Black Spot Experiments, 1903-4. 



763 



duced in the amounts of the ingredients added to the Bordeaux 

 mixture in order to see the effects of the larger or smaller quantities^ 

 and the ingredients were always added to the bluestone solution. 



In preparing Soda Bordeaux, 6 lbs. of bluestone and 1^ lbs. of 

 caustic soda were mixed and dissolved, then 1 lb. of lime was treated 

 in the usual way and the mixture made as for ordinary Bordeaux. 



The crop was gathered on 28th April, and it will be seen 

 from the returns that the season was an " off " one iov fruit, and this, 

 of course, causes the distinction between the different sprays to be 

 less marked. 



There were five plots in which all the fruit was marketable, viz., 

 Bordeaux + sal ammoniac, Bordeaux + sulphate of ammonia, 

 Bordeaux + Paris green, and Oopper-soda of two different 

 strengths. Soda Bordeaux came next with a percentage of 98 of 

 marketable fruit, while the unsprayed plot only yielded 32 per cent. 

 of marketable fruit. 



But the true test of the efficacy of a spraying mixture lies in the 

 percentage of absolutely clean fruit that is produced, and it will be 

 seen from the table that Copper-soda, 6'7'50, heads the list in this 

 respect with 51 per cent., and the next is Bordeaux + 1 lb. sal 

 ammoniac with 48 per cent. 



Of the two strengths of ordinary Bordeaux mixtures tried, that of 

 the formula 6"4*40 was the best, yielding 97 per cent, of marketable 

 fruit and 42 per cent absolutely clean. This is the formula which 

 Mr. Thiele himself uses for the general spraying of the orchard. 



