometimes you do everything right. You plant the best fruit tree cultivar that you can find. You make sure you're planting your tree in good soil and in a really nice sunny location. Of course, you feed and you prune your tree properly every single year.
And you do what you can to protect your tree from pests and disease. And yet, there are some trees that still struggle despite all the healthy hands on care. Maybe production is poor. Or your tree gets every disease that's going around, it can be so frustrating. What can you do?
[00:02:15] Boosting Fruit Tree Immune Systems
fruit trees may be big and woody, but in some ways they're similar to humans.
If our immune systems aren't working, we humans are more likely to get sick. And in the same way, if your fruit trees immune system isn't activated, your tree will be more vulnerable to pest and disease problems. Now, if I want to boost my immune system, I'll eat lots of healthy food and fruit and vegetables.
I'll rest a lot. I may go to the doctor or naturopath and ask for advice, and they'll probably prescribe some medicines or supplements. But how on earth do we boost the immune system of our fruit trees? in today's show, we're going to find out. We'll find out that strengthening your fruit tree's immune system, it is possible, and it might even be easy.
[00:03:06] Guest Introduction: Dr. Glynn Percival
My guest on the show today is Dr. Glynnn Percival from the Bartlett Tree Research and Diagnostic Laboratory in the UK. It's linked to Reading University. Now, Glenn has been studying single source mulches for five years now, and he's discovered that some mulches have amazing qualities that can help keep our trees really healthy.
So before we dig into today's topic, I would love to hear from you. Email me with your questions or comments or even just to say hi. So Glynn, thank you so much for coming on the show today. No, it's a real pleasure. Thank you for having me on the show. let's start by just dipping our toes in.
[00:03:48] The Benefits of Mulching
And I'm going to ask you, tell me about mulching in general. What does mulching a fruit tree involve and why do we do it?
it's been recognized now for many years that mulching a tree is a very simple and effective means of promoting tree vitality and fruit yield. mulches have many benefits. they keep the soil temperature relatively constant, so there's little fluctuation. They have a fertilizing effect.
They suppress weeds, and they also encourage a lot of biological activity below ground. So you get an increase in earthworms and on occasion mycorrhizae. that is one of the main reasons. for which we mulch trees.
[00:04:37] Research on Single Source Mulches
Now, for those of us, who grow fruit trees, lots of us are very familiar with mulch will go, and if we're getting wood mulch, we'll get a cedar mulch or something, or we may mulch with compost, or So, what is it that you have been studying over the past five years?
How did your study come about? one of the advantages of being at a university is obviously I do get access to graduate students who are looking for various research projects and also having working for the Bartlett tree experts. It also means that I also have. funding to employ these students.
And it was really just in some discussions when we were looking at the benefits of mulch. And when you talk to people about mulch, they pretty much say, we use a mulch for the exact reasons I've just mentioned. And we were looking at slightly differently. And now when we look at the pharmaceutical, medical, drug industry, many of the products we actually use, for example, Paclitaxel (Taxol) is used for fighting cancer, and it's derived from Taxus, which is the Yew tree.
We thought, we know trees contain lots of quite powerful chemicals, various different products and many people have looked at mulches really more for what we call their, physical properties, the weed suppression, the fertilization, but bearing in mind that the chemical makeup of different trees will differ between species, we thought just Wouldn't it be interesting just to really look at the single species mulches and just see whether or not we could pick up any differences.
for example, is a mulch tree derived from oak different from a mulch tree derived from an apple? So we just decided to begin exploring that area of research. Did you have any expectations? Did you think that it would, they would affect the trees differently? Or were you surprised in the end with your results?
Susan, it's a great question, and I'll be perfectly honest with you. When I first set this project up, I genuinely did not expect Much difference between the mulches. So when the research trial had actually concluded, we really did see big differences. our original research was actually looking at mulches
to enhance transplant survival of different species of trees, and there really was quite a huge difference in some cases. one example, and we have published this was when we looked at a mulch made purely from hawthorn or cherry trees, for example, we actually increased fruit yields of, apple and pear by about 80%.
And then. I think that was when we first began to realize that maybe we're really onto something here. Interesting.
[00:07:38] Listener Questions and Expert Answers: What difference does mulch from different parts of the tree make, when to apply mulch, what species or types of trees produce good mulch
we already have a couple of questions. Let's go to the first question here, and this is from David. So David is writing from Washington State, and I think this is very interesting. He says, Is there a difference between mulch from the heartwood and mulch from the bark and branches, ramial chips?
So that's an interesting point. What is the answer? Is there a difference depending on what part of the tree you're grinding up? It is. We tend to focus more on the branches of a diameter of between five to 10 centimeters. We tend to stay away from the heartwood.
We find the heartwood is good. If you want all, what we would say the physical properties, it will suppress weeds. You maybe don't get quite as high a nutritive value, but we were really more interested in the. The chemical side of it, the potential products that are within more the sapwood.
our research is primarily focused on the branches, and that is where we tend to have more of a pronounced effect. Aha. Okay. So interesting. So David, we've got another email here. Dave in Northern Wisconsin writes, Just found the show and I really like it. Tons of great information. Quick question. When preparing an orchard for winter, should I be adding mulch?
So I guess he's really, Dave is talking about timing of when to put the mulch. So what would you say to him about preparing your orchard for the winter? We've always found, we always have the optimal results. We also get a good response when we apply a mulch in autumn time. So we're talking it at least in the United Kingdom, August, September time, we also get a good response if we apply a spring mulch as well, and there really is a influence of timing and I would literally say autumn 1st, spring 2nd, summer 3rd, and the only problem when you apply in winter is that the trees are dormant And we always use a fresh mulch, which surprises people.
Most people think the mulch should be, composted for three to six months, but we don't. we've always found the best results using fresh. So if the tree is dormant and we apply it in winter, then really by the time the tree comes into leaf in spring, most of those chemicals where we're looking for the effect have simply been, leached away or degraded in the soil.
Interesting. okay, so we were talking back to the studies and you started five years ago. What type of wood did you start with for your first mulch tests? Originally, we looked at two species of oak and then we looked at hawthorn and then we mainly looked at fruit trees. We looked at apple and we looked at cherry and the other one we looked at was birch as well.
And the reason why was because reading the literature, we knew that the fruit trees, for example, were high in sugars. And at the time, I was actually doing some research looking at the influence of sugar feeding on, basically stimulating, or the influence of sugar feeding on, Tree roots and mycorrhizal associations.
And what we did find that was by applying small amounts of sugars, we did get some stimulation of root growth and mycorrhizas. So we wanted to focus on, as I say, primarily the fruit trees. So our original research really wasn't from the pests and diseases. It was more of a means of enhancing transplant survival.
Or maybe trying to help trees that are mature trees that are going into decline. particularly after construction or building activities that have maybe severely damaged the root system. Okay, so you're starting, let's, talk about fruit tree mulch. So you're, actually, chopping up branches of fruit trees, into small pieces, and you're mulching other trees with these fruit trees, and you were suggesting that mulch would be high in sugars.
Why would that be doing any favour for the tree you're mulching it with? Why does the tree, why is the tree craving sugar? From its mulch. It's interesting, it's a good question. And there's a number of reasons. One of them is whenever you plant it let's just say for example you buy a tree from the nursery and you plant it into the ground now trees form mycorrhizal associations.
And the question is, how does the mycorrhiza know that there is a tree close by, with which to form an association? Because most nursery stock tends to be very, is either devoid of mycorrhizae or has very little mycorrhizae. And one of the reasons why is, in nature, one of the means by which trees attract mycorrhizae to their roots is through the secretion of sugars.
So we have found that by applying these fruit mulches, we do stimulate a greater amount of mycorrhizae below ground, which is obviously a benefit for the tree. And the other reason why we look at sugars is, in essence, when you look at energy usage in any living organism, whether you're a tree, a human being, or even a giraffe, it literally is sucrose, glucose,
ATP and by applying sugars actually acts as, in essence, a direct source of energy for the tree. Very similar to humans, if we're really ill and we can't feed ourselves and we're in hospital, they put us on a drip and the drip contains sugars, which in essence keep us alive. And to a degree, we can do the same thing with trees by supplementing them with, as we say, low concentrations of the sugar we use was sucrose, which is really the one of the commonest forms of sugar, the one you buy from the supermarkets. Huh. So in your early tests with the fruit trees, were you aiming to give those roots some sugar so that these trees would last longer, would have a better survival rate? Was that the goal, to see how long you could, maybe even neglect them for a while, and would they survive longer?
Because they have access to those sugars. That was to help decline in trees, but the initial reason was, it was really to try and help trees, maybe overcome, because I work for a diagnostics laboratory, we do on occasion get samples where trees have either been maliciously treated or accidentally, Treated with a herbicide and all herbicides work either directly or indirectly by destroying the leaf photosynthetic system.
And really, once the photosynthetic system is damaged, the tree can't really, use the energy that's in light to create sugars. So originally, it was really just looking at applying these sugars, and really, of trying to put the tree on a little bit of life support. While the herbicide naturally breaks down within the tree.
And then, based on that, and we were finding we could prolong the life of the tree, particularly when they were under stress or they were in decline. It was then when we started to look at how these sugars are actually working. And that's when our research started to show that sugars are used as a direct energy source.
And sugars also stimulate mycorrhizal association. Huh, we've got an email now from Mark, and Mark is located in Huntsville, Texas. Mark asks, is it better to fertilize my fruit trees before mulching? Also, is pine mulch bad for fruit trees? Is what mulch, sorry Susan? Pine, from pine trees. Is it bad for fruit trees?
Most of our research has focused on deciduous trees, which we use fresh. I would have some reservations regarding coniferous species, because we know they are higher in tannins and resins and volatile oils. So normally, if I was to use a pine mulch, I wouldn't use a fresh one, I think I would compost it.
But once composted, as I say, you would still get those physical properties. You will get the weed suppression and you will get some fertilization effects. We also tend to find that, fruit trees by nature have been bred to produce high yields. So by default, we do need higher quantities of fertilizer.
So I would still recommend using the fertilizer and obviously a mulch as well. So would you, and he was asking, so would he fertilize before applying the mulch or does it not even matter? Sorry, Susan, I couldn't quite catch that. Oh, sorry. So he was asking, would he fertilize before applying the mulch or does it not matter when he adds fertilizer in addition to the beautiful, nutritious mulch he's putting on his tree?
Thank you. It really doesn't matter. we have looked at combinations and we tend to find we generally fertilize before and then put the mulch on top. But it doesn't have a huge amount of effect. It's just easier for us to apply the fertilizer and then put the mulch on. So it's really more kind of a labor thing, if It just takes that little bit less time if we're applying a fertilizer on top of the mulch. The fertilizer then has to work its way through the mulch. That's all. That makes sense, actually. Yeah, we've got an email from Ray. So Ray says, Hi Susan, I just love your show. Such great information. That's so nice.
Now, how can we tell if any mulch that we buy commercially is good mulch? Ray is from Boston. Good question. It is a good question. And the only way you can really tell is, you have to send it away for analysis. You really would. And that obviously would get expensive. Yeah, it really is. Actually, maybe one of the things we do at the research laboratory, is sometimes when we are testing products, one of the things you can do is you can actually take your mulch and you could maybe just like in essence, take some and put it in a bucket of water and just soak it overnight.
Now, Let's just say for example, if it's a bad batch of mulch, and we've actually been in situations where people have used mulch, which has been derived from, like walnut trees, which by the way are quite toxic or that have had heavy metals, accidentally or, Incorporated in.
And what we find is if we soak the mulch overnight in a bucket of water, then take some of the solution, what you can do is just water, maybe one or two plants, either growing in pots or, a little area out the way to do a little bit of a test beforehand just to make sure that the mulch isn't contaminated or it is fit for purpose.
That's a nice, that's an interesting idea. Yeah, good way to test it. back to, sorry, I just have a quick email from Dean. Dean is having trouble listening to the show. The player isn't working. and he probably can't hear me reading his question. But yes, this show is archived, Dean, so hopefully you'll figure that out.
I will respond to you directly about that. And so if you miss the live show, you can listen to the archive. so Yes, and one more question from Ralph from Danville, Illinois. Does the mulch need to be applied at the tree line or elsewhere? So where is the ideal place to spread that mulch? If you can, and I always recommend this, in a perfect world, I always recommend you mulch all the way to the drip line and a meter beyond.
And for example, I work closely with the Royal Botanic Gardens at Kew in London. And this is what they do with virtually all their trees. So we always recommend a meter beyond the drip line. However, I appreciate that's always easier said than done. So if you're looking for a minimal area to mulch, then I normally say take the diameter of the tree at roundabout, we say breast height, which is about 1.
3 meters. Take the diameter of the tree and let's just say the diameter is half a meter. We always go three times the diameter at breast height. So I would at least mulch to a minimum of 1. 5 meters. And I don't think I'm exaggerating, but I genuinely believe that, the life of the tree in some instances is literally won or lost based on that criteria.
Mulches really do have some very powerful benefits on trees. And, I know in the United Kingdom, if everybody mulches their trees in the United Kingdom, I genuinely think death rates of trees overnight would be reduced by 50 percent as a minimum. Wow. So always. Three times what we call diameter at breast height.
Oh, wow. That's interesting. one of the findings that you, one of the types of mulches you tried was willow mulch.
[00:21:39] Willow Mulch and Tree Immune Systems
tell me about that trial and what you learned about willow mulch. that came about as a different area because one of my areas of research is looking at the influence of the single species.
And my other area of research is controlling pests and diseases. Now, conventionally, when we control pests and diseases, we tend to rely heavily on what we call plant protection products, which is fungicides in insecticides, et cetera. And it was really just asking my students a question. And the question I asked them was, What makes a successful disease, a successful disease? For example, Dutch elm disease kills elm trees, but why doesn't it kill every single tree? And in the United Kingdom, we have a devastating disease called ash dieback, which kills ash, but doesn't kill other species of tree. And the answer to the question is, What makes a successful disease Is a disease that can attack a tree without the tree knowing it has a means.
trees can always defend themselves. They're like us. They have their own immune system. And a successful disease, in essence, bypasses, bypasses the immune system. And the tree, in many cases, doesn't even realize it's under attack. And so we were doing this research looking at ways of means of trying to, switch on tree defense systems.
Now, when we look at humans and, when we want to switch on our own immune systems, and we do this very regularly when we go abroad, particularly to countries like Africa, where we have to have a set of vaccinations. And what happens is, when we go for our vaccinations, we're injected with a weakened strain of, for example, diphtheria, or typhoid, or cholera.
And because we're injected with a weakened strain, it, it switches on our own immune system. So when we encounter the real thing, we're protected. And, I thought, can we use the same principles with trees? Can we take a disease of trees, i. e. Phytophthora, which we know is a killer, can we weaken it?
And, in essence, just apply it to a tree. the disease isn't strong enough to kill the tree. but it's kinda strong enough to let the tree know it's there. Switch on the immune systems. Now, When you look at the immune systems of trees, they're actually more advanced than humans. Because with humans, it's one injection, one immune system.
So if I have injections for diphtheria, typhoid and cholera, but not malaria, and I encounter malaria, I'm in a world of trouble. But with trees, they're more advanced because When you switch on their immune systems, you don't just switch on one immune system. You actually switch on about 13. And the other way by which trees are more advanced than us when it comes to the immune system is that with us, we need to inject ourselves with a weakened strain of the disease.
But certain chemicals actually switch on tree defense systems. And one of the earliest chemical shown to do this is salicylic acid, which we use all the time. It's aspirin. Salicylic acid is aspirin. And it was just really in conversation with one of my students, and it was like the two came together. We were looking at what mulches to use, and then it was like, Oh, wait a minute.
willow is Silax, and it's called Silax because it's high in salicylic acid. And we know salicylic acid switches on tree defense systems. where we've been looking at the fruit mulches to stimulate root growth and mycorrhizal associations, why don't we look at a willow mulch to actually see whether or not, when we use it, as I say, as a mulch, all that salicylic acid that's contained within the bark and the wood will leach into the soil, come in contact with the root systems.
And in theory should switch on the tree defense systems. And so that was our next set of experiments, and that's exactly what happened. We used mulch from white willow, Silax alba, and we used fruit trees, which were, the fruit tree species we used was very sensitive to apple scab, and when we applied a willow mulch, we actually found the degree of scab severity at the end of the growing season was significantly less, you could see a nice difference between a non mulch tree and a tree with a willow mulch. And our next set of experiments was where we looked at Phytophthora diseases. And we actually found some mulches would actually suppress disease severity by 60, 70%.
And we actually did publish that paper just to try and raise awareness of this. So this research, in a way, it's still in its infancy, but we're quite excited about it because the advantage of switching on a tree's immune system is it lasts the whole of the growing season. So for example, if I was a conventional grower and I was treating for pests and diseases, I would need to apply quite a few fungicide sprays, insecticide sprays, to control the various pests and diseases.
And the other advantage of the mulch is because you're switching on a whole battery of defense systems, it really boosts the tree's immune system against insect pests, against fungal diseases, against bacterial diseases, and even viral diseases. So it's like a one off treatment promotes the immunity against a whole spectrum.
Where if I was to control, say, fire blight of apple, I'd need to use a copper based product. And if I wanted to look at scab, I'd need to use a fungicide. And if it was an insect pest, it'd be an insecticide. It's amazing that the it's so exciting this research.
So Glenn, we've been talking about willow mulch and this possibly magical almost quality that it has of turning on fruit trees' immune systems.
so I have a question here from Kate in Ottawa, and well, Kate has two questions. She says, number one, I am clearing about an acre of willow shrubs from a field. Would running the branches through a wood chipper be sufficient to produce a willow mulch that will result in the benefits for fruit trees?
Or is additional processing of the branches necessary? And her second question is, are there any plants on which a willow mulch should not be applied? She says, thank you very much for a great show, Susan. So that's Kate in Ottawa. What are your thoughts for Kate's questions? Okay, we do exactly what Kate does.
when I have the willow, I just put them through a wood chipper. And then I just use that mulch direct. And we've looked at I think around about 20 different species of tree and we've never found any detrimental effects. I think one of the things we were trying to make our research is what we say very applied. I work for Bartlett and I do my research at Reading University, and what we do is we try to make this research we use, very, applicable. that is really it. There is no after treatment, just put it through a chipper, Put it to a depth the most to well, obviously, I'm I use metric.
So we say 5 to 10 centimeters to the drip line. And as I say, we haven't found any detrimental effects against a whole variety of different trees. I'm glad you're talking about thicknesses because as a person who from experience has done possibly everything wrong with fruit trees over the years, and that's how I learned.
I have in the past mulched too thickly. With mulch. And actually, the trees suffered because this heavy mulch maybe compressed their roots, maybe didn't let air go into, the root system. So can you do too much? Is there such a thing as too much of a good thing? You can. if, you make the mulch too deep, it will have detrimental effects on the tree.
And I know when I travel over to the U. S., for example, they call it volcano mulching. and I do see it quite frequently, and if the mulch is too thick, it's like any compost heap, if you've got a big compost heap, it's gonna get awfully hot in the center. As it starts to break down. So you may get a heat effect.
And one of the things we always recommend is don't apply the mulch right up to the base of the tree. At least leave round about one to two inches or two and a half to five centimeters of clear space. If the mulch actually goes up to the, up against the tree stem, it can get that little bit moistened and humid and diseases tend to thrive in warm, moist, humid conditions.
They tend not to survive in kind of airy environments where there's more oxygen. So we don't put the mulch right up to the base. And as you say, literally 5 to 10 centimeters. And that's it. You don't need to go any deeper. One question is when I first started to learn about your research, and Lord knows I got very excited about it.
And I decided for our orchard we had to get our hands on willow mulch. We had to. So I called a number of places. including our local Bartlett tree experts. And I said, guys, do you have a willow tree coming down? Because I would love the mulch. So I'm still waiting in line. I don't know if any willow trees are coming down in Toronto, but where do you source this willow mulch from?
And how easy is it to get to put on your trees if you don't have, some shrubs that on your property that you can cannibalize. there's two ways. in the United Kingdom, willow grows extremely well and is actually a very common tree. So within the United Kingdom, they use willow as a biomass crop and it's very easy to grow.
we just take 30 centimeter hardwood cuttings, put them into the ground, autumn, wintertime. And we normally have a success rate of 98%. Willows root incredibly easy. They will grow one to three meters depending on the growing season. And at the end of the growing season we can just harvest them.
maybe I'm a bit luckier. I can either simply, take cuttings from a tree that are close by. I call it a willow wall. I just literally create my own willow wall. We do tend to take down more willow trees. So maybe it's more of an issue in Canada than the United Kingdom.
I think, over time, maybe the listeners will reach out with their ideas, and I'm sure we will find a way. I have a question here from Joyce. Now Joyce doesn't say where she is from. Joyce says, Are commercial mulches treated with anything? Love the show, great topic. Sorry, Susan, are commercial mulches treated with anything?
So I guess she's wondering if there's any chemicals that are put on commercial mulches that we don't, might not want on our gardens. I'm not aware. I know in the United Kingdom, they steam treat the mulches. And that's really just to kill off any potential weed seeds. I'm not, as I say, I know in the UK that we can't or we don't use any chemical and I would presume it's probably the same in Canada. Mulches are normally treated if you buy them commercially, particularly the ones you buy from the garden center that come in bags. as I say, just to really kill off the weed seeds. I think something we tend to find, as I say, we mainly just use our own.
Yeah. and the chipping process itself, putting the wood through a chipper, really. it takes out all the weed seeds, things like that. So we just don't have that as a major issue. Something I've seen here, and I'm sure that it's across North America, as you can buy colored, wood mulch, like it's colored with chemical that colored black or colored red.
And I think that is something that I don't want on my garden. I don't know what they do to dye the chips, but it's I don't find it attractive. And it's also I'm assuming I just don't want those chemicals in my soil. I agree entirely, Susan. I've seen these mulches for sale. I don't recommend them.
I don't use them. I just prefer to make my own mulch. we are a tree company. we produce a lot of wood chip. In many cases, we just give it away. it's, I wouldn't say it's a waste product because we send it to use in biomass production for energy.
It's like a green form of energy, but yeah, these ones that are colored, maybe in the landscape, it might have some influence, but it's not something that's formed part of our research trials because, the coloring must be some form of chemical they've added. Exactly. in terms of, this is a question that came to my mind.
If I can't get willow mulch, and I want to put it on this year. What if I took an aspirin and smulches it up and added it to water and put that on my trees? Would it have a similar effect or is that a dangerous thing to do? it's a great question because I've asked this a lot. I actually wrote a paper called aspirin for trees.
Now, in theory, the answer is yes, you can actually take aspirin because it contains salicylic acid and you could add it to trees, but In theory, but in practice, I don't recommend it because, we don't really know what we call the dose response. I couldn't genuinely tell you how much aspirin to add into a litre of water and how much to apply.
There has been research done looking at salicylic acid and it is actually easy to burn. So I know it sounds a great idea in theory, but I wouldn't really advocate it. And also, I know when I go into the supermarkets, there's a whole different array of aspirin you can buy. And I think some brands have more aspirin in it's more of a purer form. So it's really, I would say a non starter. I genuinely wouldn't go down that avenue. Now, you also tested other types of wood and it seems like they all have different effects. for instance, you said there was birch mulch or eucalyptus mulch. What were the different effects that the other different types of wood chips had?
We actually find that the mulches fall into one of three categories. And this is broadly speaking. There are some mulches which we find are very good at stimulating root growth. Now, they are predominantly the trees that are high in sugar, i. e. the fruit trees. And then we find there are other trees which work by either stimulating the immune systems such as the willow. And you mentioned eucalyptus and eucalyptus is very good for helping suppress some of these soil borne diseases such as in the United Kingdom we have a huge issue with our malaria or the honey fungus or the boot lace fungus and some of the soil borne phytophthoras.
So we find that the eucalyptus mulch contains various products which take out those diseases in the soil. And, what we're trying to do is, fast track it a little bit, and one of the advantages of being at the university is, we can take twigs from lots and lots of different tree species, and what we do is we put them in a test tube with some water, and we put it into a centrifuge that really spins these 20, 000 revolutions a minute, or something crazy like that, and all the products that are in these little twigs of all the different tree species go into solution.
And then what we do is, we like incubate different seeds in these solutions to see if we can stimulate seed germination or inhibit seed germination. or whether or not we can spray it onto plants and see whether or not we get an increase in growth or an influence on, pest and disease severity.
And that's really where our research is at the moment. One of the areas we're very keen is most of my research is focused just on one species of willow, which is the white willow. And we've now linked up with Ness Botanics in Liverpool and obviously Kew Botanics. And what we're doing is we're trying to get a whole diversity and we're now looking to see whether or not there's a super willow out there, one that is possibly far higher in salicylic acid, which would give us an even greater response than the willow we've used at the moment.
Wow.
[00:39:51] Future Research and Applications
So let's, we'll talk a little bit more about that, where you're taking this into the future. So Glenn, we've talked about all the amazing research you've done, the interesting discoveries that you did not expect.
how has it been received? I heard that the queen is interested, or at least the royal family is interested in trying out this stuff. the company, Bartlett Tree Experts does have the royal warrants because we do look after the trees at many of the royal households and, obviously they are very keen on managing any form of pests and diseases organically.
and so this type of research has attracted some interest. It's just really trying to look at ways of managing pests and diseases differently, that's all. Really, as we say, mulch is pretty much a waste product, so that is one of the products we're looking at. we've mentioned salicylic acid, and whether you like it or not, business is very quick to kinda move on this type of research, and there are a number of products available, which we can now use commercially to as I say, switch on tree defense systems, and I don't know if it will be available in Canada, for example, but in the United Kingdom, we have one called Rigel G, and this kind of contains a salicylic acid product. So we're starting to look at combinations of them.
And also the other reason why it is attracting a lot of interest, particularly, not just at the Royal Household, but other kind of ornamental gardens and parks as well, is the products we're applying, we're actually applying them to the root system. And because it's an induced resistance, it's actually switching on those defense systems, not just within the root system, but above ground as well.
And obviously it's a lot easier to apply products. At ground level than above ground. That's all. Absolutely. Do you have organic orchards that have started to implement some of your suggestions? Literally this year, we've instigated a trial with the Soil Association who are like that they are like the major organic growers within the United Kingdom.
And we have about four or five small scale orchards that will be adopting this technology. And, so as we say, the wheels turn slowly, but they are starting to turn. So it is nice. as a researcher, it's always nice to see your research actually really moving into the real world. And that is now really starting to happen.
It's so exciting. there's a question here, Bill from Chicago. So Bill writes, have you ever measured the amount of ASA in a natural environment versus applied? How do you measure the ASA levels?
I guess ASA has to do with salicylic acid. I'm not exactly sure the chemistry. I think it's acetylated salicylic acid. I think it's one of the common forms. salicylic acid will be in many, if not all tree species, but willow are predominantly high, where we are at the moment, we're actually doing that really as we speak.
we are now, we do have PhD students looking at this. what we tend to do with our research is it's a little bit double edged. For example, we know the willow mulches do suppress the disease severity in many instances. And then we're working backwards and trying to elucidate exactly how.
We know it's switching on tree defense systems, but as I've said, there's over 13 different defense systems. So which ones is it predominantly influencing? So I guess in a long way, we are looking at that at the moment, really trying to work out exactly how the salicylic acids. Are really influencing like the tree biochemistry and physiology and how that in turn influences disease severity.
maybe in a year or two's time I'll be able to answer that one. Another question, again from David in Washington state. So and this is interesting. David writes. What about the thickness of mulch? We talked about this a little bit, but here's his specific question. Less is better in terms of being able to cover a large area, for example, commercial orchards for this use.
So I think what David is asking is how thin can you get away with it, still making a difference? that's a great question, and we've always really just stayed at as a minimum. five centimeters. And that is really based on kind of guidelines by a number of organizations, like the International Society of Arboriculture.
They always recommend a mulch layer between five to 10 centimeters. But that is a really good question. could we apply it at one centimeter? And as you say, make your mulch go even further, or would we need to do that five centimeter? that is a really great question, and that is something I will be bringing into my research trials later on.
That sounds great.
Thank you so much, Glynn, for being on the show today.
[00:45:34] Conclusion and Farewell
it's been really fun to explore these issues with you, and I can't wait to hear how things continue to go with your research.
No, it's been a real pleasure, and, and again, thank you for letting me talk about my research. It's something I enjoy doing. Okay, wonderful. we'll speak to you again someday. Thank you. Bye bye. Okay. Thanks, Susan. Take care. Bye now. Okay, that's it for today's episode of the Urban Forestry Radio Show.
We had Dr. Glynnn Percival from the Bartlett Tree Research and Diagnostic Laboratory in the UK. What an interesting conversation. I hope you enjoyed it. And if you liked the show, there is lots more information at my website at orchardpeople. com and go to Facebook and, if you like my show, just like the Facebook page, the Orchard People Facebook page, that's always nice to make me feel loved.
Anyways, you can check out my blog on orchardpeople. com. You can get previous episodes of this show at orchardpeople. com slash podcast. And if you are ready to up your fruit tree care game, you can also check out my online fruit tree care training course. My students include arborists, master gardeners, urban agriculturalists, and home growers.
And you can learn about that at orchardpeople. com slash workshops. you've been listening to the Urban Forestry Radio Show on Reality Radio 101. And I'm Susan Poizner. Thanks so much for tuning in. I look forward to digging into a new fruit tree care topic with you guys again next month.
You've been listening to the Urban Forestry Radio Show on Reality Radio 101. To learn more about the show and to download the podcast where I cover lots more great topics, you can visit orchardpeople. com slash podcast. The show is broadcast live on the last Tuesday of every month. And each time I have great new guests talking to me about fruit trees, food forests, and arboriculture.
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