66 BULLETIN 981, U. S. DEPARTMENT OF AGRICULTURE. 



Seed production at present is very often unprofitable on account of 

 low yields and uncertainty as to price. Seed yields are highest in 

 western Texas and the irrigated regions of New Mexico, Arizona, 

 and California. 



The greatest difficulty attending the production of Sudan grass 

 seed is the danger of the admixture of Johnson grass seed. Ex- 

 treme care is required to prevent such mixtures, because it is practi- 

 cally impossible to separate the seed of the two grasses by mechani- 

 cal means. 



A method of identifying the seed of Johnson grass when mixed 

 with Sudan grass has been developed and described by F. H. Hill- 

 man (11), of the United States Department of Agriculture. 



Great care is necessary in growing Sudan grass for seed to prevent 

 its hybridization with the sorghums. Sudan grass intended for seed 

 production should never be sown on a field which has produced 

 sorghum the previous year, and the field ought to be situated at 

 least 80 rods from any field of sorghum. 



The same diseases and insects that attack sorghums also injure 

 Sudan grass. The most important diseases are red-spot and kernel 

 smut; the most destructive insects are grasshoppers, chinch bugs, 

 and the sorghum midge. 



