284 FORAGE PLANTS AND THEIR CULTURE 



only in cultivated rows, taking great care to hoe out any 

 Johnson-grass that may appear in the field. 



Sudan-grass crosses very readily with all of the culti- 

 vated varieties of sorghum, so that when it is grown near 

 any such variety, more or less numerous hybrid plants will 

 appear in the progeny. These hybrids do no harm in the 

 fields intended for hay, but where a crop is to be harvested 

 for seed the hybrid plants should be rogued out. This 

 should be done preferably as soon as the hybrids appear 

 in bloom, so as to prevent further crossing in the field, but 

 in any event it should be done before the Sudan-grass seed 

 is harvested. 



