NURSERY PRACTICE ON THE NATIONAL FORESTS. 69 
Susceptibility of species to damping-off in Forest Service nurseries. 
Nursery. 
Savenac. 
Boulder 2 
Trapper Creek . 
Monument 
Bessey. 
Fort Bayard . 
Cottonwood.. 
Beaver Creek . 
Pocatello 
Pilgrim Creek.. 
Converse Flats . 
Wind River — 
Page Creek 
Species. 
Most susceptible. 
fPinus ponderosa l 
< Pinus strobus » 
| Pinus monticola 1 
(Pinus sylvestris 
{Pseudotsuga taxifolia . 
I Pinus ponderosa 
Pinus monticola 
f Pinus austriaca 
\Pinus ponderosa 
/Pinus resinosa 
\ Pinus divaricata 
f Pinus attenuata. 
1 Pinus sylvestris. 
r Picea engelmanni 
Pseudotsuga taxifolia 
Pseudotsuga taxifolia 
I Pseudotsuga taxifolia ' . . 
Sequoia washingtoniana 
Pinus jeffreyi. 1 
Pinus sylvestris. 1 
f Pinus ponderosa • 
\Pinus jeflreyi l 
( Pseudotsuga taxifolia 
\Larix occidentalis l ... 
Pinus lambertiana. 
Least susceptible. 
Pseudotsuga taxifolia. 
Larix occidentalis. 
Picea engelmanni. 
Pinus austriaca. 
Pinus ponderosa. 3 
Pseudotsuga taxifolia. 
Picea engelmanni. 
[Pinus austriaca. 
< Pinus sylvestris. 
| Pinus ponderosa. 
I Pinus ponderosa. 
Pinus jeflreyi. 
Juniperus monosperma. 4 
Juniperus pachyphloea. 4 
Cupressus arizonica. 4 
Pinus edulis. 4 
(Pinus monticola. 4 
< Pinus ponderosa. 4 
(Pinus contorta. 4 
/Pinuspo derosa.* 
\ Pinus contorta. 
(Pinus sylv v .i 
< Pinus austi 
I Pinus pondeiv^a. 1 
1 Pinus ponderosa. 4 
Libocedrus decurrens. 4 
Libocedrus decurrens.i 
Cedrus deodara. 1 
(Pinus monticola. 1 
< Pinus ponderosa. 1 
(Abies nobilis. 1 
(Pseudotsuga taxifolia. 1 
< Pinus ponderosa. 1 
(Chamaecyparis lawsonia. 1 
1 Damping-off not serious. 
2 Attack not serious except with fall-sown western yellow pine and Douglas fir. 
« Worse in fall-sown than in spring-sown beds. 
4 Not affected by damping-off. 
At nearly all Forest Service nurseries damping-off has not been 
particularly virulent, whether because of properties of the soil or 
not is unknown. When it has appeared, the most general method 
practiced for its control has been simply to expose the beds to full 
sunlight and, where practicable, to stir the surface soil. The spread 
of the fungi is promoted by damp, w T arm soil and weather, although 
Rhizoctonia and Pythium attack seedlings even in rather cool, damp 
weather. The effect both of exposing the soil to the sun's rays 
and of stirring or cultivating it is to dry it out and thus produce a 
condition unfavorable to the further development and spread of the 
fungi. 
An effective method of control has been worked out by Hartley 1 
and Pierce at a number of nurseries. At the Bessey Nursery, 
where damping-off has at times been very serious, commercial sul- 
phuric acid is applied to the beds immediately after the seeds are 
1 Hartley, Carl, and Pierce, Ray G. 
lings." U. S. D. A. Bui. No. 453. 
" Control of Damping-off of Coniferous Seed- 
