Orchard People | Apple Tree Rootstocks Explained with John Strang

Apple Rootstocks with John Strang

===

[00:00:00] When I was young, I thought that an apple tree is an apple tree. It took me years before I realized that there are lots of different cultivars of apples, and each cultivar may produce an apple that looks very different and they taste very different.

[00:00:17] some are sweet and some are tart, and in my opinion, they’re all very special. But even within a single cultivar, you can have very different trees. So some

[00:00:28] McIntosh apple trees will grow to be so large that you need a ladder to harvest them. And other McIntosh apple trees can be so small that even when they’re mature, you can pick all the fruit on the tree by hand.

[00:00:43] So what’s the difference?

[00:00:45] Why does one cultivar of apple trees come in all different sizes? Well, the answer is that the tree size depends on the rootstock that the tree is grafted onto.

[00:00:57] So in today’s program, we’re going to dig deep into apple tree rootstocks. And my guest on the show today is John Strang, retired extension fruit and vegetable specialist from the University of Kentucky. So I’m going to start chatting with John in just a moment. But first, I would love to hear from you, send in your questions, your comments, or just email us to say hello and we will enter you into today’s contest.

[00:01:27] And this month’s Prize is a book called The Modern Homestead Garden, growing Self-Sufficiency in Any Size Backyard, and it’s by Gary Pilarchik, valued at $24 and 99 cents. So to enter today’s contest, all you have to do is send an email during the live show to instudio101@gmail.com. That’s in instudio101@gmail.com.

[00:01:56] And remember to include your first name and where you are writing from. I look forward to hearing from you soon.

[00:02:03] So now to John. John, welcome to the show today. Thank you, Susan. It’s a pleasure to be here. So you are gonna tell us a little bit today about Apple Tree Rootstocks. So let’s start with the basic question.

[00:02:17] What are Apple Tree Rootstocks and how are they used? Well, rootstocks have been around for a long time. We’ve been grafting apples for in fruit trees for over 2000 years. The Greeks and Romans did that quite a bit. And originally you planted a seed and you got an apple tree, but you found one that you really like and you wanted to propagate it, but you couldn’t take a seed outta that apple and planet and get that apple.

[00:02:46] It’s like your children are gonna look exactly like you are and there’s not a chance. So, a lot of the progeny, apple trees aren’t very good for eating. And so they found out that if they grafted that variety onto a rootstock, they could maintain that genetic material and get the same tasting apple that they had before.

[00:03:07] And over time astute nursery, men and growers noticed that some trees were a little smaller than others, and they realized that they could graft these varieties onto dwarfing rootstocks. And the, they originally in 1472 they talked in the literature about a Paradise rootstock. And in the 18 hundreds European growers selected paradise rootstocks.

[00:03:36] There were two general types. There was the French Paradise or also called Paradise rootstock that was a smaller rootstock. Then there was the Duchen or English paradise that was a little larger rootstock. And of course, you know, if you’re a nursery guy, you don’t stick with one nursery, so you’d go to different nurseries and the Paradise rootstock in one nursery would give you a different size tree than the one in another nursery.

[00:04:02] So if you’re an apple grower, you want consistency in your tree sizes. And so, sir Ronald Hatton at the East Malling Station in Kent, England in about 1913, started collecting rootstocks from. all over Europe. They collected them from the Netherlands, and of course UK and France and Germany. And then they evaluated all of these and they picked the very best ones, and they numbered them one through nine, malling one through nine.

[00:04:32] And eventually they ended up with a total of 24 rootstocks out of this. And we’re still growing some of those rootstocks today. In fact, the so, so sorry, with the Malling, so this is the English station where they took all these paradise rootstocks, they’re all confused. They organized them and they labeled them well.

[00:04:53] How were they then going to propagate them so that it could be consistent so that the Malling nine or M9 is always one kind of thing. How could they in those days ensure consistency between like in one type of rootstock? Okay. Well, what they would do was they would, is create a, what’s called a stool bed, and they planted those rootstocks out as little trees and They let ’em grow the first year.

[00:05:24] Some of them laid them, planted ’em at an angle, and then laid ’em down and pinned them down on the ground and covered ’em with a little soil and let those trees grow. And the shoots would come up. And then in the fall they would cut those shoots off down to the original rootstock and they’d have a little rooted shoot.

[00:05:45] So they clonally propagated that rootstock. So it’s identical to the root system that they planted. And so then they would draft the scion variety or the variety that they wanted on this rootstock, and they would have a consistent orchard out there. So that’s how these rootstocks originated.

[00:06:04] And of course, England wasn’t the only country that looked at rootstocks. Russia developed the Budogovsky stocks, the Bud9, the bud 10. B118. Those are some of the more common ones right now. Germany developed the P I A U and supporter Rootstocks Canada developed the Ottawa and the Vineland Rootstocks.

[00:06:33] Poland developed the P rootstocks. The Czech Republic developed J T E H rootstocks. The Net Netherlands has released clones called N A K B rootstocks, particularly a Malling nine rootstock. France has a page rootstocks, and of course, the United States has. Used a lot of the rootstocks from all over the world.

[00:06:57] And Cornell University has developed a series of Geneva rootstocks. And these are some of the hotter or better rootstocks that are being grown in the United States and all over the world right now. Amazing. Such a such a wide variety. We’ve got, oh, we got a question here from Mike. Where is Mike from?

[00:07:18] I’m not sure. Oh, this subject is 2000 years. So Mike writes, hello Susan. 2000 years. John doesn’t sound that old . Only kidding.

[00:07:28] Sometimes I feel like that . Me too. I’ll tell you. Interesting show today. Thanks. So that was from Mike. Okay, so we have this mess of different rootstocks. It’s not mess, it’s organized.

[00:07:41] They’re all clones and. They all like, what is the difference between all of them? Why was there a need to have so many different rootstocks? Why didn’t they just pick three and just everybody stick with those? Well, we’re growing these all over the world, and as you would expect, they’re growing conditions in Canada are not the same as in California or in Florida.

[00:08:03] So some of these things are much better adapted in certain areas. You know,

[00:08:07] in Canada, you’re looking for cold hardiness. You want the thing to go through the winter.

[00:08:12] In Florida you the warm temperatures down there and all the moisture and things are really tough. It gives you problems with diseases.

[00:08:21] So, most people think with a dwarfing rootstock, you’re just looking for dwarfing. But commercial growers and growers are looking for something that’ll survive. That’s the bottom line. And give them a tree the size that they want. Now, one thing that you need to remember about dwarf rootstocks is that tree on a dwarf rootstock is not dwarf.

[00:08:42] Until it starts fruiting. So a tree on a dwarf fruit stock is gonna grow at the same rate as a tree on a ceiling rootstock until you put fruit on the tree. Once you get fruit on that tree, the tree mobilizes its resources with a dwarf tree into producing more fruit. Whereas one of these trees on a ceiling rootstock or a Malling Merton111 rootstock grows a lot more wood.

[00:09:09] And if you’re a grower, you’d kind of rather grow fruit rather than grow wood, cuz it takes a lot of time to prune these trees. And big trees take a lot longer to pick. They’re more expensive to maintain. We’ve got a lot of pests on apple trees and so spraying those trees is much more difficult to get that whole tree sprayed when you’ve got a big tree as opposed to a small tree.

[00:09:32] And of course with small tree, when you’re spraying, you get much better coverage of the tree. So you get a higher pack out, A number one apples off of a small tree, you don’t have as many cull apples. So there’s a real push for dwarf apples. Now part of the problem with dwarf apples, You there’s a little bit of a trade off, okay?

[00:09:54] When you go to a dwarf tree that rootstock is more brittle, okay? That tree cracks off at the graph union sometime, or the roots are brittle. Some of these newer rootstocks, the roots are like a stiff carrot. You can snap ’em, okay? So those dwarf trees have to be trellis, put on a trellis to support ’em, otherwise they’ll snap off with a heavy fruit load and a windstorm, or they may just snap off with a windstorm.

[00:10:24] So, you’ve gotta, gosh, do some extra things for these young trees. And so, yeah, so, so I’m seeing that with this huge variety. So we’ve. We’ve got an attempt to make the tree smaller for growers, so that’s great for growers. Handy also for home growers. Who don’t have room for a very big tree, so that’s fantastic.

[00:10:52] And yet is there a downside to having small trees, whether it’s in an orchard or, you know, was it a mistake in some ways to move away from these big strong, full size trees? No. There, there’s a lot of advantage to, to dwarf trees, but you’ve gotta take care of ’em if they’re planted close. If you’ve got an orchard that’s a dwarf orchard with a thousand trees per acre, that whole area underneath of.

[00:11:22] Orchard is honeycombed with roots. All of those trees are competing with each other. You know, I’ve been doing this a long time and we started out with semi dwarf trees and you know, those trees were planted 15 feet apart in the row, and then you. Start crunching the spacing down be between the trees.

[00:11:40] Now a tree grown in Canada or Minnesota does not get as big as a tree grown in North Carolina. We’ve got a lot longer growing season in the south, and those trees get bigger. And so, you control the size of that tree by the rootstock, but also you gotta prune that thing annually. You don’t over fertilize it.

[00:12:01] Okay? And you need to crop that tree consistently. Now, just apple grower says, well, I’m gonna crop it every year. But you get a frost that freezes all your flowers off the tree, or you have. Real rainy conditions during bloom, and the bees aren’t out there to pollinate it. So we get years where you don’t have much of a crop, so you put that energy into growing the tree and they can get pretty big.

[00:12:23] So, , there’s a lot involved in keeping that tree sized down. Amazing. It’s amazing because I really feel that there is this misconception that you buy a dwarfing tree and no matter what, it will be dwarfing, but if for whatever reason it’s not fruiting, it’ll just keep growing. That’s very interesting.

[00:12:44] How is it that over time we’ve filtered down to just a handful of apple rootstocks that people use again and again? And what are some examples of those very common rootstocks used these? We, the selecting rootstocks is a continuum. We don’t have the perfect rootstock. We’re always looking for something that’s better.

[00:13:08] And for example, when I first started working in Kentucky, we’d plant Malling nine rootstocks. Okay. It’s been around for a long time. It’s more prone to fire. It doesn’t have a lot of disease resistance in a lot of cases, and so, we find that Bud9 was a replacement for Malling nine. It was much harder.

[00:13:29] We’d occasionally get injury on Malling nine rootstock if we had an early fall freeze. It was much more susceptible of blight and it killed the tree. You don’t wanna lose your tree, so Bud9 is more resistant to fire. But both of those get Wooly Apple aphids. Okay? That’s a problem in the South more than it is up north.

[00:13:50] So, we’re looking the East Malling Research to Station developed the Malling Merton106 and Malling Merton111 route stocks by crossing ’em with Northern Spy apple to get Wooly Apple aphid resistance. But we’re Malling Merton111 is just too big for our grow commercial growers anymore. And Malling Merton111, Malling, Merton106 has problems with Phytophthora root rot.

[00:14:14] The trees died. So the Geneva Program has got really resistant root, you know, rootstocks that are very resistant to fire blight. They’re very resistant to Phytophthora root rot. They’re resistant to Wooly apple aphids, they’re resistant to latent viruses. You know, when we’re grafting these trees, they’re propagated cleanly.

[00:14:36] So you get a virus in that. Variety, you keep propagating it. Okay? And we’ve got some rootstocks that don’t hold up under latent viruses. That tree either dies or does very poorly. So you’ve gotta have clean cine wood to do that. It’s a lot of work cleaning that cine wood up. And we get viruses in the rootstocks, and so, They’ve cleaned a lot of these rootstock up for viruses.

[00:15:01] So it’s a constant battle. These are biological systems. They’re not static. So we’re starting to look at Geneva Rootstocks. G 41 has replaced a lot of Bud9 and Malling nine rootstocks in a lot of areas. You know, they’re still planting about 5% of the trees that are still going in are on Malling nine rootstock in the United States.

[00:15:21] But we’re getting away from that into some of these Geneva ones. It takes 20 years to evaluate a rootstock to decide whether this is a good one or not. And we want things right now in, in our society. And so we’re still looking at looking at better rootstocks and if. If you’ve got, if you’ve got a really poor soil, you want a little more vigorous rootstock.

[00:15:46] Okay, we’ve got some apples planted on a strip mine. You need to put a more vigorous rootstock out there. If you’ve got a really fertile good soil, you want a more dwarfing rootstock. Some varieties grow more than others. A Golden Delicious will produce a bigger tree then spur type gold and delicious.

[00:16:04] So let’s just have a look. We’ve got an email here from, who’s this? From? Ron. So Ron writes, your name John Strang was on the last year Midwestern Tree Fruit Pest Management, where maybe you spoke at a Midwestern Tree Fruit Pest Management Time. That’s a commercial spray guide for the Midwest Fruit Growers.

[00:16:27] Oh I retired a few years ago, so my name was on that. There’s a new one out that doesn’t have my name on it now. It just came out. Oh, okay. But it’s the Midwest. Fruit Pest management guide, and it is a spray schedule for commercial growers. Okay. We also have a question here from Glen Wright. Susan, when you go to a nursery to buy a fruit tree to plant, is that considered a rootstock listening to you in Ottawa, Canada?

[00:16:55] Thank you, Glen. What an interesting question. So, John, a lot of nurseries don’t tell you what rootstock you’ve, you’re buying. They say it’s a dwarf rootstock or a semi dwarf fruit stock or a seedling rootstock. So there’s certain nurseries like Cummins nursery in New York that tells you what rootstock you’re on.

[00:17:18] Commercial growers are very specific about the rootstocks that they want and a lot of ’em have to order their trees two years in advance of planning. So it takes a lot of planning to get the right variety and the right rootstock put together. A lot of these nurseries don’t like to graft things and then find they have to burn the trees cuz they don’t have a sale for it.

[00:17:35] So a lot of commercial orders are made ahead of time. . And something that I’ve noticed, John, is that in the fruit tree nurseries that I use, they do say, but you have to look at sort of the paragraph when they say apple trees, our apple trees are grafted onto these rootstocks. , the dwarf trees are on M9, the semi dwarf are on whatever, and you can always call them up to find out.

[00:17:59] Because over the years for me, I’ve realized that every rootstock has its own characteristics. Some are even more drought resistant, some are you know, there, there are so many different things that are customizable with a fruit tree. And so once you, Glen find out what the rootstock is, you can do some research.

[00:18:19] and see if your fruit trees need some extra special care if you get on the internet, or I believe if you look at your website the Cornell University has published the Geneva Apple Rootstock comparison chart. And that gives you a comparison of all of these rootstocks that shows you what size they’ll produce, which size trees they’ll produce, and it gives you all the characteristics that they’re resistant to or not resistant to.

[00:18:45] So that’s a really good place to start with on those rootstocks. And I will share that graph with everybody. When you wanna listen back to this podcast in the show notes, I’m going to put a link to that Cornell Geneva Apple Rootstocks comparison chart because John sent that to me. It is so useful.

[00:19:06] I’ve got two more quick questions. Okay. Here’s an interesting one from Mike, from Hammond, Ontario. Hi, I have a question for today’s show. For a home grower who would like to graft a tree or two, is there a downside other than not knowing the size to starting an apple seed to grow as rootstock? I had a few questions from people up in Canada looking at really hardy rootstocks like Antonovka and Dogo.

[00:19:38] Those are typically seedling rootstocks. They’re easy to produce, but they’re gonna give you a full size standard tree. If you want size control, you need to order some of these dwarfing rootstocks. And there’s a few nurseries that will sell small bundles of rootstocks. Typically, a commercial bot grower buys rootstock if rootstocks, if he’s gonna graft his trees from a nursery, they sell ’em in bundles of 50 or a hundred typically, and most homeowners don’t quite want that many rootstocks.

[00:20:09] We also have a question here from Dawn. Excellent question. Cle Dawn is from Cleveland, Ohio. Hello, Susan and John, what exactly is fire blight? It sounds nasty. Loving you in Cleveland, Ohio. Okay. When we’re spraying fruit trees, we’re spraying for a number of things. We’re spraying for insects like coddling moth, oriental fruit moth that puts a worm in the apple.

[00:20:34] We’re spraying for mites that are little spiders We’re spraying for fungus diseases that are the majority of the disease diseases like the fruit rots and apple scab, which is a real serious problem up north, or cedar apple, rust, which is more

[00:20:49] of a problem down south.

[00:20:51] Firelight is a bacterial disease and a characteristic of firelight or a characteristic of bacterial diseases as they multiply really fast under ideal conditions in the spring, during bloom you can go from one to a million bacteria overnight, so it literally explodes in the orchard and it kills trees.

[00:21:10] It hits the tips of the shoots, or hits the flower clusters and starts moving into the trees. Typically, it builds up on the flowers in the tree and then. Roughly about a month later, it starts hitting the young chutes and traveling down these chutes.

[00:21:24] Now, if you’re growing dwarf trees in a tall spindle system where you’re pushing them really hard with fertilizer to get ’em up to the top wire to start fruiting them they are much more prone to firelight. So commercial growers will spray with copper or streptomycin. They spray with streptomycin during bloom.

[00:21:45] They’ll spray with copper during the dormant season to kill the, what we call a epithetic bacteria or the bacteria on the outside of the tree. It’s a numbers game to get that as numbers down. And then a lot of commercial growers will spray with a light rate of copper during the season for the first year.

[00:22:05] Now, copper will rust it your fruit, so you’ve gotta be real careful with that. Rusting is a potato skin appearance like a Idaho rustic potato on the outside of the fruit. Doesn’t hurt the fruit or the flavor, but it makes it look unmarketable . And so, we don’t use that very often, but very light rates of something like Ku, Ava will tend not to rust at ’em if you don’t spray when the tree is really wet or under slow drying conditions.

[00:22:39] And you know, I’m glad that question was asked because you can see how beneficial it would be to simply buy a fruit tree grafted onto a fire blight resistant rootstock so that you don’t have to worry about those particular sprays, and you won’t have to worry about that disease. Well, firelight the rootstock is resistant to firelight.

[00:23:02] It does not impart resistance to the top of the tree. The firelight comes in when you get a sucker that comes up from the rootstock and firelight hits that and goes down and kills the tree, or ruins the efficiency of the tree. So, you still gotta take care of the top of the tree in some varieties are more resistant to firelight than others.

[00:23:23] That is so interesting and important to remember. We’ve got another question here. This one’s from Eric. Eric is from Boulder, Colorado. Hi Susan. A maybe off topic question here. Since pesticides are used in commercial apple production, what is the best way to actually wash an apple to eat? Just rinse in water or use something else to wash the fruit.

[00:23:48] Thank you. The pesticides that are used on fruit trees degrade in the environment. Otherwise you’d be able to spray in the spring and not worry about it the rest of the season. Okay, the tree grows, it gets bigger and the average consumer wants a perfect looking apple. When you go to the market, you’re gonna pick the best looking apple, so there’s a lot of coals involved.

[00:24:12] We don’t like to grow honey crisp in Kentucky, but our growers grow it because the market is there. But we only average about 50% marketable honey crisp. In one season. So, to, if you’re gonna try to grow apples organically, the best way to do it is to bag those apples. You spray the tree early in the spring till those fruit are about three quarters of an inch in diameter.

[00:24:37] Then you put a paper bag over it. The Japanese have newspaper type bags that you can put over it, but a regular paper bag, if you cut the, cut a slit on the side, slide it over the cluster and put it on with a little twist them, you’ll get a perfect looking fruit at harvest. If you’ve kept it sprayed.

[00:24:58] If you trap the insects or diseases in the bag, you won’t get a perfect looking fruit. Some of ’em will blow off in the wind, but with apples, you wanna make sure you take those bags off about a week, couple weeks before harvest, cuz otherwise a red, delicious apple will be white. You need sunshine to color those fruit up.

[00:25:16] That’s another. Another advantage at dwarf trees, you get good sunlight exposure on those apples, and you could get good color development, both red and yellow color. I’m gonna ask a question. Bring a question up that was asked on Facebook that I thought was interesting because. We’re talking about these rootstocks you said that many of them are regional because we all have different climates.

[00:25:41] So we got this email from Javier in Orlando, Florida. Hello Susan. I’ve worked with a variety of Apple rootstocks, but the best ones that I have experienced where I live in Orlando, Florida have been the larger size rootstocks of the Geneva Series. So these are Geneva 969, Geneva 210, and Geneva 890, M 11 and M 1 0 6 haven’t tolerated the long-term effects of the constant summer reigns and they get root rot even when planted in raised beds or containers.

[00:26:20] So I found that interesting because here you’ve got somebody in a warmer climate using rootstocks that have been developed in cooler climates. Yes. And that’s different growing conditions and Malling. Merton106 is very highly susceptible to phy root rod or collar. And so, we’ve quit recommending that in Kentucky because of that.

[00:26:42] Malling Merton111 is tolerant, but what you’ve gotta realize is tolerant is not immune. When we say something is resistant, it means it’s less liable to get it, but it’s not immune. So these things can still get ’em under ideal conditions. So, testing ’em out on your local situation helps out a whole lot.

[00:27:02] And I think he’s found something that works very well for him in his location. Now, Florida is not a big apple producing state. You know, if you wanna look for rootstock that do well in the south Auburn University in. In Alabama has NC one 40 trials. These, the North Central Regional Apple Trials as this is A U S D A.

[00:27:31] Usually university cooperative agreement where these rootstocks are tested all over the North America, in Canada and the United States. And so that’s probably one of the closer ones to him. They also have trials in Georgia, but most of those trials lately have been peaches. So, he should maybe check with Auburn University and see what they recommend or with his local extension service to see which ones are the best ones that are working for growers in his area.

[00:28:01] That’s a great suggestion. Florida has, doesn’t have a lot of cold winters, and so we have trouble getting the chilling requirement there. So a lot of these apple varieties that we talk about in the north don’t get enough chilling, they just don’t grow down there. So they have specific varieties that are selected for Florida, but you’re not gonna grow a Red Delicious down there or Harrelson or something like that.

[00:28:28] Gotcha. Okay. Well, there is we’ve let me see here. Just checking to see if there’s any other emails for the moment. No. Okay. So let’s, after the break, I want to talk to you a little bit about rootstock and cult of our combinations. Do some of them work better than others? I also wanna talk about the idea of a pest resistant rootstock and what that even means,

[00:28:54] So let, is it okay, John, if we go to the commercials for a few minutes and then we’ll dive back into this interview just in a minute or two. Is that okay? Certainly. Wonderful. Okay, lots more to talk about. In the meantime, you are listening to the Urban Forestry Radio Show and podcast, brought to you by the Fruit Tree Care training website, orchard people.com.

[00:29:17] This is Reality Radio 101.com. And I’m Susan Poizner, author of the Fruit Tree Care Books, growing Urban Orchards and Grow Fruit Trees Fast and we’ll be back right after the break.

[00:29:49] Hi, I’m Susan Poizner from Orchard people.com. And I’m Steph Roth from Silver Creek Nursery in Ontario. Join us for an interactive online workshop called Fruit Tree Grafting for anyone. In this workshop, we’ll teach you how to add different fruit tree varieties to an existing treat, and we’ll teach you how to create a fruit tree from scratch.

[00:30:14] This workshop includes live teaching practice exercises, lots of student participation, and professionally filmed high definition videos. This live workshop starts in February and the class size is limited. So reserve your spot today. Visit orchard people.com/workshops for more information and to sign up today.

[00:30:37] We’ll see you in class.

[00:30:50] If you are thinking of planting fruit trees and you’re looking for a wide selection of cultivars, consider wiffle tree nursery. Our 62 page full color catalog includes over 300 varieties of fruit and nu trees, berries, grapes, and other edible perennial plants. Not only that, in our catalog, we help you through this election process with tips and advice about all aspects of growing fruit trees.

[00:31:14] You can learn about adding nitrogen, fixing plants, rootstock choices, and even about planting a wind break if you have a windy site. We are a one-stop shop as we sell fruit tree care books, pruning tools, organic sprays, and natural fertilizers. We’re located in Allora, Ontario, but we can ship all over Canada.

[00:31:34] Call us at (519) 669-1349 to order your catalog. That’s (519) 669-1349 Wiffle Tree Nursery. Call us today.

[00:31:58] If you are listening to this show. You are passionate about fruit. But do you care how your trees are grown? Silver Creek Nursery is a family-owned business and we grow our fruit trees sustainably using only organic inputs. We stock a huge range of cultivars like Wolf River, an apple tree that produces fruit so large.

[00:32:19] You can make an entire pie with just one apple. We also carry red fleshed apples like pink pearl, as well as heirloom and disease-resistant varieties of apples, pears, apricots, cherries, and more. We ship our trees across Canada and we can also supply you with berry canes and edible companion plants to plant near your trees.

[00:32:40] At Silver Creek Nursery we grow fruit trees for a sustainable food future. Learn more about us at silvercreeknursery.ca.

[00:33:06] Welcome back to the Urban Forestry Radio Show with your host Susan Poizner, right here on Reality Radio 1 0 1. To get on board right now, send us an email. Our email address is instudio101@gmail.com

[00:33:34] and now back to your host of the Urban Forestry Radio Show, Susan Poizner. Hi everyone. You’re listening to the Urban Forestry Radio Show and podcast, brought to you by the Fruit Tree care training website, orchard people.com. This is Reality Radio 1 0 1, and I’m your host, Susan Poizner. In the show today, we’ve been talking about apple tree rootstocks with John Strang, retired extension fruit and vegetable specialist from the University of Kentucky.

[00:34:06] And in the first part of the show, we talked about what Apple Tree rootstocks are and how they help us to customize our trees so that these trees will be well adapted to our gardens and orchards. . But what’s interesting is that not all apple tree rootstocks and apple tree cultivars necessarily play well together.

[00:34:29] And if you are thinking of grafting a fruit tree one day, that might be important to know. So we’re gonna explore that and a few other things in just a moment. But first, I would love to hear from you. If you are listening to the show Live today, you can enter today’s contest just by sending us an email right now to intu101@gmail.com.

[00:34:53] So send your question, send a comment, or just email us to say hi. Be sure to include your first name and where you’re writing from, and if we choose you at the end of the show, you might be the winner of today’s prize, which is. A copy of the book, the Modern Homestead Garden, growing Self-Sufficiency in Any Size Backyard.

[00:35:16] It’s by Gary Pilarchik, valued at 24 99. So now back to John. So John, you know, the question is, do all rootstocks and scions or cultivars, do they all work together equally well or are some more finicky than. Some are more finicky than o than others, but most of them do fairly well. You can see overgrowth and undergrowth of graft union sometimes particularly on ceiling trees.

[00:35:48] Sometimes the scion variety or the variety on top will get larger than the rootstock and vice versa. You’ll see a big bulge right at the graft union where the rootstock is a lot larger than the cyan on top. And then we have incompatibility. Some varieties are just not very compatible with a lot of different rootstocks.

[00:36:10] Winesap is one of those. It has a little trouble hooking up with some rootstocks, so, the nurseries know most of this, so, There’s no one place that you can go to find this information out. It’s kind of well known that Honey Crisps doesn’t do really well on G 41. But a lot of people plant that one, G 41 is a really good rootstock.

[00:36:34] It is just a little bit brittle or highly brittle when the tree is really young from about one to four years old. So you’ve gotta be very careful with that one to keep it from snapping off at the graph union. So, s stake in that tree and actually trellising it on wire is better than staking it because you can get the wind blowing on that tree that twists it a little bit and that can pop it off at the graph Union.

[00:37:00] We have a question here from Michael from Alaska. So Michael says, hi Susan and John. Are you aware of any rootstock trials that are evaluating a zone two or three cold hearty rootstock in the Anchorage area? Bocata has been the go-to for years, but it’s slow to grow for the first few years. Then there’s Antonovka surprisingly, which doesn’t sup doesn’t survive consistently for us, and ska seedling rootstock is too inconsistent to rely on.

[00:37:36] Okay. One thing we need to talk about is hardiness of these rootstocks. These Geneva rootstocks are selected to be hardy, but most rootstocks get killed between 20, between 13 degrees Fahrenheit and 20 degrees Fahrenheit. So the roots are not as hardy as the top of the tree, and so the portion of the rootstock that’s sticking out of the ground is the part that is not as hardy.

[00:38:04] So in northern areas where you’re covered, the ground is covered. When s with snow and you have cold temperatures, that pretty well insulates the root system and keep helps ’em survive. We have the most problem with really rapid temperature drops where the tree can’t harden the tree well with a tree to survive, to avoid freezing inside the cells that ruptures the cell membranes.

[00:38:31] That water has to move out through the cell wall and freeze between the cells. And if you don’t have time for that water to move out, you’re more liable to get damaged. So that’s why freezing rate is so important, but mulching around the tree or protecting the lower part of that tree would do a whole lot to get ’em through the winter.

[00:38:53] Now at least in around Kentucky, we don’t like to use a lot of mulch around the trees cuz that’s a site for voles to over winter and they eat the bark off of your roots. Maybe they don’t survive that far north, I don’t know. But mulching will help out a whole lot or keeping the snow piled around the base of the trees.

[00:39:14] We’ll do a whole lot now. There are really hardy rootstock. Antonovka is one. Dogo crab is another one. Northern rootstock. I don’t think we’re growing Minneapolis in zone two. They get into zone three pretty much in Minnesota and Minnesota. They had develop to develop varieties that would be hardy enough to grow in Minnesota.

[00:39:38] A lot of the varieties like Golden Delicious don’t do well up there with the winners. So, as far as coming up with a rootstock, that’s really good for zone two. I think he’s trying ’em out and seeing what works. I would call the local extension service and see if they have any better recommendations for Hardy Rootstock.

[00:39:57] Yeah, that’s a great idea. And also I’d be very curious to know our, in Canada, our University of Saskatchewan has come up with some fantastic, really cold, hearty cherry trees. , and things like that. So they also might be, you might wanna check out the University of Saskatchewan website to see if they’re developing anything because they’ve been very creative over the years.

[00:40:20] Now talking about Saskatchewan, we got an email here from Doug. Doug writes hi Susan. Great show Today. Your guest mentioned rootstocks that you need in Canada. Where can I find these? And this is from Doug in Saskatchewan. So Doug, in Canada, it’s harder to get your hands on rootstock, but that doesn’t mean it can’t be done.

[00:40:43] And you’re a listener to this program. So I’m gonna tell you a secret. Okay, everybody, this is a secret Maple Grove nursery in Nova Scotia. They do sell rootstocks in Canada, and I think on salt springing island there are a number of nurseries that also may sell rootstock. So that’s a little lead for you, whether they have the Ontario rootstocks, I don’t.

[00:41:09] But Doug, get back to us and tell us what you find. John, do you have any suggestions as well? I don’t I think there’d be a problem shipping ’em across the border. I don’t know. But you know, the Cornell Geneva program cooperates with bridge Columbia and Vineland Station up there, and so I’m sure they’ve got rootstock available in Canada from some of the nurseries, some of these Geneva rootstock, and they are selected for hardiness.

[00:41:40] And, but your best bet if you’re in a really cold, hardy area is to check with a local extension service or go to the NC 140 Apple Rootstock page. You can search for that and look at the results on the local trials to see what’s surviving in your area. We have a question here from Dave. So Dave writes, is there any freestanding dwarf rootstocks in Kentucky?

[00:42:08] Great question because you were saying how important it is with these dwarfing rootstocks to support them with some sort of stake. So is there such a thing as a dwarf tree that’s really strong and can stand on its own? Well, one, one trunk ? No. With dwarf rootstocks some of the dwarfing seems to be associated with a higher proportion of.

[00:42:33] In the tree and that makes ’em brittle. I have a row of trees at the University Farm here in Lexington that was on Bud9 rootstock and the farm manager never got ’em Trellis. And so I just left them there. And over about 14 years, about 50% of those trees have snapped off at the graph union.

[00:42:51] So it gives you an idea. Some of ’em will survive, but you don’t want to take that chance. As the tree size gets larger, you get into trees that will self support. So Malling seven is one that we’ve used a long time. It’s. It it self supports relatively well, but it leans on heavier clay soil, so, it could use a stake in that situation.

[00:43:19] A lot of these Geneva rootstocks that we mentioned before, the G969 and G210 and G890 will self-support pretty well, but they are, you know, in the Malling seven size, which is about 65% the size of a standard tree for us in Kentucky. So, if you have a tree on planted on a dwarfing root, on a Malling seven rootstock and one on a seedling rootstock, the one on the Malling seven rootstock will be about 65% the size of the tree on the seedling rootstock.

[00:43:50] That gives you an idea. Trees don’t quit growing. They keep growing throughout their life, so even a dwarf tree can get pretty large if you don’t try to control that. I find that shocking to hear that 50% of these dwarfing trees broke broke off. That’s quite shocking. And when people come to me and they want to plant community orchards in, in public spaces, I will often suggest that they go for semi dwarf trees.

[00:44:16] They’re just stronger. Cuz if a kid starts grow, you know, climbing the tree, or kids are playing soccer and they’re kicking around a ball or whatever it is these trees can get damaged really easily. So, yeah, Dave wrote us back again. So Dave is from Cold Spring, Kentucky what are your thoughts on making Interstem rootstocks to create freestanding dwarfs?

[00:44:44] Wow, this is a great topic. So, Doug is Dave is suggesting M111 slash G 41. Or M111 slash G 214. Is this a good idea? So why don’t you start off by just telling us a little bit about what an interstem rootstock is? Well, we’ve used interstem trees for a long time, and that gives you a strong rootstock underneath it, self supports, and then you put a piece up.

[00:45:13] A piece up to nine inches long will give you the maximum amount of dwarfing that you get outta that rootstock as an inner. It’s outta the ground, and then you’ve got the signed variety on top. It’s much, it takes two graphs, so it’s much more expensive, so you don’t see much of those being sold by nurseries anymore.

[00:45:34] Malling Merton111 Rootstock with a Malling 9 or Bud9 inters stem work pretty well. That gives you dwarfing. You plant that tree so that the soil level is on the Malling nine portion of the tree. So the one 11 portion of the rootstock is completely underground. And that gives you a freestanding dwarf tree.

[00:45:59] I’m a little concerned about G 41 because of that brittle graph union. Using that as an inner stem I’m afraid it would break at the graph union there without a state to support it. But some of these other ones should give you very good dwarfing capabilities. Cornell is opposed to release a couple new Geneva rootstocks this year.

[00:46:21] I’ve heard don’t know what they are, but those are in the, it’s the future coming up. Oh, amazing. Amazing. It’s just so wonderful how much work is being done on this. Actually, here’s a nice email. So we have an email back from Javier. Javier, okay. I hope I said because I said Jer before.

[00:46:43] a poor guy. Anyways Javier writes hello Susan. I’m available to chime in about the apple rootstocks in our experience in Florida. , thank you. So, yes, we got your email. We’re gonna go through a couple more, but thank you so much. I’m sorry for hacking up your name. Oh my gosh, that’s embarrassing. Okay, now we’ve got an email from Ronald.

[00:47:08] Okay, Ron in Massachusetts on a young dwarf tree, it was said that you can go for more tree growth early by eliminating early fruiting for this to happen. Is the flowering stage or is the fruit set the point of critical elimination? Very good show. Okay. Do you wanna tackle that? Okay. With dwarf we should talk a little bit about rootstocks and apple trees.

[00:47:41] When you plant an apple seed, the tree that comes up is juvenile characteristic of a juvenile tree is it does not flower, and a lot of times they have thorns. Okay? That tree has to grow and get to a certain size several years later. It gets to the intermediate phase where it starts flowering a little bit, and then it gets to the adult phase where it flowers and fruits and doesn’t have the thorns.

[00:48:06] That’s one disadvantage of planting a seed to get a tree because it may take 10 years to get fruit on that tree. So we bypass that by grafting the roots and the base of the tree stay juvenile throughout the life of the tree. And so when you graft on a dwarf rootstock, it is juvenile. You are grafting the adult form on that flowers.

[00:48:32] Very quickly. You can get flowers on a tree that’s one year old without any problem on these dwarfing, rootstocks, they are what we call precocious, they flower very early. Now, when you’re doing this, you’ve gotta be very careful not to fruit that tree too young because you can stunt it. You get a little tree, you average homeowner says, I’ve got fruit.

[00:48:52] I’m gonna get that apple on the tree. And you leave too many fruits on the tree. And you remember we talked a little earlier about when that tree starts getting fruit, it goes into fruit production and it stunts that tree. It’s really hard to get ’em growing again. So if you’re growing a dwarf tree, you want to keep the fruit pulled off or just.

[00:49:11] Or not leave very many fruit on the tree until you get that tree up to the height that you want. So with these tall spindle plantings, we want to get that tree up to nine foot up to the top of the wire before we start fruiting it. In Kentucky on a G 9 35 rootstock with gold rush on the top local commercial grower, grew it one year, got it up to the top wire, and the second year he fruited it maybe eight, 10 apples on the tree.

[00:49:40] The second year, it does not does not stunt the tree, but he wanted to get more growth on the tree to get it up so he gets into full production much faster with these dwarf trees. The the other reason for dwarf trees is you can get ’em into fruit production much more rapidly than a semi dwarf or a a tree on a seedling rootstock.

[00:50:04] So you get a return on your money much faster. You fill that area up, you’re off. You’ve got that orchard up to full production. You know, if you planted seedling rootstocks on a 30 foot by 30 spacing like was standard and years ago, it’d take 20 years to get that tree up that acre up to full production.

[00:50:22] Now we can be up to full production in six, seven years typically. Well, my question here though is you’re saying you wanna get the tree to a certain size before you allow it to fruit. . So if you are getting blossoms on this very young wood, do you pick off the blossoms by hand? For instance, if you’re a home grower, or do you wait till the fruit forms and then remove the baby fruit?

[00:50:47] What is safer? Not all of those flowers will bear fruit. So you wait till the fruit is about three quarters of an inch in diameter and you pinch it off, you grab the stem and pop the apple off rather than grabbing the fruit and pulling it off so that you don’t damage the spur on the tree, the fruiting structure on it.

[00:51:06] Okay. Yep. And so, you know, my common practice would be I plant an apple tree. For the first two years I just take off all the fruit, just let it get strong. Right. And like you say, your average home grower, we don’t wanna wait. We wanna taste what this fruit is gonna taste like. We can’t wait. But what I say to people is, you know, this is a time for the tree to really extend its root system to get strong.

[00:51:34] And then it will feed you for, you know, Decades to come. Yeah. It needs that time for establishing itself, for expanding its root systems. Would you say that’s true? Yes. In a semi dwarf orchard, typically it’s three to four years to harvest the first fruit with the dwarf trees, if you’re really pushing them with drip irrigation and verion some varieties, vigorous varieties you can fruit the second year.

[00:52:02] Something like honey crisp or crisp that are slower growing trees that make two or three years to get ’em into production. We have just a few minutes left, but I’ve got a couple more Facebook comments that I wanted to bring up. One is from Mark from British Columbia, so Mark is enjoys grafting, and Mark says, personally, I’m switching from Bud9 to M9 since M9 has a terrible problem with burnout.

[00:52:31] Oh, it also seems to be quite a heavy sucker , if that’s a word. I like that. So comparing Bud9 to M9, you mentioned that one is more fire blight resistant, but what is this problem with burnout? And suckering burns are what we call a adventitious roots. They’re roots forming on the upper surface of the plant, on the trunk and the stems and so forth.

[00:52:59] And some rootstocks like Molly Merton111, are very prone to that. So if you leave much of that out of the ground, you get burns on there. They’re more prone to getting Wooly app aphids into those and firelight infections in those. So when we’re planting on Malling Merton111, we tell you to plant that so that the graft union is two inches above the soil line, so you don’t have that sticking out.

[00:53:24] Burnouts tend to develop under wet, rainy conditions and shade. And so, mul. Bud9 is and Malling nine are pretty similar as far as ratings for burn burns and suckers coming up from the roofs. Neither of them are prone to a lot of that. He may just have a shady or really wet condition or that’s promoting the burnout development.

[00:53:48] It does rain a lot in British Columbia from what I remember being up there. So that may be part of the problem. But I’m not, I think it’s the environment rather than the rootstock in that case. But Bud9 would be a much better rootstock to put in because of fire blight resistance.

[00:54:11] Gotcha. Okay. We’ve got also a minute for art’s question art from Minnesota, or it’s comment. I tend to graft more crab apples than bigger apples. I just seem to have more success using Dolga seedlings than anti. A N T Y. That’s, I’m on the, that’s short for Antonovka. I think. Antonovka, I see I’m on the edge of a prairie environment with hot summers and often dry periods with cold winters.

[00:54:43] I wonder if these Dolga rootstocks do better in shallow soils, slightly lower pH, and in areas where summer droughts can be frequent Antonovka rootstocks need several years to get decent growth. Both of those rootstocks are seedling rootstock, so you’re gonna have a lot of variation between trees.

[00:55:05] You know, everyone’s gonna be a little bit different and I don’t know what he’s referring to as a low pH soil. You know, we want a pH of 6.5, maybe down to six. You get to six, you wanna be putting lime on the soil to bring it up. That’s where these apple trees seem to grow the best. I don’t have a lot of experience with Dolga and antonovka other than knowing that they’re very hardy rootstocks, but he’s not getting much dwarfing out of those.

[00:55:36] He does get drought resistance, if you’re growing dwarf rootstocks, you wanna be able to water those trees because they’re packed in a little closer in, they are more sensitive to the drought stress. Earlier on we were talking, and you mentioned to me before we, we started the live show about the difference between dwarfing trees and dwarfing rootstocks and full size rootstocks in terms of watering and in terms of care.

[00:56:05] And you mentioned that . Dwarfing trees need more attentive care. Why is that? Well, when you plant those trees close together, you know, we’re planting trees three feet apart and 12 feet between rows. That whole orchard underneath it, there is honeycomb with roots beneath the ground, and when you run outta water, you’re outta water.

[00:56:31] And when you reach permanent wilting point on the tree, it quits growing. The fruit quit growing. They don’t start, they quit sizing. Now, if you’ve got a tree on a more vigorous rootstock, you know, a semi dwarf or seedling rootstock, you’ve got a much larger space to pull water from. You know, soil typically roughly for a foot of soil, you can hold an inch of water in that varies between a sandy soil and a clay soil.

[00:56:56] But if you’ve got four feet of soil, you can hold more water than if you’ve got two feet of soil and you want a area that’s well drained because roots don’t grow. Where the. The soil is saturated with water for long periods of time, so that will limit your rooting depth there and what’s available to the tree later on.

[00:57:18] We should talk a little bit about what’s going on underneath the soil cuz nobody sees that. But if you look at an apple, if you look at a root system on an apple tree, about 70% of those roots are within a foot of the surface of the soil. Then they send sinker roots down deep. They’ll go as low as 39 feet to pull water.

[00:57:39] So when a tree’s pulling water in a drought situation, it’s pulling from the surface of the soil. As it gets drier, it goes down deeper in the soil. So those lower layers in the. Are your reserve moisture for your apple tree. And so, it’s very important to irrigate ’em if they’re getting dry and permanent Wilting point is the tree is no longer able to survive when you wake up in the morning and those leaves are wilted and they don’t perk back up during the the next night.

[00:58:14] Okay, well it’s almost time now for us to find out who won today’s contest. Before we do the little contest prize ceremony. I just wanna say hello to Hank who wrote to me this month to ask about this month’s show. And Jillian wrote to me for last month’s episode on food escaping, saying thank you for the show.

[00:58:37] So thanks everybody who wrote me to all the show Listeners, if you wanna shout out during an upcoming show, it would be so fantastic if you could go to Apple Podcasts or to your local podcaster and post a review for the Urban Forestry Radio Show. If you post a new review, I will be sure to share it on an upcoming show.

[00:58:59] So now it is time for our contest, and in the studio we have Gary who’s gonna help us find a winner. I am. And John, I put all the names in a little bucket here. I’m gonna shake the bucket. You’ll be able to hear that. And you tell me when to stop and then I will pull out a little slip of paper with the names.

[00:59:19] Okay. Are you ready? Sounds good. Here we go. Stop and stop. Okay, let me grab one here and we’ll see what we have.

[00:59:34] Okay. Javier or Javier, I’m sorry, from Orlando, Florida. You’re the winner. Yes. Yay. Thank you so much. That’s wonderful. Okay, well congratulations Javier. Javier . Oh my gosh. So embarrassing when I can’t pronounce people’s names. And thank you so much, John, for helping us to choose the winner. I’m sure all the other people who sent in emails will be very upset with you right now.

[01:00:00] And disappointed. How do you feel about that, John? That’s fine. . . You didn’t come here to be popular, did you? Yeah. Yeah. So thank you so much to everybody who listened to the show today. Now I’m going to put up a video version of this podcast on the Orchard People YouTube channel in the next couple of days.

[01:00:22] So head on over to YouTube, look for Orchard People, and you can see videos of all of our shows or all the recent shows, and this one will be up soon too. So now I would like to thank you, John, for coming on the show today to chat with us about Apple Rootstocks. I’ve learned a. It’s been a pleasure.

[01:00:43] It’s nice to talk about fruit trees . Get into fruit trees cuz they enjoy it. . Exactly. Well thank you so much. So that was John Strang, retired extension fruit and vegetable specialist from the University of Kentucky. And that’s all for the show today. If you wanna listen to it again or download other episodes, go to orchard people.com/podcasts and you can learn more about growing fruit trees on orchard people.com, where I also have detailed articles and courses on fruit tree care.

[01:01:17] So that’s all for now. I hope you’ll join me again next month when we’re going to dig into another great topic.

[01:01:24] I’ll see you then.