170 
COTTON 
after cowpeas were cultivated on the land. In 
other words the peas introduced the nematode 
worm, and this in turn caused the cotton plant 
to be readily attacked by the wilt fungus. And 
more than this, the most serious attacks of the wilt 
are found on soils known to be infected with the 
nematode worms. 
Root Rot:— Root rot is a fungus which attacks 
other plants as well as cotton— alfalfa, also apples 
peaches, and other trees. The disease spreads in 
all directions through the soil. The fungus de- 
rives its nourishment from the living substance of 
the root, and this naturally uses up the material in 
the tissues, and they shrink and decay. The life 
processes in the roots are also checked, and con- 
sequently they are unable to supply the plant with 
necessary food and water. As a result the whole 
plant shrinks, withers and dies. 
Some one has suggested the application of salt or 
kerosene to the soil as a means of checking the 
development of this disease, but as yet the efficacy 
of this treatment has not been proved, and there is 
likely little or no value in it. Crop rotation seems 
to be the only method that will serve in keeping the 
fungus in check. Specific applications are natural- 
ly difficult to apply, even if effective. General 
methods that involve better management and 
provide a comfortable home for the plant, seem to 
be the way in which effective treatment or pre- 
vention must be directed. Crops like corn, millet, 
wheat, and oats seem not to be affected by this dis- 
ease, and consequently they can readily be used in 
a system of rotation that will bring cotton on the 
same field only once every three or four years. In 
this way cotton will show the advantage not only 
of crop rotation, but will improve by reason 
