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CIRCULAR 912, U. S. DEPARTMENT OF AGRICULTURE 



Figure 5. — Trees of Picea glauca var. densata suffered heavy killing back and 

 losses during the drought year of 1934. The species should be planted only 

 under irrigation or on sites of favorable moisture supply. 



planting only on the more favorable moisture sites and under irrigation. 



Picea glauca var. densata. — This species has been extensively 

 planted for windbreak and ornamental purposes. Behavior of the 

 trees (fig. 5) was similar to that of P. glauca, and the recommendations 

 are the same. The species is difficult to establish in dry seasons. 



Picea koyamai. — Testing of this species, consisting of only one tree, 

 was confined to the Mandan station. The tree suffered severe killing 

 back during the first 4 years and little or no injury during the remaining 

 7 years of its life. It is not recommended for planting in the area. 



Picea mariana. — Testing of this species was confined to the Mandan 

 station. Heavy killing back and losses occurred during the severe 

 drought years of 1934 and 1936. It cannot be recommended for 

 dry-land planting, but might be satisfactory under irrigation. 



Picea pungens. — This species has been extensively planted for 

 windbreak and ornamental purposes. Severe winter injury and 

 heavy losses occurred during severe drought periods only. Tops of 

 occasional trees planted on very dry sites have been killed back in some 

 other years. P. pungens is a very desirable windbreak and ornamental 

 tree, but it should be planted only on the more favorable moisture 

 sites or on those receiving irrigation. The species is difficult to 

 establish in dry seasons. 



Pinus banksiana. — This species was planted fairly extensively in 

 windbreaks prior to the first severe drought year (1934). Some 

 killing back and losses, resulting from the lack of sufficient moisture, 

 took place in most years. The injury and losses became heavy during 

 the severe drought years of 1934 and 1936. The species is recom- 



