U. S. DEPARTMENT OF AGRICULTURE. 



BUREAU OF PLANT INDUSTRY— BULLETIN NO. 90, PART II. 



B. T. GALLOWAY, C'liirf nf Bureau. 



THE CROWN-GALL AND HAIRY-ROOT DISEASES 



OF THE APPLE TREE. 



BY 



GEORGE G. HEDGCOCK. 

 Assistant in Pathology, Mississippi Valley Laboratory. 



VEGETABLE PATHOLOGICAL AND PHYSIOLOGICAL 

 INVESTIGATIONS. 



Issued Noyember 17, 1905. 



l^EW YORK 



30TANICAL 



GARDEN* 



WASHINGTON: 



GOVERNMENT PRINTING OFFICE. 



1 5 . 



