APPLE DISEASES 101 
source of the inoculum offers some relief as a control measure. 
In selecting a site for orchard-planting care should be taken to 
determine whether the fungus is in the soil. Newly cleared 
land should be held in high suspicion. For the pathogene, as 
already pointed out, may live in the soil as a saprophyte on dead 
parts such as roots, chunks and stumps. It is a better policy 
to grow crops other than those listed as susceptible to Armillaria 
root-rot for a period of at least three years. Likewise if a 
diseased tree is removed, another should not be planted in its 
place for three years. The same applies to a tree which is 
dead as a result of the attacks of this fungus. If it is desired to 
leave the tree in the soil, it may be isolated by digging a trench 
to prevent spread of the rhizomorphs to neighboring healthy 
trees. The trench should be dug near the ends of the roots and 
need not be more than one foot wide and two feet deep. Throw 
the dirt toward the tree, since such soil may contain rhizomorphs 
of the pathogene. In Oregon recent work shows that satis- 
factory results may be obtained in the control of this disease by 
an “aération method.” By this method affected trees may be 
recovered. The roots are exposed about the crown of the tree ; 
all diseased roots and bark are removed ; the wounds disinfected ; 
and the roots thus left exposed to the sun during the remainder 
of the summer. Finally all wounds are covered with some 
good wound-dressing and the roots are covered with soil the 
following winter. The application of chemicals to the soil 
offers some promise, although no experimental data are available 
on which to base reliable recommendations. 
REFERENCES 
Barss, H. P. Mushroom root rot of tree and small fruits. Oregon 
Crop Pest and Hort. Bienn. Rept. 1911-1912 : 226-233. 1913. 
Horne, W. T. Fungous root rot. California State Comm. Hort. 
Monthly bul. 1: 216-225. 1912. 
Horne, W. T. The oak fungus disease of fruit trees. California State 
Comm. Hort. Monthly bul. 3: 275-282. 1914. 
