118 FOREST PROTECTION 



b. The groups \ 



Pyrenomycetes J 



Discomycetes I contain parasites as 



Hymenomycetes \ well as saprophytes so 



Myxomycetes I that proof of parasi- 

 And several groupsV tism is required. 



of lower fungi and! 



bacteria. / 



This proof is obtained by artificial infection only. 



Infection reveals, — 



(1) parasitic nature of a fungus, 



(2) exact species of fungus, 



(3) relationship of heteroecious Uredinece and 



their host plants (uredinal, telial and 

 aecidial stages), 



(4) various forms of reproductive organs, 



(5) conditions favorable to attacks. 



The fungi might be further divided into two 

 large groups, namely: 



(a) Physiologically obnoxious species (tree killers 



and tree deformers) belonging to the 

 orders Phycomycetes and Ascomycetes and 

 to the family Uredinece of the order 

 Basidiomycetes. 



(b) Technically obnoxious species (wood disin- 



tegrators) belonging notably to the fam- 

 ily Hymenomycetes; this group may be 

 sub-divided into fungi living on dead 

 trees (Saprophytes) and fungi living on 

 live trees (Parasites). 



Group (a) is of greatest importance 

 in Germany and France; whilst group 

 (b) is of greatest importance in tha 

 United States. 



F. According to parts attacked, the forest fungi might be subdivided 

 as follows: 



I. Nursery fungi and plantation fungi. 



II. Boot fungi in saplings and poles. 



III. Leaf and twig fungi. (Bulletin Bureau of Plant In- 



dustry No. 149, page 18). 



IV. Fungi causing hypertrophical formations (witch 



brooms). 



V. Fungi discoloring lumber or timber. 



VI. Fungi destroying the cambium and the sapwood of 

 standing trees or poles. 



