Poivdery Mildew of Clover 



313 



TABLE III. Source of Seed and Its Bearing on Winter Injury. 

 Condition of Varieties of TufoUum pratense. Spring, 1922 



SUMMARY. 



1. The mildew of red clover, Trifoliuni pratense, is apparently special- 



ized on that host, crimson, T. incarnatum, Alsike, T. hyhridum, 

 and white, T. repens not being- infected. 



2. Considerable differences exist between varieties of red clover as to 



susceptibility to the mildew, American varieties being much 

 more susceptible than European. 



3. Resistant individuals are probably to be found in all varieties, the 



number varying with the variety. 



4. Selection and breeding for resistance offers the best means for con- 



trolling- the disease. 



The writer wishes to acknowledge his indebtedness to Dr. A. J. 

 Pieters, Office of Forage Crop Investigations, U.S. Dept. of Agricul- 

 ture, and Mr. R. R. Mulvey, Soils and Crops Dept., Purdue Agricultural 

 Experiment Station, for furnishing the seed of clover varieties upon 

 which this work was done. 



