THE RELATION OF PHYTOPATHOLOGISTS TO PLANT

DISEASE SURVEY WORK'

G. R. LYMAN

The work of plant pathology falls in three categories, each of which is coming more and more to require the services of specially trained experts. The first of these is research on the nature and development of the disease and the effect upon the host plant. The goal of phytopathological research is the 'discovery of effective methods of controlling in the field the disease under investigation. The second division of pathological work is extension,-which carries to the grower the results of research work, and demonstrates to him the practical control of plant diseases. This important work, which was formerly carried on by the research pathologist as a subordinate part of his activity, is being rapidly developed and given over more and more to extension specialists.

A third branch of phytopathological work is now beginning to be recognized the intelligence service, or the systematic gathering of field data on plant diseases. Both research and extension work are based on field study of the diseases, and the gathering of such information must precede and accompany all other pathological activity. In the past there has been little systematic survey work, the research and extension workers undertaking only as much as was absolutely necessary to the prosecution of their main projects. But the increasing importance of phytopathological work makes necessary a more efficient intelligence service, and since the collecting and correlating of field data present special problems, it follows that in the future the work must be placed largely in the hands of plant disease survey experts, who with the research and extension pathologists, complete the trio of phytopathological specialists.

Plant disease survey work was begun in the United States Department of Agriculture a number of years ago, but only last July was it given recognition as an independent enterprise, with an opportunity to work out its own problems. In formulating our plans for developing the Survey we must keep clearly before us the fact that plant disease survey work is public service work. Plant diseases, on account of the havoc

'Paper read January 1, 1918, at the Pittsburgh meeting of the American Phytopathological Society in joint session with the Botanical Society of America and Section G of the American Association for the Advancement of Science in a symposium on Phytopathology in Relation to War Service.

wrought, are of vital concern to the public, and we must handle disease data as we would handle other public property, collecting and distributing them for the good of all. We must strive to serve all parts of the country, to benefit all pathologists, and to assist all pathological work, not advancing any individual or group of individuals by the exploitation of others. In this work we are not introducing new machinery to displace or to compete with that now existing. On the contrary we propose to coöperate with all agencies now working along this line, coördinating their work, and supplementing and assisting them wherever possible. In pursuance of this policy the pathologists at the experiment stations have been made plant disease survey collaborators and are now acting as local leaders in every state but one, a state in which pathological work has not been developed. Since taking up this work last spring I have been greatly impressed with the spirit shown by these men who are the leaders in phytopathology in their respective states, with their earnest desire for coöperation in working out our problems, with the absence of unfriendly and destructive criticism, and with their enthusiastic belief in the importance of Survey work as it is to be developed in the future. We have many problems to solve,-questions of finance, of personnel, of adjustment to other lines of activity, which must be taken up in each state, but we are not, so far, confronted with difficult problems of clashing interests and jangling personalities. I believe we shall avoid these pitfalls, and if we do we shall certainly be able to develop a service of very great value to phytopathology in the United States, and one which shall serve as an object lesson in botanical coöperation and a stimulus to similar efforts elsewhere.

Before passing to a discussion of our plans of organization let us briefly consider how we expect plant disease survey work to benefit pathologists in order that the character of our aims may be better understood and the scope and details of our plans be of greater interest. It is the function of the Plant Disease Survey to gather information on plant diseases, not to investigate the diseases themselves nor to demonstrate their control. Therefore, we shall not compete with the research pathologist or the extension worker, but shall coöperate closely with both by supplying the former with data necessary to the solution of his problems, and the latter with information which will aid him in planning and carrying out his campaigns. We propose to do this by systematizing the collecting and distributing of information, thus making the data more complete, more authoritative and more timely.

In the first place we hope to assist the pathologist in selecting the most important problems for study. Every pathologist, no matter where he may be located, has a multitude of problems pressed upon him for atten

tion. Which shall he take up first? Especially embarrassing is the case of a newcomer beginning his duties as pathologist in a state or region, who finds no large body of accumulated data to guide him in orienting himself. What things are apt to influence or even to force his choice of problems? Too often it may be purely local conditions. Diseases of merely local prominence may assume an undue importance on account of lack of data to furnish a true perspective. Or it may be his choice is due to the persistence of certain persons in bringing particular diseases to his attention or to the finding of equipment at hand suitable for certain lines of work. All too frequently his personal inclination toward a certain problem or his previous training and experience govern his choice. All these points should receive due consideration, but the more vital questions are: what diseases are most important in this region or state, all things considered? In connection with what diseases will the greatest saving be made if control measures are discovered? Which are the problems most immediately important under the present war conditions? To properly answer these questions and to choose his problems wisely the pathologist must have access to a large body of plant disease data which will give him a grasp of the disease situation not only in his own state, but also in neighboring states, in order that the relations of his local problems to the broader ones of the nation may be understood.

I have talked with pathologists of many states this season and a number have frankly stated that the diseases they are investigating are probably of minor importance, but that a wiser selection is rendered difficult or impossible through lack of field data. The Plant Disease Survey must secure these data, thus clarifying the disease situation in each state, and delimiting the pressing problems. This service would be important in times of peace, but is imperative now in times of war, when, with our numbers reduced by military service, we must make sure that we are wasting no time on problems of lesser importance.

The Plant Disease Survey will also assist the pathologist in the prosecution of his research work. He needs detailed information on the nature and characteristics of the disease as they appear in the field, on the various factors influencing its development, on geographical and seasonal variation, on the methods and conditions of its spread from place to place. These and other data should be gathered by the Plant Disease Survey, working in many cases under the immediate direction and supervision of the investigator in order that he may obtain the exact information. desired. Every pathologist should himself perform a sufficient amount of field work to thoroughly familiarize himself with every phase of his problem, and certain data of a highly technical character can be obtained by no one else, but for the skilled investigator to personally accumulate

the large body of field data which is frequently necessary is undoubtedly in many cases a serious waste of valuable time which could more profitably be spent on research. On the other hand, for him to attempt to solve his problem without adequate data may lead to serious error. Neither plan makes for efficiency. Close coöperation between the investigator and the Plant Disease Survey in accumulating these data is a businesslike division of labor, for the investigator's time can thus be conserved for research, and the gathering of data be placed in the hands of those trained for this work.

The Survey will aid the pathologist and the extension worker in planning and in carrying out their campaigns for disease control. In order that they may plan wisely they must know where the disease under consideration is most serious and its relative prevalence in different regions. They must know in what localities control measures are already generally practiced and where they are neglected in order to decide where demonstrations and educational work are most needed.

An efficient watch service on the health of plants developed by the Plant Disease Survey in close coöperation with the various agencies charged with disease control would be of immense value and would tend to conserve the health of our food crops as the Public Health Service conserves that of human beings. Early warning of impending outbreaks of disease would permit the immediate use of preventive measures which might check the development of serious epidemics. Prompt notification of the first appearance each season of serious diseases which are susceptible of control, like late blight of potato, is the first prerequisite for effective control of these diseases. Careful accumulation of field data on epidemics and on unusual occurrences of important diseases would lead to a better understanding of the conditions influencing the development, spread and control of such outbreaks.

The Plant Disease Survey should also maintain a watch for new diseases which have gained a foothold in the United States and for new and virulent strains of old diseases in order that early warning may be given to plant pathologists and data furnished the Federal Horticultural Board on which quarantines to prevent the spread of the diseases may be based. Pathologists are engrossed in their work and new diseases are apt to escape observation or to be disregarded until they have so thoroughly established themselves and spread over such a wide area that their eradication becomes almost, if not quite impossible. Our chestnut trees are being destroyed by the chestnut blight, a new disease which thoroughly established itself and spread beyond control throughout the region around New York City before it was discovered. The white pine blister rust remained undiscovered for four or five years, and might have remained