102 MANUAL OF FRUIT DISEASES 
Horne, W. T. Oak fungus or Armillaria mellea in connection with 
nursery stock. California State Comm. Hort. Monthly bul. 4: 
179-183. 1915. 
Lawrence, 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. 
CurtocyBeE 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 
