Wednesday, November 14, 2012

Tuesday's Trees- American Chestnut

The mighty American Chestnut tree, the once grand giant tree is on the verge of disappearing.  Many of us know of the Chestnut Blight, Cryphonectria parasitica, and its affect on the tree.   At the turn of the last century the American Chestnut started dying in large numbers.  This fast growing, large tree, was developing  cankers.  These cankers run around the cambium layer of tree, killing first the leaves, then branches, and finally all above ground plant material is dead.  


The American Chestnut, Castanea dentata, once had a native range from Maine to Georgia and west to Ohio.  It was approximately 25% of the forest.  It is now either on endangered species list or special concern lists for many states.     
It is a fast growing, straight tree that can achieve heights over 100 feet in good conditions.  A mature tree can have a diameter of 17 feet.  These were huge trees.  Interestingly it was branch free on the lower part of the tree, sometimes up to 50 feet of trunk before branching.  


It was called the cradle to coffin tree.  From fine furniture to railroad ties, fuel to posts, this tree constituted more than 50% of the timber produced before the blight.  The timber is decay resistant, making it a useful wood for many applications.   Wildlife benefited from its nut production.   Bears to raccoon to deer to humans, everyone found the nut a good food source.  Trees will fruit 5- 7 years of age.  It needs another Chestnut to cross pollinate even though it is monoecious.  Much of the economy was based on the American Chestnut.  The bark and the wood were a great source of tannic acid, used for tanning leather.  After the blight killed a tree, the timber that remained was still used.  Worms had bored into the wood, so timber harvested after the blight was called wormy wood (holes). 


Chestnut blight was first discovered in the USA in 1904 on some trees newly planted in the New York Zoological Garden.  Many Japanese Chestnuts, Castanea crenata were imported as early as 1876 by mail order.   Chestnut blight, Cryphonectria parasitica, (known as Endothia parasitica - name changed 1978) spread as far north as Ontario.  One attempt to stop the spread of the blight was to create a firewall, sadly eliminating many healthy trees.  This practice was stopped after World War One.   By the 1940's there were more than 3 1/2 BILLION Chestnuts lost to blight.   Chinese Chestnut, Castenea mollissima, is resistant to blight, more on that in a little bit.   
Blight is a fungus and is spread by airborne spores. The spores are dispersed by animals, including man, and insects.  It can colonize on other plants, including oaks.  Chinquapin Oaks, Quercus muehlenbergii and Live Oaks, Quercus virginiana, are affected by blight.   
Sadly, blight is not the only thing that is killing American Chestnuts.  Meet Dr. Joe James, adjunct professor of Forestry, Clemson University.  Our Master Gardener group had Dr. James come and speak to us about his research with American Chestnuts.   


On his farm in Upstate South Carolina, he used to have a number of Chestnuts.  As they died he started doing some detective work.  Calling on the Forestry Department of Clemson, it was discovered that the roots were dying from Phytophthera root rot.  Phytophthera cinnamomi is a soil borne organism.   It is another import from Asia.  It is believed that it was imported by wealthy Charleston landowners in the late 1700's, bringing new plant material into the country.  This is not a fungus but similar to red algae, it is a oomycete (also called a water mold), has its own phylum.   It spreads through the soil, slowly.  Water can carry it to new locations.    It needs moist soil to live, dry conditions kill the oomycete but not the spores.  Frozen conditions kill it.  Here in the South, even if we have a cold winter, our soil does not freeze to the bedrock.  Mountain tops and further north this is not an issue.  
P.cinnamomii can remain dormant in the soil..  It is called Black Ink disease as the infected roots look as if black ink is being taken up through its cellular system.  Many plants are susceptible to it, 100% lethal to American Chestnuts.  The root rot girdles at the root collar, killing the tree.   Chinese Chestnut is immune to Phytophthera cinnamomii.  That is the good news.


Dr. James is part of a research program with cross breeding the American Chestnut with the Chinese Chestnut.  This breeding has been going on for a number of years, breeding into the American Chestnut, the resistance to Blight.  Each generation of this hybrid is tested by inoculating these new trees with blight spores.  Successful resistant trees are then crossed again with another American Chestnut, breeding out the Chinese characteristics except for its resistance to blight.  This is producing trees that have a fraction of Chinese Chestnut genes, the new American Chestnut hybrid.  Dr. James receives nuts produced from these trees, now blight resistant, and runs trials with various family groups (different lineage tree families), testing them for resistance of Phytophthera root rot.  One strain of Phytophthera is introduced to the roots after the seedlings start growing. Many die, but the survivors are transplanted into berms from the tubs they started in.  Once the tree has survived three years in the test mode, it is transplanted into the wild.   It will take many years for Chestnuts to return to the grand size that they once were.  This fascinating research bringing back this beautiful tree.  


The pictures of the small, understory trees at the top of the post were taken this past May, at the North Carolina Arboretum.  While on our guided tour, Tim Spira pointed out these small trees.  The blight keeps killing off the top growth.  Blight is coppicing (pruning to the ground to encourage suckering) these trees.  The new sucker growth will again be attacked by the blight, never allowing these trees to grow to their size of years ago.  
I did a posting on the Chinese Chestnut.  I have since learned more about the differences between American and Chinese Chestnuts.  The leaves-- American-- longer than width, prominent teeth which curve like waves breaking, base of leaf tapers sharply, leaf is thin and papery.  Chinese -- oval shaped, smaller teeth, base is rounded, leaf is waxy and thick.  The nuts are different, American nut is smaller, sweet, has fine hairs on the bottom of the nut.  Chinese nut is larger and less tasty. 
There is also some genetic research being done with isolating the gene that has the resistance to blight and phytophthera.   Many are working at bringing this tree back.  
This has been an interesting post for me to write, truly a learning experience.  My references online were
USDA Plant Profile, Duke, VA Tech, NC State, Appalachian Woods, and Columbia University.  My notes from Dr. James' talk were also used as well as a copy of "The Journal of the American Chestnut Foundation" issue on 'Phytophthora- The Stealthy Killer that Attackes Southern Chestnuts' September /October 2011.   I did double check my notes with online information.

©Copyright 2012 Janet. All rights reserved. Content created by Janet for The Queen of Seaford. words and photos by Janet,The Queen of Seaford.

27 comments:

  1. Lots of good info Janet. One of the participants in my Naturalist class has American chestnuts on his farm that are part of a study...Not sure if it's this hybrid or a native. Beautiful trees.

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    1. Gail, How wonderful that he is participating in the study. They are gorgeous trees. I envy your Master Naturalist class. Our closest one is over an hour away.

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  2. Our Master Gardener group had in a speaker from Cornell on the Chestnut Blight. It too was an interesting and enlightening talk. You made many points noted in our talk and it was nice of you to do this post. You provided much valuable information that many will use in the future.

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    1. Donna, One of the places they talked about doing the DNA research was Cornell. I think the research is wonderful I am glad to do the posting.

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  3. A fascinating post, Janet; I learned so much here. I had no idea the chesnut tree was such a valuable resource. It's good to know that scientists have finally found what is killing the American chestnut and working to create a disease-resistant hybrid.

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    1. Rose, thanks, you always say that. Glad you feel that way. As for the chestnut, yes, what a remarkable resource tree. It is interesting that there are two problems for chestnuts.

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  4. It's comforting to know so many dedicated people are working to bring these beautiful trees back. Thanks so much for the interesting update.

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    1. Lynn, yes, well said-- it is comforting to know people are working on saving these trees.

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  5. I would love to see a revival of the American chestnut. Thanks for this post, lots of good info. When we were in Turkey chestnuts were sold very commonly by street vendors, I wonder if those were Chinese or some other kind of chestnut.

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    1. Jason, yes, I would like to see the revival of this great tree too. There are six species of chestnuts worldwide, so that ones you saw in Turkey could have been one of five (American being eliminated from the list).

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  6. I do love these informative posts.

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  7. I didn't realize that chestnuts had more than one serious problem, as if the blight wasn't horrible enough. The forests must have looked so different back when there were so many and they flowered in spring. I knew there had been a hybrid of Chinese and American chestnuts but it's good to hear they are trying to get back to the American chestnut as much as possible and still retain resistance. I wonder if at some point they will isolate the gene(s) responsible for resistance and splice them into an American chestnut.

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    1. Sweetbay, yes, amazing isn't it? I agree, the forests would have been so different looking a century ago. There is genetic research going on at various universities, isolating the gene that houses the resistance. There is research hitting this issue from more than one direction.

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  8. Janet,
    Excellent posting, learned a lot about chestnuts. I was visiting a customer today and noticed chestnut outer casing on the ground. Looked and found one with the nuts still inside, but it was too sharp needled to pry open bare handed.

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    1. Randy, thanks, glad you got something from this posting. Those spines are really sharp and sticky as well....a real bear to get into.

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  9. Very informative!
    I am glad to know that they may save our Chestnut trees.
    Hope you are having a wonderul day!
    Lea
    Lea's Menagerie

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    1. Lea, I am glad that they are working on this as well.

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  10. It is indeed thrilling to know that resistant Chestnuts are being grown now. I remember my grandpaw telling me all about the chestnut trees and the blight.

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    1. Carolyn, yes it is thrilling. I imagine your grandpaw saw grand trees in the NC mountains.

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  11. Interesting background. I believe that this research has been going on for quite a while. There are a half dozen of these trees on Cliff Island in Maine that seem to be doing well.

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    1. Carolyn (Shade Gardens) Yes, there are some original trees still standing in the far northeast. Climate is its best friend. The Phytophthera won't survive in the cold and the blight hasn't gotten that far north. Hope they remain.

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  12. Great info for sure. I hope both the chestnuts and elms come back and definitely hope no other tree is attacked. It is bad enough the ash trees are under attack. Gosh the more global we get the worse it gets it seems. What a good program your MG had.

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    1. Tina, thanks. Oh my the American Elm is another one that has suffered great decline. It was a great program from the MG group.
      (Did you know there are a couple large American Elms in the Maryland suburbs of DC at Marjorie Merriweather Post's house? I did a post a long time ago about the trip where we saw these trees. http://thequeenofseaford.blogspot.com/2009/05/hillwood-estate-and-gardens-still-day-2.html)

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  13. It would be great to see a tree come back even as a hybrid....I am saddened as I see more of our trees die out. Fascinating post!

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    1. Donna@GEV, yes it would be great to have this grand tree make a comeback.

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  14. I would love it if you would join me in linking up at my weekly Clever Chicks Blog Hop: http://www.the-chicken-chick.com/2012/12/clever-chicks-blog-hop-10-rural.html

    I hope you can make it!
    Cheers,
    Kathy Shea Mormino
    The Chicken Chick

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