64 BULLETIN 981, U. S. DEPARTMENT OE AGRICULTURE. 



(Contrarinia (Diplosis) sorghicola Coq.) usually prevents the profitable 

 production of Sudan grass seed in the Southern States east of central 

 Texas. 



The diseases and insect enemies of Sudan grass and methods for 

 their control are discussed in Farmers' Bulletin 1126, entitled "Sudan 

 Grass." A full account of the insects which attack Sudan grass is 

 given in Circular No. 7 (new series) of the Texas Agricultural Experi- 

 ment Station (17). 



WEEDS. 



There are but few weeds which cause any considerable trouble in 

 Sudan grass fields. The preparation of the seed bed usually destroys 

 the spring crop of weeds, and if the soil is warm the grass starts off 

 quickly and grows so rapidly that as a rule weeds are not able to com- 

 pete with it. Sudan grass probably ranks next to millet in its ability 

 to overcome weeds. 



The common weeds, such as the pigweeds, Russian thistle, foxtail, 

 and the sand burs, are sometimes found in fields of Sudan grass. 

 They rarely occur in sufficient numbers, however, to affect the yield 

 of hay. The worst weed pest is undoubtedly Johnson grass, which 

 behaves as a perennial south of the thirty-eighth parallel of north 

 latitude and is widely distributed on the better soils of that region. 

 Its relation to the seed production of Sudan grass has been discussed 

 under that topic. 



The presence of Johnson grass in a field of Sudan grass being cut 

 for hay is of little consequence except for the very slight reduction 

 in yield that it entails. The quality of the hay when Sudan grass is 

 mixed with Johnson grass is fully as good as that of Sudan grass alone. 

 The immediate effect, therefore, of Johnson grass in Sudan grass fields 

 is not especially objectionable, but the aggressive rootstocks of 

 Johnson grass make it difficult to eradicate and cause it to persist 

 and interfere with the following crop. The succeeding crop, espe- 

 cially if it is corn or cotton, will be injured appreciably by the Johnson 

 grass, and this fact causes farmers to resist its incursion into any of 

 their cultivated fields. Because of its tendency to persist on the land 

 after another crop has replaced the Sudan grass, extreme care should 

 be exercised by the farmer to avoid introducing Johnson grass in the 

 Sudan grass seed with which he plants his fields. 



SUMMARY. 



The value of the 1918 crop of Sudan grass in the United States was 

 estimated at $10,500,000. Practically all this crop was derived from 

 the 8 ounces of seed obtained in 1909 by the United States Depart- 

 ment of Agriculture from R. Hewison, Director of Agriculture and 

 Lands, Sudan, Africa. 



