A DISEASE OF PINES CAUSED BY CRONARTIUM PYRIFORME. 15 



The largest infected tree found was 12 feet high and 3 inches in diameter at breast 

 height, approximately 22 years old, with the infection occurring 5 feet from the ground. 

 In another area here 10 saplings killed by the fungus, with only one living uninfected 

 tree, were found. 



One diseased area of Pinus ponderosa at Mills Ranch on the north 

 slope of Goosenest Mountain in the Klamath National Forest was 

 described by Boyce, which contained at least a hundred acres. The 

 largest tree diseased by the fungus in this area was 8 inches in diame- 

 ter at breast height. Spindle-shaped swellings were common, but 

 more especially on the younger, smaller trees. The girdling effect 

 and death of the host tree in the parts above the point of infection 

 were very much in evidence in this area. Small trees apparently 

 were girdled and killed much sooner than older trees. Wounds caused 

 by some gnawing animal, presumably the porcupine, were common 

 on trees in areas where the fungous disease occurred. In one of the 

 diseased portions of the forest a sample plat was established by 

 Boyce and a count of the healthy, infected, dead, and dying trees 

 of Pinus ponderosa was made. The result was as follows: Out of 314 

 trees in the plat, 153 (48.7 per cent) were apparently healthy, 52 

 (16.5 per cent) were plainly diseased by the fungus, 3 (0.9 per cent)-" 

 were dying, and 106 (33.7 per cent) were dead from the effects of the 

 fungus. In the words of the report: 



Over 50 per cent of the total number of trees of the sample plat had been infected, 

 and nearly two-thirds of the total number infected had already been killed. There is, 

 of course, a possibility that the death of some of these might have resulted from other 

 causes, but only those trees were included which I was certain in my mind had been, 

 killed by the fungus. 



Boyce' s data corroborate those taken by the senior writer both in 

 Pennsylvania and South Dakota. 



Reporting concerning an area of diseased Pinus ponderosa along 

 Browns Creek in Trinity National Forest, Boyce says: 



There were many dead trees, undoubtedly killed by the fungus, with spindle-shaped 

 swellings on the main stems. On living infected trees the secia were sporulating 

 (June 27, 1914), but not very abundantly, not to be compared with the sporulation 

 found at Rocky Gulch on May 20. One infected sapling was found in which the 

 major portion of the bark had been destroyed either by wood rats or porcupines. 



Where the trunk is not girdled, cankers or catfaces are occasionally 

 formed by the death of a portion of the cambium. In such cases 

 the continued presence of the fungus in the live tissues beyond the 

 dead area stimulates their growth, and the fungus may fruit a number 

 of times before the tree is killed. Catfaces on the lodgepole pine 

 (Pinus contorta) and on the western yellow pine (Pinus ponderosa), 

 however, are more commonly produced by another species of rust, 

 Peridermium Tiarlcnessii. 



Peridermium pyriforme, when it infects the trunk of a pine tree, 

 may spread from the trunk to such limbs as spring from a point near 



