MISTLETOE INJUKY TO CONIFERS. 



9 



or in some cases the entire tree may succumb (fig. 7 and PI. Ill, fig. 

 1.) In many parts of the Whitman National Forest, wherever the 

 heaviest infection of yellow pine occurs the percentage of dead or 

 spiketopped trees reaches a comparatively high figure. 



In a report to Supervisor Ireland, Ranger Smith, in referring to 

 the seriousness of the infection of yellow pine in the vicinity of 

 Susanville, Whitman National Forest, states that since 1907, the 

 year in which the mistletoe damage in the region first received at- 

 tention, the infection 

 of all age classes has 

 been growing worse, 

 probably 40 per cent 

 of the stand now be- 

 ing infected. Of the 

 more mature stand, 

 approximately twice 

 as many trees near 

 the station as were 

 noted in 1907 have 

 since died. Ranger 

 Smith further states 

 that for a most pro- 

 nounced general in- 

 fection of all species 

 the drainage basin of 

 the South Burnt 

 River particularly 

 illustrates the devas- 

 tating effects of mis- 

 tletoes. "Almost 

 every yellow pine 

 from seedlings up 

 and Douglas fir above 

 sapling size is heavily 

 infected and most of 

 the mature timber 

 shows great retarda- 

 tion of growth and is now adding little or no increment. This 

 infection covers a large part of the best yellow-pine sites in the 

 yellow-pine belt of this watershed." This region was not visited by 

 the writer, but to judge from studies in other parts of the same 

 forest Ranger Smith's observations are undoubtedly correct. 



In order to determine the relative amounts of different species 

 cut as snags on the W. H. Eccles Lumber Co. sale (whitman Xa- 



24182 Bull. 36016 2 



FIG. 6. Douglas fir, showing the death of the upper por- 

 tion of the crown caused by Razoumofskya douglasii. 

 The tree to the right with the series of immense brooms 

 also has a dead top. A large broom had split off from 

 the trunk of the tree on the left. All the young growth 

 in the vicinity of these trees is seriously infected. 



