Using three-quarter American chestnut hybrids for timber, wildlife, and nut production
1. FNE 06-577 Utilizing 3/4 American Chestnut Hybrids for Timber, Wildlife, and
Don W. Kines
Mountain State Chestnuts
Davis, WV 26260
(304) 259 – 4821
2. The goal of this project is to show that 3/4 American Chestnut hybrids can be utilized by Northeast farmers as a replacement for the American Chestnut tree. Asian – American chestnut hybrids are crossed to partially blight resistant American trees to produce 3/4 American hybrids that posses all the desirable traits of the American parent such as cold hardiness, vigor, upright growth and dependable nut production, but with the blight resistance of the Asian parent. These hybrid trees can be grown for timber, wildlife plantings and for nut production.
3. There has been no change in my farm status.
4. My technical advisors for this project are Dr. William L. MacDonald and Dr. Dennis Fulbright. Both are considered at the top of the field on chestnut blight research. Dr. MacDonald is a professor of plant pathology at West Virginia University and has been the treasurer of the American Chestnut Foundation since its inception. He has been instrumental in keeping me up to date on current American chestnut research. Dr. Fulbright is a professor of plant pathology at Michigan State University and is the editor of the Nut Tree Culture in North America, Volume 1. Dr. Fulbright maintains an orchard of 2nd and 3rd generation chestnut trees from Sugar Loaf Mountain, Maryland which is described later in this report. He sent me a nice quantity of pollen from those trees which he felt responded favorably to blight infections. It arrived late enough in the season to only do a few pollinations, but the majority of the pollen has been dried/frozen and will be used next season.
5. & 6. The first step of this project was to identify what Americans and American hybrids were to be included in this study. The American choices were easy. I had several Americans growing that I could collect open pollinated seed from that would give me my blight susceptible controls. I have access to only a few partially resistant Americans, so again another easy choice. WV1 is very resistant for an American and has given me my most resistant hybrids. WV2 is not as resistant, and my progeny from this tree too young and too few in number to draw any conclusions. The American labeled DFT, is actually pollen collected from 3 seedling trees from a Sugarloaf Mountain, MD tree. The trees planted at Sugarloaf Mountain were planted in the late 60’s and early 70’s by Dr. Albert Dietz of Pittsburgh Plate and Glass. The seeds were all treated with Cobalt 60 radiation in the hopes of creating mutations for resistance. The parent trees do indeed exhibit large swollen cankers which would be indicative of blight resistance. My seedlings from DFT have not been inoculated with blight so I must label it as a question mark at this time. The trees labeled R5T1 and R1T24 came from Dr. Fulbright’s orchard as mentioned earlier and have shown some resistance to blight.
Which hybrids to use for this project was a little more problematic. Some of my
first generation hybrids such as AC8, ACD, and R2T2 x PO are excellent trees in
regards to form, growth and resistance and were easily included in the study. One
hybrid, H3 x WV3 is very resistant, but dwarf in stature. If my goal is to produce
a tree of timber type proportions, this may seem a strange choice. Since neither
parent, H3 which is a Chinese or WV3 a partially resistant American, is a dwarf,
I’m assuming the dwarfing action comes from an interaction of the American and
Chinese genes. When H3 x WV3 is crossed with WV1, I should obtain some
Resistant offspring, and again I’m assuming here, since these offspring will be
75% American I will lose the dwarfing influence. I have also included A x JJA2
in the study, because when crossed with WV2 I will obtain seedlings that are
roughly 81% American. I believe this is close enough to my ¾ benchmark to not
violate my study parameters. Lastly I have included CA9 x JAC74 because of its
resistance and form. When this tree is crossed with WV1 the seedlings should be
69% American, which I again feel falls within my guidelines. My goal is to
produce trees which will be of value to farmers in the Northeast. I think any
hybrid with American genes in the 70 – 80% range should do the trick.
The next step in the process is to insure unwanted pollinations. Paper bags are
placed over flowers before they are receptive to pollen. This is generally done
just as the tree starts to shed its first pollen. The flowers become receptive
approximately 7 days later. The flowers reach their peak receptivity in 10 – 14
days. Flowers can still be pollinated as late as 21 days after the start of pollen
shedding but with a lesser degree of success. Flowers are pollinated by dragging
fresh catkins across the styles, or by dusting the flowers with dried pollen using a
small brush. When there is a difference in the pollen shedding of one tree with
the flower receptivity of another tree, the pollen can be dried and frozen for later
use. Pollen stored in this manner can even be used for the next season. I have
successfully used pollen that is 2 years old with this method. My first flowers
were bagged on 6 – 23 – 06, and final pollinations were done on 7 – 16 – 06.
Some of the Americans would have given a higher nut percentage if I had
pollinated them a week later on 7 – 23 – 0-6, but time constraints limited me to a 3
week pollination season.
Nut collection is always a bit of a challenge. As a general rule, individual trees
drop nuts over a two week period. If you wait too late to collect, open pollinated
nuts are lost to the local wildlife and bagged nuts can dry to the point of becoming
nonviable. I will usually collect green burrs from the bags once unbagged burrs
start to open on the tree. The green burrs are placed in plastic bags and allowed
to open on their own indoors. Any burrs that have not opened in 1 week are
opened with a knife. The nuts are then placed in labeled zip-lock bags with
moist peat moss. I collected a good quantity of sugar maple seeds and red
oak acorns this season and they have been stored in the same fashion as the
chestnuts. The bags are inspected periodically to allow excess moisture to
escape and to remove moldy nuts. I also destroy any weevils that are found
at this time. Weevil infestation has been high among the acorns this season.
All seeds and nuts should break dormancy in 2 – 3 months. I will plant in
Miracle Grow soil under gro-lux lights in February and March. Chestnuts
grown under these conditions have down well in the past and are planted
outdoors in late May or early June.
7. It was my hope to breed my most resistant Americans to my most resistant hybrids.
However, there were a few factors which prevented me from breeding the best to the best. My most resistant American – Chinese hybrids are pollen sterile, therefore they can’t be used as pollen parents. The most resistant American, WV1, sheds pollen so late in the season that it can’t be used on the majority of my hybrids. Further complicating matters is the fact that it sheds pollen in such light quantities that it makes it difficult to collect and store for the following season. I was able to pollinate tree (R2T2 x PO) with some WV1 pollen, but I have consider the possibility of contamination on this cross. Tree R2T2 x PO grows in a separate orchard from the other hybrids in this project and was bagged later than I had wanted. I will still include the nuts in this project, but will remove the seedlings if they exhibit heavy oriental characteristics. One other factor I need to report on is the possible loss of WV1 and WV2. Dr. MacDonald informed me that the farm containing these 2 trees is being sold for development. I may have access to them for one more season. I will definitely try to secure a good quantity of scion material from both trees this spring in the hopes of securing some viable grafts. It is quite possible that grafted WV1 and WV2 trees may ultimately be of benefit to me. Grafted trees can start producing pollen in 2 or 3 seasons. My orchard is approximately 70 miles away from where WV1 and WV2are presently located and is located at a higher elevation. The change in location may cause WV1 to shed pollen at a time that is more conducive to crossing with my hybrids.
8. There have been no economic findings generated from this project as of yet.
9. The trees need at least 5 growing seasons before I can feasibly test for blight
resistance. Therefore it’s a little early for me to speculate on the next step.
There is one thought however, that does come to mind. If I am successful in
developing a promising tree or trees, I need to develop an economical way to
propagate those trees. Grafting can be done with chestnuts, but is time consuming and leads to an expensive end product. Chestnuts have been tissue cultured, but with a poor success rate and again an expensive end product. I’m thinking at this moment what might lead to a tree that would be affordable and therefore a boon to the Northeast farmers would be to create seed orchards. When promising trees have been identified, create multiple grafts of the parents that created that tree. When these trees are grown in isolated orchards, the nuts produced could be grown into seedlings and distributed. Not all of the seedlings produced would be the perfect blight resistant timber tree we want. However, with experience we can determine roughly what percentage we can expect that would meet our standard. It might be even possible to develop a method to screen for blight resistance at an early age before releasing seedlings to the public.
10. Don W. Kines
January, 8, 2007