J. Ralph Cooper

Date of this Version


Document Type



Cooper, J. Ralph (1917) Studies of the etiology and control of blister canker on apple trees (Research bulletin: Bulletin of the Agricultural Experiment Station of Nebraska No. 12)


ISSN 0097-1343


The blister canker caused by Nummularia discreta Tul. is by far the most destructive disease of apple trees found in the United States. Serious damage due to this disease was first reported in Illinois in 1902. Since that time the disease has been reported to cause much damage in all apple-producing sections east of the Rocky Mountains. In Nebraska the disease is so prevalent that it is practically impossible to find an orchard free from it, and in many instances whole orchards have been destroyed thru its attacks. Because of the rapid dissemination and the destructive nature of blister canker, the writer in the fall of 1912 began a series of experiments in an attempt to find some means of controlling it. It was soon found that little progress could be made in this direction without a thorough knowledge of the etiology of the disease. Accordingly this phase of the work was taken up in 1914 and both phases continued to date.