PREFACE TO SEVENTH EDITION 



In revising the seventh edition of Principles of Plant 

 Culture the object has been merely to change those 

 portions which are no longer accurate because of the 

 advancement made in some phases of plant culture 

 since the last revision. The greatest changes made in 

 the new edition are to be found in the discussion of 

 "The Plant as Affected by Parasites." The recent de- 

 velopment in methods of control and materials used 

 against plant enemies necessitates these changes. It is 

 safe to say that the most rapid development at the 

 present time in Plant Culture is that vphieh pertains 

 to the methods of combatting plant parasites. A iew 

 other minor changes have been made but in the main 

 "Principles of Plant Culture" is still as it came from 

 the pen of the author. 



JAMES G. MOORE, 

 Associate Prof, of Horticulture, 



University of Wisconsin. 



