6 DEPARTMENT CIRCULAR 58, U. S. DEPT. OF AGRICULTURE. 
these varieties of apples and crabs may be under either the ordinary 
methods or any new methods that may be evolved remains to be 
determined. | 
Practically none of the plums usually sold in this area has proved 
successful. The most common faults of such varieties are lack of 
hardiness and lateness of ripening. 
Sand-cherry hybrids in the trade up to the present time have not 
proved very satisfactory. 
No desirable hardy varieties of the cherry, pear, apricot, peach, or 
of any of the native tree fruits are available for this area. 
The Mandan field station has under way extensive experiments in 
the breeding of all tree fruits that appear possible of adaptation to the 
area. This work fol- 
lows two distinct lines. 
One is the effort to 
create desired combi- 
nations of characters 
by means of crossing 
or hybridizing. In 
this work a large num- 
ber of crosses are made 
under glass each year 
and the resulting 
crosses or hybrids of 
known parentage are 
tested for hardiness 
and other characters. 
The other line is the 
growth and selection 
of seedlings. Large 
numbers of seedlings 
are grown each year 
from seeds gathered 
Fic. 1.—The ordinary high-headed nursery tree which from native groves or 
has proved a failure on the Northern Great Plains. other sources through- 
out the area. These seedlings are planted in testing orchards, from 
which the best individuals are selected when they fruit. The first 
selection of seedling plums was made in 1918 from an orchard started 
from seed in 1914. The selections were based mainly on hardiness, 
early maturity, and productiveness. 
METHODS OF PROPAGATION. 
Under methods of propagation are included the determination and 
use of hardy and congenial stocks for the several tree fruits and the 
