Influence of various factors, principally transpiration, upon infection of wheat and barley plants by the powdery mildew

Abstract

Erysiphe Graminis is the powdery mildew which grows upon the Gramineae (Grass family). Something like fifty-five species of the family are affected by this fungus. Among these species are the cereals wheat, barley, oats, and rye, so naturally this mildew has attracted much attention. The problem which is to be discussed in this paper is: The effect various conditions have on the growth of the mildew on wheat and barley plants. Most of the data presented here are on the effect of transpiration of the host plants as an influencing factor. Other experiments from which data were obtained were (1) the cross inoculation of wheat and barley with the mildew, (2) the inoculation of the Common emmer with wheat mildew and (3) the effect of alcohol on such inoculations. Although the real problem is the conditions which affect the growth of the mildew on its own host, still the results of these studies throw (indirectly) a light on this problem.