26 
Journal of Agricultural Research 
Vol. XIV, No. i 
ary 26, 1917, this area was photographed (PI. 9, A). According to 
information obtained from the grower, spinach-blight began to develop 
in this area during the first week in January. Besides this large 
area, a few smaller areas also developed in the same field. Blighted 
plants were collected from the largest area and brought to the green¬ 
house, where individuals of Macrosiphum solanifolii and Rhopalosiphum 
persicae were removed and placed on six pots of spinach seedlings 1 
month old. Similar plants were kept in another cage as controls. Nine¬ 
teen days after inoculation the majority of the plants in each of the 
pots had developed characteristic symptoms of blight. Some of the 
plants from which the aphids had been removed were placed in a cage 
with six pots of spinach seedlings, care being taken that the blighted 
plants did not come in contact with the seedlings. The next day it was 
observed that many of the aphids had crawled to the seedling plants. 
Nineteen days after inoculation numerous blighted plants were observed 
among the pots of seedlings. The controls appeared healthy. These 
results indicate that the blighted plants on farm E were produced by 
the same specific virus which caused blight on other farms. 
A few of the central leaves were removed from blighted field plants 
from which the aphids had been taken, and six pots of seedlings were 
inoculated by mashing the blighted tissue into the leaves. Seventeen 
days after inoculation, some of the plants in each of the above pots had 
mottled leaves. Forty days after inoculation plants in each of the pots 
were in the advanced stages of blight, while the control plants appeared 
healthy. 
Forty-three days after inoculation a mottled leaf was removed from 
one of the blighted plants, and five healthy seedlings in another pot were 
inoculated by mashing the diseased tissues into them. Eighteen days 
later two of the plants had developed the mottled leaves of blight. The 
control plants appeared healthy. 
With another mottled leaf, removed from a blighted plant 43 days 
after inoculation, five large plants in a field cage were inoculated by 
mashing the diseased tissues into the healthy plants. Similar plants in 
the same cage were pricked with a flamed needle and served as controls. 
Seventeen days after inoculation all five of the above plants had devel¬ 
oped decidedly mottled leaves, but the control plants appeared healthy. 
These results show that the spinach-blight on this farm is due to a 
specific virus which may be transferred from diseased to healthy plants 
either by aphids or by needle pricks, thus indicating that it is the same 
disease as that occurring on other farms. 
Farm F.—In a field of spring spinach on farm F located at least 10 
miles from the Experiment Station a few scattered plants appeared to 
be affected with blight. Some of these were collected and brought to 
the greenhouse, where aphids were removed and placed on two pots of 
spinach seedlings. Similar pots of plants were used as controls. Macro - 
