PINE DISEASES 273 



It seems more probable that winter-drying and other types of 

 winter-injury may account for the injury and that the fungus 

 is secondary and only semi-parasitic. 



Control. 



The only measure of control known is to prune off the dead 

 twigs and burn these, together with all other brush and refuse 

 from coniferous trees that may be in the vicinity. 



References 



Fink, Bruce. Injury to Pinus strobus caused by Cenangium abietis. 



Phytopathology 1 : 180-183, pi. 26. 1911. 

 Schwarz, Frank. Die Erkrankung der Kiefern duroh Cenangium 



Abietis, pp. 1-126, pis. 1-2. 1895. 



Mistletoe Burls and Witches'-Brooms 



Caused by Razoumofskya campylopoda (Englem.) Piper, and R. ameri- 

 cana (Nntt.) Kuntze 



Western yellow and lodge-pole pine are affected respectively 

 by these two dwarf mistletoe parasites. In northwestern 

 United States much damage results from the diseased condition 

 they cause. The general result of burl and witches'-broom 

 formation is a reduction in foliage which causes slow growth 

 and finally death when infection is heavy. Likewise, the dis- 

 eased areas of bark offer ready places of entrance for insects 

 and wood-rotting fungi. Trees of all ages are affected. Trees 

 with the lower branches or trunk affected early in life suffer 

 more severely than those infected later. The brooming of the 

 lower branches diverts a large part of the growth energy of the 

 tree and the tops are dwarfed and die, causing stag-headed or 

 spike-topped trees. 



SymTptoms. 



The roots from the germinating mistletoe seeds enter the 

 leafy twigs or through wounds in the bark of older branches. 



