44 BULLETIISr 428, U. S. DEPARTMENT OF AGRICULTURE, 



The summary of results at Brookings and Highmore indicates the 

 superior hardiness of Medicago falcata at these points, while Table 

 V indicates that factors other than low temperature were responsible 

 for winterkilling. , 



While the number of plants upon which the percentage of sur- 

 vival shown in Table IV was based is too small to make the data 

 really dependable, the appearance of the plantings at Highmore was 

 very convincing. The rows of Turkestan, North Sweden, Cossack, 

 and Cherno were so depleted as to give the entire block an extremely 

 ragged appearance, while the rows of Medicago falcata adjoining 

 had so nearly the full quota of plants that the mass effect remained 

 unbroken. (Figs. 18 and 19.) 



Widely spaced hill plantings, such as were made at Highmore, in 

 some respects offer very good opportunity for studying winter- 

 killing, since on such plantings the effect of the important factors 

 is greatly exaggerated. In row plantings and even in broadcast 

 stands at Highmore the mortality of the Medicago sativa varieties 



Pig. 18. — Hill plantings of Medicago falcata varieties, Jlf. sativa, andJf. sativaX falcata, 

 commercial varieties and selections. Photographed in August, 1910, Highmore, S. Dak. 



was slight, while it was almost negligible in the case of the Medicago 

 falcata strains. At Brookings the only winterkilling of Medicago 

 falcata which could be considered of any consequence occurred dur- 

 ing the season of 1912-13. The mortality in this case was doubtless 

 due to the presence of an ice sheet over a portion of the plats. It is 

 well recognized that Brookings and Highmore are not ideal places 

 at which to test the comparative hardiness of alfalfas ; nevertheless, 

 at the latter point winterkilling is a serious factor in common alfalfa 

 under field conditions. 



Georgeson {23) reports Medicago falcata to be the hardiest of all 

 the alfalfas tested in Alaska and that it survives the winter without 

 " inconvenience." His tests, which included the Grimm and other 

 variegated strains, were made under conditions much less severe than 

 those normally obtaining in the Dakota s. 



In all the trials which have been reported there is still lack of 

 data on the relative hardiness of the various forms of the species. 

 It now seems probable that this fact will be determined only in- 



