in the classroom and the extension workers' demonstrations in the field so as to make certain its application in every day practice. This is a big and important educational program for the future. Chapter VII PLANT PATHOLOGY By DONALD REDDICK Professor of Plant Pathology, New York State College of Agriculture at Cornell University During the five years 1867 to 1872 there were associated in the faculty at Halle, two men who have been accorded the title of "Father of modern plant pathology." Julius Kühn, "the microscope farmer," had published a decade earlier his well-known book "Die Krankheiten der Kulturgewächse," and at the time, had under way experiments which extended well into the present century and which proved the most extensive ever undertaken in the control of plant disease. Anton De Bary, Anton De Bary, a medical school product, had established conclusively the fact of fungous parasitism through his epochal work on Phytophthora infestans, the potato blight fungus, and on Puccinia graminis, the wheat rust fungus. There is almost no evidence that these men at Halle found a great deal in common and from this it may be inferred that there was no particular conflict or overlapping of work and no recognition of any peculiar community of interests. The present overshadowing importance of fungi as the cause of disease in plants had yet to be developed. De Bary was interested in fungi whether they caused disease in plants or not; Kühn was interested in disease whether caused by fungi, nematodes, wet soil, or what not. The condition existing at the very inception of modern plant pathology has persisted to a marked degree even to the beginning of the present decade, and, indeed, can not be said to have disappeared entirely even at the present time. No longer ago than 1910, one of the foremost plant pathologists in the United States felt impelled to justify the use of the word plant pathology, the organization of the American Phytopathological Society (which has increased from 200 to 500 in membership during the decade), the starting of new courses, indeed of departments in the universities; This report is based upon replies to a questionnaire sent to pathologists in all the land-grant colleges. The writer is under obligations to the various persons who assisted in the compilation, but obviously he must accept responsibility for the interpretations presented here. 66* * the publication of textbooks and of independent journals." "The reply is simple and we believe practically sufficient, even though not quite satisfying scientifically." [The italics are mine.] The advance of plant pathology will be just in proportion to the clear recognition of the fact that its chief problems are biological rather than economic, that the primary concern must be with the uncovering of physiological relations and principles rather than the field trial of fungicides," etc. The foregoing is from the man who has been the leader in phytopathological teaching during the decade, from the man whose previous work in the educational field helped very much to break down the ideas he has expressed in the quoted passages, and whose recent work has by no means conformed to the narrow limits prescribed in his remarks. The most notable change in plant pathology, in general, in the United States during the decade has been the disappearance of that old distinction between pure science and applied science. The idea that when the so-called pure scientist had determined the life history of a parasite or had determined the proper balance of mineral food for best development the so-called applied scientist might be intrusted safely with performing the necessary field trials to develop a suitable means of control of a disease, has broken down almost completely. Rather it appears that in the science of plant production there is a convenient natural division, plant protection, which involves a proper fragment of all of the older subjects-general biology, botany, physiology, biochemistry, meteorology, agronomy, horticulture, etc., and which properly blended may be called plant pathology, a subject which of necessity is as "pure" as the purest, and as applied as the most practical. Indications are not lacking that the last remnant of “parlor botanists" came to a true realization of the problems of plant pathology when they offered their services in stimulating crop production in 1917, while the so-called practical men some years earlier recognized the particular contributions that the skilled scientists with their microscopes and test tubes could make to the solution of problems of greatest practical importance. While it is true that indications of this general trend were not lacking prior to the decade just ended, the development of the past 10 years has been such as to indicate a rapid emergence of plant pathology as a definite unit in a department of botany or as a definite "department" in a college of agriculture, with the consequent disappearance of such courses in botany as "economic mycology," "parasitic fungi," "mycology and bacteriology," and in agronomy and horticulture of such courses as "spraying," "seed treatment," and the like. The blending of the so-called pure and applied in the development of plant pathology has been accomplished chiefly through the education of a new generation of workers, trained alike in the technique of the laboratory and of the field, intimately acquainted not only with the practical phases of the subject and the significance of them but equally alert to the most obstruse theoretical considerations. An early blend which is fundamentally important seems to have been considerably diluted during the decades and only very recently has any attempt been made to improve the mixture. The basic importance of the facts established by Pasteur never have been overlooked, but the developments in animal pathology brought about by that vast progeny of Pasteur have not been utilized to the fullest extent. There is little question that this is to be attribtuted to lack of personal contacts. The overshadowing importance of human pathology has drawn the animal pathologist to the laboratories and hospitals of the large cities while the principal materials of the plant pathologist are in the open country. No long-established institutions have established work in plant pathology, although most of them maintain animal pathology in a highly developed medical school. Thus the two branches of a subject basically identical have become widely separated, a condition surely detrimental to the most rapid progress in plant pathology and doubtless somewhat detrimental to development in animal pathology as well. GRADUATE TEACHING Plant pathology is primarily and of necessity a graduate subject, in which research on the part of the professor and his students is the principal goal. "Of necessity," because the accumulated experience in this new field is not so great that many credit hours of undergraduate college work can be justified. The instruction of professional students, for the most part is on a personal basis. The number of students in any given institution is very small and formal courses are uncommon. It is in only a few of the larger institutions that formal graduate courses in plant pathology are offered and in most of these the development of them has fallen within the decade. It is a curious fact that while every teacher of plant pathology recognizes that his teaching, whether graduate or undergraduate, is based on previous research and often very decidedly upon the researches done at his own institution, nevertheless, at half the land-grant colleges the teacher is not allotted any time for scholarly work and professional advancement, Re search is not clearly recognized as one of the functions of a teacher. The unfortunate effect of this condition upon the progress of teaching can not be doubted. It needs to be remembered, however, that many of the teachers are employed part time on experiment-station work. In this event they may have opportunity to undertake a research, although the numerous details connected with extensive field experimentation often consumes a great deal of time at the expense of real research. UNDERGRADUATE TEACHING Courses of study in plant pathology for undergraduates are now offered in most of the land-grant colleges. In less than half of the institutions plant pathology is a separately organized unit or depart ment. In the others it is a recognized division of botany. In only a single case is it attached to another department than botany (or biology), namely, to agronomy. These courses of study have been organized within the past decade in more than half the institutions. The content of the courses is as yet extremely variable, due, no doubt, to the fact that teachers of pathology have never held a symposium on the subject and that no generally adopted textbook for college students has yet appeared. Almost without exception, however, teachers try to make the elementary course general or else more or less general with local adaptations. Beginning courses, taught primarily from the standpoint of important crops within the State, are rare; but in certain States, particularly those of widely diversified agriculture, special courses of this type are being developed to follow and supplement a general course. In a great many institutions some mention of important diseases of special crops, with discussion of control measures, is made in courses in horticulture, agronomy, and the like; but, almost without exception, the tendency is away from this practice. This statement represents the judgment of teachers of pathology, but it is borne out strongly by the fact that so many departments of pathology have been established in recent years, and by the number of " prescribed " four-year courses in which pathology is made a requirement for graduation. The courses for undergraduates, without exception, are based on previous botanical courses, often including physiology and bacteri ology, so that for the most part only senior and junior students may be admitted. EXTENSION TEACHING Very extensive development of teaching away from the colleges has come during the decade. The nature of the subject is such that most satisfying, clear-cut, and obvious results of demonstrations may |