92 ReporrT OF THE BOTANIST OF THE 
Increase in yield due to spraying three times, 98 1-2 bushels 
per acre. 
Increase in yield due to spraying seven times, 123 1-2 bushels 
per acre. . 
Considering that the difference in the appearance of the foliage 
on series I and IJ was very slight, we were surprised to find the 
difference in yield so large as 25 bushels per acre. 
The loss from rot.—Although there had been considerable late 
blight (Phytophthora) on all of the unsprayed rows and a litile 
also on the sprayed rows, the tubers were found to be but little 
affected with rot. On the sprayed rows only an occasional rot- 
ten tuber was found, and even on the unsprayed rows the number 
was not large. Most of the affected tubers were completely rot- 
ten. Very few showed the early stages of the disease. 
In order to determine, approximately, the amount of the loss 
from rot, the number of rotten tubers was counted on row 12, an 
unsprayed row which probably suffered as much from blight as 
any other-row in the field except row 15. The number of rotten 
tubers was found to be 184. Unfortunately, the number of sound 
tubers in row 12 was not determined, but assuming it to be the 
same as on the unsprayed row 6, where the number was 1,628, 
the loss from rot was 7.6 per ct. In size the rotten tubers ap- 
peared to average about the same as the sound ones. This would 
make the loss from rot on the unsprayed rows about 18 bushels 
per acre, which is small, considering that the tops were so badly 
blighted. Had the conditions been more favorable for rot it is 
likely that the difference in yield between the sprayed and un- 
sprayed series would have been considerably greater. 
At Riverhead.— The potatoes were dug on August 29 and 30 
by hand and carefully and uniformly sorted into marketable 
tubers and culls. On the sprayed rows growth had ceased, the 
leaves being nearly all dead, but many of the stems were still 
green and more or less succulent. The unsprayed plants were 
entirely dead and the stems dry. 
