Annals 



of the 



Missouri Botanical Garden 



Vol. 2 SEPTEMBER, 1915 No. 8 



EHIZOCTONIA CROCORUM (PERS.) DC. AND R. 



SOLANI KUHN (CORTICIUM VAGUM B. & C), 



WITH NOTES ON OTHER SPECIES 



B. M. DUGGAR 



Physiologist to the Missouri Botanical Garden, in Charge of Graduate Laboratory 

 Professor of Plant Physiology in the Henry Shaw School of Botany of 



Washington University 



The form genus Rhizoctonia was established in 1815 to 

 include two parasitic species, both characterized in part by 

 the production of a mat of violet mycelium investing the 

 affected roots or other submerged members. The serious 

 root diseases due to these organisms (later included in one 

 species) have received consideration by many mycologists 

 since that time. The demonstration is comparatively recent, 

 however, that several important types of root and certain 

 stem and other diseases of a variety of hosts are induced by 

 two or more related species of this genus. 



The literature of Rhizoctonia diseases has grown enor- 

 mously in the past fifteen years, yet some unnecessary con- 

 fusion and difference of opinion exist regarding the two main 

 species or groups of species and their distribution and rela- 

 tion to disease in plants. This is in part due to the lack of 

 comparative study and to the neglect or inadequacy of her- 

 barium material. It seems well, therefore, to present a con- 

 spectus of the investigations relating to this subject, and to 

 include such comparative data as are available. 



In cooperation wfth:llri!F/:C: [Stewart of the New York 

 (Geneva) Agricultural 1 Experiment fetation, I undertook, in 

 1898, a general s^ftdy V)J%t£j3 Y$&fop.\6fplhizoctonia, to plant 

 diseases in Amefica*. * *Tnfe : jbiht 'investigation followed two 



Ann. Mo. Bot. (£/&».! *V<*i...* 2, 1916 ", . 5"S « ' • • • I (403) 



