Forage Crops 



335 



its derivatives, the resistance of which was noted by WilHams 

 of South CaroUna in 1900. 



Root-knot (nematodes) is especially destructive on cow- 

 peas. The Iron or Brabham varieties are resistant. 



Fig. 177. — Roots of the Iron cowpea free from nema- 

 tode galls. After Lewis. 



Minor diseases 



Leaf-spot {Amerosporium oeconomicum E. & T.). — This 

 disease is readily distinguished from the angular leaf-spot in 

 that the spots are circular, are of shiny whiteness, and are 

 studded all over with black pycnidia, smaller than a pinhole 

 (Fig. 178). The disease is often abundant, but is usually not 

 so serious as the angular leaf-spot. 



