Voi,. XXIV Washington, D. C., Juni® 2, 1923 No. 9 
CONTROL OF SNOW MOLDING IN CONIFEROUS NUR¬ 
SERY STOCK' 
ByC. F. Korstian* 
Associate Silviculturist^ Appalachian Forest Experiment Station^ Forest Service^ United 
States Department of Agriculture 
During the time that the Cottonwood Nursery of the United States 
Forest ^rvice was in operation (1906-1921) very serious winter losses 
of Douglas fir {Pseudotsuga taxifolia) seedlings and transplants occurred 
under the snow. Several other species were also injured, the extent of 
loss varying with the species, age class, and time of snow disappe^ance 
in the spring. All age classes of Norway spruce {Picea excelsd) were 
especially susceptible, while Engelmajm spruce (JPicea engelmanni) and 
the Pacific coast form of western yellow pine {Pinus pond^osct) suffered 
only moderate injury, and lodgepole pine {Pinus contorta) was practically 
immune. 
The Cottonwood Nursery is situated 25 miles southeast of Salt Lake 
City, Utah, on the Wasatch National Forest, at an elevation of 7,450 feet. 
Here the snow usually covers the ground continuously from November 
I to May 10, lasting occasionally even until May 20 or 25. The maximum 
depth varies from 6 to 8 feet. Under this heavy blanket of snow the 
ground seldom freezes, and even where freezing has occurred in the 
autunm before the advent of permanent snow, the soil soon thaws out 
^ after the snow begins to accumulate. Invariably the injury was 
' greatest during years of heaviest snowfall and consequent late meitjbajj; 
of snow in the spring. 
Hartley, Pierce, and Hahn ® studied this type of injury and foimd that 
it was caused by weakly parasitic fungi, attacking the leaves. Ihey 
succeeded in isolating, by cultural methods^ a number of organisms from 
recently snow^molded seedlings of Douglas fir, of which they most 
strongly suspected Boirytis cinerea and a dark sterile mold, as yet unidenti¬ 
fied, as causing the disease. These investigators conducted spra)dng 
experiments with fungicides, including sulphuric add, formalddiyde, 
zinc chloride, copper sulphate, copper acetate, and ammoniacal copper 
carbonate, none of which gave promise of effectively controlling the 
disease. A lime-sulphur mixture gave only very slightly benefidal 
results. Mulches consisting of thin layers of sawdust, sterilized sand, and 
gravel gave no promise. At the beginning of the present investigation 
1 Accepted for publication Sept. 2, 192a. 
’ The writer is indebted to former Fmest Planting Assistant N. J. Fethonlf for painstaking assistance in 
carrying out the experiments here reported. 
* Hartlsy, Carl, Piercis, Roy G., and Hahn, Glenn G. moulding op snow-smothbred nursery 
STOCK. In Phytopathology, v. 9, p. S 2 i“ 53 i- 1919- 
Journal of Agricultural Research. 
Washington, D. C 
aei 
Vol. XXIV, Na 9 
June 2, 1923 
Key No. F-9 
43323—23-1 
(741) 
