U. S. DEPARTMENT OF AGRICULTURE. 

 BUREAU OF PLANT INDUSTRY— BULLETIN NO. 217. 



B. T. GALLOWAY, Chiff of Bureau. 



ROOT-KNOT AND ITS CONTROL. 



BY 



ERNST A. BESSEY, 



Professor of Botany, Michigan Agricultural College, and 

 Collaborator, Bureau of Plant Industry. 



Issued Novkmber 21, 1911. 



WASHINGTON : 



GOVERNMENT PRINTING OFFICE. 



1911. 



