DAMPING-OFF IN FOREST NURSERIES. 27 
sites frequently, if not usually, do part of their work before the seed- 
lings appear above the soil. Furthermore, any treatment at all effect- 
ive against the disease is almost certain to hurt the seedlings if applied 
after the seed starts to sprout. 
Both the acid and copper-sulphate treatments which have been 
found useful in pine seed beds are of very doubtful value for most 
hosts other than conifers, as the angiosperms on which observations 
have so far been made are too easily injured by the disinfectants. 
The weeds in the nurseries have been injured or entirely kept from 
appearing by treatments which caused no injury to the pines. 
CAUSAL FUNGI. 
CORTICTUM VAGUM. 
Occurrence and parasitism.- — In a recent publication (68) Corti- 
cium vagum B. and C. (C. vagum solani Burt, Hypochnus solani 
Pril. et Del., the common damping-off Rhizoctonia) has been reported 
on a number of conifers. Inoculation, reisolation, and reinoculation 
on pine have established its parisitism on this host beyond a reason- 
able doubt, though in these inoculations, as in most, if not all, the 
work- which has been done with the fungus on angiospermous hosts, 
the cultures employed have been from plantings of diseased tissue 
instead of from single spores. The inoculation experiments have 
confirmed the field observations indicating that this fungus is fully 
as able to cause loss by destroying germinating seed below the soil 
surface as to cause damping-off of the better known type after the 
seedlings appear above the soil surface. 
An extensive list of angiosperms on which the fungus has been 
reported is given by Peltier (98). Cross-inoculations between the 
pines (68), on the one hand, and potato (40) and sugar beet (38) 
have shown the same strains to be parasitic on both conifers and 
angiosperms and established the physiological as well as the morpho- 
logical identity of the fungus attacking pines with the common 
Corticium vaguni. Now that Duggar (34) has offered strong, 
though not yet entirely conclusive, evidence of the identity of C. 
vagum with the European " vermehrungspilz " (the Moniliopsis 
aderholdii of Ruhland; 115) it is to be presumed that it is 
a cause of damping-off of conifers in Europe as well as in Amer- 
ica, though no reports of it on conifers have been so far en- 
countered in European literature. The Rhizoctonia reported by 
Somerville (132) on Pinus sylvestris and the Rhizoctonia strobi de- 
scribed by Scholz (121) as killing young Pinus strohus were both 
on trees more than 4 years old, so that they had no relation to damp- 
ing-off. Furthermore, the first of these was apparently the old 
Rhizoctonia violaeea, now known as R. crocorum (R. medacaginis) , 
a fungus entirely distinct from Corticium vagum, probably belong- 
