DISEASES OF FOLIAGE, ETC. 37 



the sprays usually turn yellow and die. Badly infected 

 trees may be seriously injured. Witches' brooms are 

 found even on small saplings. 



At a distance the witches' brooms might be taken for 

 plants of the incense cedar mistletoe (p. 57). The lat- 

 ter, however, always hangs down in thick clusters, 

 while the bushy witches' brooms stand more or less 

 erect. 



BLUE WITCHES' BROOMS OF SUGAR PINE. 



Sugar pine is comparatively free from diseases of 

 the crown. A very peculiar witches' broom, however, 

 is found on many trees in the shape of a small ball, con- 

 sisting of exceedingly short, brittle twigs and very 

 small, brittle^ bluish needles. This seldom has a di- 

 ameter of more than from 4 to 8 inches, and is gener- 

 ally of no economic importance. Several hundred of 

 these balls, however, have been found on a sugar pine 

 of pole size, showing that under certain circumstances 

 a seemingly harmless disease may become injurious. 

 The cause of the disease is unknown, but it is evidently 

 of parasitic character. 



TIP-DYING OF WHITE AND DOUGLAS FIR. 



White and Douglas fir saplings and poles often have 

 dead, yellow, or brown tips hanging 'from the otherwise 

 thrifty branches. This may be the result of an attack 

 by a fungus which invades the young, bright-green 

 shoots developed in spring, when they are about 1 



