556 Report or Horricutturist, Experrmest Station. 
On the foliage the bean rust first forms little brown spots 
nearly circular in outline about as large as pin heads. These 
break out all over the leaf on either surface, and the spores pro- 
duced in them are soon discharged as a rusty brown powder. 
After an indefinite time these spots change in color from brown 
to hlack and produce spores of larger size and different shape and 
texture. It frequently happens that one leaflet is sprinkled with 
the brown spots while its companion on the same leaf stalk is 
covered with black spots or both kind of spots may be found on 
one leaflet. This is not strange since the different colored spots 
represent different stages of the same disease. The dust which 
they discharge is composed of spores which have the same function 
as do the seeds of higher forms of plant life, namely, the propa- 
gation of the species. 3 | 
The fungus grows inside of the leaf for sometime before the 
rust spots break out and the need of treating the disease isnot 
realized till the rust spots appear. It is then impossible to 
destroy the fungus without killing the foliage with it. We are 
not aware that any experiments have been tried for the purpose 
of controlling this disease and therefore no recommendations as 
to treatment of bean rust are made at present. It is not known 
to live over winter in the seed. Probably it winters in the rusted 
leaves as is the case with wheat rust which resembles bean rust ° 
in its botanical characters. 


