Bulletin 229, Diseases of Citrus in Florida


 Since the fertility of the average Florida sandy soil is low,
citrus trees, except under the most favorable conditions, will
not long survive neglect in fertilization. From the disease stand-
point, the aim of fertilization is not only to insure the future
health of the tree but at the same time to produce large crops of
sound fruit that will be resistant to diseases.
 Soil Moisture:-Another great drawback to citrus culture on
many soil types in Florida is the tendency for the soil moisture
to fluctuate to either one extreme or the other. A prolonged
dry condition of the soil prevents the trees from making the most
effective use of commercial fertilizers and the heavy rainfall that
occurs at other times results in a heavy leaching of the soluble
fertilizer materials, especially on the lighter sandy soils. Dur-
ing the dry season of the year it is a regular occurrence in many
sections of the state for trees to suffer from lack of moisture at
some time during each year and often the trees may suffer for
months at a time. The frequent, irregular drought periods
in Florida constitute one of the greatest drawbacks to profitable
citrus culture on many soil types.
 On the other hand, groves on many soil types in Florida com-
monly suffer from excessively wet soil conditions from time to
time or may suffer first from the soil becoming too wet and
then from its becoming too dry. Extremes of soil moisture may
cause the trees to become weakened to such an extent that they
are readily attacked by disease, if indeed they have not been
killed outright. The annual loss to the citrus industry in Florida
caused by deficits and excesses of soil moisture is truly appall-
ing when fully realized. Recent studies by Rhoads have shown
that the maintenance of soil moisture conditions favorable for
tree growth in many of the groves established in Florida calls
for as much exercise of thought and attention to keep the trees
in a good state of vigor and crop production, and is often of
as much importance as the control of insect pests and the dis-
eases caused by parasitic organisms.

 IMPORTANCE OF DISEASE CONTROL
 As a rule, very little attention and thought is given, until it
is too late, to the control of either diseases or insects, or to the
prevention of other adverse influences that may have a far-reach-
ing effect on the health and productiveness of a grove. The cone
trol of diseases and insect pests and protection against drought,