There are a few fungi which closely resemble this chestnut disease in general appearance, but they are not very common, and are not confused with the disease, as a rule, when you get the lens on them.
In regard to the experiments for the control of the disease. I want to say a few words. As far back as 1907, the United States Department of Agriculture began experiments on certain experimental plots, particularly in Long Island near the region where the earliest cases of this disease were known, to see if it could be controlled on individual trees after they had become infected. Later, experiments were undertaken along the same line in Lancaster County, Pennsylvania. Spraying was tried, although there was no idea that it would be of any use, because the vegetative stage of this fungus is running through the interior of the bark, where no spray could reach it. Thus spraying was found to be of no use whatever. Then the operation of cutting out the disease was tried. Where the diseased spot appeared, it was cut out with a gouge. Then the exposed area was covered in various ways with antiseptics.
This gave, for a year or two, very promising results, but about the third year the disease appeared to get over on to the margin, where it had been cut. This led to the later discovery that the disease had been running in the wood, as we had previously suspected. So the cutting out of the bark alone is not sufficient. This year cutting has been done so as to include a portion of the sap wood.
There is just one other topic which I want to allude to. That is in regard to the immunity question. It has been found that this disease attacks the common native chestnut, the chinquapin, the various cultivated European chestnuts, but very rarely the Japanese. In regard to this point. I hope that Doctor Morris will tell us something about his experiments on the breeding of chestnuts with the idea of producing a new and immune variety.
You will understand that I have just made an outline of this disease, and I hope that, if there are any questions to be asked, you will make them easy, so that I can answer them.
President Morris: This very interesting paper is now open for discussion, and I hope that we can get some points which will allow us to know how to control the disease. With the wind-borne spores that are carried miles and miles by a single sharp gust of wind, this disease is a difficult matter to control. We must, I believe, find some natural enemies, if we can. I don't know where to look for these. I will have to ask the mycologists what we may anticipate along the line of natural enemies. I would like to ask if it is common for a weak species to become a devastating species. Have we many parallels in the field of mycology? The point relating to raising immune kinds is one for discussion. Are we to raise immune chestnuts? The history of most plants, I think, has been this, that where they have met their enemies in their natural environment, the fittest survive; and it seems to me that this is a case in which we perhaps have survival of the fittest in North Asia; for the North Asian chestnuts certainly resist the disease better than any others, but the chestnuts of southern Asia are quite vulnerable to it. In my own orchards, I have twenty-six kinds of chestnuts, and have followed them along, for the purpose of determining which ones would resist the blight best. I cut out last year 5000 old American chestnut trees on my property. There is not a tree in all that part of Connecticut, the vicinity of Stamford, that is not blighted, and very few that are not dead. Now, in the midst of this disaster, what was the behavior of my experimental chestnuts of various kinds? It was this. I had about one thousand Koreans that lived up to five years of age, growing in the midst of blighted chestnuts, and none of these blighted. It occurred to me that it might be well to graft these on the stumps of American chestnut, because these Koreans resisted the blight; but when I grafted them on the sprouts of American stumps, at least fifty per cent of the Koreans blighted, showing that the pabulum wanted by the Diaporthe seemed to be furnished by the American chestnut. I had some chestnuts from North Japan that resisted the blight, and yet these grafted on the sprouts from American chestnuts blighted. I had some Chinese chestnuts, and none of those have blighted as yet; and in grafting them, two or three have not been blighted. I have perhaps twenty-four chinquapins, both the western form and the eastern, and only one branch of one tree has blighted. Of the southern Japanese chestnuts, very many are blighted. They are not as resistant as the northern. I have a good many chestnuts of European descent, and among these some resist the blight pretty well; and some of the American progeny, like the Hannum and Ridgely, seem to resist well enough, so that now I am grafting these upon many different sprouts. This should be worked out, and I wish to know what men have tried experiments along this line. I would like to ask Professor Reddick to discuss this question.
Professor Reddick: I have very little that I can add at the present time. The points the talk has raised here are of the greatest importance, and there is certainly room for a great many people to work, though here in this state we have only one man who is devoting his attention particularly to this disease. I find in connection with the work that Professor Collins is doing, and in connection with the Pennsylvania work, that there are some people engaged on these very vital and important problems. They are not giving any particular attention to field work, but are working on these special problems. I think you all appreciate that progress of investigations on this kind of subjects is rather slow, and in the meantime the man who has his trees and his nurseries blighting is surely up against it.
I have only one thing in mind, a thing which I suggested to Mr. Rankin when he first started on this work, and it is a thing which Doctor Peck, our state botanist, suggested at the chestnut bark conference that was held in Albany not long since. Doctor Peck says that he has lived a good while, and he has seen epidemics come and go. Certain plants, certain varieties were threatened with extermination, yet at the present time they are still with us. I suggested to Mr. Rankin that, while it looked as if chestnut blight was going to be with us indefinitely, the chances were it would all be gone before he had a chance to find out all the things he thought he was going to. Our friend Doctor Clinton of Connecticut would have us think it is only a matter of a few years to have conditions come around so that the chestnut blight will not be a thing of serious importance. In other words, Doctor Clinton stoutly maintains that, while this fungus is doing so much now, it is largely due to the condition to which our trees have come, owing to a succession of very unfavorable summers and winters; and as soon as the conditions get around to normal, the disease will be no more. Some of us are not inclined to agree with him entirely.
Professor Craig: Perhaps you can tell us what Mr. Rankin has been doing this year.
Professor Reddick: At the beginning of the past summer, from the surveys and observations that had been made almost entirely by the United States Department of Agriculture authorities, it was known that the chestnut disease had extended up the Hudson River perhaps as far as Poughkeepsie. It was our idea that he would probably find the border line of healthy and diseased trees somewhere in the vicinity of Poughkeepsie, so Mr. Rankin located it opposite Poughkeepsie at Highlands. During the course of the summer, the assistance of the State Survey Commission and the State Department of Agriculture was enlisted, and there were six or eight men who spent part of July and all of August surveying the portion which now appears on this map in red. The results of this survey show that the entire Hudson River Valley, with the exception of a small part in the vicinity of Albany, is now infected. In fact, it is the general opinion that there is no use whatever to attempt in any way to save the trees in this locality. Very fortunately there is a strip of territory which is almost solid spruce forest, and in which there are almost absolutely no chestnut trees. We have already, then, abandoned the Hudson River Valley, but with this great natural barrier, you see that it is going to be relatively easy, so far as the State of New York is concerned, to put some sort of an artificial barrier across the little neck there. This all depends on what can be done in Pennsylvania. This cross-hatching of red along the Delaware River represents an area in which the infection is only partial, and the few dots of red shown about Binghamton represent localities in which the blight has now been exterminated. The diseased trees have been taken out, stumps killed, and bark burned. We are in hopes the disease will not reappear there. I don't believe things have been definitely settled at Albany in the Department of Agriculture, where the control work naturally lies, but Commissioner Pearson is very anxious that something be done to try to control or prevent the further spread of the disease in our state. Plans are being made so that a large number of men will be located in this territory next summer, making very careful inspection, removing the occasional diseased trees, killing stumps, and burning bark; and a forester will be connected with the work, for the purpose of advising with regard to the use of the diseased timber. I might call attention to the fact that our state agricultural law, as it now reads, empowers our Commissioner of Agriculture to quarantine against this or any other dangerous fungous disease,—a very broad step from what it was before that time, when the only fungous disease he had any power to act against was the black knot of plums.