32 



BULLETIN 866, U. S. DEPARTMENT OF AGRICULTURE. 



At the time of the third spraying it was noticed that three or four 

 apples on the check tree were infected with bitter rot, whereas the 

 sprayed trees seemed to be entirely free from it. On August 13, 

 the date of the fourth application, one or two apples on the Pickering- 

 sprayed, barium-water-sprayed, and Bordeaux-sprayed trees were 

 infected with bitter rot, while the check tree showed a fairly large 

 amount of rot. 



At the time of picking very little bitter rot was found on any of 

 the trees. The Bordeaux spray gave 100 per cent protection from 

 bitter rot. The barium-water spray gave a better control of bitter 

 rot than the Pickering spray. The 1918 results (Table 10) are incon- 

 clusiye because of the small number of apples infected with bitter 

 rot on the sprayed trees. 



Adherence of Copper from Various Sprays to Leaves. 



IN 1916. 



One set of leaves was gathered from the sprayed and check trees 

 on July 12, 13 days after the second spraying, and a second set on 

 July 13, three hours after the third spray had been applied. The 

 outlines of these leaves were immediately traced on paper, and later 

 measured with a polar planimeter. The area of each set of 50 leaves 

 was calculated, but one side of the leaves being used in the calcula- 

 tion. Later the leaves were dried, and the copper determined in each 

 set (Table 11). 



Table 11. — Adherence of copper from various sprays to apple leaves ( Virginia). 





Spray used. 



Copper 



sulphate 



in spray 



used. 



Time 

 between 

 spraying 



and 

 gathering 

 of leaves. 



Copper adhering to leaves. 



Plat No. 



Parts per 



million 



(dry 



basis). 



Parts per 

 million 

 per 0.1 

 per cent 

 of CuS0 4 

 in spray. 



Mg. per 

 square 

 meter of 



leaf 

 surface. 



Mg. per 

 square 



meter of 



leaf 

 surface 

 per 0.1 



per cent 

 CuSO« 



in spray. 



1916. 



Bordeaux, 4-5-50 



Per cent. 



1.00 

 .13 

 .065 

 .23 

 .115 



1.00 

 .13 

 .065 

 .23 

 .115 



Days. 

 13 

 13 

 13 

 13 

 13 

 1 



X 



1 



A 

 1 

 1 



15 

 15 

 15 



15 

 15 

 15 

 15 



425 

 59 

 90 



248 

 77 

 3,150 

 260 

 185 

 646 

 249 



42.5 

 45.4 

 138.5 

 107.8 

 67.0 

 315. 

 200.0 

 284.6 

 280.9 

 216.6 



26.0 

 1.3 



9.3 

 25.6 



2.2 

 266.6 

 16.0 

 10.2 

 15.9 

 20.3 



2.6 



3 



1.0 



4 



do 



14.3 







11.1 



6 



do 



1.9 





Bordeaux, 4-5-50 



26.7 



3 



12.3 



A 



do 



15.7 



.5 





6.9 



f, 



do 



17.7 









1917. 



Bordeaux, 4-4-50 



1.00 



644 



6.6 

 316 

 255 

 206 

 116 

 62 



64.4 



33.8 

 .3 

 15.5 

 12.5 

 10.5 

 6.5 

 3.0 



3.4 



Check 







Bordeaux, 2-1-50 



Bordeaux, 2-2-50 



.5 

 .5 



.50 

 .25 

 .125 



63.2 

 51.0 

 41.2 



58.4 

 49.6 



3.1 





2.5 



A] 



2.1 



Aj 



do 



2.6 



A, 



do 



2.4 



