PICKERING SPRAYS. 



25 



IN VIRGINIA. 



It was considered impracticable to attempt to determine the 

 weight of grapes from the different plats in Virginia. From the three 

 rows sprayed with Bordeaux 26 crates of grapes were obtained, an 

 average of 8| crates per row. From the 20 rows of grapevines sprayed 

 with the Pickering sprays 26 crates of salable grapes were secured, 

 an average of 1.3 crates per row. No grapes were harvested from 

 the unsprayed check rows. Not all of the grapes from the plats 

 sprayed with Pickering spray were picked, as some of the fruit was 

 small and immature. 



Adherence of Copper From Various Sprats to Leaves. 



IN NEW JERSEY. 



Duplicate samples of leaves from the plats treated with the various 

 sprays were gathered on June 6 (10 days after the second spraying) 

 and on June 8 (12 days after the second spraying). Forty leaves 

 from each set were analyzed, the results obtained on those gathered 

 on June 6 being shown in Table 8. The area of one side only of the 

 leaves was considered in calculating the area figures. The outlines 

 of the fresh leaves were traced on paper, and the tracings later meas- 

 ured by a polar planimeter (p. 17). 



Table 8. — Adherence of copper from various sprays to grape leaves. 



riat No. 



New Jersey: 



B 



1 



2 



2a 



3 



4 



5 



6 



7 



Check. . . 

 Virginia: 



A 



1 



2 



2b 



3 



5 



7 



Check. . . 



Spray used. 



Bordeaux, 3-3-50 



Pickering (A ) 



do... 



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



Pickering (A) 



do... 



Pickering (C) 



do... 



do 



Bordeaux, 3-3-50 



Pickering ( A ) 



do.; 



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



Pickering (A) 



Pickering (C) 



do... 



Copper 



sulphate 



in spray 



used. 



Per cent. 

 0.75 

 .64 

 .38 

 .38 

 .13 

 .065 

 .23 

 .115 

 .36 



0.75 

 .64 

 .38 

 .38 

 .13 

 .23 

 .36 



Copper adhering to leaves. 



Parts 



per 



million 



(dry 

 basis). 



1,459 

 982 

 750 

 709 

 383 

 110 

 110 

 184 

 285 

 11 



1,440 



191 



18 



392 



0) 



174 

 321 



Parts, 



per 

 million, 

 per 0.1 

 per cent 

 CuSO* 

 in spray. 



194 

 153 

 197 

 187 

 295 

 170 

 48 

 160 



192 



30 



5 



103 



Mg. per 

 square 

 meter 

 of leaf 

 surface. 



64.0 



46.2 



?9.9 



27.8 



14.1 



.4 



4.2 



6.2 



10.5 



.4 



44.6 

 6.9 



.7 

 16.1 



5.6 

 12.8 



Mg. per 

 square 

 meter 

 of leaf 

 Surface 

 per 0.1 

 per cent 

 CuS0 4 

 in spray. 



8.5 

 7.2 

 7.8 

 7.3 

 10.8. 

 .6 

 1.8 

 5.4 

 3.0 



6.0 



1.1 



.2 



4.2 



2.4 

 3.6 



1 Trace. 



The area results show more decisively than do the weight results 

 that the copper from the Pickering (A) sprays adhered to the leaves 

 in proportionately greater amounts than did that from the Pickering 



