102 MANUAL OF FRUIT DISEASES 



Horn&^.'W. T.V Gfk "fungus or Armillaria mellea in connection with 

 nursery stock. .Califorkia State Comm. Hort. Monthly bul. 4 : 



"" ' 



. 



'Lawfenc*e,* W. H. Root diseases caused by Armillaria mellea in the 



Puget Sound country. Washington State Agr. Exp. Sta. Bul. 



(Special Series), 3 : 3-16. 1910. 

 Piper, C. V., and Fletcher, S. W. Root diseases of fruit and other 



trees caused by toadstools. Washington State Agr. Exp. Sta. 



Bul. 59 : 3-14. 1903. 



CLITOCYBE ROOT-ROT 



Caused by Clitocybe parasitica Wilcox 



The name Clitocybe root-rot is used to distinguish this disease 

 from other similar root troubles. Like the Armillaria root-rot 

 it affects plants other than the apple, although the host-range 

 is less extensive. The peach, cherry and oak are more important 

 among the other trees damaged by the Clitocybe root-rot. 



The disease is confined to the southwestern section of the 

 United States. Affected trees have been reported from Okla- 

 homa, Texas, Missouri, Illinois, Indiana, Georgia, Oregon and 

 California. Greatest destruction has perhaps been wrought in 

 the state of Oklahoma; whole apple and peach orchards are 

 said to have been destroyed by this disease within the short 

 period of two years. 



Symptoms. 



It may be expected that Clitocybe root-rot will be present 

 most commonly in orchards which have been planted on recently 

 cleared timber lands. It is not known on prairie soil. The 

 most characteristic effect of the disease is the exudation of gum 

 from the crown of the tree. The amount of exudate is at times 

 so great as to unite with the soil, forming a gum-cemented soil 

 about the base of the affected tree. This often becomes 

 hardened, forming a sort of cast about the crown and the larger 

 roots. From a distance affected trees may be recognized by 

 either a yellowing or a wilting of the leaves. As in the case of 



