In Search of Resistant Butternuts

A program is trying to save another
native tree that’s being wiped out by an invasive
fungus. People who like the butternut are hoping
that by planting more seedlings, and tracking
mature trees, they’ll find some are resistant
to a blight that’s killing the butternuts.
Lucy Martin reports:

Transcript

A program is trying to save another
native tree that’s being wiped out by an invasive
fungus. People who like the butternut are hoping
that by planting more seedlings, and tracking
mature trees, they’ll find some are resistant
to a blight that’s killing the butternuts.
Lucy Martin reports:


Butternuts are rich in history. Native Americans used the tree for
medicine and dye. They ate the nuts. During the Civil War, so many
Confederates used the tree’s yellow-brown dye to make home-spun
uniforms that their army picked up the nickname “butternuts.”


Wood ducks, finches and songbirds eat the tree’s spring buds. The fall
nut crop feeds woodpeckers, turkeys, squirrels and other wildlife.
The tree’s hard wood resembles walnut, but with a lighter, golden tone.
That’s why it’s sometimes called “white walnut.”


The trees are seriously threatened by butternut canker, an invasive,
airborne fungus. The blight was first noted in Wisconsin in 1967. In
some states, up to 90% of all butternuts are now affected, but there’s
work underway to try to save the butternut before it’s wiped out.


Tucked in an old orchard, a cold-storage room serves as a distribution
station. Each spring, this is where the Rideau Valley Conservation
Authority gives away seedling trees to the public. Project technician
Rose Fleguel gave me the tour:


“So, I think there’s about 100,000 seedlings here. These are boxed or
bagged so that the trees stay moist and dark. We’ve already spent two
days re-packing into individual landowner tree orders.”


At this time of year, the dormant seedlings just look like twiggy
sticks. Many are still wrapped in brown paper sacks. Conservation
agencies plant all kinds of trees. But sometimes they target very
specific problems, like butternut canker.


“My thing is the Butternut Recovery Project, whatever amount of land
can sustain 10 seedlings, then you’re free to take the seedlings and
plant them out. ‘Cause what we’d like to do is get the seedlings out on
the landscape, get them growing. Replace the ones that have been killed
by this disease, already, and that continue to be killed, and hope for,
I mean, it’s going to be, it’s going to be a shot in the dark, but hope
that maybe some of these seedlings might be resistant.”


“Hope” is the key word. It’s not clear whether any butternuts are
resistant to the canker blight. The seedlings being handed out are
from trees that are still healthy. This recovery program also maps
mature trees and keeps track of the ones that still seem to be canker-
free. It’s a long shot, called “find the resistance.”


Rudy Dyck is the Director of the local Watershed Stewardship Services.
He says you can usually see if a butternut has been attacked by the
disease:


“Look for black patches, black streaks, black sooty areas on
the main stem, at the root collar, and always look on the underside of
the large branches, because that seems to be where the canker first
infects.”


“And if you notice that, is there anything to be done?”


“No, there’s nothing you can do. We’re asking people to keep them, as
long as they can. But one of the reasons that butternut is in such
extreme danger of extinction is that it just does not regenerate very
well.”


Dyck says that’s why it’s important to conserve existing trees.
Butternuts don’t bear seed each and every year. And when they do, the
nuts tend to get gobbled up. Growing new butternuts takes a few tricks:


“You have to stratify them, or prepare them for growing, the next
spring. So they have to spend a few months in kind of freezing
temperatures, an un-insulated garage in a pot of peat moss, or
something. Another strategy some people do, is they bury the nuts in
the fall, and they cover them with chicken wire, and then that protects
them from squirrels during that fall period and, as they start to grow
next spring, you can transplant them.”


Dyck says US and Canadian agencies are sharing ideas and results
because diseases don’t stop at borders:


“There’s literally thousands and thousands of heavily cankered, dying
butternuts out there, and we really want to focus on looking at
healthy, canker-free trees. Because those are the trees we want to get
into our geo-data base, for future seed collection, those are the trees
that may hold some resistance and those are the trees we want to
track.”


Butternut canker isn’t a well-known problem. The beautiful trees are
too big for most yards. They’re usually sparsely scattered in forests,
or old farmsteads. But Dyck says the butternut has an important place
in nature.


“There’s no question, bio-diversity and having many, many types of
ecosystems, habitats, species. They all interact, they all count on
each other, and it all makes for a healthier environment and place for
us all to live.”


Many native trees such as the chestnut, elm, and now the ash, are under
attack from invasive diseases or pests. The butternut is yet another
tree biologists want to save for future generations.


For the Environment Report, I’m Lucy Martin.

Related Links

Romancing the American Chestnut

  • The smaller American chestnuts on the left were a part of culture for people who lived in hardwood forested areas of the U.S. The Chinese chestnuts on the right are not susceptible to the blight.

Food is always a big part of the holidays. But
one traditional food has – for the most part – disappeared
from American tables. Lester Graham explains:

Transcript

Food is always a big part of the holidays. But one traditional food has – for the
most part – disappeared from American tables. Lester Graham reports:


(Sound of Nat King Cole singing, “Chestnuts roasting on an open fire…”)


That old chestnut of a song romanticizes roasting chestnuts as a part of the
holidays. But a lot of us have never even seen chestnuts, let alone roasted them
on an open fire. Chestnuts used to be a major part of the Eastern hardwood
forest. There were millions of them. In fact, 25 percent of all the mature trees
were chestnuts. But a blight, imported with some Chinese chestnut trees, slowly
wiped out the American chestnuts. Now, they’re gone.


Well… almost. Much of the root stock is still alive. Sprouts grow until the blight
knocks them back again. A blight only hurts the standing tree where it branches
out.


And, in a few isolated pockets in the Midwest, the blight hasn’t reached the trees.
A few American chestnuts are alive and growing and some of them are free of the
blight.


At Nash Nurseries in central Michigan, owner Bill Nash is guiding us through a
rare sight… a grove of American chestnuts.


“These are 20 years old and as you can see, they’re fairly good sized. The
American chestnut is quite a rapid growing tree. It’s well-suited for our climate,
so it doesn’t have any of the problems that some of the hybrids do as far as
growing and cultural care you have to take care of them. The Americans, you get
them started and they’re pretty much on their own.”


In a few places in Michigan and Wisconsin there are small groves of chestnuts.
They’re prized trees. They’re great for shade. The hardwood is rot resistant and
makes great furniture and fence posts. And the chestnuts are eaten by humans
and wildlife alike. Bill Nash says the tree will be popular again if it ever
overcomes the blight that’s hit it so hard.


“The American chestnut will make another big comeback in this country as a yard
tree, as a timber tree, as a wildlife tree.”


That part about a wildlife tree is more important than just worrying about the
squirrels and bunnies. Chestnuts were an important food source for all kinds of
animals.


Andrew Jarosz is a plant biologist at Michigan State University. He says the loss
of chestnuts has been hard on wildlife populations.


“Chestnuts shed nuts in a more regular pattern than oaks, which will have what
are called mast years – where they’ll have major crops, massive crops one year
and very small crops in other years – which means it’s either feast or famine if
you’re depending on oaks.”


Since the blight first began hitting American chestnuts about a century ago,
researchers have been looking into all kinds of ways to stop it. One way is to cross
it with the Chinese chestnut which has a couple of genes that resist the blight. But
it takes a long time to breed out the Chinese characteristics from the American
chestnuts and still keep the resistant genes.


Another approach is genetic manipulation. Genetically modifying the American
chestnut tree to make it disease resistant. Again, work is underway, but it takes a
long time. And even after success, it’s likely some people won’t like the idea of
releasing a genetically modified organism into the wild.


The final approach worked in Europe when the blight hit there. It seems there’s a
naturally occuring virus that kills the blight. It spread naturally in Europe. There
are a few groves in Michigan that have naturally acquired the virus and it’s
working to keep the blight at bay.


Andrew Jarosz is working on the research. He says the trick is figuring out how to
get the virus to spread to other trees short of manually spreading it on cankers
infected by the blight.


“If we’re literally talking about millions of trees across probably, you know, the
eastern third of the country, we obviously can’t treat every canker on every tree.
And we need to be able to figure out a way to deploy the virus in a way that it can
spread.”


Even with all that hopeful research, it’ll be ten years at least before some practical
solutions end up in the forests, and Jarosz believes a couple of centuries before
the American chestnut holds the place it once did in the forests.


Bill Nash knows it’ll be a while before there are major changes, but he is
optimistic about the American chestnut.


“Oh, I would think the tree has a bright future. There’s enough people working on
that, enough programs going on now. So, I would suspect that in the not-too-
distant future we should have some of this progress made. You know, Robert
Frost in his poem predicted the comeback of the American chestnut, that
something would arise to offset that blight. And we’re starting to see that.”


Frost put it this way: “Will the blight end the chestnut? The farmers rather guess
not, It keeps smoldering at the roots And sending up new shoots Till another
parasite Shall come to end the blight.”


Seems Frost was an optimist too.


For the Environment Report, this is Lester Graham.

Related Links

Will Chestnut Trees Make a Comeback?

  • Due to a blight, American chestnuts are now rare in the Midwest. (Photo courtesy of the National Park Service)

In the first half of the last century, there were millions of American chestnut trees ranging from the Eastern seaboard to the Upper Midwest. Now, there are virtually none… because a fungus killed them. A campaign is being launched to bring back a blight-resistant version of the chestnut… and it’s being planted here in the Midwest. The Great Lakes Radio Consortium’s Bill Cohen
reports:

Transcript

In the first half of the last century, there were millions of
American chestnut trees ranging from the Eastern seaboard to the Upper
Midwest. Now, there are virtually none because a fungus killed them.
A campaign is being launched to bring back a blight-resistant version of
the chestnut, and it’s being planted here in the Midwest. The Great
Lakes Radio Consortium’s Bill Cohen reports:


Sprouts from diseased chestnut trees don’t get the killer fungus until
they’re 4 inches tall, so researchers like Brian McCarthy of Ohio
University have had plenty of raw material to breed a new version of the
chestnut tree.


“Fifteen-sixteenths pure American chestnut and one-sixteenth Chinese
chestnut. And that one-sixteenth of the genome confers blight resistance.”


Ohio is now planting hundreds of the new seedlings on top of abandoned strip
mines. McCarthy believes they may help reclaim the land.


“It’s not that chestnuts like this kind of soil. It’s that probably that chestnuts can
tolerate this type of soil better than other broadleaf tree species can.”


McCarthy hopes that a century from now, the blight-resistant chestnut
trees will once again be prominent in forests, providing high-quality
lumber and food for wildlife.


For the GLRC, I’m Bill Cohen in Columbus.

Related Links