FLORIDA STATE HORTICULTURAL SOCIETY 
37 
gation and the encouragement of the na¬ 
tural enemies of pests. 
We fertilize the soil to supply it with 
those plant food materials which are 
either lacking or present in a non-avail- 
able condition. We select those sources 
of the food materials and combine them 
in such proportions and apply them in 
such quantities and at such times as we 
believe will give best results. We add 
soil improvers, such as lime and humus, 
to improve chemical, physical and biolo¬ 
gical conditions in the soil. 
We cultivate the soil to add air to them, 
and thus bring about chemical and phy¬ 
sical changes favorable to the growth of 
the tree. We also cultivate to break the 
capillary movement of water to the sur¬ 
face and thus hold the moisture in the 
ground for the use of the tree, especially 
during periods of drought. 
We grow cover crops in the summer 
season to protect the soil from excessive 
heat, to help remove excessive amounts 
of water from the soil and to add humus 
and organic nitrogen to the soil. 
We practice drainage to rid our soils 
of an excess of water which would be in¬ 
jurious to the tree. We practice irriga¬ 
tion to supply water, the lack of which 
not only prevents the trees from main¬ 
taining the proper supply within their 
bodies, but also prevents them from ob¬ 
taining the necessary food materials for 
developmental stages. 
We make use of orchard heaters for 
protection from low temperatures which 
may prove injurious. We prune and re¬ 
move trees when they become so crowd¬ 
ed that they do not receive proper light 
or when the heads become so dense that 
the branches in the interior die from lack 
of light. 
And we prune, spray, fumigate and 
encourage natural enemies of pests in 
order to give our trees proper freedom 
from diseases. 
Of those life functions of the tree that 
were mentioned, namely, respiration, 
transpiration, nutrition, growth, irritation 
and reproduction, we are most interested 
in these functions, growth and reproduc¬ 
tion; because it is these functions that we 
try directly to influence when we employ 
the control methods just reviewed. How¬ 
ever, it should be kept strictly in mind 
that the methods of control influence the 
other functions just as directly. 
In the use of these methods of control, 
the element time enters very largely. The 
citrus tree puts on and matures three 
successive flushes of vegetative growth 
during the year; the first in the spring; 
the second in the summer, and the third 
in the fall. The bloom comes out for 
the most part in the spring. The fruit that 
is set passes through successive stages of 
development until it matures in the fall, 
or winter. At certain seasons the roots 
are spreading in the soil and are increas¬ 
ing in size, and buds of different types are 
being developed. 
The whole aim of the use of the meth¬ 
ods of control is to overcome any adverse 
action of the growth conditions, and thus 
allow the tree to make a steady normal 
growth in all of its parts. In order to 
do this all of the methods must be timely. 
If they are not timely they may not only 
not be effective themselves, but also in¬ 
hibit the good effect of other methods and 
conditions. A good example is that of 
