Dieback, Ammoniation, and Frenching 
R. E. Lenfest, Winter Park 
It is not the purpose of this paper to 
give any technical discussion of the above 
tree conditions but to give some observa¬ 
tions concerning these conditions and 
some of the factors influencing them. The 
first of the subjects really covers those 
following, but each will be taken up sep¬ 
arately with reference to its relationship 
to the others. 
Described in every-day terms, dieback 
is a sort of malnutrition or indigestion of 
the tree. It is a name applied to a condi¬ 
tion of the tree and is not a very accurate 
name. It should not be confused with the 
effect and appearance of withertip. Die¬ 
back may be divided into two types, acute 
and chronic. Ammoniation is the effect 
of the disease as shown by the fruit. 
Frenching is one serious phase of the dis¬ 
ease and when this stage is reached it may 
be said that the trouble has become 
chronic. 
Dieback seems to be brought on by a 
number of conditions or combination of 
conditions. Giving the trees an unbal¬ 
anced feed does its share in causing the 
trouble. This may be done in several dif¬ 
ferent ways. Overfeeding trees will give 
an unbalanced ration and may be done by 
using too large amounts of fertilizer or 
too high an analysis of ammonia or both. 
This is very apt to bring on dieback con¬ 
dition, especially if most or all the ammo¬ 
nia is derived from inorganic sources. 
Some organic sources of ammonia if used 
in excess will probably produce dieback 
and ammoniation but generally in a lesser 
degree and taking longer to do the harm. 
This is not meant to condemn the use of 
inorganic sources of ammonia a*s they are 
very important in the satisfactory grow¬ 
ing of citrus trees and fruit, but to call 
attention to the fact they should be used 
carefully and understanding^, and when 
thus used the results are quite sure to be 
good. Another way in which overfeed¬ 
ing may be done is putting fertilizer too 
close to the trees and in too narrow a band 
—fertilizer should be spread each time 
just a little farther than the roots extend 
until the roots and fertilized areas meet. 
It should then be scattered broadcast and 
evenly. A great many growers do not 
realize how far out the roots extend. The 
only safe way to make sure of this is to 
dig near a number of average sized trees 
and find the average distance to which the 
roots extend and whether or not they 
meet in the middles. 
One reason why many growers over¬ 
feed orange trees is because they have 
orange, grapefruit and tangerine trees of 
the same age and have overlooked the fact 
that orange trees cannot handle as much 
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