Royle, D.J. <br/><br/>
Infection periods in relation to the natural development of hop down y mildew (pseudoperonospora humuli) /    
D.J. Royle. 
 - Ashford, Kent  :   Wye College, University of London,   1970. 
 - 281-291 p. :    charts ;    26 cm. 
 - Reprint ;   no. 499. .
<br/><br/>Includes bibliographical references : p. 290-291. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Hops --Diseases and pests --England.----