INJURIES INDUCED BY PLANTS 



95 



Climatic conditions, especially frost, are essentially without 

 influence on the disease, and the same is true as regards the soil. 

 Although the damage inflicted by this parasite is by no means 



small, still I doubt if, in practice, 

 anything can successfully be done 

 to combat it. The injured trees 

 remain alive as a rule, and at least 

 yield firewood. Their removal in 

 the thinnings is certainly advisable, 

 so long as the ground is not there- 

 by injuriously exposed. In oak 

 woods also, whenever thinning and 



FIG. 43. A stem of the beech, FIG. 44. Cross section taken from the 



half natural size, showing numer- lower end of the beech stem repre- 



ous canker-spots ; these, how- sented in Fig. 43 ; natural size, 



ever, are increasing in size only 

 at certain places, and it is only 

 where increase is taking place 

 that the red perithecia are to be 

 found. 



opening out are undertaken with a view to underplanting, the 

 cankered trees should be the first to be removed. I cannot advise, 

 however, that one should go so far as to fell all cankered trees, if 

 this should mean the formation of large blanks in the wood. 



