MONILINIA 49 



composite stroma, that is, it is an admixture of living fungous 

 hyphae and dead host cells in contrast to the typical sclerotium 

 characteristic of the genus Sderotinia as represented by Sclero- 

 tinia sclerotiorum in which the sclerotium is composed entirely 

 of fungous hyphae. The term pseudosclerotium has been used 

 to designate this composite stroma which is so characteristic of 

 the monilioid group. 



"Emphasis has been placed on the life-history of the various 

 species in showing relationships. It is felt that the study of any 

 one stage, as for example, the stromatic, the apothecial or the 

 conidial in the life-history of these species is not sufficient to 

 adequately show true phylogenetic relationships. In order to 

 obtain either the specific or the generic concept, all stages de- 

 veloped during the life-history must be given consideration. 

 On the basis of life-histories which appear to be correlated with 

 certain morphological characteristics, the genus Monilinia may 

 be divided into two general groups:— 



"(1) Those species in which in the spring ascospores infect the 

 young leaves and stems resulting in the development of an 

 ectostroma. Upon these host organs the ectostroma gives rise 

 to conidia which in turn function as inoculum for blossom infec- 

 tion. Young developing fruits become infected through the 

 blossom, and as a result pseudosclerotia are formed which com- 

 monly drop to the ground and overwinter, giving rise in the 

 spring to apothecia which produce ascospores (the primary 

 inoculum which again infects the young leaves and stems). 

 Commonly but a single cycle occurs. The majority of the 

 North American representatives fall in this sub-group, the 

 members of which are also characterized by the presence of dis- 

 junctors within the conidial chains (a specialization for the dis- 

 semination of conidia). They are furthermore characterized by 

 a marked sweetish odor (mandelic acid; benzaldchyde and hydro- 

 cyanic acid) emitted from infected parts of the host at about the 

 time of conidial production and they appear to be more special- 

 ized and limited in their host range. In the Vaccinium-mhahit- 

 ing members there is a tendency to suppress the development of 

 the ectostroma in infected fruits, and to further segregate the 

 conidial production from the apothecial production which, ac- 

 cording to certain European workers (Fischer, Ed., etc.) reaches 

 its climax in such forms as Monilinia Ledi ( = Sderotinia heteroica 

 Woronin and Nawaschin) and Monilinia Rhododendri {Sdero- 



