380 JOURNAI. OF FORESTRY 



injuries or infection by mistletoe, if otherwise vigorous, are still classi- 

 fied as healthy. The outstanding feature of Table 3 is the high per- 

 centage of unhealthy yellow pine on the old private cuttings, plots i 

 and 2. As previously explained, this is due to the fact that most of 

 the defective trees were left standing. The black jack on these plots 

 compares favorably with the plots cut under Service regulations. 



The high percentage of unhealthy black jack on plots 2 and 3 is due 

 to mistletoe. On plot 3 many young trees are being killed by this pest. 

 The records show a loss of 1.5 per cent of the black jack on plot 3 

 from 1909 to 1914, due to mistletoe alone or in conjunction with other 

 factors. While this figure is not alarmingly high, the indications are 

 that the death rate will increase from year to year. Although when 

 this area was marked for cutting an effort was made to remove all 

 badly mistletoe-infected trees, it is evident that mistletoe was not given 

 the attention it requires. Mistletoe presents one of the most serious 

 silvicultural problems in this region. The facts at hand point to heavy 

 cutting as the only practical remedy, although it is probable that the 

 removal of lightl\- infected trees would not be generally warranted. 

 Since the mistletoe problem has recently been made the subject of a 

 special investigation by Long and Korstian, whose report will soon be 

 published, no detailed discussion will be entered into in this article. 

 It is worthy of note that no mistletoe is reported on plot 4. No mis- 

 tletoe occurs on western yellow pine in the entire cinder region repre- 

 sented by this plot, while elsewhere on the Coconino Forest and gen- 

 erally throughout the two States it is abundant. 



The porcupine is responsible for much damage on certain areas. 

 Saplings are frequently killed by girdling. Trees are seldom killed, 

 but the leaders are often girdled, thus setting the trees back from 3 to 

 10 feet or more in height. A new leader is usually formed and even- 

 tually all external traces of the damage may disappear. Usually, how- 

 ever, there is a bend and a pronounced constriction in the stem. This 

 peculiarity is very common in yellow pine. Doubtless the porcupine is 

 responsible in most instances. 



Squirrels do a considerable amount of damage in certain localities 

 by cutting ofif terminal shoots. It is not uncommon in the winter time 

 to find several hundred shoots 6 to 8 inches long beneath a tree. This 

 greatly reduces the active leaf surface of the crown. 



Of the agents listed in Table 4 as responsible for the death of trees, 

 the most important are windfall, lightning, mistletoe, and bark beetle. 



Windfall is being partially controlled on timber sales by leaving 



