PICKEEIKG SPRAYS. 



13 



experimental work, however, where the treatment of the soil was 

 uniform, increased yields were obtained from the plats treated with 

 the Pickering and Bordeaux sprays. 



Series 2. — A second series of tests was conducted in northern 

 Maine in 1918, usmg (1) a Bordeaux spray, (2) Pickering (A) and (C) 

 sprays, (3) a spray hi which the limewater was replaced by barium 

 water, and (4) an 0.6 per cent solution of copper sulphate to which 

 powdered arsenate of lead (1 pound to 50 gallons) had been added. 

 In all cases the sprays were made to contain 0.6 per cent of copper 

 sulphate. Green Mountain (Norcross strain) potatoes were first 

 sprayed when the vines were 5 or 6 inches above the ground, after 

 which they received five applications with a Watson sprayer, using 

 two nozzles to a row. The results of this work are recorded in Table 3. 



Table 3. — Effect of various sprays on blight and yield of tubers (northern Maine, 1918). 



Plat No. 



Spray used. 



Copper 



sulphate 



in spray 



used. 



Late 

 blight. 



Yield of 

 tubers. 1 



Farm 1. 



Check. 

 Farm 2... 



Farm 3. 



Farm 1 (2d series): 



1 



2 (check). 



3 



4 



5 



6 



7 



9 (check) 2. 



Pickering (A) 



Barium water 



Bordeaux, 5-5-50. 

 Bordeaux, 4-4-50. 

 Bordeaux, 4-2-50. 

 Bordeaux, 4-1-50. 



Pickering (A) 



Barium water 



Bordeaux, 5-5-50. 

 Bordeaux, 4-4-50. 

 Bordeaux, 4-2-50. 

 Bordeaux, 4-1-50. 



Pickering (A) 



Barium water 



Bordeaux, 5-5-50. 

 Bordeaux, 4-4-50. 

 Bordeaux, 4-2-50. 

 Bordeaux, 4-1-50. 



Bordeaux, 5-5-50. 



Pickering (A) 



Pickering (C) 



Bordeaux, 2J-2A-50 



Barium water 



Copper sulphate and lead arsenate . 

 Bordeaux, 5-5-50 



Per cent. 

 0.7 

 .7 



1.25 

 1.0 

 1.0 

 1.0 



.7 



.7 

 1.25 

 1.0 

 1.0 

 1.0 



.7 



.7 

 1.25 

 1.0 

 1.0 

 1.0 



1.25 



.60 

 .60 

 .60 

 .60 

 .60 

 1.25 



Per cent. 

 2.0 

 1.0 

 1.7 

 1.0 

 3.0 

 2.7 

 20-50 



1.2 

 1.6 

 1.2 

 1.5 

 1.7 

 1.8 



1.3 

 2.3 

 2.0 

 1.3 

 1.9 

 2.5 



.5 

 33.0 

 1.7 

 1.3 

 3.0 

 1.7 

 1.8 

 1.2 

 45.0 



Pounds. 

 274 

 277 

 247 

 276 

 258 

 277 

 215 



261 

 264 

 279 

 243 



227 

 303 

 224 

 295 

 370 

 375 



244 

 235 

 241 

 251 

 248 

 241 

 237 

 242 

 175 



1 Determinations made on two rows, each 150 feet long. 



2 Plat partially shaded. 



The blight readings of all the plats sprayed were practically the 

 same (1 to 3 per cent), while the vines on the check plats showed 

 33 and 45 per cent infection. The yields were remarkably uniform 

 for all the plats, with the exception of the last check plat, which was 

 shaded by the adjacent trees. The dry season and the fact that the 

 vines were killed by frost on September 9 tended to reduce the 

 increased yields which are usually obtained from sprayed plats. 

 Here the Pickering sprays containing 0.6 per cent of copper sulphate 



