THE PRESIDENT: Dr. Metcalf, Chief of the Bureau of Forest Pathology, of the Department of Agriculture, has been in charge of the investigations concerning the chestnut blight for a number of years.
DR. HAVEN METCALF: Mr. Chairman and Members of the Society: I will present, first, a few general facts regarding the present status of the chestnut bark disease, and, for the greater part of the information you desire, I will rely on you to ask me questions.
The chestnut bark disease is getting to be an old story, but that plant hyphenate, that objectionable imported disease, is more of a live issue today than it ever has been before. All my attention during recent months has been taken up with another imported plant disease, the white pine blister rust, of which you have heard, and which does not concern the special subject matter in which this Association is interested, unless, perhaps, you may be interested in the piñon nut as the piñon pine may ultimately be subject to attack by blister rust. However, this disease, like the chestnut blight, is an example of what a relatively harmless, or at least, not serious disease in a foreign country can do when it is permitted to get into the United States.
This brings us to the question of the origin of the chestnut bark disease, which, although the story has been told many times before, has been the subject of so much dispute that I probably had better recapitulate that matter. It has been proved beyond question that the chestnut bark disease is a native of eastern Asia, China, Japan and Korea; that it was introduced into this country in the '90's, upon diseased chestnut nursery stock. It was not critically observed until 1904, but the condition of trees which were observed at that time shows conclusively (provided the disease progressed in those early years as it has since) that it was introduced into the country as early as the late 90's. The final demonstration of the fact that the disease is a foreign disease and a native of Asia we owe to Mr. Frank Meyer, of the Office of Seed and Plant Introduction, of the Department of Agriculture. Mr. Meyer's observations are so interesting that I will pass around a few pictures illustrative of his observations in China, the first picture showing the country that is the home of the chestnut bark disease. The second picture shows a chestnut orchard in China where the trees have, with characteristic thrift, been planted around human burial mounds. The remaining pictures show how the chestnut blight acts in China—very differently from the way it acts in this country. In China, it produces, as the pictures show, definite cankers, which do not girdle the tree, which kill young trees occasionally, mutilate old trees, kill branches, but the cankers do not girdle the trees. That disease has been known in China we have no idea how many years, and, while it does a certain amount of harm, is said by Mr. Meyer not to be really serious in China. You can readily see, upon examining these pictures, that there is a sharp contrast in the behavior of the disease as observed in China and its behavior as observed in this country, where it will girdle a comparatively large tree and the fungus spread all through the bark, completely covering it, and doing that in a very short time. Of course, then, the chestnut blight is one of those cases of which we have so many, where a disease, passing to a new country, finds new surroundings, hosts more favorable to its development, and progresses rapidly.
The natural range of the chestnut bark disease at the present time—that is, I mean, its range on the native chestnut and the range through which it is now spreading by non-human agencies, is, on the north, practically co-extensive with the range of the native chestnut. The disease is found in Maine, New Hampshire, Vermont, as far south as Virginia, and as far west as western Pennsylvania and eastern West Virginia. Throughout this area it is spreading by what I may call natural means, and the disease has been shown to be unusually well provided with means of dissemination. I will speak a little later about the spread of the disease outside of this area—that is, west and south, since in the West and in the South it is being spread, as far as we know, exclusively by human agencies.
The question is often asked me, "What is the future of the chestnut—that is, the native chestnut—in this country? What is the course of the disease going to be?" The only way in which we can answer that is to look in the parts of the country where the disease has been present longest—Long Island, for example; Westchester county, New York; Bergen county, New Jersey; Fairfield county, Conn. Upon a recent examination of those areas I found no chestnut trees surviving in a healthy condition. We have, of course, from the beginning, hunted, and hunted hard, to find individual chestnut trees that might be immune to the disease—native American chestnuts. We expected to find such trees, but up to date we have not found them. It is a very extraordinary fact and an almost unparalleled fact, because with the majority of plants affected, by any given disease, we can find some individuals that are not only resistant, but immune.
Now, in these old areas, particularly on Long Island, in 1907, when the disease first came under my observation, I marked certain trees in order to observe how long the stumps of these trees or the dead trees would continue to send up sprouts from the ground. It is an interesting fact that some of those trees which were dead in 1907 are still putting up sprouts. The sprouting capacity of the chestnut tree is indeed marvelous, but I am sorry to say that I haven't been able to find any healthy sprouts over three years old. I haven't been able to find any living sprouts more than four years old. The disease seems to be following up the sprouts as it followed up the original stem.
Right there, in the behavior of the disease toward the sprouts, we have an interesting fact. During the first year of its life the chestnut tree or the chestnut sprout is immune to this disease, or practically so. You can rarely find a seedling or sprout of the first year that is attacked by the disease, and even in the second or third years a comparatively small per cent of them are attacked. It is thus possible to produce chestnut nursery stock that for several years does not show the disease.
So far as I can see, the chestnut blight is not stopping naturally in its course anywhere. I cannot get a particle of reliable evidence that it is. In this part of the country and to the south of here, in Virginia, for example, the parasite has more months in the year during which it can grow, it appears to be utilizing that time in spreading more rapidly, at least killing trees more quickly, than to the north of this area. From the standpoint of the grower of nuts, the important question is, of course, whether the disease can be controlled. I think your Secretary, in a recent article, summed the situation up as clearly and briefly as can be done. He said, in an article entitled "The Progress of Nut Culture in the East:"
"Of the chestnut we have excellent varieties such as the Rochester, Boone and Paragon, but all development in the culture of this nut is being held up by the blight. Everybody is awaiting the results of the government work in breeding immune hybrids. There may be great opportunities, nevertheless, in chestnut growing outside its native area, where the blight can be controlled."