DISEASES OF FLOWERING PLANTS 199 



of a hetercecious fungus for tHe purpose of saving the 

 other host or hosts. 



C. The avoidance or removal of conditions which favor infection. 



(1) Preventive measures against wound infection; anti- 



septic and aseptic wound treatment. 



(2) Avoidance of localities favorable to disease. 



(3) Avoidance of the massing together of plants of the same 



species and like age; rotation of crops on the same 

 cultivated area. 



(4) Avoidance of neighborhood of those plants which are 



hosts of the same hetercecious fungus." 



CLASSIFICATION OF PLANTS CAUSING DISEASE 



Various methods of classification of disease-forming 

 plants have been suggested by students of mycology. 

 The following classification, given by Tubeuf and Smith, 

 seems best suited for a general consideration such as this : 



A. Myxomycetes Slime fungi. 



B. Schizomycetes Bacteria. 



C . Phy corny cetes Lower fungi. 



D. Mycomycetes Higher fungi. 



The larger number of diseases are included in Phycomy- 

 cetes and Mycomycetes. 



Phycomycetes include the families ChytridiaceaB, 

 Zygomycetes and Oomycetes; Mycomycetes includes 

 Ascomycetes, Ustilagineae, Uredinese and Basidiomycetes. 

 Tubeuf includes also another division of the Mycomycetes, 

 which he calls Fungi Imperfecti. Under Fungi Imperfecti 

 are placed those diseases which have not been completely 

 investigated, most of them being known only in the form 

 of pycnidia and conidia. The number of species included 

 in this group was much larger, but it has gradually been 

 reduced as the forms proved to be stages in the life of some 

 species of definite systematic position in the groups C and 



D. Fungi Imperfecti is classified into the families Sphae- 

 ropsidese, Melanconiese and Hyphomycetes. 



