12 BULLETIN 1113, V. S. DEPARTMENT OF AGRICULTURE, 



DECIDUOUS OR HARDWOOD SPECIES INTRODUCED TO THE REGION. 



Carolina poplar. — The Carolina poplar (Populus sp.) is propa- 

 gated by commercial nurseries and has been widelj" used in past years 

 for shelter-belt planting on the prairies east of the northern Great 

 Plains region. It is probably a selection of the common cottonwood 

 taken in the central or eastern United States. Extensive tests with 

 this variety in shelter belts on the northern Great Plains have proved 

 it entirely unsuited for general planting in this region. 



Norway poplar. — The Norway poplar {Populus sp.) is propagated 

 extensively by commercial nurseries. It closely resembles the Caro- 

 lina poplar. Extensive tests in shelter-belt plantings in the northern 

 Great Plains indicate that it is unsuited for general planting in this 

 section. 



Canadian poplar. — The Canadian poplar {Populus sp.) is one of 

 several varieties imported a number of years ago from northern 



Fig. 6. — Shelter-belt planting of box elder, northwest poplar, and green ash planted 6 by 6 

 feet at Archer, Mont., showing clean cultivation in the first year of growth. 



Russia or Siberia and propagated by commercial nurseries in the 

 United States and Canada. This variety has been extensively 

 planted in the Plains region of Canada, where it has proved quite 

 adaptable for shelter-belt use. Plantings in the Plains region of the 

 United States, however, have shown that it is subject to attack by 

 canker, which kills the trees in three or four years. This disease 

 makes it a questionable variety for general use in this region. 



Laurel-leaf willow. — The laurel-leaf willow {Salix pentandra) is 

 extensively propagated by commercial nurseries for shelter-belt 

 planting in the Northwest. It was imported a number of years ago 

 from Europe. While it is reasonably hardy, it does not seem able to 

 establish itself in the upland prairie locations on the Great Plains. 

 Extensive test plantings have grown nicely for one or two years 

 and then killed out for what seems to be lack of sufficient moisture. 



