164 Report oF THE BOTANICAL DEPARTMENT OF THE 
knapsack sprayer. The first spraying was made July 4 and the 
last one August 15. One row 170 feet long was left unsprayed. 
This experiment was located near the Experiment Station 
where the writers had opportunity to watch it closely. ‘There 
was a rank growth of vines which completely covered the ground 
early in the season. By August 15 only a few green leaves were 
left on the unsprayed row, all the others having been killed by 
late blight, Phytophthora imfestans. At the same time the 
sprayed rows were perfect. 
On August 23 the rows were photographed (See Plate XV). 
At this time most of the plants on the unsprayed row were not 
only dead but their stalks were dry and shriveled. Sprayed 
plants on both sides were in full foliage showing only traces of 
blight. By September 9 the sprayed plants were commencing 
to die, apparently of old age, and by September 15 were dead 
after having outlived the unsprayed plants by a whole month. 
Aside from the ten-year experiment at the Station the past sea- 
son, this experiment of Mr. Hadlow’s was the most striking 
demonstration of the value of spraying that we have ever seen. 
It should convince the most skeptical that spraying, properly 
done, will prevent blight. 
At digging time, Mr. Hadlow, assisted by the writers, weighed 
the potatoes from the unsprayed row and from the adjacent 
sprayed row on either side with the following results: 
West sprayed row, 16114 pounds of marketable tubers. 
East sprayed row, 266 pounds of marketable tubers. 
Average of sprayed rows, 21334 lbs., or 304 bu. 14 Ibs. per acre. 
Middle unsprayed row, 104 lbs., or 148 bu. 2 Ibs. per acre. ~ 
Gain from spraying, 10934 lbs., or 156 bu. 12 Ibs. per acre. 
The gain of over 100 per ct. was almost wholly due to pre- 
venting the ravages of late blight and the rot which follows it. 
There was no other disease or insect enemy of importance. The 
unsprayed rows were not injured by bugs. There appears to 
have been considerably more rot on the unsprayed row than on 
the sprayed. It was impossible to determine accurately the 
amount of rot on the unsprayed row because the affected tubers 
were in an advanced stage of decay. On the sprayed rows there 
was only an occasional rotten tuber. 
