PLATE 39 

 Potato stems showing seed-piece rot : 



A. — Stem split to show rotting due to organism entering through seed piece from 

 soil. Note decay of roots from point of attachment outward. 



B. — Stem split to show slight discoloration at base where infection from soil-infected 

 seed piece occurred. 



C. — Seed piece of potato plant shown in Plate 40, B. The center top leads to the 

 center of decay. 



D. — Seed-piece rot in field. The seed piece is well decayed, but plant is unaffected 

 and the roots are healthy. 



