1916] PARASITIC RHIZOCTONIAS IN AMERICA 337 



Percentage 

 Seedlings Damping off, September 2, 1914 of loss 



Aquilegia (6 species) 35 



Campanula (8 species) gO 



Cineraria (several species) 20 



Dianthus plumarius 35 



Erysimum pulchellum 2 



Linaria Cymbalaria 2 



Ly thrum sp 



Matthiola incana (stocks) 2 



Primula malacoides 2 



' ' obconica grandi flora 



Schizanthus (mixed) 2 



Silene Schafta . . 100 



Stachys lanata 2 



Viola tricolor (3 varieties) 20 



Cuttings Damping off, September 25, 1914 



Abutilon hybridum, var. Savitzii 100 



Acalypha Wilkesiana, var. Toicolor 100 



tricolor 100 



marginata 90 



Ageratum mexicanum vars ; 2 



Alyssum odoratum (3 varieties) 100 



Coleus (10 varieties) 2 



Cuphea platy centra 2 



Iresine (Achyranthes) (5 varieties) 95 



Petunia (several varieties) 100 



Piqueria trinervia (Sterna} 100 



Santolina chamcecyparissus 2 



Sedum spectdbile 2 



Telanthera (Alternanthera} (9 varieties) 2 



Vinca major (several varieties) 2 



TYPES OF SYMPTOMS 



From a study of the symptoms caused by Khizoctonia Solani on 

 the various hosts, it is seen that, except for a few minor points, they 

 are the same when appearing on the same type of host. The damping- 

 off of seedlings and cuttings of various plants is identical, as is the 

 rotting of a number of root crops. In most herbaceous plants a stem 

 rot is produced, the symptoms of which are also identical on the vari- 

 ous hosts. On very resistant plants lesions only are formed ; these are 

 apparently identical on the different hosts. 



INOCULATION EXPERIMENTS 



The main purpose of these inoculation experiments was to ascer- 

 tain the degree of biologic specialization which may exist between the 

 various cultural strains of Ehizoctonia, or between strains isolated 

 from different hosts or of different geographical origin. With three 

 thousand square feet of glass available in the floricultural greenhouses 

 and with the assistance of the members of the floricultural division, it 

 was possible to carry on cross-inoculation experiments involving about 



