Picture Sheet No. 23 
STEM RUST 
(See other side for 
life history and control) 
HARVARD 
UNIVERSITY 
a. Germination of overwintered 
black teliospores; b, sporidia or 
secondary spores (arrows) that in- 
fect susceptible barberry bushes; 
c y pycniospore or sexual stage on 
upper surface of barberry leaf; dy 
aeciospore or cluster-cup stage on 
lower surface of barberry leaf; e y 
urediospore or red stage on grain 
stem; /, teliospore or black stage on 
grain straw. (All greatly enlarged.) 
Wheat From Rust-Free Plants 
Wheat From Rust- Infected Plants 
Bureau of Entomology and Plant Quarantine, Agricultural Research Administration, U. S. Department of Agriculture 
