[Vol. 2 



422 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



observations de cette annee (1912), quelle doit etre rapportee 

 a un groupe d 'Ascomycetes. " This suggestion is both in- 

 teresting and surprising since Eriksson adopts the Tulasnes' 

 name for the Rhizoctonia on carrot and this would seem to 

 concede the identity of the carrot and alfalfa forms. It is 

 also in a measure inconsistent with his inoculation results, as 

 reported later. 1 



CROSS INOCULATION AND CULTURAL STUDIES 



The amount of cross inoculation work yet reported is not 

 considerable, and for this, doubtless, the inability to cultivate 

 the organism is largely responsible. Throughout the early 

 literature numerous indications are offered showing that fol- 

 lowing a severe outbreak of the disease on any crop, it may 

 appear on susceptible plants grown in the affected area — ob- 

 servations which tend to establish the identity of the fungus 

 on different hosts. Among later observations may be men- 

 tioned those of Giintz ('99) who records that in a field where 

 alfalfa and red clover had been seriously affected, beans, 

 potatoes, and tuberous artichokes were planted ; the potatoes 

 subsequently developed the disease in serious form, and the 

 other plants showed indications of its presence. In England 

 it is reported (Bd. of Agr., '06) that potatoes are affected by 

 the violet felt fungus, especially when following alfalfa ; and 

 under similar conditions the fungus appears upon clover, car- 

 rots, beets, and mangolds. 



Eriksson ('13) undertook some cross inoculation work em- 

 ploying, in zinc cylinders, soil from diseased carrot fields 

 (eight cylinders) in contrast with soil taken from areas free 



from the disease (two cylinders). At the same time, to the 

 diseased soil he added pieces of carrots affected by the 

 fungus. The cylinders were permitted to stand over winter 



l Since obtaining proof of this paper I have received from Prof. Eriksson 

 an advance reprint of his paper, "Fortgesetze Studien tiber Rhizoctonia violacea 

 DC." Arkiv for Bot. 14 (Art 12) : 1-31. f. 1-18. 1915. It is impracticable to 



include here a full discussion of this paper. It is necessary to state, however, 

 that he treats at length Rhizoctonia M edicaginis DC. and R. Asparagi Fckl., and 

 includes inoculation experiments indicating form differences. After germinating 

 the spores of Leptosphaeria circinans he comes to the conclusion that, in spite 

 of his earlier work on Hypochnus violaceus, the pyrenomycete mentioned is the 

 perfect stage of R. Medicaginis. Prof. Eriksson has also furnished material of 

 R. Asparagi and of the Leptosphaeria. 



