534 



Journal of Agricultural Research 



Vol. XV, No. lo 



Table; I. — Inoculation with initial and reisolated strains of Corticium vagutn on pine 

 seedlings in autoclaved soil — Continued 



Source. 



Trial host. 



Num- 

 ber 

 of 

 pots. 



Location of in- 

 oculum. 



Results. 



Ger- 

 mi- 

 nat- 

 ed. 



Damp- 

 ed-ofi. 



Sur- 

 vi- 

 val. 



Reisolations of No. 

 147 from western 

 yellow pine, ex- 

 periment 58. 



do 



Red pine. 



.do. 



.do. 

 .do. 



Reisolation of No. 147 

 from jack pine, ex- 

 periment 58. 



Damped-off sugar- 

 beet seedlings. 



Reisolations of No. 

 213 from jack pine, 

 experiment 58. 



do 



Russian wild-olive 

 seedlings. 



Reisolations of No. 

 230 from jack pine, 

 experiment 58. 



do 



.do. 



.do. 

 .do. 



.do. 

 .do. 

 .do. 



.do. 

 .do. 



Agar culture frag- 

 ments scattered 

 over one side of 

 pot. 



....do 



....do 



....do 



....do 



....do 



....do 



....do 



....do 



....do 



Sterile agar frag- 

 ments scattered 

 over one side of 

 pot. 



Per 3 



pots. 



14 



Per 

 cent. 



Per 3 

 pots. 



75 

 100 



57 



31- S 



63 



o Cultures furnished by Dr. H. A. Edson, Bureau of Plant Industry. 



It is evident from the results in Table I that the reisolated cultures 

 were able to cause germination loss or damping-off, or both, in both the 

 hosts on which they were tried. The approximate agreement in viru- 

 lence in experiment 71 and 72 of the original strains and the strains isolated 

 from the pots inoculated with them is an additional evidence that the 

 strains recovered were the ones originally used. Strain 341 seemed 

 rather more virulent than 230 from which it was reisolated; it was, 

 nevertheless, obviously less active as a parasite than strains 147 and 213, 

 and their reisolations. The possibility that a strain of Corticium vagum 

 obtained from an autoclaved and inoculated pot is not a true reisolation 

 of the strain used in the initial inoculation is very slight, in view of the 

 lack of adaptation of the fungus to aerial dissemination and the fact 

 that in the writers' numerous cultures from autoclaved soil experiments, 

 C. vagum, unlike Fusarium spp. and Pythium debaryanum, has never 

 been detected in pots in which it had not been intentionally introduced. 

 As the cultures used were all, or nearly all, obtained by the planted- 

 plate method, their purity is not entirely beyond question. However, 

 their apparent purity, continued in the case of strain 147 through eight 

 years of growth on artificial media, and the permanence of the relative 



