NUTRITIONAL STUDIES ON FUSARIUM LINI

The study of the nutritional relationships of parasitic fungi is fundamental to a satisfactory knowledge of the diseases which they produce as well as to a correct understanding of the causes of infection, parasitic invasion and resistance. The problem of resistance to disease is undoubtedly very complex, since not only are there many types of parasitic invasion, but there are also many contributing causes which interact with parasitic invasion to give rise to a given diseased condition. The nutritional demands of the invading organism must, however, be met by the host in order to have a successful invasion. Therefore a knowledge of the demands made by specific fungi, and of the substances available in their hosts, will lead to a better understanding of the conditions which make disease possible in those specific cases. Hence it is necessary to know the range of food substances of a given parasite and those available to it in a given host. Resistance as a nutritionazl problem, then, may be due either to the presence of antagonistic substances, or to the absence of essential food requirements, or to various combinations of these. The direct object of the present research is to learn the nutritional requirements and range of specific parasitic organisms, and, in specific hosts, the type, range and abundance of materials which may affect the growth of the parasite. The ultimate object is to give a more definite idea of the causes of resistance, especially where resistant and susceptible strains of the same host are known. It may well be expected also that careful attention to this subject will reveal many facts which will bring about a better understanding of the physiology of the higher plants. The physiological investigation of obligate parasites is difficult and the methods of attack upon the problems involved are vague and uncertain. It seems more hopeful to begin the study with organisms which are on the border line between saprophytism and parasitism and to progress toward the obligate parasites from that direction, building upon the knowledge gained from research on the facultative organisms. Such a program has been adopted in the physiological work of this department. A general survey of