Chestnuts - Hybrids- 2,453- oldest planted as seed in 1978
American- 203- oldest planted as seed in 1982
Our real interest lies with the hybrids. The Americans are planted partly out of sentiment, partly to provide blight susceptible trees to aid in understanding how blight behaves here, when it gets here; and possibly to provide more genetic cold hardiness for the hybrid program, should it prove necessary. The Americans are planted 1/4 mile away from the hybrids, so the two groups are essentially reproductively isolated.
The figure of 2,453 represents plants now living. Total seed planted out was about 5,000; the current number reflects natural mortality, primarily through genetic incompetence or lack of cold hardiness, and active culling.
There are two chief problems in growing chestnuts in our area; cold hardiness, and looking to the future, blight resistance. Although we have no blight on the farm yet, it has been found within 70 miles of us to the north and east, and 150 miles to the south. Apart from it being just a matter of time before the blight reaches us, it is also clear that if the varieties we hope to develop are to be of broad utility, they must be adequately resistant to the blight.
We have chosen to select first for cold hardiness, as in the absence of active blight it is considerably more difficult to screen for resistance. Also, there is real hope that blight screening techniques will improve greatly in the not-too-distant future. The stocks we are putting the most effort into are from New York, both Earl Douglass's hybrids, (Castanea dentata X Castanea mollissima , in varying generations) and a strain we acquired from Dennis Perry, which is derived from Gellatly selections crossed back to native New York Americans. We feel that while these seed sources are perhaps not ideal, still their seedlings should have the potential to be cold hardy, blight resistant, and have good nut and bearing qualities, and they have the outstanding attraction of being available to work with right now. We have stopped importing seed from blighted areas, on learning that it is possible for the seeds to carry blight spores inside the seed coat. (Jaynes, 1982). While no infection has been transferred here, we do not wish to take the chance. For the near future, we will rely on seed from our own trees for new plantings. We have a considerable amount of genetic diversity collected here already, perhaps sufficient for the initial stages of selection.
So far our guesses about hardiness and bearing characteristics seem to be about right; while no stock we have tested has proven truly hardy here, at least in the juvenile stages, some individual trees appear to be significantly and reliably more hardy than the majority, and these trees are sufficiently hardy that most fruit buds survive and bear. In general, the Douglass hybrid chestnuts will freeze back somewhere between 4 inches and a foot, in an average winter. We have had some freeze all the way to the ground; not as seedlings, but as 5 year old trees. Some of our Douglass hybrids originated in John Gordon's planting, rather than at Earl Douglass', and while some of Gordon's seedlings tend to "look" more American, we have not noticed any significant difference in cold hardiness. That adequate hardiness can be had is demonstrated by the occasional old, pure American trees planted in our area by early settlers. These have survived all the test winters here for up to 120 years, and most of them have shown no twig die-back at all in the years we have watched them.
As would be expected, most of the nuts of these hybrids are of moderate size, but several trees are bearing nuts large enough to run fewer than 50 nuts/ pound, a respectable size. The older trees are just starting to bear in quantity, so it will be some years before we have reliable information on crop sizes and other bearing characters.
In addition to these larger collections of hybrids, we have a small group of miscellaneous trees from various sources. Without a doubt, the most interesting of these are seedlings given us by Al Szego, from his C. seguinii X C. dentata F2. It must be pointed out that the pollen parent(s) of these seedlings is (are) unknown, and might be almost anything in Al's remarkable collection. We have only 9 of these, but they are unusual in several ways. None of them is very cold hardy, but this has allowed one surprising characteristic to become apparent. Two years ago, in a fairly normal winter, all of the saplings died to the ground from the cold. Normally, that would mean instant culling, but since these are specimens of special interest, the sprouts were maintained. The trees made an average of 4' of growth in the next season, and 2 of them showed an indication of their seguin heritage by flowering in the fall, on these one-year sprouts. The following winter was the mildest on record, which led us to fear that many trees would be damaged by early growth, but that did not happen. Most of the seguin hybrids survived that winter with no, or minimal, dieback. All but one of them flowered, with the following results: All of these hybrids are male sterile, as is their female parent; the male catkins are present, but dry up and drop off at about half growth, never releasing any pollen. Several of them showed the seguin trait of "perpetual flowering"; ie. new crops of female flowers appear all summer long, right up until frost. We were successful in using this trait to make 2 different classes of cross on one of them. Although these were sprouts in their second growing season, one of them bore 108 nuts, averaging 4 grams (range from 10 to 2 gm). Flowers appeared on most of them not only from the buds at the shoot tip, but along the entire length of the last season's growth.
There are several traits of interest here: the fact that all of them are male sterile either indicates a cytoplasmically transmitted form of sterility or a dominant nuclear gene. Male sterile cultivars may be desirable, in that they can put more energy into nuts, and less into catkins. The lateral bearing ability to set fruit along the entire branch, regardless of tip dieback, is intriguing, and would also be important in realizing the productive potential of any good cultivar. The visibility of so many seguin characters in these trees would indicate that the genes for these traits may have some measure of dominance, always of interest. We are crossing these with our hardiest hybrids, and also with pure American trees, to clarify the genetics of the various traits. Al Szego has been saying for some time that his F2 is an interesting tree- we certainly agree.
While we have trees growing from seed we have produced, most of the seedlings are too young to have demonstrated whether they are worth further observation or not. An exception to this is a tiny seedling that is part of one of our major projects; the creation of a population of exceptionally precocious trees for use in breeding.
Precocious means bearing flowers and fruit at an unusually young age. Many of the growers I have talked to have noticed an occasional chestnut seedling that will flower right in the seedbed, sometimes just with male flowers, and sometimes with atypical female flowers as well. We have also seen a few of these random individuals, and have been working to elucidate the genetics of such extreme precocity, and also to create such individuals intentionally, rather than by chance.
Our only surviving fortuitous seedling has had no progeny yet, due primarily to bad timing in our pollination attempts: we have missed a few seasons simply because we were busy elsewhere at the wrong time. This year, however, this particular tree bore a sound nut, and its pollen was also used in other crosses which have yielded several nuts, so we hope to learn more about it soon.
The one seedling we have observed from our own controlled pollinations was the result of crossing two moderately precocious trees- both bore flowers in their third growing season. The one resulting nut was planted in a pot, and outplanted to a permanent location when it was 3 months old, whereupon it bore several male flowers, at the ripe old age of 4 months. In its next growing season, it bore both male and female flowers, but the females were atypical, and developed no nuts. This tree is important because it bears out the assumption that the precocity is under genetic control, rather than perhaps being a random physiological freak.
So far these extremely precocious trees are not well adapted to the burden of flowering at such a young age. They grow very slowly in their first years, although they later may grow normally (3' a year), and their inflorescenses are often deformed or atypical. They clearly do not have any reserves which can be used for nut production, and the presence of flowers, an adult phenomenon, could be expected to cause some hormonal imbalances in a plant which needs to put its energy into root and top growth, not flowering. With the creation of a population of such trees, however, some individuals may be expected to appear which will retain the precocity, but will also be more vegetatively vigorous. An analogy can be found in St. Bernard dogs- they are essentially hyper-thyroid giants, but though years of breeding and selection, they now have a series of genetic adaptations to hyper-thyroidism which allow them to be reasonably healthy. By crossing the best adapted precocious trees with each other, we hope in time to achieve a strain that both grows strongly and flowers immediately on germination of the seed.
We do not foresee such plants as being useful in orchards, but they would be very useful as breeding tools. We have begun calling such seedlings "Vector" chestnuts, as an indication of their function: they are tools for carrying genes from one strain to another. One of the greatest barriers to tree improvement is generation time. In addition to reducing generation time to the minimum, with the Vector strain we will have a breeding population of trees which we will be able to characterize genetically, by the performance of the progeny they produce.
Imagine the following situation: A random seedling has been found, of normal stock, that produces a nut of extraordinary flavor. This tree, which we will call "Tasty", has the misfortune to be rather unproductive. Both of these traits, flavor and productive bearing, are genetically complex, or "quantitative", which means they are due to many genes. If one were to attempt to make a productive, Tasty-type tree by crossing Tasty with a normal tree that is productive, the great majority of the progeny could be expected to be at best intermediate for both the Tasty character and productivity; not a very desirable result. And since most chestnuts do not bear significantly before the age of 4 or 5, one must grow the progeny at least that long in order to evaluate them. If one were very lucky, it might happen that one of the progeny could be as productive as desired, and showing some of the Tasty character. In that case, one could logically cross this seedling back to the Tasty parent, to reinforce that trait. Once again, the progeny will have to be grown for 5 years before they will show their performance. Even at this stage, it would be very unusual to find the productive, true Tasty tree that is the goal. So far, we are 10 years into the program, and if more crosses are necessary, the total will be at least 15 years.
Using a "breeding bank" of Vector chestnuts, however, the program might progress in this fashion: The Vector strain parents, after a few years, will be well characterized as to the general performance of their progeny; it will be known that one typically throws offspring that are more cold-hardy than usual, for instance, while another has a high percentage of offspring that have the lateral bearing character. For the Tasty program, we can start with a Vector tree that is known to throw productive offspring. This is already a gain over the common situation, where all that is usually known is that the parent is itself productive; by no means a guarantee that it can pass that trait to its offspring. Further, the productive-Vector X Tasty seedlings will be more precocious than the Tasty parent: so far all indications are that precocity is also a quantitative trait, and offspring should be intermediate. We would expect to have a higher than usual percentage of productive offspring from such a cross, and they should bear in 2-3 years, instead of 4-5. At this point we would cross the interesting seedlings with each other, rather than back to the Tasty parent. Out of such a cross (given sufficient numbers) we might expect to find such things as a Tasty-Vector, with both the flavor and precocity fully expressed, and a productive-Tasty, which may bear in the intermediate 2-3 years, perhaps desirable for orchard cultivars, as well as many other intermediates, both useful and useless. The end result is the practical expectation of success in creating a productive Tasty tree in 6 or 7 years, instead of 15, and the addition of a Tasty-Vector to the breeding library, for use in future crosses.
While few workers like to contemplate 15 year projects, 6 or 7 years do not seem so forbidding. It is worth pointing out that resistance to chestnut blight is a character that might be added to desirable cultivars in this way.
Besides cutting the time for conventional kinds of breeding in half, the creation of Vector "breeding banks" would raise a possibility entirely new to tree breeding. Within the Vector population, crossing should result in progeny with the extreme precocity trait fully expressed; they should all flower immediately after germination. If pollen from such seedlings were used to fertilize flowers on an older tree capable of producing nuts, the generation time for crosses could be reduced to one year. While it would often not be possible to screen such seedlings for the presence of desired traits, the use of parents with known genetics would make it possible to make crosses "blind", knowing that the characteristics sought are present, even if unseen. This could create the very real possibility of being able to breed chestnut trees on the same basis as annual crops, and would bring within reach much more complicated breeding projects requiring many generations, possibilities never even considered today.
To be sure, such a breeding bank may prove impractical for some unforeseen reason, but at the moment it appears to be a reasonable goal, and we are working to begin creating a viable Vector strain at Badgersett.
Other Chestnut Projects:
Besides the work on extreme precocity, we a have a number of experiments in progress in our chestnut plantings. In addition to the fertilizer experiment mentioned above, we are measuring the later performance of plants that were large, medium, or small sized after 2 years in the seedbed, watching the effect of early pruning on age of bearing, and evaluating the effect of coppicing on the growth form of trees intended for orchard use. For several years we ran controlled experiments on various deer repellents. We also keep track of a number of smaller observations on orchard establishment, care, and maintenance.
Having virtuously proclaimed our intention to work only on chestnut and hazel, we must confess to being backsliders. While visiting the Weschcke plantings to gather hazel seed, I of course took time to look at the extensive collection of grafted hickories. They are impressive, and the nuts are delightful. In 1985 there was a bumper crop, and the only beneficiaries would have been the squirrels. Those seeds struck us as having a unique genetic potential. Since there are no native hickories there (except a few bitternuts), all the seed must be the result of the cross-pollination of the grafted selections. Few of those grafted trees are in any way related, most are from widely different regions, yet they all share the desirable traits of thin shell, and larger than average size. It seems highly likely that the progeny of crosses between such outstanding individuals might contain trees the equal of, and even the superior of, the parents. In order to find out whether such potential can be realized, it is necessary to grow out a significant number of seedlings. We truly do not have the time to pursue this strongly, but having a childhood attachment to hickories the genetic potential represented in those nuts was irresistible. Our intention is to outplant about 1,500 of them, this year, and grow as many to bearing age as possible. We already have one interesting experiment running with them in the seedbed, and intend to make an effort to enhance any precocity that may show up in the seedlings. Long generation time is one of the greatest barriers to making hickories truly useful. Beyond these plans, the hickories will probably be on their own; but at least we will have the trees planted, and if someone wants to work with them at a later date, they will be underway.
A few other trees have sneaked their way into our plantings. John Gordon's northern pecans are growing here; we have 47 in permanent locations. They have been slow starters, but many of them made growth in excess of 3' this year; two of them growing so fast that they fell over, due to the weight of the leaves on the unhardened wood. We also have 3 putative oak-chestnut hybrids given to us as acorns by Miguel Marquez, only 2 years old. We are not yet ready to pass judgement on their actual hybridity, but we can state that they do look a little odd. In our spare time we take care of the Christmas tree plantings (we are gathering some seed from the better trees, in self defense against stock bought from warmer areas), and tend the growing orchard of cider apples.
It is our hope to gradually introduce people to the more unusual crops and ideas here through the sales of the standard crops of Christmas trees and cider. Our ideal scenario would have folks coming to get their tree, and discovering that we also have unusually good cider for sale. We will then hand out free samples of roasted chestnuts (there is little tradition for them here), and perhaps cookies made with hazel nuts. With any luck, folks will find the food attractive, and buy some to take home. If we can show our farmer customers that we are making money at this, they will quickly begin to consider planting chestnuts or hazels themselves. Many farmers are eager to find alternatives to growing corn and soybeans, and would prefer crops that are not so hard on the soil, but economically realistic options are currently rather limited.
We would welcome the comments of readers who have suggestions to make about any of the above; either the wildly idealistic philosophy, or the dirty details of growing trees. We also hope any who are interested will come and visit the Farm, and see for themselves what we are attempting here.
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