MILDEWS, RUSTS AND SMUTS 
INTRODUCTION 
T he fungi dealt with in this volume are popularly 
known as " rusts" and “ mildews." From an 
economic standpoint they are of considerable 
importance, being the direct cause of a loss to culti¬ 
vated plants throughout the world, of an annual sum 
amounting to many millions of pounds sterling. Much of 
this loss can be averted by the timely application of proper 
preventive methods, but this can only be successfully 
accomplished by a person possessing a clear knowledge of 
the particular fungus causing the disease, hence the study 
of fungi is imperative on the part of all who aspire to the 
position of what is commonly termed a plant pathologist, 
or student of economic mycology. The reasons for the 
possession of this special knowledge are various ; the full 
life-cycle or course of development are in many instances 
so complicated, that the detection of a vulnerable point 
in such development can only be discovered by those who 
have made a special study of the whole course of develop¬ 
ment of these parasites. All the rusts and mildews are 
microscopic in size, and their reproductive bodies are so 
infinitesimally minute, that they are readily dispersed 
wholesale, and over large areas by wind, birds, insects, 
etc., hence extermination is an impossibility, and only a 
full knowledge of the habits and mode of life of such para¬ 
sites can enable a person to anticipate their advent, and to 
formulate proper precautions against the outbreak of an 
epidemic of disease. Finally, all rusts and mildews are 
parasitic on living plants, more especially on wild plants, 
and it is generally from wild plants that the parasitic fungus 
in the first instance passes on to cultivated plants that are 
botanically related to wild ones. 
It is now nearly half a century since the last British 
book on Fungi, including the rusts and mildews, was pub¬ 
lished. At that date economic mycology, or the true 
