FORAGE CHOPS 381 



soil to adjoining plants, and the affected spot in the field 

 thus enlarges, sometimes at a rate of 7 m. radially per year. 

 Though long known in Europe, it has not yet appeared in 

 many parts of America. 



Rhizoctoniose is a typical soil disease and is kept aHve 

 in the soil by its sclerotia, which may live at least two or 

 three years. The general suggestions given under soil dis- 

 eases apply. 



Texas root rot (Ozonium omnivorum Shear.). — This rot is 

 the same that affects the cotton so disastrously, and which is 

 discussed fully under cotton diseases. It is a soil cUsease 

 which in its general characters is the same as those shown 

 upon cotton, and the treatment appUed to cotton is the 

 only one to be recommended for alfalfa. It has been very 

 destructive in Texas since 1892. 



Anthracnose (Colletotrichum TrifoUi Bain). — Alfalfa 

 anthracnosc was first mentioned in 1905 ^ by Bain and 

 Essary, who stated that it was abundant in Tennessee 

 in 1906 and was one of the chief causes of alfalfa failures in 

 that state. It has also been noted in destructive form in 

 Virginia and New York. It appears as elliptical, sunken 

 spots, 5-6 mm. long, upon the stems. The spots are gray 

 and have dark acervuU scattered over them. Where the 

 disease becomes aggressive, dead or withered stalks or 

 plants are seen scattered over the field. These stalks arise 

 from diseased crowns, which are characterized by blacken- 

 ing of the woody parts, below the point where the diseased 

 stalks are attacked. The only remedy seems to be the use 

 of resistant varieties. 



Ascochytose (Ascochyta Medicaginis Bres.). — This leaf 



» Bain, S. McC, and Essary, S. H., Sci. n. s. 22, 503, October 20, 1905. 



