ALDER DISEASES 87 



Catkin-Deformation 



Caused by Exoascus amentorum Sadebeck 



The catkins of several species of alder are affected by this 

 disease. The same disease is common in Europe. The scales 

 of the fertile catkins become much enlarged and project as 

 curled, reddish tongues. Later they are covered by a white 

 glistening coat of the fruiting structures of the parasite. The 

 mycelium is perennial in the twigs. Practically no damage is 

 done to the tree. If preventive measures are desired, the prun- 

 ing of the diseased parts should eventually eliminate the 

 difficulty. 



Brown Checked Wood-Rot 



Caused by Polyporus sulphureus Fries 



The alder is one of the many deciduous trees commonly af- 

 fected by the brown checked wood-rot. Chief among the other 

 kinds affected are oak, chestnut, walnut, butternut, maple and 

 locust. The causal fungus enters through some wound where 

 the heartwood is exposed. The heartwood and sapwood are 

 both decayed and become like red-brown charcoal. Thin 

 yellowish sheets of mycelium, within concentric and radial 

 checks, divide the decayed wood into small punky cubes. The 

 fruiting-bodies emerge, usually, from old branch wounds and 

 consist of many overlapping shelves forming a large, more or 

 less globose mass. . The upper surfaces of the shelves are orange- 

 red, while the under surfaces are sulfur-yellow. For further de- 

 tails concerning this wood-rot see under oak diseases, page 247. 



Common White Wood-Rot 



Caused by Fames igniarius Fries 



Alders are destructively affected in Europe by the common 

 white wood-rot. In the United States such trees as beech, 



