118 
FLORIDA STATE HORTICULTURAL SOCIETY 
casionally, the seeds are found floating- 
in this gum. 
“Ammoniated” fruit may or may not 
be characterized by the development of a 
thick rind and abundant rag. The flavor 
of such fruits is often insipid. 
CHARACTER OF DISEASE 
It must be kept strictly in mind that 
“ammoniated” fruit is not a disease in 
itself, but is one of the symptoms of the 
disease known as dieback. The other 
characteristic symptoms of this disease 
are (i) pockets of gum between the wood 
and bark in the young terminal stems; (2) 
double-convex to more or less rounded ex¬ 
crescences of gummous tissue on the bark 
of the older stems or twigs; (3) a stain¬ 
ing of the bark of terminal stems in spots 
and irregular areas similar to that on the 
fruit; and (4) the presence of multiple 
buds. 
In severe or chronic cases, all of these 
symptoms may be present on the tree and 
plentiful. In less severe cases some one 
or more of the symptoms may predomin¬ 
ate, with others scarce or even entirely 
absent. It frequently occurs that the only 
symptom, or the predominant symptom, is 
the ammoniated fruit. 
It is thus seen that dieback is a disease 
that is characterized primarily by the pro¬ 
duction of gum in different tissues of the 
tree and at various stages of growth. 
♦ 
« 
CAUSE OF DISEASE 
The cause of dieback is thought to be 
in the soil, and there are numerous con¬ 
ditions that are known to be favorable to 
its development. Of these the ones that 
are probably responsible for the most of 
the “ammoniated” fruits that are brought 
into the packing house are: (1) feeding 
the trees with excessive quantities of or¬ 
ganic sources of ammonia; (2) excessive 
or improper cultivation; and (3) irregu¬ 
lar moisture conditions in the soil. 
PREVENTION OF DISEASE 
As is the case in a number of other dis¬ 
eases, once the marks have been developed 
on the fruit, they cannot be cured. There¬ 
fore, the methods of control must be those 
of prevention. The “ammoniated” fruit 
can be prevented by determining and pre¬ 
venting those conditions favorable to the 
dieback. In some cases where the trees 
are left alone and nothing is done to them, 
they grow out of the disease. It is only 
in chronic cases that the disease persists 
year after year. 
In the feeding of citrus trees with or¬ 
ganic sources of ammonia, it is difficult, 
to foretell the exact conditions under 
which they may be used with safety, and 
the quantities that can be used without 
doing harm. Generally speaking, they 
should be used with great care on low, 
damp or heavy soils and for bearing trees. 
Many of the complete fertilizers offered 
on the market contain organic sources. 
When these are used in moderate amounts 
and in locations and under'conditions not 
favorable to the disease, they are not suffi¬ 
cient in themselves to induce the disease. 
But when they are used either in excess¬ 
ive quantities, or on trees that are inclined 
to dieback, marking of the fruit is pretty 
sure to result. 
The same applies to the growth of leg- 
