20 
BULLETIN 934, U. S. DEPARTMENT OF AGRICULTURE. 
nurseries in Illinois and Minnesota were obtained from the nursery- 
men by Mr. R. G. Pierce and are indicated by the initial " P." In- 
formation obtained directly from the nurserymen by the writer is in- 
dicated by " X." For nurseries where the statements are based on 
the writer's personal observation rather than on the authority of the 
nurserymen, his own initial ("H") is given. Most of the writer's 
own estimates of relative susceptibility are based on a comparison 
of detailed counts of the damped-off seedlings in a large number of 
untreated plats at different times, as well as on observation. The 
nurseries on which Tillotson reported were all west of the Missouri 
River, most of them being in the mountain region. The reports in- 
dicated by " H " and " X " were mostly from nurseries east of the 
Rocky Mountains. In cases in which the data permit it, the species 
are classified as most susceptible, intermediate, least susceptible, or 
immune. In a number of cases, however, it is only possible to classify 
them as " more " or " less " susceptible. 
Table II. — Relative susceptibility to dam ping-off of different conifer species. 
[Figures in parentheses in this table indicate the number of nurseries from which the susceptibility noted 
has been reported by the observer to whom the preceding letter refers.] 
Reports of relative susceptibility.^ 
Host species.a 
Not 
sus- 
cep- 
tible. 
Least 
sus- 
cep- 
tible. 
Less 
than 
average. 
T f Moresus- 
™Hi ceotible 
^ than the 
ate - average. 
Most 
suscep- 
tible. 
Pinaceae (Abietoidese): 
( c ) 
Nb.... 
Abies cephalonica 
Nb 
Bu, Nb. 
T 
Nb. 
Abies nordmanniana 
Nb.... 
Abies picea (A. pectinata) ; 
Nb.... 
Nb.... 
Nb*... 

Nb. 
Cedrus deodara 
T. ....... 
---------- 
Nb.... N(2) 
Larix leptolepis 
Nb. 
Larix occidentalis 
T 
: T 
Ne 
Nb.... 
Nb.. 
P..... 
N.. 
T (2). 
H, N, Ne, 
T. 
Ne, N 
Ne!!!!!!!! 
Ne 
Nb. 
Picea excelsa 
P 
Nb .. 
H, Bu.... 
Picea omorika 
Ne 
Xe 
N(2)..... 
Nb.... 
Nb.... 
H, P.. 
Picea pungens 
N (2), 
Nb. 
Nb. 
Pinus aristata 
Nb.... 
Pinus attenuata 
N 
Nb.... 
Nb.... 
N 
T 
P 
B, P, H 
(2), T. 
B., H. 
T 
T 
Pinus edulis 
a Host names for American species follow the usage in the publications and a later verbal commimication 
of Mr. George B. Sudworth, of the United States Forest Service. For exotic species the Standard Cyclo- 
pedia of Horticulture, New York, 1916, edited by U H. Bailev, is taken as the standard. The classification 
follows Saxton (118). 
b Symbols signifying the authority for the report: B=Boerkcr (13). Bu=Buttner (2T), 26), Bp= Bates 
and fierce (7j,C=Clinton (28), 11= Writer's estimate, N= Nurserymen s estimate (obtained by the writer), 
Xb=Xegerand Biittner (94), Ne=Neger (93), P= Nurserymen's estimate (obtained by Pierce), T= Forest 
officers' estimate (compiled by Tillotson, 139). 
c Susceptibility to Phytophthorafagi. 
