48 Forest Club Annual 



bility between each other. Needles formed during the latter 

 part of the 1909 growing season were much more resistant 

 than those formed in the early part of the season ; the terminal 

 third or fourth, or in some cases twentieth of the season's 

 growth always survived if there was any survival whatever 

 among the needles of this year. Marked individual variations 

 in resistance were manifest, in trees standing side by side 

 of the same age and height. In general, however, trees that 

 had grown the slowest were hardest hit, possibly on account of 

 having smaller proportions of their roots a.t a low depth. 



Trees which had been set out 16 to 20 years earlier were 

 scarcely injured at all, irrespective of exposure. Some of 

 them were much more exposed than the young trees which 

 suffered. 



Western Yellow Pine (Pinus pondcrosa). 



Whether or not these trees are typical of the species or 

 belong to the form known as scopulorum was not determined. 

 Six-year-old trees in the nursery row which had made a very 

 rapid growth, had a number of terminal shoots killed back, 

 both stem and needles, on the northwest and north sides. Part 

 of the trees originally in this nursery had been transplanted 

 again two years earlier to a north slope where the}' were only 

 protected from southeast wind. These trees were not at all 

 injured. 



White Pine (Pinus strobus). 



The trees in the nursery row, side by side with the seri- 

 ously injured Scotch Pine, suffered no injury. 



Slightly older trees, planted earlier than the trees in 

 the nursery row and where they were more exposed, had about 

 one-third of the terminal growth of the branchlets killed back, 

 especially on the northwest side, and many needles on the 

 surviving terminals were killed back part way from the tip. 

 The terminal growth on the leaders of the branches and on the 

 main leader of the tree were more resistant. 



Trees which were 19 or 20 years old, and had been set 

 out in exposed positions on the hill top 8 or 9 years before, 

 were injured somewhat more than those mentioned above. 



Austrian Pine (Pinus austriaca). 

 A single tree about 8 years old, which two years earlier 



