Florida Agricultural Experiment Station


 The control of cotton diseases is a matter of preventing infec-
tion rather than of fighting it after it has appeared, since one of
the-most effective means of combatting plant diseases, spraying
or dusting, has not proved feasible on cotton. To devise satisfac-
tory means of controlling a disease of cotton it is necessary to
understand the disease and the conditions favorable to it. The
chief means used in controlling cotton diseases really pertain
to good culture and are relatively easy to carry out. They are
the use of good, disease-free or resistant seed, proper fertilization
and cultivation and suitable rotations. The application of these
methods to particular diseases will be taken up under the discus-
sion of the diseases, but it is well to explain them in a general
way at this point.
 Good seed denotes viable seed of a productive variety that is
well adapted to the area in which it is to be grown. In addition
to these characters, the seed should be as free as possible of seed-
borne diseases, or if they are to be used on wilt infested soil they
should be resistant to wilt. Reliable seed dealers have selected
seed only from uniform, vigorous, productive, and disease-free
plants. Resistant seed have been saved from plants of the fore-
going type grown on soil heavily infested with the wilt organ-
ism, in order that plants showing the slightest susceptibility can
be eliminated. By doing this year after year some extremely re-
sistant varieties have been developed. A fact that should be men-
tioned here is that wilt is the only disease for which resistant
varieties have been developed; therefore, claims of resistance
to other diseases should be regarded with suspicion. On the
other hand, gin-run seed, the type generally used by Florida cot-
ton growers, offer none of these advantages. They are from
plants of varying uniformity, vigor, and productiveness, and
they have not been especially selected for resistance to the wilt
disease, nor for freedom from seed-borne diseases. Even if the
farmer has taken special precautions in saving his seed, his seed
will usually be mixed with poor seed at the gin, or contaminated
with diseases. It is, therefore, evident that seed should be pur-
chased at frequent intervals from seed companies of established
reputations, and seed saved should be ginned separately in order
to avoid admixture with undesirable seed.
 Cotton that is in a vigorous, healthy condition is less liable
 to attack by fungi than cotton that is weakened by poor cultural
 methods and insufficient fertilization. Consequently, proper