ALFALFA 353 



is also beginning to be troublesome in alfalfa. Blue-grass 

 is best eradicated by means of a spring tooth harrow, 

 especially one with broad pointed teeth. Care must be 

 taken to subdue the blue-grass as soon as it begins to 

 appear. The disk harrow is also commonly used, but 

 this does not destroy the blue-grass as well as the spring 

 tooth, though it may be used to precede the latter. Disk- 

 ing often splits the crowns of the alfalfa plant, and the 

 opinion is growing that this is injurious rather than 

 beneficial, as some writers have claimed. 



Quack-grass (Agropyron repens), in Michigan, Vermont 

 and other Eastern States, is a serious weed. Owing to 

 its deep running rootstocks, it cannot be eradicated by 

 harrowing, and thus continues to spread as long as the 

 field remains in alfalfa. 



Crab-grass (Digitarid) and foxtail or pigeon-grass 

 (Setaria) are the worst alfalfa weeds in the Southern 

 States. The former is troublesome as far north as Kansas 

 and Maryland, and the latter still farther. Both are 

 annuals and reseed in spite of any practical precaution. 

 The plants are rather easily destroyed by harrowing, as 

 they are annuals and lack the rootstocks characteristic 

 of blue-grass. Humid weather especially favors crab- 

 grass, while it injures alfalfa, which under such conditions 

 may be smothered and practically destroyed. 



Bermuda-grass is becoming an increasing menace in 

 alfalfa fields in Arizona and California. In this region, 

 Bermuda-grass produces an abundance of seed which 

 reaches the alfalfa fields in irrigation water. Its eradi- 

 cation without plowing has not been accomplished. In 

 Virginia, Bermuda-grass, even when abundant, has not 

 proven to be troublesome in alfalfa. 



Squirrel-tail (Hordeum jubatum), a grass native to the 



2A 



