SHADE TREES. 



203 



less alike as regards water supply, each branch is likelj* to be affected 



similarly. In evergreen trees possessing a defective root system, sun 



scorch or burning of the tip of the 



leaves sometimes follows. Tliis is 



often serious and may cause a loss 



of all the foliage, and later the death 



of the tree (white pine blight). 



Many small fruits, grape vines, 

 etc., qiiite -commonly suffer from 

 winterkilling of roots. Plants affected 

 in this way will leave out in the 

 spring, set their fruit and then 

 usually die before it is matured, 

 demonstrating that the maturing 

 and ripening of fruit acts as a severe 

 drain on the water supply of the 

 plant. A fairly large number of 

 shade trees located remotel.y, or near 

 one another, ha^'e died from winter- 

 killing of roots in recent j^ears, ne- 

 cessitating considerable outlay in re- 

 moving them. Trees located on 

 embankments are very likely to 

 winterkill, that portion of the tree 

 towards the embankment being 



Fig. 74. — Winterkilled root from elm 

 tree. Note lack of fine librous roots, 

 which have died. 



Fig. 7.5. — Norway m.aple affected with 

 Xectria cinnabarina following 

 winterkilling of twigs. 



affected. Roots growing under favor- 

 able conditions are less likely to be 

 affected than those growing under 

 poorer conditions, even in case of 

 a single tree. The smaller, younger 

 feeding roots are usually most 

 severely affected, and there is a 

 marked tendency in some species 

 for the roots continually to die back 

 to the trunk when the terminal root 

 system is affected. In these cases 

 numerous new lateral roots are often 

 formed, but as the dying back con- 

 tinues, these are eventually involved. 

 Various fungi soon attack any part 

 of a tree dying from root injury. 

 Later, the bark falls off, but deteri- 

 oration is not so rapid as in trees 

 killed by other causes. 



While the symptoms of dying back 

 resulting from winterkilling of roots 



