32 
BULLETIN 139, U. S. DEPARTMENT OF AGRICULTURE. 
ment Station, in Minnesota. Two methods of seed collecting have 
been tried out at the experiment station. One was to follow the 
logging crew and gather the cones as the trees were felled. The 
other was to collect the cones from squirrel hordes. The latter 
method was found to be by far the best. Thus, when collecting the 
cones from felled trees from 1 to 2 bushels was the average pe,r man 
per day; from 1 to 4 bushels was the average collected from squirrel 
hordes. The largest caches of Norway pine found contained 1 
bushel, while caches consisting of jack pine and Norway pine cones 
often held 2 bushels. The average number of seed from cones was 
found to be 37, of which 23 were good and 14 bad. 
In general it was found that temperatures from 130° to 140° were 
the ones at which the seed could be extracted easiest with the highest 
percentage of germination. While for all temperatures used in the 
test the mean per cent of germination was 70.8, for 130° to 140° the 
per cent was 78.5. The lower germination per cent for tempera- 
tures of less than 130° is accounted for by the fact that at that 
temperature only the smaller and less fertile seed are released. In 
Table 17 is given the length of time necessary for Norway pine to 
crack and open at different temperatures. 
Table 17. — Length of time necessary for Norway pine cones to crach and open at different 
temperatures. 
Tempera- 
ture. 
Cracking. 
General 
opening. 
Not open. 
o 
E. m. 
H. m. 
Per cent. 
125 
1 20 
4 35 
12 
130 
1 15 
4 15 
14 
135 
1 30 
4 
14 
140 
45 
3 45 
8 
145 
40 
2 30 
8 
150 
40 
2 22 
4 
155 
50 
2 25 
6 
160 
45 
2 30 
2 
165 
40 
2 15 
170 
35 
2 20 
2 
175 
15 
2 
200 
15 
1 30 
SOWING. 
Sowing is best done when the ground is free from weeds after log- 
ging. If the seed averages 55,000 to the pound, with a germinating 
per cent of 90, broadcasting would require about 5 pounds per acre. 
With the seed costing $4.50 a pound, sowing broadcast under these 
circumstances would be absolutely prohibitive. In any event, broad- 
casting will rarely be successful unless the soil is harrowed and raked 
clear of weeds, though this would not be necessary on soil cleared 
by fire directly after logging. It may often be practicable to sup- 
plement natural regeneration by broadcasting on a soil bared by 
logging when there is no seed crop. 
