CHAP, xiii.] Fungoid Diseases of Trees 281 



genous matter contained in the wood determines its liability 

 to decay from fungoid causes (Memlius lachrymans, &c.) ; hence 

 Beech or Willow wood is far less durable than Oak or Pine. 

 But if there were no albuminous substance in woody tissue, or 

 if it could be kept absolutely dry, fungoid decay would not 

 take place in wood-work ; for moisture is an absolute necessity 

 to fungoid growth. 



In woodlands, fungoid disease may sometimes be noticeable 

 as epidemic or somewhat general simultaneously throughout 

 the crop, otherwise it may be merely sporadic or distinctly 

 localized in places here and there. In the former case it is due 

 to conditions closely connected with soil and situation or with 

 climatic factors unsuited for the species of trees forming the 

 crop, and can usually only be prevented by change of crop to 

 a more suitable species ; whilst in the latter case it can generally 

 be eradicated by excision, root and branch, of the infected 

 individuals so as to obviate the spread of the disease. 



Within the short space here at disposal it is impossible to 

 undertake the detailed descriptions of any but the more 

 important and frequent fungal diseases of our forest trees : 

 and, in considering them, it will be advantageous to discard any 

 attempt at the natural classification according to reproductive 

 peculiarities in orders and families, and merely to group them 

 together according to the general tendencies they show with 

 respect to the infection of Foliage, of Stem and Branches, and 

 of the Roots and the base of the Trunk. 



It may be remarked, generally, that (as will also be seen 

 to be the case as regards injurious forest insects) fungoid 

 diseases do much more damage in coniferous crops than in 

 woods formed of broad-leaved species. This may be accounted 

 for not only by the natural attraction they seem to offer to the 

 different kinds of fungi, but also partly on account of the much 

 weaker recuperative power the conifers possess in comparison 

 with deciduous, broad-leaved species of trees. 



