126 Principles of Plant Culture. 



branches; and the bark is loosened from the wood 

 nearly or quite around the trunk. Such trees are prac- 

 tically ruined, but trees slightly injured by bark burst- 

 ing may fully recover. 



Bark-bursting is usually most severe on deep, rich, 

 moist soil and in seasons that favor late growth, or in 

 which freezing weather occurs unusually early. Late- 

 growing varieties are most subject to it. Its occurrence 

 is lessened by treatment that favors early maturity of 

 the wood (199, 200). 



195. Root-Killing of trees. When a very dry au- 

 tumn passes to winter without rain or snow, the surface 

 layers of the soil sometimes freeze so severely as to de- 

 stroy the roots of trees. Root-killing is usually most 

 serious on light soils, and on one-year-old, root-grafted 

 (391) nursery trees, especially when grafted with short 

 cions (386). With very severe freezing on bare ground, 

 root-killing sometimes occurs on soil well supplied with 

 water. The destruction of the roots may be complete 

 or only partial. In the latter case, the tree, if of a vig- 

 orous variety, may largely outgrow the trouble, though 

 complete recovery is rare. 



Treatment that prevents late growth (199, 200), or 

 mulching the ground about trees tends to avert root- 

 , killing. 



196. Flower-Buds are often Destroyed by Cold while 

 other parts of the plant are uninjured. This frequently 

 occurs in the peach, cherry, apricot, nectarine and cer- 

 tain species of the plum in climates of rather severe 

 winters, especially after the buds have been somewhat 

 excited by unseasonable warm weather. Flower-buds 



