I?, 'r. \\ IUkkkk and (\ T. (liMiNGiiAM 1 :J 



especially round the edges of the leaves. These results have been con- 

 firmed several times. 



In another series, aphides were introduced into the muslin cage 

 surrounding the foliage and allowed to increase until many of the leaves 

 were badly infested ; the plants thus damaged were then covered with 

 the " no- excess-lime " mixture. The result was very bad scorching, 

 largely confined to the underside of the leaves where they were most 

 damaged by aphis. 



The relative degrees of injury under various conditions are shown 

 in the accompanying drawings, the shaded portions representing 

 browning of the leaf. 



Similar experiments with the protected foliage of apple shoots stand- 

 ing in water gave confirmatory results. The leaves in this case being 

 much less well developed were mostly entirely killed by the Bordeaux 

 where the artificial damage had been at all severe, but undamaged leaves 

 remained healthy. It was found, further, as was to be expected, that 

 these effects were very much more marked when the Bordeaux was put 

 on soon after the damaging of the leaves. In a moist atmosphere, bad 

 "scorching" followed treatment with the spray fluid up to 24 hours 

 after the damage had been done ; if a 48 hour interval was allowed, the 

 effect was markedly less severe and after 72 hours it was very slight. 

 In a fairly dry atmosphere both out of doors and in the greenhouse, 

 the " scorching " following treatment 18-24 hours after the leaves 

 were damaged, was not very serious ; although in some cases it got 

 noticeably worse after several days. In these experiments the damage 

 to the leaves was made as far as possible equally by means of pins fixed 

 in a cork, and the spray fluid was usually put on the leaves with a brush 

 so as to ensure a uniform coating. 



We have then definite evidence of the importance of the presence 

 of artificially or naturally damaged foliage in considering the scorching 

 by Bordeaux mixture. The extreme difiiculty of finding leaves which 

 have altogether escaped damage has already been mentioned ; and has 

 been experienced by many other workers. CrandalU in America, for 

 example, made a careful examination of 6000 leaves taken at random 

 from 60 different trees and found only 27 (less than 0'5 %) which he 

 could call perfect leaves ; although the appearance of the foliage on 

 these trees, on the whole, was good. Wallace^ in his work on spray 

 injury by lime-sulphur preparations also emphasises the rarity of 



^ Univ. Illinois Agric. Expt. Sta Bull. 135. 

 2 Cornell Univ. Coll. Agric. Bull. 288. 



