PICKERING SPRAYS. 



11 



per sulphate. Green Mountain (Norcross strain) potatoes, grown on 

 new land, were sprayed six times during the season, using a Watson 

 sprayer, after the vines were 10 or 12 inches above the ground. 



Portions of the two middle rows of each plat were read for blight 

 and used for the yield data. The blight readings (Table 2) are the 

 averages of the last readings of four individuals who worked inde- 

 pendently of one another. The results obtained with Bordeaux spray 

 (PL I, fig. 1) are more favorable than those secured from using 

 the Pickering spray, with the exception of that applied to plat 1, 

 where they were equally as good (PI. I, fig. 2). The Pickering 

 sprays which contained less than 0.5 per cent of copper sulphate did 

 not control the blight as effectively as the standard Bordeaux and 

 the Pickering sprays containing 0.6 or 0.7 per cent of copper sulphate. 



Table 2. — Effect of various sprays on blight and yield of potatoes (northern Maine, 1911)} 



Plat No. 



Check. 



Check. 



Check. 



Check. 



Check. 



Check. 



Check. 

 Check. 



Check. 



Check. 



Check. 



Spray used. 



Pickering (A) 



Bordeaux, 5-5-50. 



Copper 



sulphate 



in spray 



used. 



Per cent. 

 0.7 

 1.25 



Pickering (A) 



Bordeaux, 5-5-50. 



0.6 

 1.25 



Pickering (C) 



Bordeaux, 5-5-50. 



0.6 

 1.25 



Pickering (A) 



Bordeaux, 5-5-50. 



0.5 

 1.25 



Pickering (CJ 



Bordeaux, 5-5-50. 



0.5 

 1.25 



Pickering (A) . .. . 

 Bordeaux, 5-5-50. 



0.4 

 1.25 



Pickering (C) 



Bordeaux, 5-5-50. 



Pickering (C) 



Bordeaux, 5-5-50. 



Pickering (A) and rosin-fish-oil soap. 

 Bordeaux, 5-5-50 



Pickering (A) and lead arsenate. 

 Bordeaux, 5-5-50 



Pickering (C) and lead arsenate . 

 Bordeaux, 5-5-50 



0.4 

 1.25 



0.3 

 1.25 



0.5 

 1.25 



0.5 

 1.25 



0.5 

 1.25 



Late 



Yield of 



blight. 



tubers. 



Per cent. 



Pounds. 



44 



406 



45 



384 



57 



347 



52 



409 



41 



414 



85 



321 



48 



404 



42 



415 



95 



335 



53 



392 



42 



393 



88 



301 



53 



349 



43 



325 



84 



296 



67 



355 



37 



415 



96 



309 



76 



381 



39 



399 



96 



320 



63 



337 



41 



451 



96 



270 



56 



345 



41 



366 



96 



294 



56 



406 



42 



430 



96 



270 



57 



358 



44 



396 



96 



294 



Rotten 

 tubers. 



Per cent. 

 12 

 14 

 12 

 13 

 10 

 10 

 10 

 11 

 10 

 12 

 10 

 10 

 14 



8 

 12 

 10 

 11 



7 

 11 



8 



9 

 14 

 11 



9 

 11 

 17 

 11 

 11 

 13 



9 

 10 

 16 

 11 



1 Determinations were made on two rows, each 300 feet long. 



The total yield results for plats 1, 2, and 3, treated with Pickering 

 sprays, and for the corresponding Bordeaux-sprayed and check plats 

 are as follows: Pickering, 1,219 pounds; Bordeaux, 1,213 pounds; 

 and check, 1,003 pounds. Plats 4 and 5, to which the Pickering 

 spray having an 0.5 per cent copper sulphate content was applied, 

 yielded 741 pounds of tubers; the corresponding Bordeaux-sprayed 

 plats, 718 pounds; and the check plats, 597 pounds. The plats 



