142 Report of the Botanist of the 



potato foliage. Later in the season there was a Httle yellow foliage 

 among the sprayed plants. 



In this field, spraying kept the blight almost completely under 

 control, except on the strip of heavier soil above mentioned and in 

 two other places where a few rows were skipped in one spraying. 

 An examination of this field at any time during the last half of Sep- 

 tember should have convinced even the most skeptical that spraying, 

 properly managed, will prevent blight. The unsprayed rows were 

 dead and dry while on both sides the sprayed rows were in almost 

 perfect foliage. (Plate XIII.) The sprayed plants remained green 

 so long that it was feared their growth would be cut short by frost, 

 but, fortunately, frost held off unusually late. On October 9 it was 

 estimated that on the average about one-half the foliage on the 

 sprayed plants was still green. This late growth was, doubtless, 

 partly the consequence of the late planting, June 16 to 20, but other 

 fields in the neighborhood planted equally late died nearly a month 

 earlier. 



The potatoes were of two varieties. Carman No. 3 and Rural New 

 Yorker No. 2, mixed. There was no early blight, no damage done 

 by flea-beetles, and " bugs " were thoroughly controlled. There was 

 only an occasional rotten tuber even on the unsprayed rows. 



The yield of the seven unsprayed rows was 192 1 pounds of 

 merchantable tubers which is at the rate of 83 bushels per acre. 

 Seven sprayed rows adjacent yielded 3403 pounds of merchantable 

 tubers or at the rate of 147 bushels per acre. Thus the increase in 

 yield was 64 bushels per acre or yj per ct. Considering that there 

 was no loss from rot this is a remarkably large increase. 



The total expense of spraying the fourteen acres five times was 

 $55.76, the items being as follows :— 



504 lbs. copper sulphate, at 6c $30 24 



8 bushels lime, at 35c ' 2 80 



12 lbs. white arsenic, at 5^/4c 66 



55 hours labor for man, at i7Kc 9 63 



47 hours labor for team, at i7Hc 8 23 



Wear on sprayer 4 20 



Total ....'. $55 76 



