CHAPTER IV 



ROOT DISEASES AND INJURIES 



The roots serve both for anchorage and for gathering from 

 the soil the water and dissolved raw materials needed by the 

 tree in its growth. The structure of certain types of soil, 

 and the food materials contained, often determine the kinds 

 of trees which will grow best in it. However, it is not the 

 intention to discuss here the adaptability of different species to 

 soil-types or of the poor growth or injuries resulting from a 

 lack of such adaptability. Although a tree may be growing in 

 suitable soil and obtaining from it the proper materials for 

 normal growth, there are other factors which often inter- 

 vene to cause injuries to the root system. Any such injuries 

 to the roots of the tree may impair certain functions or destroy 

 living tissues and cause various symptoms of disease to appear 

 in the aerial portions of the tree. 



•v^In diagnosing tree troubles, the possibility of root diseases 

 should be considered and care should be taken to ascertain 

 whether or not the condition of the roots may be the primary 

 cause of the difficulty. Impairment of the root functions may 

 be due to such conditions as : too much water in the soil, causing 

 drowning ; too little water because of sod, pavements, or packed 

 soil above the roots; poisonous gases or over-abimdance of 

 certain food materials applied to the roots with fertilizers ; and 

 the attacks of certain parasitic fungi and bacteria which invade 

 and kill living tissue. These various injurious factors work 

 more or less slowly, and the usual symptoms noticed in the parts 

 above ground are : slow growth, thin foliage, sun-scorch of the 



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