200 



limbs and branches where the light was more or less excluded, 

 and was very rare on thinned trees. On the other hand, too 

 intense light may cause injury to tender growths when 

 shaded, as when young trees are suddenly stripped of their 

 foliage by insects, or where too rajjid growth results from 

 severe pruning, followed by cultivation and fertilization. 

 Sun scald is occasionally found on the larger limbs of trees 

 which have been more or less shaded, and therefore receive 

 too much light from severe pruning. , A well-thinned tree 

 is likely to be less affected by different diseases, and the 

 danger from burning of various kinds is lessened. 



Undoubtedly much of the spraying injury to fruit and 

 foliage is associated with lack of light and other climatic fac- 

 tors, and the injury from fumigation has a relation to light 

 intensity and moisture. There is much evidence to show that 

 the practice of pruning apple trees is of much importance in 

 controlling certain troubles. 



