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 

 vigorous 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 fre- 

 quently occurs in the peach, cherry, apricot, nectarine 

 and certain species of the plum in climates of rather 

 severe winters, especially after the buds have been 

 somewhat excited by unseasonable warm weather. 



