18 



BULLETIN 712, U. S. DEPARTMENT OF AGRICULTURE. 



There was no injury from the copper spraj^s, and again foliage 

 injury from sulphur sprays was negligible, while as a result of late 

 spraying sulphur spotting of the fruit resulted in material loss. A 

 period of hot weather again preceded the first appearance of fruit 

 injury, as is shown by the following statement of the maximum tem- 

 peratures recorded by a shaded thermograph in the near vicinity of 

 the experimental plats, covering the period between the last spraying 

 on June 11 and the appearance of severe fruit burning on June 19. 



Maxirmim shade temperatures. 



Date, 1917. 



Maxi- 

 mum. 



Date, 1917. 



Maxi- 

 mum. 





°F. 

 74 

 81 

 87 

 95 



June 15 ... 



"F. 

 98 



June 12 



June 16 



91 





June 17 



79 



June 14 



June 18 ' 



90 









Table III. — Results of spraying experiments for the control of apple powdery 

 mildew on trees of the Pryor Red variety at Wenatchee, Wash., in 1D17. 





Spray 

 formula.! 



Dates of 

 application.2 



Spray injury .3 



Infected. 



Plat. 



On June 19. 



On July 9. 



Total. 



Foliage. 



Fruit 





Foliage. 



Fruit. 



Foliage. 



Fruit. 



Foliage. 



Fruit. 





No. 1 



No. 2 



[2 



|2L 



(2 



<^2L 



L 



2 



-^2L 



14LS... 

 f8 



|8L 



15 



15L .... 



(15 



nSL 



L 



14S 



|l4SL... 



14S 



h4SL... 



L 



9 



pL 



9 



kh 



L 



9 



^9L 



15L.... 



May 9 



/May 22 



yune 11 



May 9 



May 22 



Per ct. 

 1 



Perct. 



33 



Perct. 



(■') 



Per ct. 



0) 



Perct. 

 1 



Per ct. 

 33 



Per ct. 

 1.0 



2.4 



2.5 



1.8 



5.5 



5.8 



4.0 



8.7 



2.2 



1.9 



2.2 

 17.4 



Per d. 

 1.5 



No. 3 



June 11 



May 9 



May 22 

















No. 4 



No. 5 



June 11 



May 9 



/May 22 



\Junell 



May 9 



/May 22 



4 



45 



0) 



(») 



4 



45 



.5 

 .9 



No. 6 



\June 11 



May 9 



May 22 















2.0 



No. 7 



June 11 



May 9 



/May 22 















1.2 



No. 8 



\J une 11 



May9 



May 22 















2.0 



No. 9 



No. 10 



June 11 



May9 



/May 22 



\June 11 



May 9 



May 22. . . . 





19 





0) 





19 



.9 



.8 



No. 11 



June 11 



May9 



Say 22 















.4 



No. 12 



June 11 



Not sprayed.. 















6.8 



(check) 





















> For composition of sprays u,sed, see pp. 11-12. 



2 Buds in the "pink" (just before full bloom), May 9; petals fallen, calyx not yet closed, May 22. June 

 11 application at the time of regular codlLag-moth spraying. 



' Foliage ii^ury expressed in percentage of leaf-.surface reduction; fruit injury expressed in percentage 

 of injured apples found on the south side of the trees. 



* No increase. ^ Heavy drop of injured apples. 



