78 MANUAL OF TREE DISEASES 



References ox Ga&-Ixjukt 



Stone, G. E. Effects of illuminatiiig gas on trees. In Shade trees, 

 characteristics, adaptation, diseases and care. Massachusetts 

 Agr. Exp. Sta. Bui. 170 : 220-228, figs. 93-97. 1916. 



Stone, G. E. Effects of illuminating gas on vegetation. Massa- 

 chusetts Agr. Exp. Sta. Ann. Rept. 25:1: 45-60, figs. 1-3. 1913. 



Shoe-Sthixg Root-Rot 

 Caused by Armillaria mellea (Pries) Quelet 



The shoe-string or honey-mushroom root-rot is common 

 throughout the United States on many kinds of coniferous and 

 deciduous trees. It has been noted especially on oak, pine, 

 chestnut, larch, sycamore, poplar, locust, hemlock, birch, alder, 

 maple and many kinds of fruit-trees and shrubs. In some 

 sections of the country, especially in south central United States 

 and on the Pacific Coast, orchard-trees are commonly affected 

 and killed. The disease is most destructive in orchards on, 

 land recently cleared of oak. In Europe this disease is also 

 common on cedar, pine, fir, peach, cherrj', olive, grape and 

 many other kinds of woody plants. There seem to be no 

 definite host relations for the activities of the fungus causing 

 this root-rot. It is known to attack the potato. 



Xo very accurate facts are available as to the parasitic po- 

 tentialities of the honey-mushroom. It occurs ever\-where on 

 stumps and dead wood and is commonly found on trees in poor 

 health or badly wounded. The relation between the decline of 

 the tree and the attack of this fungus is hard to determine. 

 However, abundant evidence is at hand that young thrifty 

 trees in the forest and orchard are often killed, when there is 

 no doubt that the honey-mushroom was directly and primarily 

 the cause of the decay of the roots. It is, therefore, reasonable 

 to expect that on further investigation this root-rot will be 

 fully shown to be a primary cause of the decline and death of 

 the trees. In many cases, however, it may play only a sec- 



