The) Potato Industry or Colorado. 37 
all of these diseases come under the common name of “potato 
blight,” and are caused by various species of fungi that work on the 
outside of the foliage or stem of the potato above ground.* 
Late Blight. —The disease most talked about and which prob¬ 
ably causes more trouble to potato growers of the East than any 
other is that known as late blight, or Phytophthora infcstans. This 
fungus came to the United States from northern Europe, its native 
homef, being the home of the potato in South America. The first 
we hear of this disease causing trouble to any great extent was at 
the time of the famine in Ireland during the forties of the last cen¬ 
tury. The ravages of this disease in destroying the potato crop of 
Ireland, resulted in the death of 300,000 people in one year from 
starvation, and brought to a crisis the political agitation and the 
emigration from Ireland that is only now being abated. This 
fungus did its first damage in the United States in 1843 and has 
gradually spread from the eastern states, west, as far as the hu¬ 
midity of the climate would permit its growth .% 
Late Blight Described. —Where this disease is prevalent, it 
may be seen in early fall, on the lower side of the leaves as a fine 
mould. When the seasons are comparatively dry with little humid¬ 
ity, the plants seem to withstand the disease, so it will not be notice¬ 
able, except that the plants appear to mature earlier than where the 
disease is prevented by spraying. We found at the Connecticut 
Experiment Station, that while unsprayed plots showed no partic¬ 
ular signs of disease, the foliage appeared to ripen off so that the 
plants were dead two or three weeks before frost, while sprayed 
plants were still in good condition until frost struck them. 
Damage of Late Blight. —Not only does the fungus kill the 
vines or injure them so as to reduce the yield, but in seasons when 
the weather conditions favor the development of the fungus, the 
tubers decay in the ground, or if infected tubers are taken to the 
cellar many of them will decay later. This loss by decay is some¬ 
times as great as fifty per cent, of the crop of a whole district. It 
is not uncommon for this disease to destroy the plants over a large 
part of a state within three or four days from the time the effect 
of the fungus is first seen on the plants. 
*For this reason the old, almost universal remedy has been the 
fungicide Bordeaux mixture. It is not uncommon to find Colorado potato 
growers planning to spray their potatoes for diseases which have never 
been known in this State. 
fThe Potato, Samuel Fraser. 
$It is not probable that the disease will visit Colorado, for as the 
fungus lives over winter in the tubers it certainly must have been brought 
to the State and planted many times in the last ten or fifteen years. 
Therefore, we may conclude that as the disease has not been found in 
the State our climate is not favorable to its development. 
