Keller E. Rockey
Forester in charge of Demonstration Work, Pennsylvania Chestnut Tree Blight Commission
The history of the blight, briefly outlined, is as follows:
In 1904 the diseased condition of the chestnut trees around New York City was noted and an examination of them showed that they were being attacked by a disease at that time unknown. Investigations since then have shown that the blight had been at work there and elsewhere for a number of years before that time, but it has been impossible to determine just when it first appeared or where. The disease was studied and described at that time.
On display here are specimens and photographs showing the appearance of the blight so that I will not go into that part of the subject in detail. I hope that you will notice, however, the symptoms by which the disease is recognized: 1st. The small red pustules which produce the spores and, on rough barked trees, appear only in the crevices. 2nd. The peculiar mottled appearance of the inner bark of the canker. 3rd. The discoloration of the outer bark. 4th. The danger signals, such as withered leaves in summer or persistent leaves or burrs in winter, suckers which develop at the base of cankers, and the yellowish cracks which soon appear in the bark over the cankers.
Workers in the Bureau of Plant Industry, Washington, D. C., have been studying the blight since 1908. In the Spring of 1911, a bill creating the commission for the investigation and control of the blight in Pennsylvania was passed, and the active work began in August 1911. The method upon which the Commission is working is outlined in Farmers' Bulletin No. 467, of the Department of Agriculture, and consists briefly of determining the area of blight infection and in removing diseased trees west of a certain line, with the purpose of preventing the western spread of the blight.
This Commission has ascertained as accurately as possible the amount of infection in the various parts of the state and the results are given in a map on display here. The state is divided into two districts by a line drawn along the western edge of Susquehanna, Wyoming, Columbia, Union, Snyder, Juniata and Franklin Counties, which is approximately the western line of serious blight infection. West of this line a large portion of the state has been scouted, and the remainder will be finished early in 1913. We have learned by experience that in the winter, after the fall of the leaves, the best scouting work can be done. Persistent leaves and cankers along the trunk are readily seen, and more and better work can be accomplished than in the summer, except when the snow is very deep.
Blight infections have been found in counties adjacent to this line: also in Fayette County, near Connellsville, in Warren County, near Warren, and in Elk County, near St. Mary's. These three infections were directly traceable to infected nursery stock, and in one case the blight had spread to adjacent trees. A large area of diseased chestnut in Somerset County illustrates the harm done by shipping infected nursery stock. The centre of this infection is a chestnut orchard where about 100 scions from an infected eastern orchard were grafted to native sprouts in 1908. The percentage of infected trees in the orchard from which the scions were obtained, according to a count made this Fall, averages 80 per cent. Evidently these scions brought the disease into this region, for the grafts have all been killed by the blight and every tree in the orchard is killed or infected by disease. On adjoining tracts over 5,400 infected trees have been cut, and there are a number of others in process of removal, radiating in all directions from the orchard as a center to a distance of three miles. Another infection of 143 trees was found in Elk County. It is thought that three trees at the centre of infection were diseased in 1909, although it is possible that one of these trees was already infected in 1908. In 1910, 27 additional trees were infected; in 1911, 50 additional trees, and in 1912, 228 additional trees. The disease spread in all directions from the center of infection to a distance of 700 feet.
These infections are interesting in showing the rate at which the blight may travel in healthy timber.
These infections have all been removed and it is the expectation that by the end of January 1913 all scattered spot infections will be removed from the territory west of the line previously mentioned, and that, to the best of our knowledge, these western counties will be free from blight. In 1913 the field force will be concentrated on the advance line and the work will be carried eastward. The Commission has the power to compel the removal of infected trees. In the western part of the state this power has been exercised in the few cases where it was necessary. As a rule, however, the owners are not only willing but anxious to get rid of the infected trees, and our field men are given hearty support by individuals, granges and other organizations. The timber owners of Elk County had printed and posted an announcement that the chestnut blight had been found in the locality and warned the people to be on the look-out for it. In addition the Commission has had a man, for a short time at least, in each of the eastern counties of the state, and their time has been taken up principally by those who requested inspections of timber with the view of determining the percentage of blight infection and the best method to be pursued in combating it and realizing on their timber. Our men are all deputy wardens, with the authority which is attached to this office, and are instructed to do their utmost to prevent fire damage.