Jan. 15, 1917 
Blackleg Disease of Potato 
87 
In all probability the disease has been introduced in the same way 
into other States along the northern border. It was carried to the 
Southern States by northern seed. There is one authentic instance of 
the introduction of blackleg into this country directly from England. 1 
At Kingston, R. I., in the summer of 1907 five hills of potatoes showing 
blackleg were found. These potatoes were grown from seed tubers 
which were obtained from England in the spring of the same year. This 
was the first and only case of blackleg that had been reported from 
Rhode Island up to that time. 
One interesting and apparent case of importation of the disease from 
Europe and its transference in this country is as follows: In the summer 
of 1912 it appeared commonly on a field in Parkman, Me., in a part of 
the State where the disease was practically unknown, and on a farm 
where the owner had never observed it before. The field was planted 
with a variety known as Delmany Challenge, which came from Twin 
Falls, Idaho. Inquiry showed that this variety had been grown on a 
farm near Twin Falls for three years, having been shipped there from 
Carbondale, Colo., where it had been planted for two years. The Car- 
bondale grower imported the original seed tubers from Scotland. The 
writer has since visited the farms mentioned in Carbondale and Twin 
Falls and found blackleg present in the potato fields on each. 
ECONOMIC ASPECTS OF THE DISEASE 
Wherever the type of disease under consideration occurs, those who 
have described it emphasize its economic importance. Apparently a 
loss of from' 5 to 10 per cent of the plants on affected fields is not an 
uncommon occurrence in Germany, and much greater losses are reported. 
Frank (13) reports cases where at least 75 per cent of the plants on a 
given field were killed from this cause alone. Pethybridge (25) reports 
the result of experimental trials in which apparently sound tubers taken 
from an infected crop of the previous season produced 94 per cent of 
diseased plants. 
During the past nine years the writer has had opportunity to make 
some rather extensive observations on this subject. In Aroostook 
County, Me., in a fairly continuous area, there are about 50,000 acres of 
potatoes grown annually. In this region there are few potato fields of 
less than 10 acres, and usually the acreage of individual farmers runs 
from 20 to 50, although fields of 60 to 80 are not uncommon and there 
are those which run to 100 acres or more. 
Considerable time was spent in this and other potato-growing sections 
of the State each year, and during the first five years large areas of 
potatoes were inspected annually. In many fields only scattered plants 
have been observed and not infrequently these amount to 1 or 2 per cent, 
1 Reported by Prof. G. E. Adams, of Rhode Island State College, in correspondence with the writer. 
