PLANT DISEASES 183 
into all parts of the infested plant. Instead of seeds, fungi 
produce immense numbers of spores which serve the same 
purpose and are as tiny as grains of dust. These spores 
may be carried long distances by the wind, and if some of 
a, PUFFBALLS; 6, ComMMoN MusHRoomMs; c, SHELF OR BRACKET MUSHROOMS 
them happen to lodge upon a tender part of the plant that 
is their favorite victim, they sprout and soon send their 
thread-like fibers into its tissues. 
Some familiar plant diseases caused by parasitic fungi 
are rust, smut, flax wilt, mildews, potato scab, late potato 
blight, and bean-pod 
spot. 
Parts Attacked. — Al- 
though a certain part 
of the plant may be the 
chief point where the 
disease shows itself, as, 
for example, the head 
in case of grain smut, Biue Mop 
yet the effect is gen- 5, Spores. 
eral. All these diseases reduce the vitality of the whole plant. 
Remedies. — Many of the most destructive plant diseases 
that afflict our crops, such as grain smut and potato blight, 
