DISEASES OF TIMBER. 



J. Horace Faiill, Ph. D., University of Toronto. Toronto. 



Trees while living are subject to the attacks of various plant 

 en<^mies, mainly fungi and bacteria, and when dead are immedi- 

 ately set upon by a legion of other members of the same groups. 

 Biologically, the first set are parasites, for they derive their nour- 

 ishment from the' life streams or stores of their hosts, and the 

 latter are saprophytes, for they obtain thdr livelihood from dead 

 tissues and plant remains. The parasite is of interest to the 

 biologist in that it presents a three-sided struggle in the fight for 

 existence, the struggle between the parasite and the host on the 

 one hand, and between the host and its uninfected fellows on the 

 other. i\Iore than one termination is possible in such a struggle, 

 but in most cases the greatest desideratum of the economist is the 

 evolution of a form that is proof against attack. The saprophyte 

 is of interest because it is a factor in the breaking up of complex 

 organic compounds (incidentally ridding the earth of vegetable 

 deliris), and restoring again to soil and air the simple food mat- 

 erials essential to the existence- of present and future generations. 

 Without the restoration of these all life would soon cease to be, 

 fcr the reserves of unused food substances in nature are too small 

 to allow for a break in their circulation. 



The forester, the lumberman, and the wqod-consumer, look 

 at these wood-attacking bacteria and fungi from a somewhat 

 different standpoint. To them the parasites are the causes of 

 the deformation, stunting, and death of greater or smaller quan- 

 tities of timlxr. decreasing and depreciating the supply, and pro- 

 viding mate;-ial for destructive fires ; and the saproi)hytes are tlie 

 cause of certain rots and discolorations, resulting frequently in 

 the ruin of sawn but unused timber, and the necessity for the 

 untimely renewal of such as has been put into use. There is 

 hence a demand made by them of the economic botanist for two 

 things, first, the prevention of further infection in the forests, and 



