SPRUCE DISEASES 321 



blue spruce. The first species of fungus mentioned above is 

 also found on black spruce in the northeastern states. The 

 mycelium is perennial in the twigs of the spruce and they are 

 dwarfed. Two irregular rows of whitish or slightly pinkish 

 blisters are formed in early spring on the under sides of the 

 needles of the affected twigs and brooms. Although it is ex- 

 pected that these fungi have another stage in their life history 

 on some flowering plant, this has as yet not been discovered. 



Reference 



Arthur, J. C, and Kern, F. D. North American species of Perider- 

 mium. Bui. Torrey Bot. Club 33 : 403-438. 1906. 



Mistletoe Witches'-Broom 



Caused by Razoumofskya pusilla (Peck) Kuntze 



This species is the only member of either the dwarf or leafy 

 mistletoes that grows in northeastern United States. It occurs 

 on black, red and white spruce and has been found once causing 

 a witches'-broom on eastern larch in Vermont. It is only seen 

 occasionally on the red and white spruce but is more or less 

 common on black spruce. When the parasite occurs, the spruce 

 is frequently killed or at least dwarfed to half its normal size 

 and makes very irregular growth. 



Symptoms. 



Two types of symptoms are noticeable on black spruce. 

 The weaker and more shaded branches when attacked make an 

 abnormal growth in length and the branches are more spread- 

 ing. The foliage of these branches is yellowish and the leaves 

 much smaller than normal. The usual symptom, however, is 

 the production of upright clumps of branches, known as witches'- 

 brooms (Fig. 62). A lateral branch near the infected part 

 assumes an upright growth. Around the base of this branch 



