A study of the physiological relations of Sclerotinia cinerea (Bon) Schröter,

Abstract

This paper reports the results of an experimental study regarding certain physiological activities of the brown-rot fungus of stone fruits. The investigation concerns itself primarily with the conditions influencing the penetration and infection of green and ripe fruits by the fungus in question, the action of the parasite on the host cell, and the secretion of the enzymes which act upon the cellulose and pectic substances of the host. The work was undertaken with the hope of throwing some further light upon the factors concerned in fungous parasitism. Our present conception of this subject is based upon fragmentary and, in some respects, contradictory evidence-.However, each year there are acquired new facts, or new applications of known facts, bearing upon this exceedingly involved and complex question. An examination into the history of investigations concerning the interaction of host and parasite shows that the study of this subject dates back to the work of the pioneers in plant pathology; modern methods and recent discoveries have, however, given an added impetus to research along this line. Progress in combating fungous diseases depends not only upon a familiarity with the life history of the parasite, but more especially upon an intimate knowledge of the metabolism of the parasite and the nature of the changes which it induces in the host. Indeed, many of our recommendations for controlling parasitic diseases of plants will perhaps be modified when a moreexact knowledge of the interrelations of host and parasite is gained. Furthermore, a more intimate knowledge of the physiological aspects of plant pathology will undoubtedly throw much light on the question of immunity and susceptibility. We should, -of course, like to know more about the factors favoring or inhibiting parasitic action, as well as the conditions