120 SHADE TKEES. 



METHODS OF CONTROL. 



It will be readily seen that the treatment of trees must 

 be primarily protective, rather than curative. It is impos- 

 sible to use orchard methods in the forests and 



Prevention . . 



better than frequently impractical to use such methods on 

 shade and ornamental trees. Good forestry 

 practice in the forest and proper care of shade and orna- 

 mental trees will greatly reduce the ravages of many of these 

 diseases. 



The heart and sap rots usually (probably always) origi- 

 nate with wounds through which the organisms gain en- 

 trance. Of course not all wounds give rise to diseases any 

 more than all wounds of human beings and lower animals 

 give rise to blood poisoning, but all wounds 



Wounds . c . 



induce must be looked upon as points where infections 



are likely to occur and therefore as sources of 

 danger. Frequent inspection of shade and ornamental trees, 

 the cutting out of broken branches, proper pruning, and the 

 care of all wounds are important factors in preserving the 

 beauty and contributing to longevity. (See page 26.) De- 

 caying wood forms a most excellent garden for many fungi 

 which are both saprophytic and parasitic in habit. It should 

 always be removed and burned. 



Spraying may be practiced to some extent for foliage dis- 

 eases on shade and ornamental trees, especially small ones. 

 Among the most important of the spraying mixtures is lime- 

 sulphur which is used extensively for scale insects. It is 

 also a fungicide and will reduce the organisms that winter 

 on the stems and trunk. 



spraying Bordeaux mixture is the old and reliable 



mixtures. fungicide and can be used on most trees for 



foliage diseases. However, it is unsafe for some trees and 

 has the disadvantage of discoloring the parts to which it is 

 applied. Where the discolorations are undesirable, the am- 

 moniacal-copper-carbonate solution can frequently be used to 



