1915] 



DUGGAR RHIZOCTONIA CROCORUM AND R. SOLAN! 



451 



Sclerotia, when present, Sclerotia normally free from 

 densely wooly with invest- any definite or permanent 



m 



investment 



of short, ovoidal or ellip- filaments of elbowed hyphal 

 tical hyphal cells. Internal 



structure not truly plec- 



tenchymatic, cells variable 

 in size. 



Cultures difficult. — not vet 



cells. 



homogeneous ii 

 denser sclerotia. 



structure 



methods 



ob- Cultures readily obtained on 



any nutrient medium. 

 Typically a parasite, with per- Grows rapidly saprophytic- 

 haps the possibility of con- ally on the invaded host, 

 tinuing existence only for a and apparently on debris in 



aprophytically 



the soil when conditions are 

 favorable. 



The following species may be excluded from Rhizoctonia 

 as far as can be judged from reference to the descriptions 

 and to the exsiccati material examined: 



Rhizoctonia Allii Graves, de Thuemen, Myc. Univ. Fasc. 



(obviously not closely related to the forms here dis- 



6 



d) 



R. bicolor Ell. N. Am. Fung 



sclerotia like those of a Botrytis, e. g., B 



Fasc. 10: 977 (with 



R. Bra 



Lib., Libert, PI. Crypt. Arduennae, Fasc 



characteristics of Rhizoct 

 Am. Fung. Fasc. 13 \12( 

 Fasc. 2 : 141. 



i). R. muscorum Fr. Ellis, N 

 Libert, PI. Crypt. Arduennae 



From the descriptions alone it would seem that the follow- 

 ing species have insufficient affinities with Rhizoctonia to be 

 included, but critical study of material is needed : 



Rhizoctonia aurantiaca Ell. & Ev. on decaying wood of 

 Acer; R. Batatas Fr. on Ipomoea Batatas; R. placenta Schw., 

 and R. radiciformis Schw., on decaying wood (the three last 

 mentioned are distributed in Schweinitz', Syn. N. Am. Fung., 



hich, however, the writer 



dest 



T 



not yet had access) ; R 



reported parasitic on five species of Del 



and on Lobelia laxiflora, and H 



R. moniliformis Ell. & Ev. on branches of Nyssa 



Rhizoctonia Strobi Scholz ('97) on roots of Pinus strobus 

 in Austria, is insufficiently described to warrant a suggestion ; 

 and R. subepigea Bertoni ( '97) on coffee should be included in 

 a further comparative study. 



