APPLE DISEASES 101 



source of the inoculum offers some rejief "as* a* Control measure. 

 In selecting a site for orchard-planting ,care ^houl*d* bei t^^en^ to 

 determine whether the fungus is in the s'oll* * '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 "aeration 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. Kept. 1911-1912 : 226-233. 1913. 



Home, W. T. Fungous root rot. California State Comm. Hort. 

 Monthly bul. 1 : 216-225. 1912. 



Home, W. T. The oak fungus disease of fruit trees. California State 

 Comm. Hort. Monthly bul. 3 : 275-282. 1914. 



