182 REpPorRT OF THE BOTANICAL DEPARTMENT OF THE 
Irom the above table it will be seen that the gains due to 
spraying were as follows: 
Soluble bordeaux, 10 bu. 58 Ibs marketable tubers per acre. 
Soda bordeaux, 51 bu. 40 Ibs. marketable tubers per acre. 
Lime bordeaux, 68 bu. 21 lbs. marketable tubers per acre. 
COMMENTS ON RESULTS. 
It is possible that the soluble bordeaux was at a slight disad- 
vantage in the first spraying for the reason that five of the rows 
were but partially dry when rain came. However, we believe 
it improbable that this had much influence on the results because 
a second spraying was made only six days later, August 8, and 
subsequent events indicate that but little infection occurred 
during the interval. Blight did not get well under way until 
after September 1. 
With the exception above noted, the test seems to have been 
a fair one. While there were doubtless slight inequalities in 
planting, it is probable that they were pretty evenly divided 
among the four series. 
It will be seen that there was more than twice the weight of 
rotten tubers on the soluble bordeaux rows that there was on 
the check. The reason for this is not clear. The rot was prac- 
tically all due to Phytophthora, that is, a direct consequence of 
the blight affecting the tops. Most of the affected tubers were 
in the early stages of the rot and it is unlikely that the smaller 
amount of rot on the check can be attributed to the more com- 
plete decay of the tubers on those rows. Probably the soil and 
weather conditions were more favorable to rot late in the season 
after most of the blight spores on the check rows had dried up. 
On the sprayed plants the blight spores lived longer because the 
foliage continued green longer. 
The increased yield on the sprayed series was chiefly due to 
the prevention of Jate blight, Phytophthora infestans. There was 
no early blight and no injury by flea-beetles. 
In this experiment blight was not as virulent as in other spray- 
ing experiments in the same field. This was largely due to the 
fact that the plants were much smaller, owing to lack of fertil- 
izer. Probably, also, the three heavy applications of paris green 
to the check rows protected them considerably against blight. 
