140 Report OF THE BoTANICAL DEPARTMENT OF THE 
marked contrast, the unsprayed rows being practically dead while 
the sprayed rows were still green. On September 23 the test rows 
were photographed (See Plate V). At that time the unsprayed 
rows were dead and the stalks of the plants mostly dry while the 
nearby sprayed rows on the west still retained one-third to one- 
half their foliage. For some unexplained reason the sprayed rows 
on the east side of the unsprayed strip were considerably less green 
than those on the west. Still there was much contrast as is plainly 
shown in the photograph. 
Not having an opportunity to examine the field after the out- 
break of blight until September 23 the writers are in doubt as to 
the nature of the disease which killed the unsprayed rows. Tip- 
burn and early blight were certainly factors and probably late 
blight, Phytophthora infestans, also, played an important part 
although there was little evidence of it on the plants September 23. 
The test rows were dug October 30 and the yields found to be 
as follows: 
Second sprayed row on the west, 468 lbs. marketable tubers. 
Second sprayed row on the east, 278 lbs. marketable tubers. 
Average of two sprayed rows, 373 lbs. marketable tubers. 
Middle unsprayed row, 227 lbs. marketable tubers. 
Yield, sprayed, 135 bu. 53 lbs. marketable tubers per acre. 
Yield, unsprayed, 82 bu. 42 lbs. marketable tubers per acre. 
Gain, 53 bu. rr lbs. marketable tubers per acre. 
Spraying increased the yield of marketable tubers 64.3 perc 
There was no rot worth mentioning either on the sprayed or un- 
sprayed rows. 
The yield of culls was at the rate of 10 bu. 53 lbs. per acre for 
the sprayed and 16 bu. 23 lbs. per acre for the unsprayed rows, 
making a difference of 5% bushels per acre in favor of the un- 
sprayed. 
Why there should have been such a wide difference in yield be- 
tween the two sprayed rows is not known. Mr. Gott states that so 
far as he knows the two rows had an equal chance in all respects. 
Although they were sprayed alike the west row remained green 
somewhat the longer. 
At 60 cents per bushel, the market price at digging time, 53 bu. 
11 lbs. of potatoes would be worth $31.91. Subtracting $2.44, the 
cost of spraying, there is left a net profit of $29.47 per acre. 
