‘NORTHERN GREAT PLAINS FIELD STATION, 1913-1922 15 
Insect and animal pests may cause considerable damage unless 
precautions are taken. 
With such species as box elder, green ash, and white elm, stock 
raised from seed procured from native trees has shown greater hardi- 
ness than that coming from more southern and eastern localities. 
Seed for propagating any species for planting in shelter belts on the 
northern Great Plains should come from a northern source. 
The best spacing for trees in shelter belts has not yet been deter- 
mined. Present data indicate that for the average planting site in 
the area, the 4 by 8 feet distance used in these demonstrations is too 
close. Further information is needed on this point. 
The experience of these seven years of tree planting has shown con- 
clusively that it is possible to start successfully a planting of trees on 
the average upland farm site in the northern Great Plains. Future 
investigation must show whether or not it is possible for such plant- 
ings me maintain themselves after they have attained their maximum 
growth. 
Instructions to cooperators, and details of the plan of cooperation 
for the information of prospective cooperators, have been published 
in circulars, which may be obtained on request from the Northern 
Great Plains Field Station, Mandan, N. Dak. Further information 
is given in United States Department of Agriculture Bulletin No. 
1118, and Farmers’ Bulletin No. 1312.° 
HORTICULTURAL INVESTIGATIONS ° 
Climatic conditions on the northern Great Plains are so severe that 
horticultural development has been slow and meager. Particularly is 
this true of perennials, such as fruit and ornamental shrubs and trees, 
which, to be successful, must endure the climate over a period of 
years. In general, success has been more marked in cities and towns 
where the trees are partially protected from wind, and where irriga- 
tion on a small scale is possible. Few farmers have succeeded in their 
efforts to grow fruit trees, ornamental trees, or shrubs, and farm life 
thus lacks one of the factors that tend to make it more desirable and 
attractive. 
The climate of this region has been described on previous pages. 
The factors that make horticulture especially difficult are long, cold 
winters, droughts, severe winds, and short growing seasons. 
Temperatures of —30° to —40° F. sometimes occur during the 
winter months, but there are other regions having temperatures 
approximately as low which have been far more successful along 
horticultural lines, so the difficulty is not one of temperature alone. 
Winterkilling has sometimes been very severe following dry autumns, 
which suggests the possibility that winter injury is often at least 
partially caused by drying out, or desiccation. 
5 Wilson, Robert, and F. E. Cobb. Development of cooperative shelter-belt demonstrations on the 
northern Great Plains. U.S. Dept. Agr. Bul. 1113, 28 p., 15 fig. 1923. 
Johnson, Fred R., and F. E. Cobb. ‘Tree planting in the Great Plains region. U.S. Dept. Agr., 
Farmers’ Bul. 1312, 33 p., 18 fig. 1923. * 
_ A copy of the latter bulletin may be obtained free by addressing the Department of Agriculture, Wash- 
ington, D. C. The former may be purchased from the Superintendent of Documents, Government 
Printing Office, Washington, D. C., for 10 cents. j 
6 By W. P. Baird, Associate Agronomist, and T. K. Killand, Scientific Aid, Office of Dry-Land Agri- 
culture Investigations. 
