Welcome to the Good Growing Podcast. I am Chris Enroth, horticulture educator with the University of Illinois Extension, coming at you from Macomb, Illinois, and we have got a garden bite for you this week. Chestnuts roasting on an open fire. We are going to be pulling an excerpt out of our 2021 webinar, where there were several of us, horticulture educator, good growing folks, talking about going nuts over tree nuts. In this excerpt, horticulture educator Ken Johnson talks about the American Chestnut, really kind of chestnuts in general.

And in this, he will discuss the American Chestnut, kind of the downfall of that when it comes to the dreaded chestnut blight, and then growing chestnuts, kind of how we are using other Asian type chestnut types in our production of chestnuts, and then bringing the American chestnut back. Even talks about eating chestnuts and how you can do that. It's gonna be a fun, fun garden bite today, folks. So enjoy.

Alright. So next up, we have got chestnuts. So you may or may not have ever eaten chestnuts before, but, there are there are references to some Christmas songs and stuff. So it is a, at one time at least, a popular nut here in the United States, and it is rather popular around the world, as well. So chestnuts are in the same family as beeches and oaks, the Phagaceae.

Chestnuts belong to the genus castania. So all of the chestnuts that grow around the world belong to the single genus. The chestnuts themselves, those nuts are within the spiny burr, and you can see that picture here. If you've never seen one of these or handled one, those spines are very sharp and they are rather painful to pick up with your bare hands. So if this is something you're gonna grow, that's something you want to keep in mind.

Maybe not the best shade tree out there, since they're dropping these rather spiny burs. Kind of think of them like sweet gumballs on steroids. And then the nuts themselves are kind of unique, different than most of the nuts we think about. They're rather fleshy and they have a starchy texture. They're about 49% carbohydrate, 44% water.

So because of this, they will spoil rather easily. We can't leave these, you know, on the on the counter in a bowl of other nuts. These need to be refrigerated, or the quality will decline rather quickly. So there are some other plants we refer to as chestnut. Horse chestnuts or buckeyes are sometimes called horse chestnuts, that can be confused with one another.

The horse chestnut or buckeye are toxic. So that's not something you want to eat. As you can see in comparison here, again, our chestnuts have that spiny, burr that isn't closing the nuts, whereas our buckeyes or horse chestnuts have a more fleshy covering on them and their their the husks are more bumpy than they are spiny. And then the nuts themselves on chestnuts, they have these little tufts on the end of the nuts. That's the style and other flower parts that are still attached to that nut.

Whereas the the buckeyes, the horse chestnuts are round, and smooth all the way around. And then chestnuts, are going to have a flat side to them. Typically, at least one side is going to be flat if they if they develop properly within that bur. So when it comes to growing chestnuts, there's 4, primary species that are going to be grown or hybrids of them. So all of these, species will cross with each other and form hybrids.

So Chinese chestnuts are probably the most widely grown mainly because they have very high blight, chestnut blight resistance. So you can see, the size of these trees, American Chestnut, can get rather large. They have rather small nuts, which is a drawback, but they from people who have eaten them, they're kind of considered the best flavored nuts, even though they are smaller. Problem is they have absolutely no resistance to chestnut bites, so they are not really, grown at least extensively east of the Mississippi. And we also have European and Japanese chestnuts as well.

And a lot of those will be some hybridized of these other species for our more commercial varieties that are grown. So we'll talk about briefly about the American Chestnut here. So the American chestnuts are capable of reaching a 100 plus feet tall. Trunk diameter is over 10 feet. So these are kind of the redwoods of the eastern United States.

These are massive, kind of keystone species or they were at one point. At one time, you can see in that map there, they stretched from Maine to Mississippi, covered an estimated 200,000,000 acres, of the United States, primarily along the Appalachian Mountains. And at some point some areas in the Appalachian Mountains, 1 in 3 trees was a chestnut. I think about overall about 20% of the trees in the Appalachian Mountains used to be chestnuts, at one point. They are a very important, species.

They produce a large consistent seed crop. When we think about some of our other nut trees, especially like oaks and stuff, we have, mast years where they may be real heavy 1 year, and then the next year or 2, seed production isn't as high. With chestnuts, you will get a the American chestnut, you've got a consistent seed crop every year, which is very important not only for wildlife, but also for the people that lived, in this area. You can look in kind of the literature and see references to in some areas where there are really a lot lot of chestnut trees, chestnuts will be 4 inches deep on the forest floor because these these plants have put out, so many chestnuts. They're also a vital lumber source.

They are straight grained, very strong wood, and that is also rot resistant. A very valuable tree, not only for food, but also, for lumber. They also grow a lot faster than oaks, so you can get that that wood a lot quicker in comparison to oaks anyway. And many, if not most of the of the log cabins that were built east of the Mississippi, used to be made, from Chestnut American Chestnut, at least, when it was still around. I mean, I came across a quote from George Coleman, who said that the American Chestnut carried a man from cradle to grave and crib and coffin.

So not only were homes built with the wood from these, furniture, fence posts because they were rot resistant, barns, all kinds of different things. So an incredibly important, tree species. Unfortunately, they have absolutely no resistance to chestnut blight. Chestnut blight is a pathogen that is native to Asia. It was first noticed in New York City, the New York Zoological Park, which is now the Bronx Zoo.

It was in 1904. That was when it was first noticed. It's kind of speculated maybe earlier than that came in, probably late 1800s, early, a few years early, like 1900 or so. So when it first got into the US, more than likely on imported chestnut trees from either China or Japan. By 1906, so 2 years later, 98% of the trees in the Bronx were infected.

By 1912, all the trees in New York all chestnut trees in New York City, at least American chestnut trees, were dead and spread to 10 states. And it was spread at a rate about 50 miles a year, primarily human aided. So as these trees died, people would go out and log them. Now they would get the spores from this pathogen on their tools, on their clothes, on their boots. And then when they would go to other areas, they would transport it.

By 1930, it had reached Georgia. So gone from New York to Georgia, in about 26 years, 25 years or so. By 1940, almost every chestnut tree in the Appalachian region was either dead or showing symptoms. So basically within about 50 years, American chestnuts were almost completely wiped out in the eastern United States. It's estimated about 3 to 4000000000 trees, were destroyed.

So again, this is a lot of trees. And it had some really it has some really big effects on ecosystems. Again, all of those nuts that typically fed animals are now gone. So there's a lot of reduced food out there for the people that live in the area. Again, a vital food source for not only them, for their livestock.

Also disappeared building material, all of that stuff. So kind of a cautionary tale of, again, of invasive species and stuff. So enough of the doom and gloom. So when it comes to growing chestnuts, obviously they need to be blight resistant. If you don't have blight resistant trees, more than likely they will succumb to it at some point, or you just need to assume that.

When you're planting chestnuts, you wanna plant at least 3 tree 3 trees. They are not self pollinating. They're incompatible. So you need multiple trees so you get good pollination. If you have one tree, you're probably not gonna get any nuts off that.

If you're growing, named cultivars that are grafted, again, you're gonna have to have multiple cultivars, so they can pollinate one another. You can do, either seeds, or seedlings. So seeds, you know, if you buy a chestnuts for people, you can plant those seeds. You can either plant them directly in the ground, in the fall, or you can put them in a, a plastic bag with some moist potting mix, poke some holes in there, put that in your refrigerator. A lot of times, the crisper drawer, about 34 to 38 degrees.

Check those occasionally because you may get some mold in there. If you have any moldy nuts, remove those. And then after about 60 to 90 days, those seeds are probably gonna start germinating. Will start root development. When you see that, you wanna remove those seeds.

Pot them up, give them sunlight, full sun, all that stuff. And then after the danger of frost has passed, you can then go plant those outdoors in their permanent area. You can also buy seedling or grafted trees, as well. Again, those named cultivars. And you would just go out and plant those like you would, a typical tree.

Spacing, at least in a in a in a home setting, typically you wanna do those about 40 to 50 feet apart. You don't wanna get them too close because when they start shading each other, you have reduced nut production. So 40 to 50 feet apart is a good is a good distance. You can go up to 200 feet. If you get much further than that, then pollination can become an issue.

They do need well drained soils. Slightly acidic would be best pH 5.5 to 6.5, maybe a slight slope. Like you can see in this picture here, this is at University of Missouri. One of their research stations, they have a big chestnut planting there. But those well drained soils are really important because that's going to help with some of the some soil disease issues we can have.

And like I mentioned before, these do not necessarily make good shade trees because they are dropping these big spiny birds that you really don't wanna be walking on, and you have to clean those up. So if if you don't like sweet gums, chestnuts may not be the tree for you, at least from the dropping stuff perspective. These are just a few of the chestnut cultivars that are recommended by University of Missouri. Again, they've got, some plantings where they've done some research, on chestnuts. So those first four are recommended, by them.

Nuts per pound, the smaller the number, the bigger the nuts are. So that's people tend to want larger nuts than they do smaller nuts.

For those of you listening to the podcast, the cultivars recommended by University of Missouri are Gideon, which produces 28 to 38 nuts per pound, Sleeping Giant, producing 28 to 35 nuts per pound, Ching, which is spelled Qing, producing 21 to 35 nuts per pound, and Auburn Homestead producing 27 to 35 nuts per pound.

That Dunston variety, that wasn't one recommended, but I do know there is at least one orchard in in Illinois, and there's probably more that grow, don't stand, and have done so successfully for a number of years. So that would be another one if you're looking at chestnuts that you may wanna look into, as well. When it comes to pollination, again, they are not self fertile, so you do have to have multiple trees and multiple cultivars. If you're planting seeds, you don't have to worry about, that they're not genetically the same like cultivars would be, some of the named cultivars. They produce 2 types of catkins or 2 types of flowers.

So you have male only flowers. And then you have flowers that are both male and female. So those longer white fuzzy, strands are those are the male flowers. And then the female flowers are those little green, kinda spiky balls. There, the the female flower is gonna have 3 pistols for each birth.

So again, we're getting 3 seeds out of those if you get proper pollination. Typically blooming from end of May to mid to late June. A lot of it depends on a little bit on the cultivar and a little bit on where you are located. Mid to late June or mid end of May to to mid June for Missouri, when you start getting into Michigan. Michigan State's done a lot of research on chestnuts.

They're getting more into late June. So depending on where you're at in the state of Illinois, that that flowering timing could vary a little bit. And again, pollinator trees need to be within 200 feet, of one another to get proper pollination. They are primarily wind pollinated, although their insects will feed them. When I took this picture here, there is beetles everywhere visiting these flowers.

But insect pollination does not necessarily. They are primarily wind pollinated, so you don't have to worry about, pollinators and stuff visiting these necessarily. And they also have kind of a unique smell to them. It's kind of a sweet smell. Some people don't like it, some people do.

I think it smells good personally, but your mileage may vary on that. When it comes to pests, these are some of the common pests. So chestnut weevils can be an issue. What they're gonna do, you can see that weevil on the top picture there. They have these long snouts.

Their mouth is at the end of that snout like structure there. So they will, go around. They'll, chew holes, in those burrs and the eggs in the nuts and lay their eggs in there, kinda like, acorn weevils do. If you've ever collected acorns and they have those circular holes in there, it's because that larvae gets crawled out of there. Same idea with chestnut weevils.

So good sanitation is going to be important, making sure you're picking up all the nuts at the end of the year. If those kinda get established in your planting, you can take a couple years of management to get those out of there if they get into the soil. A lot of times they're starting to show up kind of mid August as those nuts start to fill. So insecticides typically mid August, at least in Missouri, is probably similar in a lot of parts of Illinois as well. That bottom picture that is the oriental chestnut gall wasp.

It's not in Missouri. I have not heard of it being in Illinois, but this is one to be concerned about. You can see they can form these leaf, and twig galls on those plants. And these these galls are gonna reduce shoot elongation, so the branches aren't gonna grow as much, reduce fruiting, and you can get twig dieback on these as well. There's really not any good chemical management.

There are some, heresoid wasps that will attack them, but that's kind of a boom and bust cycle. Sometimes they're there, sometimes they're not. It takes a while for them to catch up with those gall wasp populations. And just going back to chestnut weevils real quick, if if you were to grow chestnuts and you have issues with chestnut weevils, you can, treat your nuts with a hot water treatment. So you put them in a 122 degree, water bath for about 30 minutes and then immediately cool them, put them in a refrigerator, that's 32, 34 degrees, and that would kill any, weevil larvae that may be present, in those nuts.

Japanese beetles and caterpillars can also be issues, can be defoliators. They're more of an occasional issue. So you may or may not have to treat for those. And again, we're talking about trees. And, you know, if you're in a residential setting, you may or may not have the equipment once these trees get large to be able to treat for those.

In an orchard setting, populations get high enough, they would spray for them. But, most people are probably are not going to have the equipment in order to adequately spray their trees, for some of the stuff. So just keep that in mind. Critters, mammals can also be an issue. So young trees have relatively smooth bark.

The tree in this picture is not a chestnut. This is just an example of those tree guards you can put around there, to help with rabbits and voles feeding on those those young trees stripping that bark. Again, if you're using tree guards, you want to put that down a couple inches into the soil so voles can't tunnel underneath of that. Also a good idea to remove vegetation around trees so voles and stuff can't hide in it. Makes it easier for birds of prey to spot them, in the winter and stuff.

And as those trees get larger and that bark gets thicker, voles and rabbits really don't aren't an issue anymore, with those trees. Deer will also feed on trees, and the and the bucks will rub their antlers on there. So again, having a way to keep them out of there, whether that's fencing, again, that fencing has to be rather tall, 8 plus feet, so they can't jump over it. Some kind of tree guard, putting in t posts around there so that the bucks can't get in there with their antlers or rub. Various different ways you can go about that repellents, what have you.

And then the nuts themselves, when the nuts start dropping, all kinds of animals, will will feed on those, whether that be squirrels, possums, all kinds of other mammals, deer, stuff like that, will feed on those nuts. So making sure you're getting out there and picking those up before wildlife can get to them. As far as diseases, 2 really big diseases. So again, chestnut blight, you can see that on the top picture there, you kinda start off with orangish brown areas on the trunk. Eventually that will turn into a sunken canker, and that canker will girdle the tree, basically choking that tree off from the flow of water nutrients up and down the tree that everything above that canker is going to die.

So if that gets on the trunk, that tree is dead. So you're gonna grow resistant trees. If you're not gonna grow resistant trees, you know, it's not guaranteed you're gonna get it, but it's pretty close to guarantee, that you're gonna end up with, chestnut blight. Phytophthora root rot can also be an issue. This had this phytophthora root rot had killed off a lot of the American chestnut trees in its southern range before chestnut blight, showed up.

So typical, like a lot of other phytophthora diseases, you start to get wilting and die back of the canopy. This pathogen is in the soil and affects the root and crown area. You can see in this bottom picture there, this is the discolored wood near the base of that, that tree on that trunk that has been infected by this phytophthora. So planting in well drained soils is important to preventing this. That's going to be the best way.

Avoidance is going to be the best way of dealing with this particular pathogen. Once trees get it, there's really nothing you can do about it. So when it comes to harvesting and storing chestnuts, Typically harvest is going to be between September October. Again, this is, from Missouri. So it's going to match up with most of Illinois here.

You want to harvest your nuts at least every other day, preferably every day, again, to keep critters away from there. And 2 is that they don't store particularly long because they have such high water and carbohydrate, content in them. So pick them up. As soon as you're done, you wanna refrigerate them immediately in a plastic bag. Typically, you can put them in a 1 to 2 gallon, plastic, zip top bag would be good.

If you're using larger bags, you might put some holes in there, so you get some airflow through there so it doesn't get too too moist and start getting mold issues in there. For best so when it comes to picking up the nuts, again, those those burrs are very sharps. You need to have, heavy leather gloves are going to be a good idea. In a home situation, you can kind of roll those burrs underneath your foot, underneath your shoes, make sure you have some pretty good soles on your shoes to release those nuts and they can go pick them up by hand. In orchard situations, they have machinery that they'll use, almost kind of like a vacuum that they can use to suck it up.

Because the nuts have flat sides on them, it can be kind of difficult to use some of the mechanical harvesting tools, because they lie flat to the ground. It makes it hard to pick up. But there is some specialized equipment, especially from Europe, from Italy where there's a lot of chestnut production that people have imported some of that machinery to use to harvest. So you need to let these nuts cure for 2 to 3 weeks for best quality. So those starch will start converting into sugar and those nuts will get much sweeter.

So you're gonna put again, put these in the refrigerator store, 32 to 40 degrees for 2 to 3 weeks, is the best way to do it. You can also store them at room temperature for a couple days. That process will take place much faster, but you do run the risk of those nuts dehydrating, and that quality, being kind of reduced. Just be careful if you go that route. A chestnut that's kind of fully cured is gonna have a slight give to it.

If it's rock hard, it needs to cure a little bit longer. And if there's a lot of give, either it's starting to decline, it's really starting to dry out, or there's some other kind of issue with that nut. So when it comes to eating chestnuts, that shell is leathery. It's not again, like we think of the typical nut, it is not a very thick shell. It's rather thin and leathery, and they have an inner fuzzy skin called the pelicil.

And you can see that in some of these chestnuts here. You want to make sure to remove that. That's kind of has a bitter taste to it. So make sure you fully remove that. Typically, a lot of times they're going to be roasted.

And when you do that, you want to score those chestnuts. So you can see here, they've got an x on those, and then they can be roasted, in an oven, typically around 300 degrees for 20 minutes. You can put them in a microwave for a minute and a half, 2 minutes, depending on the microwave. And if you don't do that scoring, the nuts will explode and you'll have a big mess. Like, I can tell you from personal experience, it's not fun cleaning it up.

So make sure you score those. And like the songs, you can roast them over an open fire. Typically, you wanna do it more on the embers. If you have flames on there, the the the nuts tend to scorch. So put them in embers, and depending on how hot the embers are and how many you have, it can take 15 to 30 minutes, to cook those nuts.

And when they're cooked, they kinda have a texture similar to a potato, a little bit firmer than a baked potato. But there's kinda like that and it's a sweet taste. You can also eat them raw. Again, after they've been cured, it's the consistency is kinda like a carrot, maybe a little bit softer than a carrot, it's kinda crunchy. And again, sweet if it's properly cured.

If you have chestnuts that dry out too much and become rock hard, you can then grind those into flour and use that for baking. And there's a variety of different recipes out there, with chestnuts. There's a lot of Italian cuisine that has chestnuts in it. Chestnuts are very popular in China. It's like a lot of recipes from Chinese recipes are gonna have chestnuts in them as well.

And then one last slide for me. There are efforts to restore the American chestnuts in its native range. There's kind of 2 different ways, 2 main ways they're going at this. There is traditional breeding, and this comes from the American Chestnut Foundation, some of the work they're doing. So what they're taking, they're taking American chestnut trees and Chinese chestnut trees and crossing those, and they are back crossing.

So they're taking those trees that they get from that, crossing those with American chestnuts to try to get as pure of American chestnut as they can. They've been doing this for about 30 years. They're currently on their 3rd generation, and they've got trees that are about 60 to 90 percent, American Chestnut, genetically. And when it comes to, Chestnut blight resistance, they're intermediate. So they're in between American and Chinese chestnut.

So the idea is they wanna introduce this resistance from the Chinese chestnut, but to keep as many of those qualities from the American chestnut. So those big, tall, kind of lumber producing species, whereas Chinese chestnut is a much shorter, multi branch tree. There's also a transgenic approach. So when it comes to chestnut blight, that pathogen, it's going to enter into wounds from the tree and colonize those. It will produce oxalic acid and that acid is going to kill that, those tree tissues.

That pathogen will start feeding on that and then it just kind of spreads. They've inserted the oxalate oxidase gene, the OXO gene from wheat. This gene breaks down oxalic acid so that those that plant tissue isn't being killed. It doesn't affect the pathogen, but that breaks down that oxalic acid so the tree is not damaged. The tree they've come up with is called Darling 58 that is currently they have submitted that to the USDA for approval for planting.

And this tree is basically a pure, American chestnut. It just has that one gene inserted from wheat, and a lot of other plants also have this gene as well. So kind of the the benefit to this is that you can have a lot more genetic diversity of pure, American chestnuts. So they can release this. They can they can cross it with some of the surviving stands of American Chestnut, and kind of maintain that diversity of a virtually pure American Chestnut.

So again, that's that's in the USDA's hand hands for approval now at this point.

Well, that was a lot of great information about chestnuts, growing chestnuts, bringing the American chestnut back. What a good growing podcast is production of University of Illinois Extension edited this week by me, Chris Inroth. Well, that does it for 2024. It's our last podcast of the year. So we want to wish everybody a happy holidays.

Hopefully, we all get a little bit of time off and some r and r, you know, bust out those garden catalogs. I know they're starting to arrive in my mailbox. I'm sure they are showing up in yours as well. Well listeners, thank you for doing what you do best, and that is listening. Or if you're watching us on YouTube watching.

And as always, keep on

growing.