128: Report oF THE BoTANICAL DEPARTMENT OF THE 
At digging time the market price of potatoes was 35 cents per 
Pushel. At this price 314 bushels would be worth $1.14. Add- 
ing to this $1.80, the cost of spraying, we have in this experi- 
ment a loss of $2.94 per acre. 
Although the spraved rows yielded less than the unsprayed 
it is very improbable that the plants were injured by the spray- 
ing. The small difference in vield, 314 bushels per acre, may 
easily have been due to slight differences in soil. Differences 
much greater than this often occur between adjacent rows 
treated as nearly as possible in the same way. Examples of 
wide difference in vield between rows close together and treated 
exactly alike may be seen in Tables V and VII on pages 100 and 
103 respectively. 
This was Mr. Clark’s first experience with spraying potatoes. 
In fact very little spraving has ever been done at Peru al- 
hough the potato crop is an important one there. In spite of 
the unsuccessful outcome of Mr. Clark’s experiment we believe 
that. one year with another, it will pay to spray potatoes in 
that section. Another experiment will be made in 1905.. It can 
scarcely be possible that potatoes are exempt from blight at 
Peru. At Burlington, Vt., onlv a few miles distant, late blight 
is destructive nearly every season. The Vermont Experiment 
Station, located at Burlington, has made potato spraying ex- 
periments every season since 1891, the average gain for fourteen 
vears being 12514 bushels per acre. Strange to say, the largest 
gain was obtained in 1904 when plants sprayed twice outyielded 
unspraved plants at the rate of 261 bushels of marketable tubers 
per acre. The gain was due chieflv to a reduction in the amount 
of rot among the tubers. 
THE SLITERS EXPERIMENT. 
This experiment was made by John S. Middleton about eight 
miles southeast of Albany. Three acres of potatoes were 
sprayed with a five-gallon, compressed-air sprayer bought of the 
Rochester Spray Pump Company, Rochester, N. Y. (Plate 
XVI, fig. 1.) The potatoes were of the variety Late Delaware 
planted in hills two feet six inches apart each way. The soil 
was a shaly loam. Three rows 600 feet long were left unsprayed. 
The entire field excepting the three unsprayed rows was sprayed 
twice and one-half the field was sprayed a third time. The 
-unsprayed rows were in the portion sprayed three times. The 
dates of spraying were: First, July 11 and 12; second, July 27 
and 28; third, August 8 and 9. 
at 
