4^ 



THE CANADIAN HORriCULTURISl . 



feet circulation of air in the soil. The vital 

 processes in the roots demand a supply of 

 oxygen, and if this gas is excluded the roots 

 die of asphyxia, or root rot. Oxygen is re- 

 tjuired, not only for growth, but also for the 

 formation of reserve materials. A good 

 dorist knows how to provide for drainage in 

 potted plants ; he knows that a hard cla}- 

 liottom is unsuitable. 7'cw nincJi water and 

 soil of too close a texture will prevent the 

 circulation among the roots and root-hairs, 

 and a free interchange of the atmospheric 

 and soil gases. The best foresters advtjcate 

 drainage for every tree. Too often the 

 w^ater which is given the tree lodges in the 

 hole made for the tree, so that the soil be- 

 comes saturated and aeration is prevented. 

 When ti'ees are planted along the sides of 

 cement pa\ ements and paved streets as is the 

 case in many of oin- towns and cities, thev 



Fig. 1739. Maplk Tree Affected with 



Stag Head. 



(Suffering from Liack of Proper Drainage.) 



Fig. 1740. Maple Tree Suffering from 



Stag Head 



(Sutferinf,' frou) Lack of Proper Nourishment.) 



suffer from an imperfect supply of air among 

 the roots. The hard impervious pavement 

 prevents not only a proper supply of oxygen, 

 but also proper evaporation from the soil 

 beneath. 



A common form of disease arising from a 

 diminution of the supplies of food and water 

 is Stag Head., " when the top branches be- 

 come leafless, dry off and remain as dry 

 sticks, like antlers projecting above the 

 foliage." The lower branches remain green, 

 but make but little growth. 



In the treatment of Stag Head the sod 

 should be removed from a space two or three 

 feet in radius of about the tree. This circular 

 area should be frequently stirred by the 

 spade and kept raked, as this process will 

 tend to promote aeration ; but unless pro- 

 vision has been made for proper drainage 



