26 BULLETIN 1244, U. 8. DEPARTMENT OF AGRICULTURE. 



soon found that common alfalfa, especially regional strains from Utah, 

 Kansas, and States southward, would not withstand the very severe 

 winter conditions that often obtain. This was quite a handicap to 

 the extension of alfalfa growing. In 1904 the Minnesota Agricul- 

 tural Experiment Station called attention to what is now the well- 

 known Grimm alfalfa. This variety, a hybrid of the common blue- 

 flowered alfalfa (Medicago sativah.) and the yellow-flowered species 

 (M.falcata L.) and apparently adjusted to the severe winters of Car- 

 ver County, Minn., where it had been grown in a small way for 

 years, has gone far toward filling the need for a hardy alfalfa. It is 

 a superior variety for the region from all agronomic standpoints. 

 Since the advent of the Grimm variety other hybrid alfalfas have 

 been introduced and are apparently becoming more or less popular. 

 Among these the Cossack seems to be the best known: but carefully 

 conducted tests have not indicated their superiority to the Grimm 

 in any important respect. 



























































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Fig. 11.— An alfalfa field invaded by Russian thistles at Havre, Mont. Russian thistles are .1 

 serious menace to young stands of alfalfa. 



A careful study of alfalfa on the northern Great Plains discloses 

 the fact that inability to produce satisfactory yields under condi- 

 tions of low rainfall is much more of a handicap to its extension than 

 a tendency to succumb to winter conditions. The list of alfalfas 

 purporting to be varieties or strains suitable for the region is quite 

 large, but the number of those actually in general use is relatively 

 small. A great many varieties of alfalfa have been introduced from 

 many parts of the world and have been tested at the various stations. 

 A- might be expected, a large proportion of them have shown no ad- 

 vantages over the varieties already established. Hay-yield data 

 arc not given here for all the varieties and strains in general use. 

 In most cases data, are given only for the typical representatives of 

 the important groups. In addition to possessing differences in win- 

 ter hardiness, alfalfa, exhibits a latitude relation which, stated briefly 

 and generally, is that strains exhibit a tendency to produce the best 

 results in the latitude where they are developed. Data are given 

 in Table L2 from what have proved to he the four leading varieties 



