BULLEtTIN of the 
UOTMlNTOFAfCDIHl 
No. 64 
Contribution from the Bureau of Plant Industry, Wm. A. Taylor, Chief 
February 10, 1914. 
(PROFESSIONAL PAPER.) 
POTATO WILT, LEAF-ROLL, AND RELATED 
DISEASES. 
By W. A. Orton, 
Pathologist in Charge of Cotton and Truck Disease and Sugar-Plant Investigations. 
INTRODUCTION. 
During recent years there has been much doubt and misunder- 
standing among plant pathologists and observant farmers concerning 
the group of potato diseases variously referred to as wilt, leaf-roll, 
leaf -curl, Fusarium blight, bacterial ring disease, etc., which in 
different countries of the world appear to constitute problems of 
increasing importance to practical agriculture. 
This bulletin seeks to clear up the situation and to open the way 
for more efficient measures of control by differentiating these pre- 
viously confused diseases and fully describing the methods of diag- 
nosis. The results afford a strong argument to pathologists for a 
broader outlook over the field and for international as well as national 
comparisons of conditions. The fundamental importance of thorough 
laboratory investigations is not minimized, but the interpretation of 
results in their relation to the basic principles of plant pathology and 
to the general problems of agriculture require a better conception of 
the different environmental influences to which crops are subjected 
in the several States and in foreign countries. 
To the practical potato grower to whose attention these new potato 
diseases are brought, the feature of greatest significance will be their 
effects in impairing the vigor of his seed stock and on the deterioration 
of varieties. New evidence is presented that large but insidious 
losses have been suffered from seldom-recognized weaknesses in vege- 
tative vigor and from diseases transmitted through the seed — losses 
that threaten to be greater in the future unless active measures are 
taken at once to secure more vigorous and disease-free strains or 
varieties through seed selection and breeding. 
Note.— This paper is of interest to plant pathologists; it is suited to the potato-growing sections of the 
North, West, and South. 
22741°— 14 1 
