Bl ac k or s tem r u s t Cau sa l O rg a ni s m : P u ccinia g ra m inis t r i tici S y m p t o m s S y mp t o m s a r e p r o du c e d o n a l m o st a ll ae r i a l pa rts o f t h e w hea t p l a n t b u t a r e mo st c om mo n o n st e m , le a f s h ea t h e s a n d up p e r an d lo w e r le a f s u rfac e s. U r ed i a l pu st u l e s a re o v a l to s p in d le s h a p e d an d d a rk o ra n g e - red ( r u st) in c o lor. T h e y e ru p t t h ro u g h t h e ep i d e r m is o f t h e h o st a n d a re s u r r oun d e d b y t a t te r e d ho st tiss u e . The pu st u l e s a re du sty in app e a ra n ce d u e t o t h e v a st numbe r o f s p o res p ro du c e . S po r e s a re r e a d i l y rel ea s e d w he n t ou c he d . T e l i o s po res a re p r o d u c e d in t h e s a m e pu s t u le. T h e c o lor o f t h e pu st u l e c h an ge d f r o m rust c o l o r ...
