• TABLE OF CONTENTS
HIDE
 Front Cover
 Credits
 Table of Contents
 Important facts
 Introduction
 The fungi
 Conditions favorable for the...
 The red aschersonia
 Introducing this fungus
 Summary for the red aschersoni...
 By spraying on spores of the...
 By pinning on leaves
 The yellow ashersonia
 The brown fungus
 Scale and whitefly
 Trimming trees
 Spraying and fumigation
 Copperas
 Sooty mold
 The snail
 Life history of the whitefly
 Food plants
 Quarantine
 Nursery stock
 Vehicles and private roads
 Picking implements
 Plants to be condemned
 Plates
 Appendix














Group Title: Bulletin - University of Florida Agricultural Experiment Station ; 88
Title: Whitefly conditions in 1906
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Permanent Link: http://ufdc.ufl.edu/UF00027697/00001
 Material Information
Title: Whitefly conditions in 1906
Series Title: Bulletin - University of Florida Agricultural Experiment Station ; 88
Physical Description: Book
Language: English
Creator: Berger, E. W.
Publisher: University of Florida Agricultural Experiment Station
Publication Date: 1906
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Bibliographic ID: UF00027697
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Rights Management: All rights reserved by the source institution and holding location.

Table of Contents
    Front Cover
        Page 47
        Page 48
    Credits
        Page 49
    Table of Contents
        Page 50
    Important facts
        Page 51
        Page 52
    Introduction
        Page 53
    The fungi
        Page 54
    Conditions favorable for the fungi
        Page 55
    The red aschersonia
        Page 56
    Introducing this fungus
        Page 57
        Page 58
    Summary for the red aschersonia
        Page 59
    By spraying on spores of the fungus
        Page 60
        Page 61
        Page 62
    By pinning on leaves
        Page 63
    The yellow ashersonia
        Page 64
    The brown fungus
        Page 64
    Scale and whitefly
        Page 65
    Trimming trees
        Page 66
    Spraying and fumigation
        Page 66
        Page 67
    Copperas
        Page 68
    Sooty mold
        Page 69
    The snail
        Page 69
    Life history of the whitefly
        Page 70
    Food plants
        Page 71
        Page 72
    Quarantine
        Page 73
    Nursery stock
        Page 73
    Vehicles and private roads
        Page 74
    Picking implements
        Page 74
    Plants to be condemned
        Page 75
    Plates
        Page 76
        Page 77
        Page 78
        Page 79
        Page 80
        Page 81
    Appendix
        Page 82
        Page 83
        Page 84
        Page 85
Full Text


BULLETIN NO. 88


Florida
Agricultural Experiment Station


Whitefly Conditions


in 1906


The Use of the Fungi


(\le-vro les C'itri.

By E W. BERGER, Ph.D.
The Bullelins o, this Slation will be sent Iree to any address in Floraa upon Iap))pb IbIlin, i Ib i e-Wlor
ol the Experiment Station. Gainesville. Fla.


E. (. Printer Printing Co., DeLand, Fla.


JANUTAR Y 906




















BOARD OF CONTROL.


N. P. BRYAN, Chairman ............... .. Jacksonville, Fla.
P. K. YONGE............ .............. Pensacola, Fla.
A. L. BROWN ........ .. .. ........ ....... Eustis, Fla.
T. B. KING .... .................. .... Arcadia, Fla.
J. C. BAISDEN ................. ...... Live Oak, Fla.



STATION STAFF.

P. H ROLFS, M .S................ .......... D director.
A. \V. BLAIR, A.M .. ....................... Chemist.
JOHN M. SCOTT, B.S ................ Animal Industry.
E. H SELLARDS, M.A., Ph.D.................. Geologist
CHARLES F. DAWSON, M.D., D.V.S.,
Jacksonville, Consulting Veterinarian.
E. \. BERGER, Ph.D............. Assistant Entomologist.
H. S. FAWCETT, B.S .......... Assistant Plant Pathologist.
R. Y. WINTERS, B.S ................ Assistant in Botany.
K. H. GRAHAM ... .... .... .Auditor and Bookkeeper.
R. D. ALGEE ............................ Stenographer.
M. CREWS........................ .Farm Foreman.
F. M. STEARNS. ............. ................. Gardener.












CONTENTS.
Page.
Im portant Facts ......... ...................... .. .... 51
Introductory .................. ................... ............ 53
The Fungi ....................................... ....... .. 54
Conditions favorable for the Fungi ............................. 55
T he Red A schersonia ........................................ 56
Introducing this Fungus ......................... .. ......... 57
Summary for the Red Aschersonia .............................. 59
By Spraying on Spores of the Fungus .......................... 60
By Pinning on Leaves ......................................... 63
The Yellow Aschersonia .................................... 64
The Brown Fungus ......... ....... ............................ 64
Scale and W hitefly ............................................. 65
T rim m ing T rees ..................................... .......... 66
Spraying and Fum igation ....................................... 66
Copperas ........................................ .......... 68
Sooty Mold .................. ................................ 69
T he Snail .................................................... 69
Life History of the Whitefly ................... ........... .... 70
Food Plants ........... .................. ..... ......... 71
Q u a ran tin e .......................................... .... .. 73
Nursery Stock ................... ............................. 73
Vehicles and Private Roads ..................................... 74
Picking Implements ..................................... ..... 74
Plants to be Condem ned ............ .... ................... 75
P lates .............................................. ....... 76
Appendixes i. Where to Obtain Fungus ........... ................ 82
2. The Fungi in Florida ............................. 82
3. Spraying Apparatus ............................ 82
4. The Weather at Leesburg ........................ 83
5. After Freeze Suggestions ......................... 84
Acknowledgments .............................................. 86

PLATES.

Plate I. Whitefly egg and Adult .............................. 77
Plate II. Larvae and Pupa ............................. ...... 79
Plate III. Fungi and W hitefly on leaf .......................... 81








Whitefly Conditions in 19o6.


IMPORTANT FACTS.

I. The fungi parasitic on the whitefly larvae and pupae can be
started in whitefly-infested trees by spraying the spores suspended in
water, by pinning on leaves having pustules of the fungi upon them,
or by planting infested trees. The writer's success by the first two
methods during the past summer was 98 per cent.
2. There are three of these fungi-the Red Aschersonia, the
Yellow Aschersonia and the Brown Fungus. The spores of the latter
have not been discovered, hence this fungus can probably not be
successfully introduced by spraying. Dried fungus pustules have been
kept for a month and found efficient for starting the fungi. They
probably will retain their vitality much longer.
3. All these fungi will apparently thrive in any part of Florida.
The Red Aschersonia was observed to thrive well as far north as
Lake City during the past summer, while the Brown Fungus was also
successfully introduced.
4. A humid atmosphere in a grove is important for the thriving of
the fungi. Suggestions for aids in accomplishing this are given in the
test. Considerable warmth also appears to be necessary.
5. It appears from our present state of information that the best
time for starting the fungi in whitefly-infested trees will be the months
of May, June, July and August. March and April may also be good
months. In general, periods of rain and summer temperature are
considered favorable.
6. To insure the efficiency of the fungi, repeated "plantings"
should be made to get a good start. Keep the fungi abreast of the
whitefly, instead of tandem, or at its heels, which is the general
situation 'at present.
7. Trees of all kinds along roadways should be trimmed high to
avoid the distribution of the whitefly by carriages brushing against
the branches.
8. Not every tree, bush or weed in the hammock is a food plant
of the whitefly. The number of authentic food plants can probably
be counted on the fingers of two hands.
g. The Cape Jessamine, Chinaberry, Umbrella Tree, Prickly Ash,








Bulletin No. 88.


Privet, Trifoliate Orange, Mock Orange (Cherry Laurel), and all
useless and neglected citrus stock should be condemned and destroyed.
These should be cut down and BURNED AT ONCE.
io. The greatest injury done by the whitefly is during its several
larval and pupal stages while it lives in a wingless state attached to
the under surface of the leaves.
ii. Where it is desired to spray or fumigate for the whitefly, the
best time for doing this is during the months of December, January
and February; or better, after the fruit is picked and the danger from
frost is past. All of the eggs are probably hatched by December.
The eggs are not easily killed either by spraying or fumigating.
12. There appears to be no good evidence to show that copperas
is of any value for reducing the whitefly, to say nothing of exter-
mination.
13. Snails in groves should be encouraged by providing mulch
(coarse and fine mixed) under the trees, and burlaps in several of the
narrower crotches.
14. Snails do not destroy whitefly, except incidentally some eggs
and a few larvae, but feed upon the sooty mold, other fungi and
lichens. They keep the tree clean when in sufficient numbers. They
appear to avoid the fungi parasitic upon citrus tree insects.
15. The picking implements and the clothing of pickers should
be disinfected by one of the several methods described in the text,
before being transferred to a noninfested grove.
16. See the Summary for the Red Aschersonia, which probably
holds good for all the fungi.












Whitefly Conditions in 1906-The

Use of the Fungi.



INTRODUCTORY.
The whitetly is on the increase and spreading to citrus
growing sections of the State hitherto not infested. No doubt
the mild winter of 1905 to 1906 favored its spread and increase
in the more northerly sections of the State. Citrus trees that
were generally quite defoliated during more severe winters re-
tained some of their leaves and of course the whitefly larvae
with them. This gave it an uncommonly good start last
Spring. Railroad trains, carriages and other less understood
means of dissemination are spreading it to all parts of the
State.
The situation is urgent. and some excitement prevails in
orange growing sections that have recently become infested.
Some have "Hit the line hard" when thev found the fly pres-
ent last fall and winter, with very gratifying results, going
even to the extent of cutting down infested trees, such as um-
brella, Chinaberry, and others. Such means are rather drastic
but are a certain remedy where the situation justifies it. Oth-
ers have made strenuous efforts, doing everything in their
power to keep the pest down. but found their efforts mainly in-
effective because of the indifference of their neighbors. There
appears to be the expectation on the part of some that a pan-
acea will be discovered, which will do away with the whitefly
on short notice. This is something to be hoped for, and possi-
ble, but not very probable. It is of no use to wait: fighting in-
sects is much like fighting wceeds in a garden, one must be ready
to cut them down with the means at hand whenever they raise
their heads.
The main purpose of this bulletin is to urge growers to
do something and not to wait, and especially to urge the intro-
duction of the fungi. While many new facts and demonstra-
tions are introduced, much of necessity follows in the nature








Bulletin No. 88.


of suggestions which only future experience can prove neces-
sary or erroneous. It would be well if growers generally fol-
lowed out some of the suggestions made by the Station, if
only on a small scale, for by so doing they will be of great aid
to the Station Staff.. The writer believes that future work
upon the whitefly will consist, not so much in the discovery of
new remedies and enemies, ,though this is desirable, but in a
better understanding of how to use the remedies at hand.

THE FUNGI.

Plate III, Figs. 2 and 3.

Broadly speaking, the fungi belong to the lowest order of
plants known, and are devoid of the green coloring matter
(chlorophyll) so characteristic of the higher plants. Mush-
rooms, toadstools, mildews and the several molds are familiar
examples of fungi. The majority of fungi generally propagate
themselves by minute microscopic bodies called spores. These
are produced in countless millions and chiefly relied upon when
we desire to propagate, or start, fungi. These spores take the
place of seeds produced by the higher plants, but structurally
they are not seeds.
There are three fungi at present known to be parasitic upon
the whitefly larvae and pupae. These are the Red Ascher-
sonia (Aschersonia aleyrodes), the Yellow Aschersonia (As-
chersonia flavo-citrina) and the Brown Fungus. Each oc-
curs on the under surface of citrus leaves and transforms
(kills) the larvae and pupae of the whitefly living there into
pustules having the color characteristic of each fungus named,
except that the young pustules of the Red Aschersonia are pink
and only develop the scarlet red fruit bodies as they become
mature. There is another fungus that occasionally destroys a
few whitefly larvae, namely the Red Scale Fungus (Sphaero-
stible coccophila), but this occurs only rarely upon the whitefly
and will not be further discussed in this paper. None of these
are known to attack either the eggs or the adult whitefly.
It appears to be the observation of some that the Brown
Fungus works more rapidly than the Red Aschersonia. On
the other hand, the observation of others is quite the reverse,
that the Red Aschersonia spreads more rapidly and is more
efficient. This last is also the writer's personal observation to







Whitefly Conditions in 1906.


date. The Yellow Aschersonia appears to be quite the equiva-
lent of the Red so far as present observations indicate.

CONDITIONS FAVORABLE FOR THE FUNGI.

All fungi thrive best in the presence of an abundance of
moisture, and observations show that the Red and Yellow As-
chersonias and the Brown Fungus work best in destroying
the whitefly where the ground is sufficiently moist; or where
the surrounding conditions are such as to retain the moisture
in and about the trees and the ground. Plenty of dense vege-
tation (trees, shrubs, tall grass etc.) about and in the grove,
will do this to a great extent. The trees and shrubs should be
arranged in the nature of windbreaks, while the grass and beg-
garweed should be permitted to grow tall and rank at the
proper season as a cover crop. It appears also, that where the
fungi thrive best, there is frequently some decaying rubbish
such as weeds, grass, etc., in the nature of mulch near or
about the trees, which helps to conserve the moisture. That it
is not such a difficult matter to reproduce these conditions, in
some degree at least, will be admitted. It is easy to mulch a
grove, and still easier to grow tall cover crops. Windbreaks
can, of course, be planted. An occasional wetting in dry
weather of both the trees and soil, where convenient, will add
to the efficiency of the above provisions. Where groves are
irrigated the problem is simple. Even a slight daily wetting of
the trees and ground would no doubt be very favorable for the
thriving of the fungi. Such a sprinkling outfit would have
its other uses. To say nothing of its value for irrigation, it
would above all be effective in reducing the red spider and
favor the activities of the snail wherever present, besides be-
ing a possible protection against frost. But these problems
are beyond the scope of this paper.
The conditions above set forth appear to be those very
generally existing in groves on hammock land, and this no
doubt accounts for the fact that the fungi thrive there so
much better than on high pine land. If then, the grower
can succeed in approximating these conditions in groves on
pine land, by a liberal mulching and wetting when possible and
the growing of tall cover crops and windbreaks, he will suc-
ceed in helping the fungi a long way toward the destruction
of the whitefly. The main object is to produce a moist atmos-






Buill/tii No. 88.


here in the grove, and the mulch aids in this respect not
only by conserving the moisture, but by actually adding a cer-
tain amount of water produced by the decay of the mulch.
The question of a temperature sufficiently high to meet
the requirements of the fungi is also important. But the con-
trol of this is wholly beyond any means possessed by the
grower. Careful observations covering the months of the dry
season from some time in September, 1906, until January,
1907, indicate that the fungi have spread but little during this
period. These months have been very dry this season, there oc-
curring only one or two slight rains at Lake City, and in
many other parts of Florida. The temperature, furthermore,
probably averaged something like 7o degrees F. The fact,
however, that heavy dews were quite frequent during these
months, points to a high temperature as an important factor
for the growth of these fungi. Efforts to start the Red and
Yellow Aschersonia during the months of September, October
and November have so far been only partially successful.
Summing up the conditions favorable for the growth and
starting of the fungi, it is clear that abundant moisture together
with a Florida summer temperature are important.

THE RED ASCHERSONIA.

Plate III, Fig. 2.
The Red Aschersonia, otherwise known as the Red Fungus
of the Whitefly. has been known to occur in Florida since 1892.
(See appendix 2.) It was observed to be doing good work
then, and is doing good work now. It is at present reducing
the whitefly in a yard near Lake City. On July 8th it was
found on this place (Agnes Jones') and August 6th 47.2 per
cent. (counting all larvae, purpae, and empty pupae cases) were
infected and killed by the fungus. This is the count upon
eighteen leaves that were brought to the laboratory. Not
counting the empty cases upon the leaves the per cent. of
infection was 59.9 per cent. This shows that over one half
of all the living larvae and pupae upon the leaves brought to the
laboratory had been killed by the fungus and the work is still
going on. Dr. Herbert J. Webber wrote, for Gainesville
(about 1895) : "On many leaves it was difficult to find a liv-
ing larvae or pupa of the mealy wing [whitefly] and in such







TI h0 11 timis 111 19o6.


cases the leaves were thickly dotted over with the pustules of
Aschersonia." The destructive freeezs during the winter of
1894 to 1895 killed all the citrus trees to the ground, but left
unharmed a number of species of host plants upon which the
insect survived the winter. From these plants the new citrus
sprouts were again infested the following spring and sum-
mer.
The large quantity of fine fruit shipped from the Man-
atee section and the large acreage of new groves being set out,
indicate that any reports of the citrus industry being ruined in
that section by the whitefly, are not well founded. Many
of the most successful growers of this section depend upon the
fungi to keep their trees clear from the whitefly, while others
are abandoning spraying and are going to permit the fungi
to take their course. Summing up all the facts and observa-
tions. it is difficult to understand bwhy a more general effort
has not been made to spread this useful remedy. It is admitted
that in some groves the conditions are not as favorable for the
growth of the fungi as in others, but extensive observations in-
dicate that \where conditions are naturally unfavorable, they can
be greatly improved, so that the fungi will thrive better.
INTRODUCING THIS FUNGUS.

The chief drawback to introducing the fungi has been the
supposed difficulty of starting ("planting") then in whitefly-
infested trees. The matter appears to be much more simple than
was heretofore supposed. At Lake City the writer succeeded
(June 2oth and August 8th) in introducing the Red Ascher-
sonia into four out of five trees by pinning leaves, with an
abundance of fungus pustules, upon them, to the leaves of the
trees. In two instances the fungus started in another part of
the tree some distance from the pinned leaves, but as no other
infected trees could be found within one-half mile of these, it
is considered safe to assume that the fungus started from the
infected leaves placed there. In two of the successful instances
the leaves with the fungus pustules upon them cvcrc dry and
had been picked about a month before being pinned into the
trees, showing that the spores of the fungus retained their
vitality for at least a month and no doubt longer. It was also
found that the fungus had started in three different trees at
Leesburg. into which Judge J. B. Gains had pinned some leaves.







Bulletin No. 88.


No Red Aschersonia had hitherto been observed at Leesburg,
Since writing the first part of this paragraph, the writer has
found the fungus started in each of thirty-seven trees into
which he had pinned leaves of the Red Aschersonia six weeks
previously (August 15th) at Leesburg. In all, forty-two
trees had been treated in this manner, but five of them were
not examined for lack of time. In many of these trees the
fungus had made good headway, and in one instance Judge
Gaines reported that it had started at the end of two weeks
from the time of infection. W. H. Maxwell of Titusville, also
reports that he has observed the Yellow Aschersonia to start in
two weeks after "planting" (pinning leaves) the same in trees
infested with whitefly.
The writer has also succeeded in starting the Red Ascher-
sonia by spraying a mixture of spores and water on the under
surfaces of the leaves in trees infested with whitefly. This
method of application was successful in starting an infection in
two out of three citrus trees, sprayed at Lake City (July Io).
In each case (leaves pinned or spores sprayed) the fungus was
observed to have started in three to four weeks from the time
of application of the spores or leaves. Eight trees were also
sprayed at Leesburg at the same time (August 15th) that
the fungus was started there by pinning on leaves, and examin-
ation six weeks later, showed that the fungus had started
in each tree.
These experiments are a complete demonstration that
this fungus can readily be started either by pinning on leaves
or by spraying on spores, there being only one failure in fifty-
two trials made during the months of June, July and August,
19o6.
Hitherto, planting into a grove small trees with fungus-in-
fested whitefly larvae upon them has been considered the only
sure way of introducing it. This method is good and sure,
where the trees can be kept from dropping their leaves, but is
rather impracticable on a large scale. The infected trees should
be planted so that their branches and leaves extend among the
leaves of the tree to be infected. If necessary, the infected trees
may be planted in tubs and raised on platforms or otherwise
elevated.
One serious objection is raised in regard to the efficacy of
the fungus, namely, that when it has practically killed off the
whitefly and the fly starts to infest the grove anew, it takes the
fungus so long to start that the fly has done considerable







Whitefly Conditions in 1906.


damage before the fungus gets it under control. The situation
appears to be about as follows. During one year the fungus
cleans up the fly; the second year the grove is generally clean,
also the fruit; the third year the fly reinfests the grove, and
the trees and fruit are again black with sooty mold; then the
fungus does its work again; etc. Now, in view of the fact, that
the fungus can be introduced by pinning on leaves or by spray-
ing on spores, the fungus should be started at the same time that
the whitefly larvae are first observed, and while the progress
and injury of the fly may not be wholly offset, yet I believe a
great deal can be done in this way to lessen the injury. It is
purely a question of helping nature (the fungus) along by
guiding her at the critical moment. This is an important point.
A grower should not wait for the fungus to start of its own ac-
cord but should start it himself as soon as he discovers the
presence of the whitefly, and this should be done whether the
fungus has previously been present or not. The fungus should
be introduced and handled with the same rational considera-
tion with which spraying or fumigation is carried on. Because
the fungus is a natural remedy and will of itself (generally)
spread and reduce the whitefly is no reason why rational means
for artificially spreading the same should not be used.
The problem of getting sufficient fungus many involve some
difficulty, but a number of nurserymen advertise citrus stock
having the fungus upon it for sale, and these no doubt will be
glad to furnish leaves at reasonable prices. (See Appendix.)
SUMMARY FOR THE RED ASCHERSONIA.
I. Get it into your whitefly infested trees at almost any
price,
2. By spraying on the spores,
3. By pinning on leaves,
4. By planting trees with fungus upon them,
5. Mulch the trees and where convenient keep the mulch
damp by an occasional wetting.
6. Spray the trees often with water in dry weather,
where convenient,
7. Permit the cover crop to grow tall in the grove and
let it remain there as long as possible,
8. Plant windbreaks.
9. Spray again with fungus spores and oftener, if neces-
sary, in order to get a good start of fungus.






Bulletin No. 88.


BY SPRAYING ON SPORES OF THE FUNGUS.

If it is decided to introduce the fungus by means of spray-
ing on spores, care should be taken to spray against the under
surface of the leaves. Future experiments may show that
this precaution is not necessary but we are not likely to go
very far astray by adopting it for the present. Forty well de-
veloped pustules having the bright red spots upon them are
sufficient for a pint of water. Two well infected leaves may
be taken as representing the forty pustules but one leaf will
frequently have the required number and often more. A pint
of the solution, I believe, should be sufficient for a tree of ordi-
nary size where a very fine spray is used. From this it will be
seen that spraying is the most economical in so far as infecting
material required is concerned. Three thousand leaves will
about fill a bushel measure. Two leaves per tree to make the
spray, gives us fifteen hundred trees that can be treated with
this number of leaves. Where an abundance of leaves are
available the spraying solution may be made stronger; it can-
not be made too strong. After having poured the water over
the leaves and stirred the same about for a few minutes, fifteen
to thirty minutes should be allowed for the spores to become
dissolved out of the red spots on the pustules of the fungus.
Then the mass should be stirred again, thoroughly, in order
to wash out all the spores possible. Do not permit the solu-
tion to settle but strain the liquid at once through a piece of
cheesecloth or fine wire sieve. An atomizer spray is to be pre-
ferred because it does not require so much liquid to spray the
tree. At all events, a nozzle that produces a very fine spray
should be used. The above estimate of one pint of liquid per
tree was based upon an atomizer spray. If on the other hand,
no atomizer is available, a spraying machine may be employed.
The spraying solution should under no conditions be permit-
ted to stand in a copper or brass tank, for the amount of cop-
per that would go into the solution might be fatal to the
spores, as these are very sensitive to copper. If a spraying ma-
chine made wholly or in part of copper or brass, must be used,
the same should be thoroughly cleaned before using, and then
the work should be done as expeditiously as possible. If it is
necessary to use the copper or brass reservoir connected with
the spray pump or spraying machine this should be partially
filled with the solution, enough only being put in, to spray three







Whitefly Conditions in 1906.


or four trees. Spray the solution on the under surface of all
the infested leaves giving special attention to the heavy infec-
ted new growth. If it happens that only a limited amount of
the spraying solution is available it may be diluted with water.
Thoroughly spraying all the trees with a weaker solution is
considered preferable to spraying half the trees, or only part
of each tree, with a stronger solution.
It goes without saying, that it would be futile to intro-
duce fungus into a tree not infested with whitefly. The fungi
in question, so far as known, can thrive only upon the whitefly,
so that there would be nothing for them to live upon in a
non-infested tree. It will also be well to wait before introduc-
ing fungus into a tree until the whitefly larvae can be abundant-
ly found under a considerable number of leaves. To spray
every tree in a grove regardless of the individual requirements
of each tree would frequently lead to waste of material and
labor. The writer's plan of campaign would be as follows:
Stait the fungus in all the trees in which the whitefly larvae
can be readily found. Later, say in three or four weeks, in-
spect the grove and spray all the trees not previously sprayed
and which now show the presence of whitefly. In another
three or four weeks inspect again and spray. Each tree
should be considered individually and treated accordingly. Any
trees not showing a good start of fungus in three to six weeks
should be sprayed again, wholly or in part. This kind of pro-
cedure should be continued from year to year, and the pre-
diction is made that in a comparatively few years, when the
citrus growing sections of the State have in this manner been
thoroughly saturated with the fungi, there will be no whitefly
problem.
I have stated above that the fungi in question can thrive
only upon the whitefly larvae and pupae and this is probably
true in nature. In the laboratory, however, Professor H. S.
Fawcett has been successful in growing the Yellow and Red
Aschersonias and to produce spores, upon several of the media
generally used for such work. There is but little doubt that the
Brown Fungus can be cultivated on the same media. This
opens up the possibility of producing spores of the fungi in
the laboratory for use upon trees. But as an abundance can
generally be obtained from infected groves it is not likely that
we shall very soon be compelled to depend upon artificial
means for a supply. The fact, however, that a fungus can be







Bulletin No. 88.


cultivated artificially gives the scientific investigator greater
opportunity for careful and varied experiments and observa-
tions that may eventually lead to broad scientific principles
of practical value.
It is considered important, especially on the drier soil, to
mulch the grove or trees treated, and the more liberal the
mulching the better. As already stated, this not only has the
effect of permitting the ground moisture to evaporate slowly
and during a longer period of time, thus increasing the humidi-
ty of the grove, but also some water is actually formed during
the process of the decay of the mulch, and this too adds to the
humidity or dampness of the atmosphere. An occasional wet-
ting of the mulch in dry weather is also recommended, or the
trees can be sprinkled, as previously suggested. Reference to
the usefulness of tall cover crops and windbreaks has already
been made and also to the fact that the conditions herein set
forth very closely approximate those existing in many groves
on hammock land. The mulch, may furthermore, serve other
purposes, such as harboring insects that aid in the distribution
of the spores of the fungus throughout the tree, or as a possible
medium for the development of other stages of the fungus.
I wish to state again that if the first attempt at introducing
the fungus fails to produce a good start in a grove, or in indi-
vidual trees of a grove, a second attempt should be made and a
third one if necessary. This kind of spraying is much cheaper
(and I believe spraying on the spores is preferable to pinning
on the leaves; but both methods can be used,) than spraying
with insecticides, and is perfectly harmless to the trees. This
point, furthermore, should not be lost sight of, that the in-
crease of the fungus in a tree (other things being equal) is in
the same proportion that we succeed in starting it in that tree.
Thus, if we succeed in starting Ioo pustules of fungus in one
tree and 300 in another, it will be evident that the spread of the
fungus in the last tree will be three times as rapid as in the
first one, and hence the importance of making as good a start of
fungus as possible by repeated sprayings.
Attention should also be directed to the fact, that for sub-
sequent sprayings, fungus from the trees previously treated
may be used, provided it is sufficiently developed. This will be
evident as the pustules increase in size and become a bright
scarlet red in the Red Aschersonia or a bright yellow in the
Yellow Aschersonia.







Whitely Conditions in 1906.


When is the best time for doing this work? Future ex-
periments will give us more information. The months of
June, July and August, as the experiments previously indi-
cated show, are favorable months. Ordinary periods of cold
and dry weather generally have only the effect of retarding the
growth of fungi. We know that neither ordinary cold nor dry-
ing kills the fungi parasitic upon the whitefly. Note the fact
already stated that leaves with fungus, and dried for a month,
were as efficient as fresh leaves for starting the Red Ascher-
sonia and the Brown Fungus.
The months of September (last half), October, November
and December (1906) were found unfavorable, probably be-
cause of drought and cooler weather. No experiments in
starting the fungi have been tried during January, February,
March and April, yet it is hardly to be expected that these will
be exceptionally favorable. May being generally quite warm
and immediately preceding the rainy season is believed to be a
good month, and any one beginning work with the fungi
at this time will hardly go far wrong. Prospective warm
summer weather and rains may be taken as a guide for starting
the work, and since the spores are to be mainly sprayed on
the under surfaces of the leaves there is little danger that they
will be washed off during heavy rains.
BY PINNING ON LEAVES.
To introduce the fugus by pinning on leaves I would sug-
gest that from one to a dozen or more well infected leaves be
pinned to a tree. The number will be determined by the
amount available. As Leesburg 12 leaves per tree were used.
Each infected leaf should be pinned to the under surface
of the leaf on the tree, with its under surface down,
that having been its position before it was removed
from the tree and is in closest keeping with nature. The in-
fected leaves might be pinned with the infected (or under) side
against the under side of the leaves on the tree, and I have ob-
tained good results in this way, but for the sake of keeping
close to nature I advise the other way for the present.
Each infested leaf should be pinned as high up in the tree
as is convenient, that is, at least as high as a man can reach.
To pin it higher is desirable. It should, furthermore, be so
placed that the drip from it, when it rains, will drop onto a
cluster, or several clusters, of leaves beneath it. Use two pins







Bulletin No. 88.


for each leaf. I have observed that the fungus sometimes starts
on the leaves beneath the pinned leaf rather than at the leaf to
which the infected leaf was pinned. It is well to pin a small
piece of paper on the upper surface of the leaves to which the
infected leaves are pinned as a mark. This will greatly facilitate
later inspections.
THE YELLOW ASCHERSONIA.

This fungus, known at present to occur at Winter Park,
Orlando and Miims is very much like the Red Aschersonia,
but the pustules are of a rich yellow color. It appears to
spread rapidly: ninety per cent. of the larvae on some leaves
examined in the laboratory being infected. It should be treat-
ed exactly like the Red Aschersonia, as the conditions under
which it thrives seem to be the same, and each produces spores
in abundance.
THE BROWN FUNGUS.

Plate III. Fig. 3.
What has been said for the Aschersonias applies (with
one probable exception) also to the Brown Fungus. The spores
of the Brown Fungus have not been discovered, and this
fact makes it uncertain whether it can be successfully intro-
duced by spraying. This leaves two methods available for in-
troducing the Brown Fungus: (i) to pin leaves having white-
fly larvae infected with the fungus upon them onto the
leaves of the tree into which it is to be introduced; (2) to plant
small trees, having the fungus upon them, into the grove as
previously explained for the Red Aschersonia.
Since writing the above paragraph I have been agreeably
surprised to find that the Brown Fungus has started in four
of the eight trees sprayed at Leesburg (August i5th 'o6)
with spores of the Red Aschersonia and previously noted in
this paper. Some Brown Fungus was scattered over the
leaves with the Red Aschersonia, used in preparing the mixture
of spores and water for this spraying, and this clearly indi-
cates that the Brown Fungus can be started by spraying. In-
spection of these trees September 29th, 1906, did not reveal any
of the Brown Fungus, but at a later inspection (December
21st, 1906) leaves having an abundance of this fungus upon
them were found in four of the trees. Further experiments







Bulletin No. 88.


for each leaf. I have observed that the fungus sometimes starts
on the leaves beneath the pinned leaf rather than at the leaf to
which the infected leaf was pinned. It is well to pin a small
piece of paper on the upper surface of the leaves to which the
infected leaves are pinned as a mark. This will greatly facilitate
later inspections.
THE YELLOW ASCHERSONIA.

This fungus, known at present to occur at Winter Park,
Orlando and Miims is very much like the Red Aschersonia,
but the pustules are of a rich yellow color. It appears to
spread rapidly: ninety per cent. of the larvae on some leaves
examined in the laboratory being infected. It should be treat-
ed exactly like the Red Aschersonia, as the conditions under
which it thrives seem to be the same, and each produces spores
in abundance.
THE BROWN FUNGUS.

Plate III. Fig. 3.
What has been said for the Aschersonias applies (with
one probable exception) also to the Brown Fungus. The spores
of the Brown Fungus have not been discovered, and this
fact makes it uncertain whether it can be successfully intro-
duced by spraying. This leaves two methods available for in-
troducing the Brown Fungus: (i) to pin leaves having white-
fly larvae infected with the fungus upon them onto the
leaves of the tree into which it is to be introduced; (2) to plant
small trees, having the fungus upon them, into the grove as
previously explained for the Red Aschersonia.
Since writing the above paragraph I have been agreeably
surprised to find that the Brown Fungus has started in four
of the eight trees sprayed at Leesburg (August i5th 'o6)
with spores of the Red Aschersonia and previously noted in
this paper. Some Brown Fungus was scattered over the
leaves with the Red Aschersonia, used in preparing the mixture
of spores and water for this spraying, and this clearly indi-
cates that the Brown Fungus can be started by spraying. In-
spection of these trees September 29th, 1906, did not reveal any
of the Brown Fungus, but at a later inspection (December
21st, 1906) leaves having an abundance of this fungus upon
them were found in four of the trees. Further experiments







TWhitefly Conditions in 1906.


will be necessary to determine whether the method of starting
the Brown Fungus by spraying can be made practical. How-
ever, in preparing a mixture of spores and water of the Red
or Yellow Aschersonias for spraying, it will not be amiss to
mix in any leaves at hand having Brown Fungus upon them. It
may be well, however, to thoroughly triturate the pustules of
this fungus to insure getting an abundance of small particles of
it into the mixture. As already stated we are not certain that
we have discovered the spores of this fungus, and it may have
started in tte trees at Leesburg from small particles that were
in the mixture sprayed into the trees.
I do not think that the infection could have come from
another source since inspection of neighboring trees that had
not been sprayed showed no signs of it.
It has been suggested that the Brown Fungus probably
spreads more rapidly in cool weather that the Aschersonias, and
this observation at Leesburg seems to be corroborative of this
suggestion. Further observations will determnie this point.
That this fungus can be introduced by planting small trees
having the Brown Fungus upon their leaves was first demon-
strated by Dr. H. J. Webber and this method has since been
successfully employed by many individuals throughout the
State. It will be preferable, however, to use the method of pin-
ning on leaves as it is easier and more practicable. The writer
has something like seven instances on record where he succeed-
ed in starting this fungus by pinning on leaves. Dr. H. J.
Webber, also notes an instance where this fungus was started
by this means (Bull. 13, U. S. Dept. Agri., Div. Veg. Phys.
and Path.).
SCALE AND WHITEFLY.

The question is sometimes asked, "If I depend upon the
fungus to keep down the whitefly, what shall I do to keep
down the scale? If I spray for the scale then I will kill the
fungus." There are several fungi that are very effective in
reducing the scale, and it may be desirable to introduce some
of these. These fungi are the Red Headed Scale Fungus
(Sphaerostilbe coccophila. See Bulletin 41). the Gray Headed
Scale Fungus (Ophionectra coccicola), and the Black Scale
Fungus (Myrangimn Duryii), and material can be obtained
without much difficulty in many parts of the State. The best







Bulletin No. 88.


present known method for introducing them is to tie leaves
and twigs having some of these fungi upon them into the
scale-infested trees.
If the case requires immediate and drastic measures a thor-
ough spraying of the tree with some good spray should be ef-
fective in reducing both scale and fly. Then, when the fly
again shows signs of increasing in the tree one of the whitefly
fungi should be introduced as previously directed.

TRIMMING TREES.

Trees infested with the whitefly and located where ve-
hicles and persons pass, should be trimmed sufficiently high to
give free passage; so that the flies cannot be brushed off and
in that manner carried about the country. There is no doubt
that this is one of the chief means by which the fly is carried
from place to place, and it would require but very little effort
along this line to reduce this source of infection. Everybody
owning infested trees should become awake to the situation and
do their part. In towns the city officials could compel the
proper trimming of trees, while Boards of Trade could warn
people, and instruct them in the desirability of keeping their
premises in proper condition. I desire here to commend the
Leesburg Board of Trade for their efforts in getting infor-
mation and their foresight in issuing a circular to interest the
people.
The railroad trains carry the fly farther than perhaps any
other agent, and something could be done to lessen this means
of distribution if railorad officials as well as people along the
line would see to the proper trimming and destruction of
infested trees and bushes on and near the right of way. This
suggestion is important and should receive attention.

SPRAYING AND FUMIGATION.

For more complete directions in regard to spraying with
contact insecticides, I shall refer the reader to the following
bulletins: Press Bulletins 4 and 56 treat of the whitefly and
methods of repression, and are both available for distribu-
tion; Bulletin 67 is the standard bulletin on the whitefly and is
,out of print but thousands of copies have been distributed
throughout the State; Bulletin 76 is on Insecticides and Fungi-







Bulletin No. 88.


present known method for introducing them is to tie leaves
and twigs having some of these fungi upon them into the
scale-infested trees.
If the case requires immediate and drastic measures a thor-
ough spraying of the tree with some good spray should be ef-
fective in reducing both scale and fly. Then, when the fly
again shows signs of increasing in the tree one of the whitefly
fungi should be introduced as previously directed.

TRIMMING TREES.

Trees infested with the whitefly and located where ve-
hicles and persons pass, should be trimmed sufficiently high to
give free passage; so that the flies cannot be brushed off and
in that manner carried about the country. There is no doubt
that this is one of the chief means by which the fly is carried
from place to place, and it would require but very little effort
along this line to reduce this source of infection. Everybody
owning infested trees should become awake to the situation and
do their part. In towns the city officials could compel the
proper trimming of trees, while Boards of Trade could warn
people, and instruct them in the desirability of keeping their
premises in proper condition. I desire here to commend the
Leesburg Board of Trade for their efforts in getting infor-
mation and their foresight in issuing a circular to interest the
people.
The railroad trains carry the fly farther than perhaps any
other agent, and something could be done to lessen this means
of distribution if railorad officials as well as people along the
line would see to the proper trimming and destruction of
infested trees and bushes on and near the right of way. This
suggestion is important and should receive attention.

SPRAYING AND FUMIGATION.

For more complete directions in regard to spraying with
contact insecticides, I shall refer the reader to the following
bulletins: Press Bulletins 4 and 56 treat of the whitefly and
methods of repression, and are both available for distribu-
tion; Bulletin 67 is the standard bulletin on the whitefly and is
,out of print but thousands of copies have been distributed
throughout the State; Bulletin 76 is on Insecticides and Fungi-







Whitefly Conditions in 1906.


cides, and is full of valuable information on spraying and
fumigation in general.
Judicious spraying with insecticides should be effective in
reducing the ravages of the whitefly provided a grower can
persuade his neighbors to spray at the same time. Co-operation
is absolutely necessary for effective spraying.
December, January and February are the best months to
spray for the whitefly as it is then in one or the other of its
several larval stages or pupae under the leaves, and is more
readily killed in these stages. It is practically useless to
spray for the adults since the females lay their eggs when they
are from 18 to 0o hours old, so that the grower would have
to spray every day during the swarming periods to insure
killing them before they laid their eggs. The eggs are not
readily killed either by spraying or fumigation. Spraying to
be effective should, furthermore, be drastically thorough, and
one such spraying in winter after the fruit is picked and danger
from frost is past will be worth more than several less thorough
applications. To postpone spraying until danger of frost is
past may save much labor and spraying material, since, should
the leaves be dropped by freezing but little if any spraying
would be necessary. In case of a freeze sufficiently severe to
cause many leaves to drop, these should be plowed under or
burned to insure against the possibility of any nearly mature
whitefly from completing their development. It will thus be
evident that a freeze may be a blessing to a whitefly infected
grove.
Summer spraying may be practiced when conditions re-
quire it. The difficulty with spraying lies not so much in
getting an insecticide that will kill the insect as in applying it
so that all or a very large percent. will be killed. Any of the
contact insecticides (including whaleoil soap) generally used
for destroying insects on citrus trees, will be found useful.
However, all kinds of spraying with emulsions and other chem-
ical compounds generally in use, appear to be more or less in-
jurious to orange trees. Of these, whaleoil soap is probably
the least injurious. Before spraying, all excessive foliage
should be removed from the trees by a thorough trimming.
Spraying with insecticides is, also, more or less harmful to the
Fungi, so that having decided to use the Fungi, spraying
should be discontinued.
Fumigation has not been sufficiently tested in this State to







Bulletin No. 88.


warrant its being 'boomed' into disfavor," as Professor H. A.
Gossard has aptly put it.

COPPERAS.
Much has recently been said and written in regard to the
use of copperas for killing the whitefly. Examination by com-
petent persons of groves treated with copperas indicates that
the latter is not efficient for reducing the whitefly, to say
nothing of extermination. In one instance (Orlando) it was
reported that an application of copperas had killed the whitefly,
but examination showed the trees treated to be just as full
of larvae and pupae as the trees not treated.
The following is taken from the Florida Farmer and
Fruit Grower of August 31st, 1906.

"ROYAL PALM NURSERIES, REASONER BROS.,
Oneco, Fla., August 22, 1906.
Editor Farm and Fruit-Grower:
I will again state, however, that I think it sim-
ply impossible to kill or drive away the whiteflies by any such
mild measure as spreading copperas under the trees. I have
evidence that it will not affect them at all! In Bradentown
two of the best known citizens used copperas liberally on the
soil, giving several applications through the year; 2 to 4
pounds per tree on from Ioo to 200 trees each were used by
them about six years ago and no effect whatever was no-
tived on the flies which continued as thick as ever for some
years thereafter. Now that the natural fungoid enemies of
the flies are present, the groves look very well and are carry-
ing a fair crop of fruit.
The fungus (two species) keeps groves generally clean
in the infected localities of this, Manatee county, where the
flies have been known about fiften years. Parts of the county
have never had the flies present at all, and if we have normally
wet summers the flies can never get bad again wherever the
fungus has been introduced. It remains the only known suc-
cessful "cure" for whiteflies."
(Signed). E. N. REASONER.







I 'i7,: Conditions in 1906.


SOOTY MOLD.

This mold (a species of meliola) of a sooty black, as its
name implies, is found wherever whitefly or other insects, that
excrete a sweet solution (honeydew) occur. As this sweet
secretion (also relished by ants )nearly always collects on the
upper surfaces of leaves, it follows that the mold, which
thrives in this secretion, also occurs on the upper surface.
Other insects that are accompanied by the sooty mold are:
mealy bugs, plant lice (aphids), soft scale (Lecaniums), wax
scales, cottony cushion scale, and others, so that sooty mold
visible upon a tree is not necessarily a sure sign of whitefly.
This fungus does not ordinarily become visible until after the
trees have been infested by the whitefly for some months.

THE SNAIL.

There appear to be several species of snails that will feed
upon the sooty mold accompanying the whitefly. Besides the
Manatee Snail (Bulimulus Dormani), another species brought
from Miami by Professor Rolfs and spoken of by us as the
Miami Snail, is also a good feeder upon the sooty mold and
may become of considerable value. Their usefulness consists
mainly in the fact that they will clean the sooty mold from all
parts of a tree and the fruit. They do not feed upon the white-
fly larvae as sometimes reported. That they will swallow and
destroy some larvae and eggs is a fact but this is only inci-
dental, the larave and eggs being swept off the leaves with the
mold. This is, however, not of frequent occurrence since the
snails seldom feed on the under surface of the leaves where
the eggs and larvae are found, except when food is getting
scarce. To those who have or suspect the presence of snails in
their trees, the following may be recommended: Keep a lib-
eral amount of mulch, coarse and fine mixed, around the base
of the trees and hang pieces of burlap into several of the
narrowest crotches of each tree. The purpose of the above
is to provide moisture-conserving places in and about the trees
in which the snails can lay their eggs and conceal themselves.
The above directions are important.







I 'i7,: Conditions in 1906.


SOOTY MOLD.

This mold (a species of meliola) of a sooty black, as its
name implies, is found wherever whitefly or other insects, that
excrete a sweet solution (honeydew) occur. As this sweet
secretion (also relished by ants )nearly always collects on the
upper surfaces of leaves, it follows that the mold, which
thrives in this secretion, also occurs on the upper surface.
Other insects that are accompanied by the sooty mold are:
mealy bugs, plant lice (aphids), soft scale (Lecaniums), wax
scales, cottony cushion scale, and others, so that sooty mold
visible upon a tree is not necessarily a sure sign of whitefly.
This fungus does not ordinarily become visible until after the
trees have been infested by the whitefly for some months.

THE SNAIL.

There appear to be several species of snails that will feed
upon the sooty mold accompanying the whitefly. Besides the
Manatee Snail (Bulimulus Dormani), another species brought
from Miami by Professor Rolfs and spoken of by us as the
Miami Snail, is also a good feeder upon the sooty mold and
may become of considerable value. Their usefulness consists
mainly in the fact that they will clean the sooty mold from all
parts of a tree and the fruit. They do not feed upon the white-
fly larvae as sometimes reported. That they will swallow and
destroy some larvae and eggs is a fact but this is only inci-
dental, the larave and eggs being swept off the leaves with the
mold. This is, however, not of frequent occurrence since the
snails seldom feed on the under surface of the leaves where
the eggs and larvae are found, except when food is getting
scarce. To those who have or suspect the presence of snails in
their trees, the following may be recommended: Keep a lib-
eral amount of mulch, coarse and fine mixed, around the base
of the trees and hang pieces of burlap into several of the
narrowest crotches of each tree. The purpose of the above
is to provide moisture-conserving places in and about the trees
in which the snails can lay their eggs and conceal themselves.
The above directions are important.







Bulletin No. 88.


LIFE HISTORY OF THE WHITEFLY.

Plates I, II and III.

The name whitefly is a misnomer, the insect in question
not being a fly at all but a member of the Hemiptera, the order
to which the plantlice and scale insects belong. Flies have only
two wings, but the whitefly has four, which fact at once sepa-
rates it from the Diptera, or flies proper.
There are three well defined broods of the whitefly, with
an interval of several days to several weeks between each
brood, when few or none are seen on the wing. The first
brood generally appears sometime during March, April or May,
the second during June, July or August, although this summer
it appeared as two quite distinct divisions at Lake City, and
the third during September and October. Variations that
occur are due to variations in the seasons and the locality. No
doubt many people supposed that they had exterminated the
whitefly by means of some treatment copperass) when one or
another of the several broods disappeared from the wing.
Larvae (the young stages) and pupae (the transformation
stage) of the whitefly can, however, always be found on the
under surfaces of the leaves, and seldom elsewhere. The lar-
vae are scale-like (Plate III, Fig. i.) and closely appressed
against the leaf. They vary in size from the very young, just
visible to the unaided eye, to the fully matured larvae which
measure about one-sixteenth of an inch in length.
The larvae are white and translucent with a tinge of yel-
low, and almost invisible upon the leaf. By holding a leaf
(under surface up) at the ends, with the thumb and forefinger
of each hand and then rubbing lengthwise along the leaf with
one of the unused fingers, the larvae will appear as flattened
whitish scales. The pupa (Plate II, Fig 8) (plural pupae) is
the transformation stage from the larva (plural larvae) to
the adult, winged fly. The pupae are readily visible as yel-
lowish white, plump, oval bodies with a dark reddish spot on
the back. From the pupa emerges the adult winged fly. The
little white cases, with a T-shaped split on the back, and found
on the under surface of a leaf, are the empty pupa cases from
which the adults have emerged (Plate II, Fig io). The eggs
(Plate I, Fgs. 3, 4) are just visible to the unaided eye as a fine
dust upon the under surface of the leaves. An ordinary hand







Whitefly Conditions in 1906.


lens (magnifying glass) will show them as little egg-shaped
bodies much resembling grains of wheat. There are, therefore.
four stages in the life history of the whitefly: The egg visible
as a fine particle of dust; the larva, a flattened scale; the pupa,
plump and readily visible; and the adult winged insect. All of
these stages are nearly always confined to the under surface of
the leaves. (Plates I, II, III.).
The following facts are a summary from Professor H. A.
Gossard's Bulletin 67. Twenty thousand eggs have been esti-
mated on a large orange leaf. From observations made in the
laboratory, egg laying begins when the female is from eighteen
to thirty hours old, and from seventeen to twenty-five eggs are
deposited. These eggs are generally all laid within twenty-four
hours after the first egg has been laid. Her length of life
has been estimated at from three days in warm weather to
three weeks in cool weather, and the complete length of life
cycle from egg to adult is from forty or fifty days in summer to
six months in winter.
It will thus be evident that in order to spray successfully
for the adult fly it is necessary to spray practically every day
to catch the females before they lay their eggs; an impossible
task when a man has more than a few trees.
FOOD PLANTS.

There appears to be a great deal of misapprehension in
regard to the number of food plants of the whitefly. Every
tree, bush, or weed in the hammock is not a food plant, as
many suppose. The definitely known number of food plants
is a relatively small one. I cannot do better, perhaps, than to
quote verbatim the page on Food Plants from Professor Gos-
sard's Bulletin 67.
"White fly occurs upon all varieties of citrus. C. trifolia-
ta is, of course, only infested during the summer months, being
a deciduous variety. The deciduous character of some of the
C. trifoliata hybirds will tend to retard the multiplication of the
pest upon them. The kumquat is still less a favorite than the
pomelo, and the latter, though, often badly infested, is usually
attacked only after the adjacent oranges are ovestocked. The
adult flies as well as the larvae sap the leaves, and their taste
for certain varieties leads them to oviposit on these when pos-
sible, going to less favored plants only as they are driven by







Bulletin No. 88.


necessity to do so. Besides citrus, the Chinaberry tree (Melia
Azederach), Viburnum nudum, the Cape jessamine (Gardenia
tforida), the Japan persimmon (Diospyros kaki), California
privet (Ligustrum Amurense), Golden privet (Ligustrum sp.)
and Mock orange (Prunus Caroliniana) are food plants. Va-
rious species of Ficus are said to be food plants; I have seen
it on two species, F. altissima, and on an unknown species
introduced from Costa Rica.
The water oak (Quercus aquatica) is occasionally infested,
according to Quaintance, and I have taken two or three larvae
advanced to third and fourth stage on scrub palmetto. Their
presence upon the latter plant is very rare, having been ob-
served but once, though opportunities have been plentiful.
Prickly ash (Xanthoxylum sp.) is reported as a food plant
upon what I consider to be reliable authority, but I have not
personally seen the insect upon any one of the three species
found in this State."
To this list but few if any additions can be made at this
time. The Umbrella tree, a variety of the Chinaberry, be-
comes as much infested as the latter. During the past summer
the Prickly ash (Fagara Clava-Herculis) has been observed to
be an undoubted food plant and several badly infested trees
were found at Lake City. A similar observation was made at
Leesburg. Specimens of whitefly were also found upon the
wild persimmon. (Diospyros Virginiana) along a roadside
south of Orlando. The umbrella tree and the wild persimmon,
seem thus to be about the only additions that we can make at
this writing.
That a definite knowledge of the food plants of the white-
fly is important in devising means for its control will be evident
to all, and all persons interested should send samples of any in-
fested (or supposedly infested) plants, not in the above list, to
the Experiment Station at once upon their discovery, so that we
can make our knowledge as complete as possible. Were we
to count all plants upon which a few larvae may occasionally
mature, the number of food plants would be increased to two
or three times the number listed; but the majority of these
would represent plants that become slightly infested only
when in close proximity to some tree that is badly infested.
Thus Dr. Webber states (verbally to the writer) that larvae
will occasionally mature upon magnolia under such conditions.
It appears that plants, in their food relations to the white-







l'Vhit'dy Conditions in 1906.


fly may be divided into three classes: (i) Food plants proper,
(2) Partial food plants (those not generally infested or but
little infested) and (3) Plants immune. The majority of
plants listed above belong to the first class, and all but six-are
of Oriental origin, which furthermore, suggests that the fly
is of Oriental origin. These six native plants, Viburnum
nudium Mock Orange (Cherry Laurel,) Water Oak, Scrub
Palmetto, Prickly Ash, and Wild Persimmon become only
slightly infested (Prickly Ash excepted) and belong to class
two.
QUARANTINE.

In localities where the whitefly is not present, or where
the amount present is very small and the chances for its elimi-
nation by a vigorous application of drastic methods are favor-
able, quarantining should be effective to a great degree, at least
in putting off the evil day, and thus be the means of saving
thousands of dollars. This could be, and in fact has been,
made effective in several different ways: by keeping out suspi-
cious nursery stock; closing up private roads and gates and
keeping out vehicles coming from infested districts; keeping
out pickers' implements when coming from infested districts,
or compelling their disinfection at some safe point.

NURSERY STOCK.

In buying nursery stock the buyer can well afford to
travel to any part of Florida to determine for himself the
condition of the stock he desires to buy, provided the section
in which he desires to plant the trees is free from the whitefly.
If the section is already infested this is not so important. On
the other hand, the present status of our knowledge indicates
that it would be perfectly safe to buy nursery stock from any
infested district provided the same be cut back, defoliated, and
as a special precaution, fumigated with hydrocyanic acid gas.
While eggs are frequently laid upon the tender wood of
growing shoots, yet no larvae have ever been known to be-
come mature there, and whenever this wood is cut back and
the rest defoliated, and the tree fumigated as a special precau-
tion, reasonable safety can be assured, especially during De-
cember, January and February, when absolute safety can be
guaranteed. During these months all the eggs have hatched







l'Vhit'dy Conditions in 1906.


fly may be divided into three classes: (i) Food plants proper,
(2) Partial food plants (those not generally infested or but
little infested) and (3) Plants immune. The majority of
plants listed above belong to the first class, and all but six-are
of Oriental origin, which furthermore, suggests that the fly
is of Oriental origin. These six native plants, Viburnum
nudium Mock Orange (Cherry Laurel,) Water Oak, Scrub
Palmetto, Prickly Ash, and Wild Persimmon become only
slightly infested (Prickly Ash excepted) and belong to class
two.
QUARANTINE.

In localities where the whitefly is not present, or where
the amount present is very small and the chances for its elimi-
nation by a vigorous application of drastic methods are favor-
able, quarantining should be effective to a great degree, at least
in putting off the evil day, and thus be the means of saving
thousands of dollars. This could be, and in fact has been,
made effective in several different ways: by keeping out suspi-
cious nursery stock; closing up private roads and gates and
keeping out vehicles coming from infested districts; keeping
out pickers' implements when coming from infested districts,
or compelling their disinfection at some safe point.

NURSERY STOCK.

In buying nursery stock the buyer can well afford to
travel to any part of Florida to determine for himself the
condition of the stock he desires to buy, provided the section
in which he desires to plant the trees is free from the whitefly.
If the section is already infested this is not so important. On
the other hand, the present status of our knowledge indicates
that it would be perfectly safe to buy nursery stock from any
infested district provided the same be cut back, defoliated, and
as a special precaution, fumigated with hydrocyanic acid gas.
While eggs are frequently laid upon the tender wood of
growing shoots, yet no larvae have ever been known to be-
come mature there, and whenever this wood is cut back and
the rest defoliated, and the tree fumigated as a special precau-
tion, reasonable safety can be assured, especially during De-
cember, January and February, when absolute safety can be
guaranteed. During these months all the eggs have hatched







Bulletin No. 88.


and proper fumigation can be depended upon to kill any stray
larvae or pupae that might be attached to the bark.

VEHICLES AND PRIVATE ROADS.

Private roads should simply be closed to all vehicles, at
least to any whose previous whereabouts are uncertain. This
has been done in many places and no doubt has saved growers
thousands of dollars by delaying infection, even if it was not
effective in keeping out the whitefly permanently.

PICKING IMPLEMENTS.
The picking implements used by pickers, coming from an
infested district have been excluded, from at least one section,
(the Subpeninsula) of Florida, and this no doubt was one
of several important factors that aided in keeping this section
practically free from the whitefly for many years. On the
other hand, a thorough disinfection of the implements, includ-
ing ladders, sacks, etc., as well as the outer clothing of the
pickers should be effective in reducing the chances of infection
from this source to nothing. It has been suggested that where
picking of citrus fruits is let by contract a clause requiring dis-
infection of the implements and clothing should be included. It
is the writer's opinion that this is a very valuable suggestion.
Ladders could be best disinfected by painting or spraying them
with kerosene or kerosene emulsion, whaleoil soap, linseed oil,
or by slowly passing them through the flames of a fire when
the other means are not at hand. For disinfecting the picking
bags, clothing, etc., nothing, perhaps, would be simpler than
placing these in an air tight barrel or box, pouring a liberal
quantity of gasolene over them, and closing the barrel or box
tightly for several hours. If carbon bisulphide is at hand this
can be used instead of the gasoline, and a treatment of an
hour is sufficient. Three ounces (about one-fifth of a pint) of
carbon bisulphide will be sufficient for a case the size of a bar-
rel. If gasoline is used the dose should be several times as
large. Finally, if a fumigating box is at hand, such as is used
for fumigating nursery stock with hydrocyanic acid gas, the
implements etc., can be fumigated in this, using the normal
dose of the gas for forty minutes. The picking bags, etc.,
should be arranged loosely and with spaces between them to







Bulletin No. 88.


and proper fumigation can be depended upon to kill any stray
larvae or pupae that might be attached to the bark.

VEHICLES AND PRIVATE ROADS.

Private roads should simply be closed to all vehicles, at
least to any whose previous whereabouts are uncertain. This
has been done in many places and no doubt has saved growers
thousands of dollars by delaying infection, even if it was not
effective in keeping out the whitefly permanently.

PICKING IMPLEMENTS.
The picking implements used by pickers, coming from an
infested district have been excluded, from at least one section,
(the Subpeninsula) of Florida, and this no doubt was one
of several important factors that aided in keeping this section
practically free from the whitefly for many years. On the
other hand, a thorough disinfection of the implements, includ-
ing ladders, sacks, etc., as well as the outer clothing of the
pickers should be effective in reducing the chances of infection
from this source to nothing. It has been suggested that where
picking of citrus fruits is let by contract a clause requiring dis-
infection of the implements and clothing should be included. It
is the writer's opinion that this is a very valuable suggestion.
Ladders could be best disinfected by painting or spraying them
with kerosene or kerosene emulsion, whaleoil soap, linseed oil,
or by slowly passing them through the flames of a fire when
the other means are not at hand. For disinfecting the picking
bags, clothing, etc., nothing, perhaps, would be simpler than
placing these in an air tight barrel or box, pouring a liberal
quantity of gasolene over them, and closing the barrel or box
tightly for several hours. If carbon bisulphide is at hand this
can be used instead of the gasoline, and a treatment of an
hour is sufficient. Three ounces (about one-fifth of a pint) of
carbon bisulphide will be sufficient for a case the size of a bar-
rel. If gasoline is used the dose should be several times as
large. Finally, if a fumigating box is at hand, such as is used
for fumigating nursery stock with hydrocyanic acid gas, the
implements etc., can be fumigated in this, using the normal
dose of the gas for forty minutes. The picking bags, etc.,
should be arranged loosely and with spaces between them to







WhiteZfy Conditions in 1906.


insure a perfect circulation of the vapor or gas used, whether
in barrel, box, or fumigating box.

PLANTS TO BE CONDEMNED.
The following plants should be condemned by every citrus
grower and by all people in any community where citrus grow-
ing is an industry. These plants are: the Cape Jessamine, the
Chinaberry, the Umbrella Tree, the Prickly Ash, Golden Priv-
et, California Privet, the Trifoliate Orange (Citrus trifoliata)
and any useless and abandoned citrus of all kinds. The Mock
Orange (or Cherry Laurel) should be included in this list
whenever it is observed to become badly infested. These plants
are generally of little value and can well be spared and re-
placed by others not subject to attack by whitefly. Including
the trifoliate orange in this list does not preclude its being used
as a foundation stock in nurseries. Of course anyone having
only one or two of these trees may overcome the danger of
their becoming a source of infection by spraying them to the
extent of defoliation, or they can be defoliated by trimming;
but in either case the work must be done thoroughly, every leaf
must come off, and as a special precaution the tree should be
sprayed besides, to insure the killing of any larvae that might
be on the buds and elsewhere. Such an operation, however,
might have to be repeated each year, and possibly oftener, so
that cutting down and burning such trees and shrubs is the
better plan. Do not cut them down and then let them remain
about the premises so that the fly can continue to develop, but
burn them at once!
It may seem akin to vandalism to be expected to sacrifice
some of our garden and orchard pets, but all successful warfare
consists in some degree at least in reducing the number of the
enemies' strongholds. One Cape jessamine and two or three
umbrella trees in a certain yard in New Smyrna seem to be
responsible for the spreading of the whitefly in that place. In
looking over this ground one is soon impressed with the fact
that these trees were the focus of infection.
















EXPLANATION OF PLATE I.*


Aleyrodes Citri.

Fig. I.-Adult female with expanded wings much en-
larged.
Fig. 2.-Adult female with wings folded over the body in
normal roof-like position.
Fig. 3-Egg and footstalk of same, greatly magnified.
Fig. 4.-Eggshell, showing the split through which the
larva emerged.
Fig. 5.-Tip of male abdomen, showing claspers.
Fig. 6.-Antenna, showing annulated joints.
Fig. 7.-Fore margin of front wing.
INSECTS SOMETIMES MISTAKEN FOR A. CITRI.
Fig. 8.-Larva of. Aleyrodes floridensis greatly magnified.
Fig. Io.-Greatly enlarged section of waxen fringe sur-
rounding A. floridensis
Fig. I .-Outline of Lecaniinii hcs/priduin. (A soft
scale).


*All .plates are the same as in Bulletin 67. By Prof. H A Gossard.













1i 1



) &

/ ; kj i,

7~ ~7


PLATE I.



















EXPLANATION OF PLATE II,

Aleyrodes Citri.
Fig. I.-Larva, first stage, greatly magnified.
Fig. 2.-Larva, first stage, drawn to same scale as figures
3, 4, 5, 8, 9 and Io.
Fig. 3.-Larva, second stage.
Fig. 4.-Larva, third stage.
Fig. 5.-Larva, fourth stage.
Fig. 6-Margin of advanced larva, greatly enlarged.
Fig. 7.-Vasiform orifice of fourth larval stage showing
crenulated operculum with lingua in the center.
Fig. 8.-Pupa, showing embryo and distribution ot orange
colored areas, waxen tufts extending from the breathing tubes
are sho-vn.
Fig. 9.-Adult with folded wings, emerging from the
pupa case.
Fig. io.-Empty pupa case, showing split through which
the fly emerged.





















/A
b07




-U








PLATE II.

























EXPLANATION OF PLATE III.

From Photographs.
Fig. I.-Larvae and Pupa of Whitefly on Orange.
Fig. 2.-Red Fungus, Aschersonia Aleyrodes, Webber.
Fig. 3.-Brown Fungus on Orange.
Fig. 4.-Adult Flies and Eggs on Orange.





























Fig. J.


Fig. 3.


PLATE III.


Fig. 2.


Fig. 4.







Bulletin No. 88.


APPENDIXES.



I. WHERE TO OBTAIN FUNGUS.

The following persons living in Florida have consented to
furnish leaves having fungus-infected whitefly larvae and pu-
pae upon them at fifty cents per one hundred leaves.
A. J. Pettigrew. Manatee, (Red and Brown),
A. F. Wyman, Bradentown, (Red and Brown),
F. D. Waite, Palmetto. (Red and Brown),
C. A. Boone, Orlando, (Red, Yellow and Brown),
C. B. Thornton. Orlando, (Yellow and Red).
Larger quantities can no doubt be obtained at reduced
rates.
2. THE FUNGI IN FLORIDA.

The following data have been taken from Bulletin No. 13,
U. S. Dept. Agr., Div. Veg. Phys. and Pathology, by Dr. H.
J. Webber. Red Aschersonia first observed: Panasoffkee,
1892; Crescent City, August 1893; Bartow, January 1894;
Citra, December 1894*; Myers, June 1895*; Gainesville, Man-
atee. I893-1897*. (Years with stars may be too great by one
or several years).
Brown Fungus first observed: Manatee, March 1896.
Yellow Aschersonia first recognized as distinct from the Red
Aschersonia by Professor P. H. Rolfs on specimens sent from
Winter Park by J. F. Adams, September, 1906.

3. SPRAYING APPARATUS.

For those who expect to give the fungi a thorough trial
it will be desirable to have a special outfit for spraying the
mixture of fungus spores and water. Having a special outfit
and using it only for the fungi, there will be no risks of poi-
soning the spores by small traces of any chemicals that may re-
main in an old outfit, especially one used for spraying fungi-
cides. The writer has found the Lowell Fountain Compressed
Air Sprayer, made by the Lowell Specialty Company of Lowell







Whitefly Conditions in 1906.


Michigan, a very desirable machine. The tank holds three
gallons and is furnished with nozzles giving three sprays of
different degrees of fineness, and a solid spray. The finest spray
makes a mist and this is the one to use for spraying the fun-
gus spores. It should be ordered with about ten feet of ex-
tension pipe for spraying in the tops of trees. It is made of
brass or galvanized steel. The latter metal should be ordered
for spraying the fungi. E. O. Painter & Company, Jackson-
ville, are the agents. Cost complete about six dollars.
The "Auto" Compressed Air Sprayer sold by Peter Hen-
derson &Company, New York, appears also to be a desirable
machine. It can be obtained, made from galvanized steel, for
$6.00, extension pipe extra. Order with nozzle capable of
producing spray as fine as mist.

4. THE WEATHER AT LEESBURG.
The following is an abstract from notes kindly kept for
the writer by Mr. H. S. Budd, of Leesburg, during the period
of the observations at that place noted in the text. These ob-
servations were begun August 15th and terminated December
22nd, 1906. Unless otherwise mentioned, the weather was fair
during this period.
August: I7th, some rain; i9th, light shower; 23rd, 5/2
hrs, rain; 24th, cloudy; 25th, heavy rain one hour, then steady;
26th, cloudy all day with frequent rains; 27th, cloudy all day,
some rain; 28th, heavy showers and rain all day; 30th, rain and
thunderstorm; 3rst, fine but rain after dark.
September: 3d, partly cloudy and heavy storm; 8th, fine
but one half hour rain at 7 p. m.; 9th, heavy storm p. m.; Ioth,
little rain; I8th, rain; 23d, light rain for one hour; 24th, rain;
25th, rain; 26th, rain; 27th, light rain.
October: ist, rain and thunderstorm; 2nd, rain; 5th, rain;
8th, little rain; 9th, slight rain; i5th, some rain; I6th, fine and
cloudy; I7th, wet; i8th, rain, 19th, cloudy; 2oth, mostly
cloudy; 21st, rain; 22nd, cloudy; 23d, drizzle; 24th, dull; 28th,
colder; 29th, colder.
December: Drought broken night of i9th; 19th and 20th
cloudy with light rains.








iuillCtiln Vo. 88.


APPENDIX 4.
THE WEATHER AT LEESBURG.
The following notes have been inserted for the purpose
of showing the contrast between the weather conditions as they
existed during the months of June, July. August and part of
September, when the Fungi started readily and spread rapidly,
and the conditions during September, October, November and
December. when this was not the case. There being no Weath-
er Bureau Station at Leesburg, Mr. H. S. Budd kindly kept a
record of the rainy days for me. but as I have since been able
to get a complete record taken at Orange Home, only about
eight miles from Leesburg, I have decided to let the latter re-
cord represent the conditions at Leesburg, but giving also Mr.
B>udd's record.
It will be observed from the table that during the months
most favorable for the Fungi, the mean temperature was
above So and the precipitation (rain) very abundant; that dur-
ing the less favorable (or unfavorable) months the temperature
either dropped considerably below 80 or the amount of precipi-
tation became strikingly less, or both. No experiments in
starting the Fungi have been tried during January, February,
March, April or May. but judged by the conditions repre-
sented in the table, the first four months were very likely un-
favorable. On the other hand, the Fungi would probably
have done well during May, there being then an abundance of
rain and a temperature fairly high.
The weather conditions here indicated were, of course, not
exactly the same throughout the State, and variations will
also occur from year to year. These observations, and others,
indicate, however, about the time when we may expect to get
a good start of Fungus and when we may expect to get only a
poor start or none at all.
Table showing mean temperature in degrees Fahrenheit,
precipitation in inches, and number of rainy days at Orange
Home, Sumter county.
Jn Feb. Mar. April May I JuneI July Aug.l Sept. Oct. _No. Dec.
Mean temp........... 59 8 70 766 813 80.7 81 81.6) 72 6 67.8 59.6
Precipitation .. 56 4 1 05 2 4 231 5 25 9 0 8 4 7 1I7 1 2 49 14
Rainy days ... 6 8 6 10 15 20 15 12 5 3 1
Mr. Budd's record' .. 9* 10 11 0 ? 2
Last half. ( Or more.








Whitefly Conditions in 1906.


AFTER FREEZE SUGGESTIONS.

In trees and groves where the friendly fungi are found in
abundance, it is advised to collect large quantities of the dead
leaves still found clinging to the trees, or fallen leaves, with
plenty of fungus upon them. These should be dried and
stored for use in again starting the fungi the next spring or
summer. Should the fungus upon the leaves prove useless by
the time it is desired to use it, little labor will have been lost.
Samples of such leaves sent to the Station at the proper
time will be gladly tested for the vitality of the fungi.
Again, in view of the fact that freezing has begun the work
of defoliating, it may be desirable to complete it, and thus as
far as possible reduce the whitefly at one stroke. If but few
green leaves remain upon a tree it is advisable to complete
the defoliation by trimming, otherwise spraying with some
good insecticide may be adopted. There being but relatively
few leaves upon a tree it should be possible to spray success-
fully, at such a time. All whitefly larvae and pupae (the
stages found under the leaves at freezing time) will die when
the leaves dry, but to insure against the possibility of any
nearly mature insects completing their development and aiding
in reinfesting a grove, all fallen leaves should be carefully
plowed under or burned.

ACKNOWLEDGEMENTS.

Acknowledgement is due Mrs. E. W. Berger for criti-
cisms and aid in preparing the manuscript. Also to Mr.
H. S. Budd, of Leesburg, for advice and valuable data.




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