Potato Cuvi'urk in Colorado 
29 
indicates the presence of the disease. Seed potatoes showing the 
presence of the disease should not be planted, as a matter of 
safety. While it is true that seed potatoes showing the presence 
of the disease often produce healthy, normal plants with a satis¬ 
factory yield, the fact is that the disease is present and may, un¬ 
der favorable conditions, develop and attack the growing plants. 
It is also believed, though not proven by careful experiments, 
that cut seed is more apt to become infested with the disease than 
whole seed. This may be due in some cases at least to the lack 
of vigor of plants grown from small seed pieces. It would seem 
that where the disease is prevalent and where the conditions are 
favorable for its development, that whole seed would give better 
results. The planting of whole seed, however, does not insure the 
grower against loss by this disease, as it may attack the growing 
sprout and cause great losses. 
The disease being internal, it cannot be reached by any rem¬ 
edy that we may use against it. Precautionary methods, such as 
planting of disease-free seed, crop rotation, and the best cultural 
methods, will be in the main effective in preventing the disease 
from doing great damage. 
The appearance of the disease in the field is in many cases 
identical with that of the early blight, with the exception that the 
leaves turn a'paler shade of yellow, and do not show the brown 
patches and circles. The stem of the plant is first attacked, and 
if a cross section is made of the stem close to the ground, dark 
areas will be found in the bundle or the fiber portion of the stem. 
These dark areas indicate the presence of the disease, and its 
presence greatly interferes with the transportation of food ma¬ 
terials. 
Curly Lea/.—This is a disease of unknown origin, which oc¬ 
curs some seasons in the State. As the name would indicate, the 
leaves assume more or less of a curly outline, and the plant l)e- 
comes more or less stunned in its growth. It is believed that this 
disease is transmitted or carried by the seed tuber. The fact that 
the plant does not show any marked discoloration is responsible 
for the fact that this disease is often passed over by the grower 
and no attention is paid to it, although the loss from the disease 
may be considerable. The grower should be on the lookout for 
plants showing the symptoms of the disease, and destroy them 
at once. 
Rhizoctonia .—This disease is present in practically all of our 
cultivated fields, and, under favorable conditions, does consider- 
