FIR DISEASES 163 



References on Gray Mold Twig-Blight 



Weir, J. R. A Botrytis on conifers in the northwest. Phytopathology 



2:- 215. 1912. 

 Smith, R. E. Botrytis and Sclerotinia : their relation to certain 



plant diseases and to each other. Hot. Gaz. 29 i 369-407, pis. 



1-3, figs. 1-3. 1900. 

 Tubeuf, C. F. von. Botrytis Douglasii. Eine neue Krankheit der 



Douglastanne. Beitrage zur Kenntniss der Baumkrankheiten, 



pp. 4-8, pi. 1. 1888. 



Mistletoe Burl and Witches'-Beoom 



Caused by Razoumofskya Douglasii (Englem.) Kuntze 



Douglas & is seriously damaged in northwestern United 

 States by this species of dwarf mistletoe. The roots of the 

 germinating mistletoe seeds enter the bark through wounds. 

 Swellings of the stem and enormous brooms are formed by 

 the abnormal branching from the affected parts. Burls are pro- 

 duced on the larger limbs and the trunk. The general effect 

 of the deformed growths is a diversion of the growth energies 

 of the trees to these parts. A dwiarfing of the tops and a de- 

 creased amount of foliage results. Large trees are not directly 

 killed by the mistletoe infestation, but the trees are suppressed 

 to the degree that insects and fungi cause a higher mortality 

 than in stands of normal trees. A general discussion of the 

 mistletoe parasites on trees will be found on page 54. 



Reference 



Weir, J. R. Mistletoe injury to conifers in the northwest. U. S. 

 Dept. Agr. Bui. 360 : 1-38, pis. 1-4, figs. 1-27. 1916. 



Pecky Wood-Rot 



Caused by Tram&tes pint Fries 



This wood-rot is commonly known as red-rot, ring-shake and 

 peckiness, and is the most destructive wood-rot of fir, spruce, 



