76 FRUIT TREES AND THEIR ENEMIES 



should be selected (p. 6i). All badly cankered 

 branches should be cut off, and burnt, cutting them 

 well below the cankered area, at a point where no 

 staining of the wood is seen ; other canker wounds 

 should be cut away down to clean wood, and all fresh 

 wood exposed in these operations, or in ordinary 

 pruning, should be tarred. Stockholm tar is generally 

 preferred for this purpose, but damage seems rarely, 

 if ever, to result from the use of gas tar. In damp 

 ground, the trees should be planted high, i,e.^ placed 

 on the surface of the ground, and the earth mounded 

 up over the roots. 



Apple mildew {PodospJuvra leniotricJid). — In spring 

 and early summer the young shoots attacked by this 

 mildew become covered with a powdery, silvery-white 

 mould, and their development is arrested. 



Remedies, — Before the buds open, spray with potas- 

 sium sulphide (24), or copper sulphate (8), or with the 

 caustic winter wash made with copper (io<:); and, in 

 early June and July, spray with potassium sulphide, 

 Bordeaux mixture {^ga or 9^), or Bordeaux emulsion 

 (9^). The sulphide is more effective than the copper 

 washes. These dressings seem only to check the 

 mildew temporarily; but the early dressing will result 

 in the strengthening of the tree during the blossom- 

 ing, and thus help to secure a crop of fruit ; while the 

 later dressing will prevent the early falling of the 

 leaves, and help to mature the wood. The disease 

 may be further checked by cutting off and destroy- 

 ing all young shoots, as soon as they are found to be 

 affected. 



