6 
BULLETIN 475, U. S. DEPAETMEXT OF AGRICULTURE. 
lected from caches on the Boise National Forest after the cones on 
the trees had opened. 
Burlap sacks with a capacity of about 2 bushels of cones have 
been found ver}^ suitable for collecting operations. After sacking, 
the cones should be put in a cool, dry place to prevent their opening 
and the escape of the seed, and to prevent their molding, which results 
in deterioration of the seed. 
DRYING THE CONES. 
It is exceedingly important that the cones be air-dried promptly 
aft^r collection; and it is the usual practice to extract the seed soon 
after collection is completed. If the cones are placed in well venti- 
lated bins and thus kept dry, immediate extraction is unnecessary. 
It often happens that collecting and extracting can be carried on 
simultaneously. Promptness is often necessary to prevent molding 
and heating of the cones. Good drying weather does not continue in 
most parts of the West very long after the cones are ripe, and fresh 
seed is desirable for fall sowing or nursery operations. 
Drying with Natltbal Heat. 
The plan commonly followed in drying western yellow pine, Doug- 
las fir. and spruce cones is to spread the cones on canvas sheets of 8 oz. 
material, 12 feet by 14 feet in size, to dry in the sun (PL II, fig. 1). 
Ordinarily 1 bushel of cones should be spread out to occupy 20 square 
feet of canvas. This is usually much cheaper than transporting the 
cones to the drying house and opening them by artificial heat. Fur- 
thermore, experiments with western yellow-pine seed at the Priest 
Eiver Forest Experiment Station show that the viability of seed ex- 
tracted without artificial heat is much greater than of that extracted 
with it. 
The time required for cones to open varies greatly with climatic 
conditions and somewhat with different species. A succession of clear, 
sunny days and frosty nights, with brisk winds, will open cones very 
rapidly. In such weather mature western yellow-pine cones open in 
from three to five days. Under ordinary weather conditions, from 4 to 
10 days are required, and in damp, stormy weather, often as many as 15 
days. Douglas fir and Engelmann spruce usually require a day or two 
longer under the same conditions. Lodgepole pine takes so much 
longer that sun drying is seldom attempted. Cones picked early in 
the season before they are thoroughly ripe open much more slowly 
than those picked later. If the drying is likely to continue until the 
ground becomes cold and wet, it is well to keep the canvas off the 
ground by means of brush or a slightly raised platform. At night 
and during damp weather the canvas sheets should be drawn up by the 
