Fungus and Bacterial Diseases 55 



If the timely examination of insect conditions has been 

 neglected, then the diagnosis will be made wlien the dam- 

 age has begun or has progressed to some degree. The 

 insect can be observed at work, the culprit captured and its 

 name or character determined. With the leaf-eaters this 

 is usually readily accomphshed, but the sucking insects 

 whose damage is not at once apparent, as well as the bark- 

 beetles and borers are discovered by close observation 

 only. 



The small round entrance holes in the bark of conifers, 

 accompanied by resinous exudation, and finally the loosen- 

 ing of patches of bark where the cambium has been de- 

 stroyed give evidence of the presence of bark-beetles. The 

 presence of borers is indicated by the entrance holes, usu- 

 ally near the base of the tree, and by the excreta or finely 

 divided wood particles, wood-Jioiir, found at the base of the 

 tree. 



Fungus and Bacterial Diseases. The fungus diseases 

 of the foHage make themselves known -by the partial dis- 

 coloration of the leaves, usually in spots of various colors, 

 and by the powdery aggregations of fruit-bodies, silky, 

 smutty, or otherwise. Sometimes also the foliage wilts 

 or dries up. 



As there is only one practicable remedy for all these 

 fungi, namely, spraying with poisons, it is not necessary to 

 be familiar with the different kinds, beyond recognizing 

 their existence. The same can be said of the rot fungi, 

 which practically behave alike, and are treated alike. Dis- 

 coloration of the wood in wounds, and whitish or yellowish 

 mycelia strands breaking through the tissues, and finally 

 the fruit-body proclaim the presence of rot fungi. The 

 dying of portions of the crown on account of reduced water 

 conduction may also be due to these fungi. 



