FLORIDA STATE HORTICULTURAL SOCIETY 
117 
thing better is found as a remedy or until 
we know how to prevent the disease. 
However, I should also advise great care 
in its use and the application of relatively 
small quantities. I hope some day we 
may know more about it and how it acts. 
Until we do, we cannot use it most in¬ 
telligently. 
Question: I wish to ask what results 
would be secured by the application of 
sulphate of iron to the leaves of trees 
which show lack of color, or frenching? 
Dr. Wheeler: I think it is impossible 
at this time to predict surely what effect 
spraying with protosulphate of iron 
would have. Pineapples have been 
sprayed with it successfully in an exten¬ 
sive way in the Sandwich Islands on soils 
which contained excessive amounts of 
manganese, and where the plants were not 
able to secure enough iron under the 
usual cultural conditions. Upon spraying 
the leaves, the plants absorbed the iron 
and developed a healthy color and normal 
crops became possible. 
In Porto Rico, Gile found that lime 
caused chlorosis and a bleaching effect on 
pineapples, which was overcome by spray¬ 
ing with protosulphate of iron. This re¬ 
sult indicates that the addition of lime to 
the soil rendered the iron so insoluble 
that the plants were not able to take up 
enough of it. Recent successful experi¬ 
ments have been made in spraying con¬ 
ifers with protosulphate of iron. Re¬ 
peated sprayings with a i% solution 
caused certain kinds of pine trees to de¬ 
velop normally and to develop good color, 
whereas the use of a 2% solution resulted 
in positive injury to the trees. 
It should be determined at the outset 
by a few careful experiments what 
strength may be used on citrus trees with¬ 
out injury. The next problem will then 
be to ascertain whether frenching can be 
overcome to any extent by such spraying. 
Doubtless the results will depend upon 
what causes the frenching; for, according 
to many observations by our best author¬ 
ities, it seems to be caused by several dif¬ 
ferent conditions. It would be of the ut¬ 
most interest and importance to have 
spraying experiments made with proto¬ 
sulphate of iron and possibly with ferric 
chloride wherever frenching has followed 
an application of lime, in order to ascer¬ 
tain if the condition can be corrected. In 
Porto Rico, Gile found that several* suc¬ 
cessive sprayings were necessary in order 
to accomplish the wished-for results with 
pineapples; and obviously the finer the 
spray and the more generally it is distrib¬ 
uted over the leaves, the better the results 
should be. 
I should like to ask if anyone in this 
audience has sprayed with protosulphate 
of iron and, if so, with what result. I 
ask for the reason that about four years 
ago I suggested the idea of spraying with 
it to some of the members of this Society 
who were present at our meeting at Ar¬ 
cadia. I am not aware that any of them 
ever followed up the suggestion. 
In general it has been found that when 
protosulphate of iron is applied to the 
soil, it is not so effective in overcoming 
chlorosis, or frenching, as it is when it is 
sprayed on the leaves, and very large 
quantities may often be necessary to cause 
material benefit if the application is made 
