COWPEAS 511 



Stubble and first 6 in. of roots 912 Ib. an acre 



Second 6 in. of roots ( 6-12 in.) 45 Ib. an acre 



Third 6 in. of roots (12-18 in.) 54 Ib. an acre 



Fourth 6 in. of roots (18-24 in.) 34 Ib. an acre 



Fifth 6 in. of roots (24-30 in.) 63 Ib. an acre 



Sixth 6 in. of roots (30-36 in.) 59 Ib. an acre 



Seventh 6 in. of roots (36-42 in.) 40 Ib. an acre 



At the Delaware Experiment Station, it was found that 

 the cowpea did not have more than 10 per cent of the total 

 weight in the roots. 



624. Disease resistance. In the United States, only 

 two diseases of the cowpea can be considered serious ; 

 namely, rootknot, caused by the nematode (Heterodera 

 radidcola) ; and wilt, caused by a Fusarium on the roots. 

 The Iron variety first found in Barn well County, South 

 Carolina, a region infested by these diseases is almost 

 perfectly immune to both. Orton has found that the 

 immunizing character is transmitted to crosses. One 

 such cross, the Brabham, whose parents are Iron and 

 Whippoorwill, has become very popular in the Atlantic 

 coastal region of the Southern States. 



Several other diseases attack the cowpea, among 

 them rust ( Uromyces phaseoli), white leaf -spot (Amero- 

 sporium economicum) , red leaf-spot (Cercospora cruenta) 

 and mildew (Sphaerotheca sp.). Most standard varieties 

 of cowpeas are immune to rust, and the other diseases are 

 rarely serious on the best varieties. 



625. Insect enemies. The leaves of cowpeas are more 

 or less subject to attack by various insects, but this damage 

 is seldom serious. 



The seeds, however, are much subject to injury by two 

 species of weevil (Pachymerus chinensis and P. quadri- 

 maculatus) whose habits are practically identical. The 

 weevil lays its eggs on the pods of the cowpea in the field 



