Vol. XX NOVEMBER 15, 1920 No. A 



JOURNAL OF 



AGRICULTURAL 

 RESEARCH 



CONTENTS 



Page 



Studies on the Life History and Habits of the Beet Leaf- 

 hopper --_-_--_. 245 



C. F. STAHL 



( Contribution from Bureau ol Entomology) 



Hypertrophied Lenticels on the Roots of Conifers and 



Their Relation to Moisture and Aeration - 253 



GLENN G. HAHN, CARL HARTLEY and ARTHUR S. RHOADS 



(Contribution from Bureau of Plant Industry) 



Degree of Temperature to Which Soils Can Be Cooled 



without Freezing _______ 267 



GEORGE BOUYOUCOS 



(Contribution from Michigan Agricultural Experiment Station) 



Changes Taking Place in the Tempering of Wheat - 271 



E. L. TAGUE 



(Contribution from Kansas Agricultural Experiment Station) 



Vascular Discoloration of Irish Potato Tubers - - 277 



H. A. EDSON 



( Contribution from Bureau of Plant Industry) 



Crownwart of Alfalfa Caused by Urophlyctis alfalfae - 295 

 FRED RUEL JONES and CHARLES DRECHSLER 



(Contribution from Bureau of Plant Industry) 



Pathological Anatomy of Potato Blackleg - 325 



ERNST F. ARTSCHWAGER 



( Contribution from Bureau of Plant Industry) 



Sclerotinia minor, n. sp., the Cause of a Decay of Lettuce, 

 Celery, and Other Crops - - - - - -331 



IVAN C. JAGGER 

 (Contribution from Bureau of Plant Industry ) 



PUBLISHED BY AUTHORITY OF THE SECRETARY OF AGRICULTURE, 



WITH THE COOPERATION OF THE ASSOCIATION OF 



LAND-GRANT COLLEGES 



WASHINGTON, D. C. 



WASHINGTON : GOVERNMENT PRINTINQ OPFI0E I ItM 



