160 
FLORIDA STATE HORTICULTURAL SOCIETY 
one of many factors which govern the 
growth and productivity of the citrus tree. 
Most of these factors are not under our 
control, and consequently have never been 
given their just amount of importance in 
our discussions before the Horticultural 
Society. I will discuss these briefly in 
connection with my address this morning, 
so that my thoughts in connection with 
what I have to say may not be misunder¬ 
stood. 
j 
The application of fertilizers, the aera¬ 
tion of the soil (cultivation), the humus 
content of the soil, diseases and insect 
pests, are factors which are all more or 
less under our control. The moisture of 
the soil is only imperfectly under control, 
the temperature is outside of our control, 
and the kind of soil and its chemical com¬ 
position, as well as its physical make-up, 
is entirely outside of our control. 
Moisture is probably the most import¬ 
ant of the factors which enter into the 
making of a grove and the production of 
fruit. An excess of moisture is as injuri¬ 
ous as not enough; yet we cannot stop the 
rains and only in a general way can we 
prevent rapid evaporation, and only in a 
few instances are we able to irrigate suc¬ 
cessfully. In order that our groves may 
utilize to best advantage the fertilizer 
which we apply there must be a sufficient 
amount of moisture in the soil to dissolve 
the plant food; also, to supply the tree 
with the necessary moisture for its make¬ 
up and to replace that lost from the tree 
through transpiration or evaporation. If 
a very hard rain, or a series of hard rains, 
should occur shortly after fertilizer has 
been applied, it is more than probable that 
a large part of the ammonia in the fer¬ 
tilizer would be lost and with this element 
lacking, the grove would harly produce 
the growth that should follow the appli¬ 
cation of fertilizer, if normal moisture 
conditions prevailed. 
Thus we see that insufficient moisture, 
or an excess of moisture, may be largely 
responsible for disappointing results, fol¬ 
lowing the use of fertilizer. 
Temperature is also a very important 
factor in determining for or against the 
production of fruit. The citrus tree needs 
some variations of temperature with the 
different seasons. This is borne out by 
the fact that citrus fruits grown near the 
northern extremity of the citrus belt, 
where there are a greater number of cool 
nights in winter, have a more pronounced 
flavor than other fruits of the same vari¬ 
eties grown farther south and not having 
the same periods of low temperature. Ab¬ 
normal temperature conditions, however, 
disturb the equilibrium of growth and 
fruit production. For instance, periods 
of unusually high temperature in winter 
tend to stimulate growth, and when fol¬ 
lowed by periods of low temperature, es¬ 
pecially if frosts occur and cause either 
partial or total defoliation, succeeding 
growth develops leaves, rather than fruit. 
If, instead of good growing weather, low 
temperatures prevail and result in a late 
spring, and again if low summer and fall 
temperatures occur when warm growing 
weather would be normal, growth and 
production are again impaired; and yet 
the application of fertilizer is in no way 
responsible. 
Diseases and Insect Pests, whether pres- 
