106 Canadian Forestry Journal. 



second, the treatment of wood products to ensure reasonable ser- 

 vice. 



The parts of the trees attacked and the immediate effects pro- 

 duced are various. In some cases the disease works in the roots, 

 rendering treatment extremely difficult. In other cases the fungus 

 may grow in llie soil at first, and then entering by the roots work 

 its way up through the stem, its presence becoming apparent on- 

 ly when the tree begins to die or the, fruiting bodies of the fungus 

 are found at its surface. More frequently the spores of the para- 

 site infect the host at some wounded spot or region of careless 

 pruning, and as in the last instance may live in the host unsus- 

 pected for years. Such a case is represented in figures i and 2, 

 in which the fruiting bodies of a polyporus are shown upon the 

 surface of the trunk of a red oak. The removal of these plague 

 spots should be attended to promptly when they make their ap- 

 pearance on trees in streets and parks. The carelessness display- 

 ed in the treatment of shade trees is lamentable, people and ani- 

 mals being allowed to wound and maltreat them, thereby expos- 

 ing them to the almost certain entrance of destructive fungi. The 

 smallness of the number of undiseased and undeformdd trees 

 along the streets of most cities is deplorable, and altogether in- 

 excusable. Illustration 3 tells its own story. 



Sometimes the disease reveals its presence by swellings, or 

 other malformations. Even in the case of the red oak in Figure 

 I, it is observable that the base of the trunk is abnormally enlarg- 

 ed. This local stimulation to growth is not at all uncommon. 

 A rather interesting example of defformity is to be seen in the 

 so-called witches' brooms of the balsam fir (photograph 4), the 

 cherry, alder, some of the birches, and a few others. Generally 

 the infected area becomes swollen, and all of the buds, including 

 the dormant ones, develop, forming a dense mass of distorte'd and 

 stunted branchlets. Another manifestation of disease and its 

 effect^ is represented in Figures 5, 6 and 7. The host in this par- 

 ticular example was black spruce, and the parasite a rust that 

 attacked the leaves. In Figure 5 there is one uninfected leaf, 

 and the spore cups of the rust are shown growing upon all of 

 the rest. Nearlv all of the leaves on the diseased trees, which 



