in which they injure other
crops.

The "cotton stainers," various species of _Dysdercus_, are widely
distributed, occurring for example in America, the West Indies, Africa,
India, &c. The larvae suck the sap from the young bolls and seeds,
causing shrivelling and reduction in quantity of fibre. They are called
"stainers" because their excrement is yellow and stains the fibre; also
if crushed during the process of ginning they give the cotton a reddish
coloration. The Egyptian cotton seed bug or cotton stainer belongs to
another genus, being _Oxycarenus hyalinipennis_. Other species of this
genus occur on the west coast of Africa. They do considerable damage to
cotton seed.

_Fungoid Diseases._--"Wilt disease," or "frenching," perhaps the most
important of the fungoid disease of cotton in the United States, is due
to _Neocosmospora vasinfecta_. Young plants a few inches high are
usually attacked; the leaves, beginning with the lower ones, turn
yellow, and afterwards become brown and drop. The plants remain very
dwarf and generally unhealthy, or die. The roots also are affected, and
instead of growing considerably in length, branch repeatedly and give
rise to little tufts of rootlets. There is no method known of curing
this disease, and all that can be done is to take every precaution to
eradicate it, by pulling up and burning diseased plants, isolating the
infected area by means of trenches, and avoiding growing cotton, or an
allied plant such as the ochro (_Hibiscus esculentus_), in the field.
Fortunately the careful work of the U.S. Department of Agriculture and
of planters such as Mr E. L. Rivers of James Island, South Carolina, has
resulted in the production of disease-resistant races. In one instance
Mr Rivers found one healthy plant in a badly affected field. The seed
was saved and gave rise to a row of plants all of which grew healthily
in an infected field, whereas 95% of ordinary Sea Island cotton plants
from seed from a non-infected field planted alongside as a control were
killed. The resistance was well maintained in succeeding generations,
and races so raised form a practical means of combating this serious
disease.

In "Root rot," as the name implies, the roots are attacked, the fungus
being a species of _Ozonium_, which envelops the roots in a white
covering of mould or mycelium. The roots are prevented from fulfilling
their function of taking up water and salts from the soil; the leaves
accordingly d