The return of the chestnut -- a tree crop archetype | Hill Craddock | TEDxUTChattanooga

the the first chestnut tree I ever saw I grew from a seed I planted myself when I was about 15 years old I got the seeds from a neighbor of mine John Todd of the new alchemy Institute in Woods Hole Massachusetts he told me they were American chestnuts I think he got them from dick Jane's at the Connecticut agriculture Experiment Station I planted the seeds in flower pots in a little green lean-to greenhouse that my that my father had built and when the seedlings were about a year old we transplanted them to a nursery bed in John's front yard from the nursery they were mostly most of them were planted at the new alchemy farm in hatch ville but one of those trees I set out in my front yard where it is still growing today when when my chestnut tree was about a year old I read tree crops a permanent agriculture by J Russell Smith the book made a lot of sense to me at the time this was the late 1970s some of you remember the 1970s I was concerned about the end of oil and overpopulation and world hunger and tree crops made a lot of sense to me it offered practical examples of real solutions to many of the problems of Agriculture soil erosion the use of pesticides toxic pesticides the loss of biological diversity on sloping and mountainous lands not bearing trees and other woody crops may be the only sustainable solutions to producing food of all the tree crops that were discussed by Smith the chestnut tree was by far the most interesting to me I was particularly moved by his description of the thousands of years old chestnut groves in Italy and the island of corsica a veritable chestnut civilization it may be exaggeration to claim that the chestnut tree the European chestnut is one of the columns upon which Western civilization is built but it certainly ranks right up there with the grapevine and the olive tree as Mediterranean staples it was during the seven years that I lived in Italy that I had many of my most significant chestnut experiences talking to the Italians learning about their chestnut trees about their shared memories of the chestnut forests about recipes about famine during the war and how at the end of the war all they had left was the chestnut tree became to appreciate the cultural and historical values of the personal values and the intrinsic values that this tree represents to the peoples of Italy and I came to appreciate the enormity of the tragedy that would befall the earth if this heritage were lost agriculture causes environmental degradation especially when it depends on the plow to plant annual crops it causes soil erosion it leads to biological diversity cropping systems based on perennial plants may mitigate those negative ecological impacts by by allowing soil building processes to flourish the chestnut tree comes very close to representing the archetypal tree crop they are very long-lived examples of Castagna sativa in Italy are known to be more than 1,000 years old they produce annual crops of delicious nutritious nuts that are easily harvested and easily stored chestnuts coppice well they sprout back tremendously when they're cut and they can be managed on 15 to 20 year rotations the standards can be left for two or three cycles for larger saw Timbers the tree provides wood for fuel for poles for lumber for tannin extraction for leather tanning because a mature chestnut orchard resembles a temperate hardwood forest in both structure and function it offers environmental ecological benefits far be merely producing a nut it it offers habitat for myriad animal species it acts as a keystone in its community it to steep slopes that might otherwise be completely unsuitable for any other form of Agriculture it intercepts rainfall and moderates the local climate by shading the understory and transpiring water into the atmosphere it serves as a host for the mutualistic symbiotic relationships with fungi including the choice edible chanterelles and porcini mushrooms whose niches are those of the great recyclers and and and decomposers in the soil mobilizing minerals and nutrients into the human air the landscape value of the chestnut may be unequaled by that of almost any other forest type possibly because the Grove itself is evocative of a simpler quieter past when our relationship to the to nature was based on regular cycles of Sun and Moon and season the American chestnut was the largest of all the chestnut species in East Tennessee and Western North Carolina where it reached its greatest proportions the canopy of the chestnut forest was well over 100 feet from the ground it was one of the fastest growing trees keeping pace with with tulip poplar and easily outgrowing the Oaks on on most sites it covered an enormous area from the uplands of Alabama and Georgia throughout Appalachia into Canada and New England there were more uses for American chestnut than for any other than for any other kind of tree European it's its sheer its sheer abundance was unrivaled by any other one kind of tree European settlers described vast areas covered by you know pure stands of chestnut forests the annual harvest the annual production of the American chestnut supported entire communities of wildlife and game animals and local economies all that came to an end in 1904 with the discovery of the chestnut blight the 20th century was very hard on chestnut particularly in North America but also in Europe conspiracy of circumstances the catastrophic diseases two world wars changing diets cultural revolutions the almost insane economics of the global village contributed to the almost total extinction of the American chest the total loss of the American chestnut and the and the and the almost near extinction of the chestnut civilization worldwide the blight chestnut blight is caused by a fungus an orange mold it literally eats the bark of the tree necrotic lesions quickly girdle the tree and kill it within 50 years of the discovery in the Bronx in New York City of chestnut blight the pandemic had completely removed the American chestnut from its ecological niche as a forest canopy dominant tree it may be difficult for us today to comprehend the scale and the scope of this destruction in fact there is no other example in the history of forest pathology where a introduced pathogen so quickly and completely removed its native host it was a true pandemic there were no unaffected individuals but chestnut trees are not extinct the American chestnut is not extinct because the fungus only kills the bark but not the roots they continue to sprout from the base in fact throughout much of the eastern woodlands we can still find chestnuts they rarely grow large enough to flower and produce a seed but they they may still be there the situation in Europe was very similar to the American experience the consequences though were less severe because of the discovery of a natural biological control for chestnut blight called hypo virulence it's based on a virus the virus attacks the fungus and keeps the fungus from killing the tree remember the enemy of my enemy is my friend so the virus attacks the fungus the biocontrol has not worked as well in north america we have not seen the land scape scale changes in the United States that we've seen in Europe but it does work well in some locations and on some individuals on individual trees I am working with a group of citizen scientists to restore the American chestnut we've organized ourselves into state chapters of the American chestnut foundation primarily we are plant breeders we use classical plant breeding techniques our goal is to breed for resistance to chestnut blight and to Phytophthora root rot and other disease based on the genes for disease resistance found in the Asian species the disease resistant hybrids must be able to survive and reproduce on their own in the forest we use repeated back crosses to the American species to dilute out the Asian portion of the hybrid genome selecting at each generation only those individuals that combine the desired blight resistance with the American form the seeds are grown in the greenhouse some of them when the weather settles we can move those outside we can establish new experimental orchards by the direct seed method planting the seeds and the in their permanent orchard locations or by transplanting seedlings container-grown seedlings like like these when the trees after four or five years of tender loving care the trees are ready for screening the screening is rigorous and ruthless screening is a euphemism for killing trees we give each tree a potentially lethal dose of the chestnut blight fungus susceptible trees die very quickly resistant trees form a callus that begins to wall off the canker and they begin to heal within a few years the cankers on the remote resistant trees are completely healed most of the trees must die though the value of those few remaining trees is great only those individuals only the very best individuals are advanced to the next generation we are currently testing for the first time in history in cooperation with private landowners and the u.s. Forest Service blight resistant American chestnut trees that are between 94 and 97 percent American meanwhile in the laboratory we've worked out the genome sequences of the chestnut tree and the fungus that causes the blight and the virus responsible for hypo virulence chestnut trees are being planted once again all over the world in the areas where chestnuts have been grown traditionally and in areas where and in places where chestnut growing has only been recently introduced advances in plant breeding and molecular biology promised us disease resistant chestnuts I am very optimistic about the return of the American chestnut I'm confident that future generations will be able to enjoy this magnificent tree once again but ecological restoration is a very ambitious goal the work is multidisciplinary the scale and the scope of this project is very long-term the pedigrees of my most recent hybrids date back to the 1930s and 1940s to cross is made by Russell clapper and Arthur graves at Glendale and New Haven our strategic vision includes experiments that are planned for 100 years of observation chestnuts should be they can be a part of a healthy diet a healthy agriculture and a healthy forest I'd like to end with a poem by the American poet Robert Frost it was first published in 1936 during the darkest days of the chestnut blight pandemic and 30 years before the discovery of hypo virulence evil tendencies cancel will the blight end the chestnut the farmers rather guess not it keeps smouldering at the roots and sending up new shoots until another parasite shall come to end the blight thank you you

Channel: TEDx Talks

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Keywords: United States, Science (hard), ted talk, TEDxTalks, ted x, tedx talks, English, Biology, Plants, ted talks, ted, tedx, tedx talk, Sustainability, Agriculture

Id: bz_NgKnVKxE

Length: 13min 39sec (819 seconds)

Published: Sat Nov 15 2014