POTATO WILT, LEAF-ROLL, AND BELATED DISEASES. 37 
appearance of the disease was normal, but later harvests fell to 
nothing. No reliable results are available in this country. Con- 
flicting reports come from farmers in the Greeley section; but, as no 
pathologist accustomed to the diagnosis of leaf-roll saw either crop, 
the relative amount of disease in home-grown and outside seed 
remains unknown. 
It seems a wise precaution to use only selected seed from such 
sources as Minnesota and Wisconsin for planting next year where 
leaf-roll occurred last season. It may be that the disease will not 
appear on crops from home seed, but the chances are that it will. 
The introduction of new and more vigorous varieties affords a 
still more hopeful means of ultimately controlling the situation. The 
problem of finding the best source of seed is the most important one 
now confronting potato growers in the region affected by these 
troubles. What is needed are selected stocks, true to name, with 
vigor unimpaired and free from disease. The present difficulty is 
that it is almost impossible to find such potatoes in large quantities. 
Where growers have made experiments with outside seed they have, 
as a rule, made their purchases in the open market or from middlemen 
who have filled their orders with uninspected stocks, for which reason 
no conclusions can be drawn from any experiments to date. 
There is fortunately a movement to organize among potato growers 
in the principal Northern States, and this is backed by their State 
experiment stations in a way that should in time make a supply of 
reliable seed available. 
It would be well to follow the example of Germany, where a 
system of official inspection is being inaugurated, through which 
growers and purchasers may be assured that the crop from a given 
estate is free from leaf-roll. Such a certificate can be granted only 
after an inspection of the growing crop. The importance of such an 
inspection in midsummer by a representative of the purchaser or by 
an official expert can not be overstated. It is entirely impossible to 
determine the vigor and freedom from leaf-roll of a stock of potatoes 
after harvest. 
The practical phases of such a system of seed inspection and 
certification will be discussed more fully in a later publication. 
CURLY-DWARF. 
Under the name "curly-dwarf" there is to be differentiated from 
the leaf -roll a peculiar disorder, characterized by a dwarfed devel- 
opment of the potato plant, accompanied by a pronounced curling 
and wrinkling of the foliage, which has been compared to Scotch 
kale and Savoy cabbage. It is known in Germany as "Krausel- 
krankheit." The accompanying illustrations from photographs 
(Pis. X and XI) show the typical appearance of this disease more 
clearly than the printed description. 
