1920.] 



Potato SpRA\^NG Trials. 



in the weighings of this plot. Neglecting this plot, spraying 

 with I per cent. Bordeaux mixture once at the rate of 85 gal. 

 per acre (Plot i) reduced the 3deld by over 16 cwt. per acre, and 

 spra\^ng twice (Plot 5) with Bordeaux mixture at the rate of 

 200 gal. per acre has reduced the yield rather more. Spraying 

 with Burgundy mixture at the rate of 200 gal. per acre caused 

 very bad scorching, and reduced the yield by over 2 tons per 

 acre, while dry spraying reduced the yield nearly as much as 

 the Burgundy mixture. (In the case of Evergoods in neigh- 

 bouring fields, spraying with a patent Burgundy mixture 

 containing copper sulphate and sodium carbonate, in the pro- 

 portion of 4 parts of crystalline copper sulphate to 4-68 parts 

 of crystalline washing soda also caused bad scorching.) 



Field 2. — The history of this field is as follows : — 



1915 .. Potatoes .. .. 10 cwt. superphosphate. 



1916 .. Potatoes .. . . 10 ,, 



1 91 7 .. Onions .. .. 2 



1 91 8 .. Onions .. .. 2 



1919 .. Potatoes .. . . 10 



The variety of potato was Majestic (from Scotland). Each 

 plot consisted of 9 rows, 28 in. apart, and was about \ an acre 

 in area. The potatoes were lifted on i6th-i8th October in 

 dry weather, and each plot was weighed and clamped 

 separately. There were few blights, and only a very small 

 proportion of seed. The yields per acre are shown below : — 



Plot. 



Xo. of 

 Sprayings. 



How sprayed. 



Total Yield 

 per Acre. 











Tons. 



cwt. 



I 









12 



2 



2j 



I 



Bordeaux mixture, i per cent. ; 



28th 











July 





II 



16 



3 





Bordeaux mixture, i per cent. ; 

 July and i6th August 



28th 



II 



10 



4 









13 



4 



5 





Burgundy mixture, i per cent. ; 

 July and i6th August 



28th 



II 



10 



6 



I 



Burgundy mixture, i per cent. ; 



July 



28th 



12 



12 



7 



I 



Bordeaux mixture, i per cent. ; 



1 6th 











August 





13 



8 



8 









13 



16 



At the time of the second spraying the weather was duller 

 than when the Evergoods were sprayed. The aphis attack 

 was not nearly so bad as on the Evergoods, and the scorching 

 was much less pronounced. Very little scorching was notice- 

 able with the Bordeaux mixture, but both sprayings with the 

 Burgundy mixture caused scorching. 



