io4 Injury to Foliage by Bordeaux Mixture, [may, 



tricts of North America, Europe, Australia, Tasmania, and 

 New Zealand. 



In this country the same kind of injury may occasionally 

 be observed, and the following notes are given in the hope 

 that they may prove of some assistance to growers who, while 

 wishing to use Bordeaux mixture as the only proved remedy 

 against apple "scab," and other fungus diseases, are anxious 

 to take all possible precautions to prevent the trees being 

 injured by this spray. 



The injury which I have noted as sometimes following 

 the application of Bordeaux mixture on apple trees becomes 

 evident sometimes on the leaves and sometimes on the fruit. 

 With regard to the leaves, these may show (i) local injuries 

 in the form of brown spots which soon drop out, and, when 

 the portions affected fall from the central part, give a u shot- 

 hole " appearance to the leaf, while if the portions affected 

 fall from the edges of the leaf, a jagged or notched appear- 

 ance is given to the leaf, at first sight suggestive of the action 

 of caterpillars; (2) a "scorching" of the edges or tip of the 

 leaf, or the formation of brown patches which do not fall out ; 

 (3) a yellowing or browning of the whole leaf, which subse- 

 quently falls. In my experience the "shot-hole " effect on the 

 leaves is the form of injury which results when a too heavy 

 spraying is given, i.e., when leaves are coated over with a 

 .thick, instead of a very thin, layer of Bordeaux mixture. The 

 injury denoted by the yellowing or browning and subsequent 

 fall of the leaf may follow after careful spraying with a 

 properly prepared mixture, and seems to be dependent on 

 unknown weather conditions. This form of injury occurs 

 apparently only on certain varieties of apples. 



As regards the fruit, this may sometimes show injury in 

 that the apple becomes rough and "russeted," due to the 

 formation of dead corky cells at the places where the action 

 of the spray has caused a rupturing of the skin ; in cases of 

 severe injury the apple cracks. Or the effect of the 

 spray (on young apples from a quarter- to half-grown) may 

 be to produce unnatural blotches of a purplish colour on the 

 sprayed portion. Both these kinds of injury are liable to 

 appear only on certain varieties of apples. The "russeting " 

 or "rusty" appearance is most marked in those cases—if, 



