04 
FLORIDA STATE HORTICULTURAL SOCIETY. 
given to numerous subjects of less im¬ 
portance, or narrower scope. Among 
these may be mentioned the study of the 
effect of food plants, other than citrus, 
on the efficacy of remedial measures; the 
study of the result of removing water 
shoots from citrus trees at advantageous 
times; the collection of data concerning 
the losses from the fly; and data con¬ 
cerning the distribution. The results of 
the investigation thus far indicate that 
conclusive results can be obtained from 
most lines of the experimental work in a 
shorter period of time than is usually re¬ 
quired for insects of a like prominence 
and destructiveness. At the present time, 
from the results we have obtained, we are 
unable to predict the results of the efforts 
to control the White Fly thru its natural 
enemies, but whatever the results obtained 
this line of work should be continued un¬ 
til every practicable effort has been made 
to substitute natural control for the more 
expensive direct means. 
DISCUSSION. 
Mr. Skinner—Do you have different 
size tents, or the same tents? 
Dr. Morrill—Tents for the largest 
trees will do, if necessary, for the 
smaller trees, but if a grower has one 
grove of large seedling trees and an¬ 
other of medium-sized budded trees, 
it would be better for him to have two 
sizes of tents. 
Mr.-Do the tents have to be 
black ? 
Dr. Morrill—That is not necessary. 
Most of our work has been done at 
night and after a little experience this 
is not as objectionable as it would ap¬ 
pear. It is much cooler, and much 
pleasanter. 
Mr.-What effect does the fumi¬ 
gation have on fungi? 
Dr. Morrill—So far as I have ob¬ 
served, no effect whatever. It is gen- 
enerally considered by plant patholo¬ 
gists that hydrocyanic acid gas is not 
fungicidal. I believe Prof. Rolfs will 
agree with this. 
Prof. Rolfs—It has no effect on 
fungi. 
Mr.-At what stage is it best to 
fumigate ? 
Dr. Morrill—It is best to fumigate 
in the winter time, because at that 
time there are practically none of the 
flies on the wing. As Dr. Berger has 
said, there is no time when you can¬ 
not find a few adults, but there are 
comparatively few in the middle of the 
winter; too few to be taken into con¬ 
sideration. Occasionally, there is more 
or less shedding of leaves following 
fumigation, but of the four thousand or 
more trees fumigated under our super¬ 
vision during the past winter, in no 
case was the tree injured more than 
was offset by the benefits of destroy¬ 
ing the insects. In one case in Man¬ 
atee county we fumigated a tree that 
was shedding its leaves from some un¬ 
known cause, and I believe only five 
per cent, of the leaves were left on 
the tree, but there were trees near by 
which were not fumigated which shed 
their leaves to nearly the same extent. 
Mr.-How long does it take to 
fumigate a tree? 
Dr. Morrill—The tents are left on 
about forty minutes. 
I would like to say, in connection 
with the injury from fumigation, that 
there is some misunderstanding with 
regard to this, owing to injury some¬ 
times caused by emptying the contents 
