2 BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 
While the parasites reported as causing damping-off are probably 
not as numerous as the host species which are subject to it. a con- 
siderable number are known. Two quite different types of damping- 
off parasites may be recognized. In the first type we have fungi, 
such as Pythium debaryanum Hesse and C orticium vagum B. and C, 
soil inhabiting and primarily saprophytic, which attack a great 
variety of hosts, and are at least better known, if not more destruc- 
tive, as damping-off organisms than as parasites on older plants. 
They are specialized as to the type and age of tissues which they at- 
tack rather than as to host. The second type includes fungi less 
common as saprophytes and with a relatively limited, sometimes very 
closely limited, host range. Phoma betae, the systemic parasite of 
sugar beet (37), is an excellent example of the host-specialized para- 
site, transmitted in the seed and capable of seriously injuring various 
parts of the older plant at different stages of growth as well as at- 
tacking seedlings. 
Most damping-off parasites are intermediate in habit between the 
extremes of these two types. Of those which are somewhat host 
specialized, the following may be mentioned : 
Phomopsis reruns, the cause of foot-rot of eggplant, reported by Slierbakoff 
(12S) as a frequent cause of damping-off of this host and believed to be 
carried on seed. 
Gibherella sauMnetii (Mont.) Sacc. (29) and the imperfect fungi which kill 
grain seedlings as well as cause diseases of the older plants (80; 126, 
p. 218). Species of Gloeosporium and Yolutella named by Atkinson (2, 
p. 269 ; 52) as able to kill seedlings or cuttings of particular host plants. 
Glomerella (Golletotrichum) gossypii, described by Atkinson (1) and Barre 
(4) as likely to cause damping-off of cotton (112). 
Fusariurn lini, the flax parasite, reported by Bolley (14) as destructive .to 
young seedlings. 
Plwma lingam, the cause of black-leg of cabbage, at least under inoculation 
conditions able to kill quickly seedlings of cabbage and other crucifers 
(72). 
Peronospom parasitica (Pers.) De Bary, a downy mildew attacking cabbage 
and various other crucifers, reported as killing thousands of very young 
cabbage plants in Florida seed beds (41). 
The entomophthoraceous Completoria complens, on fern' protha Ilia (1; ST. 
p. 203). 
Bacillus malvacearum, a parasite of the leaves of cotton plains, which can 
also cause damping-off of its favorite host (113) and the bacteria from 
diseased cucumber plants with which Halsted (53) caused typical 
damping-off of cucumbers. 
Damping-off fungi with wider host ranges include Phytophthora 
fagu Aphanomyces levis (100), Rheosporangium aphanidermatus 
(38, 39), Botrytis cinerea, and certain Fusaria. The so-called prop- 
agation fungus, " vermehrungspilz." a sterile damping-off mycelium 
which Sorauer (133. p. 321) believed related to Sclerotinia and for 
which Ruhland (115) has erected a new genus, considered by both 
