186 NATURE STUDY AND AGRICULTURE 
SMUT 
a. Head of wheat affected 
with stinking smut. 6. Head 
of oats affected with loose 
smut. 
of the grain-heads or the ears of corn. 
Smut is a fungus growing within the 
body of the stem and leaves, and when 
the kernels form it enters them, fills 
them with its own tissues and soon 
with a mass of minute, black spores. 
When the grain is threshed, some of 
these spores adhere to the kernels and 
are planted with them to infect the 
next crop. 
Rusts cause brownish spots on the 
leaves and stems of grain and many 
other plants, often doing great damage 
tothe crops. The rusty patches on the 
surface are merely the spores, the rest 
of the fungus being within the tissues 
of the host plant. There are many 
species of rust, each having its own fa- 
vorite plants upon which it flourishes. 
Often two different kinds of plants are 
used by a species in different parts of 
its life history. For example, the 
wheat rust may live in the spring upon the barberry, and later 
in the season the spores find their way to the wheat fields. We 
are therefore digging up all our barberry bushes in hopes of 
making it more difficult for the 
rust spores to develop. Grain 
rusts produce two different 
kinds of spores in different parts 
of the season. Those that ap- 
pear just before harvest, called 
black rust, come from the same Corn Smut 
