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FLORIDA STATE HORTICULTURAL SOCIETY 
to the soil. This is probably for the rea¬ 
son that lime and other basic compounds 
in the soil may make the iron insoluble 
as soon as the two compounds are 
brought into contact with each other. 
Answer from the Audience: I have 
made experiments in spraying with proto¬ 
sulphate of iron, where the trees were 
very much frenched and bore small fruit, 
and the result from one to three sprayings 
was excellent. In other cases it apparent¬ 
ly did little or no good, but I presume the 
conditions giving rise to the frenching 
were different in the two cases. 
Another answer: About four years 
ago, one or two acquaintances of mine 
had groves which showed frenching, and 
they suspected that this was due to a lack 
of iron; and after spraying them with 
protosulphate of iron from three to six 
times at rather frequent intervals, a 
marked improvement in the trees re¬ 
sulted. 
Another answer: I have noticed cases 
of frenching in the Indian River region 
where it seemed probable that too much 
fertilizer had been used, and I am satis¬ 
fied that you must have a satisfactory 
amount of humus in the soil in order to 
get the best results from fertilizer. 
Dr. Wheeler: I have had my attention 
called to cases of frenching which may 
have been caused by too much water and 
also by to deep cultivation and injury to 
the feeding roots. This injury to the 
roots results especially in cases where a 
deep cutting disc or cutaway harrow is 
used instead of the acme harrow which 
works the soil only to a slight depth. 
What has been said about the impor¬ 
tance of humus in the soil is deserving of 
special attention, since it is fundamental 
to the best results in growing practically 
all kinds of crops, including citrus trees. 
The humus may also play an important 
part in connection with the assimilation 
of iron. It is well known that where 
great accumulations of vegetable matter 
come in contact with sands containing 
iron, the iron is often so largely dissolved 
out that the sands become greatly 
bleached. This shows that the humus has 
a solvent action on the iron. It is much 
better to maintain conditions in the soil, 
if possible, which will prevent frenching 
than to take the chance of curing it after 
it appears. 
Another point concerning which I 
would utter a caution is in regard to mak¬ 
ing spraying experiments with protosul- 
phate of iron on a large scale at the out¬ 
set. My advice would be to determine in 
a small way on a few branches, or at least 
on a few trees, what strength of proto- 
sulphate of iron will be tolerated without 
injury to the foliage or trees. By pro¬ 
ceeding cautiously in this way, no great 
damage can be done; and after this point 
is determined, you can then spray exten¬ 
sively with reasonable safety, provided 
you find it helpful. 
