• TABLE OF CONTENTS
HIDE
 Front Cover
 Summary
 Table of Contents
 Favorable conditions in Florid...
 These fungi do not attack...
 Care necessary for success
 Time necessary to secure infec...
 The experiment station cannot supply...
 The red-headed fungus
 The white-headed fungus
 The black fungus
 The red fungus of the whitefly
 The yellow fungus of the white...
 The brown fungus of the whitef...
 The cinnamon fungus






Group Title: Bulletin - University of Florida. Agricultural Experiment Stations ; No. 119
Title: Fungus diseases of scale insects and whitefly
CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00027211/00001
 Material Information
Title: Fungus diseases of scale insects and whitefly
Series Title: Bulletin University of Florida. Agricultural Experiment Station
Physical Description: p. 69-82 : ill. ; 23 cm.
Language: English
Creator: Rolfs, P. H ( Peter Henry ), 1865-1944
Fawcett, H. S ( Howard Samuel ), b. 1877
Publisher: University of Florida Agricultural Experiment Station
Place of Publication: Gainesville Fla
Publication Date: 1913
 Subjects
Subject: Scale insects -- Biological control -- Florida   ( lcsh )
Citrus whitefly -- Biological control -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: by P.H. Rolfs and H.S. Fawcett ; rev. by P.H. Rolfs.
General Note: Cover title.
Funding: Bulletin (University of Florida. Agricultural Experiment Station)
 Record Information
Bibliographic ID: UF00027211
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: aleph - 000921879
oclc - 18161162
notis - AEN2347

Table of Contents
    Front Cover
        Page 69
    Summary
        Page 70
    Table of Contents
        Page 70
    Favorable conditions in Florida
        Page 71
    These fungi do not attack trees
        Page 71
    Care necessary for success
        Page 72
    Time necessary to secure infection
        Page 73
    The experiment station cannot supply fungi
        Page 73
    The red-headed fungus
        Page 74
    The white-headed fungus
        Page 75
        Page 76
        Page 77
    The black fungus
        Page 78
    The red fungus of the whitefly
        Page 79
        Page 80
    The yellow fungus of the whitefly
        Page 81
    The brown fungus of the whitefly
        Page 81
    The cinnamon fungus
        Page 82
Full Text




UNIVERSITY OF FLORIDA

Florida

Agricultural Experiment Station


FUNGUS DISEASES OF SCALE
INSECTS AND WHITEFLY
BY
P. H. ROLFS and H. S. FAWCETT
Revised by P. H. ROLFS





















Fig. 13.-The remedy applied.
The Station Bulletins will be sent free upon application to the Experiment
Station, Gainesville, Fla.


THE E. O. PAINTER PRINTING CO.. DE LAND. FLA.


BULLETIN I19


NOVEMBER, 1913










SUMMARY

. The climate of Florida is especially favorable to the development of fungus
diseases of insects.
2. The peculiar life habits of scale insects and whitefly larvae make them es-
pecially liable to attacks of fungus diseases.
3. Treating orchard pests by means of their diseases is the natural method, and
an economical one.
4. Spraying with insecticides to reduce the number of scale insects is recom-
mended for small and badly infested trees, or for older trees that have been
greatly neglected.
5. The six fungi discussed in this bulletin have been known for years and used
successfully.
6. These parasitic fungi have saved the Florida citrus-growers many hundreds
of thousands of dollars.
7. The Experiment Station is unfortunately financially unable to supply fungus
material, but this can be obtained from private parties. (See list on page
73.)




CONTENTS

Page
Favorable Conditions in Florida _.. ----------__ --_71
These Fungi Do Not Attack Trees------------------------------- 71
Care Necessary for Success -- -------- ----------------------- 72
Time Necessary to Secure Infection------------------- --------73
The Experiment Station Cannot Supply Fungi -------------_-----73
Where Fungi May Be Bought-------7---- ------------ 73
The Red-Headed Fungus --- ----_-------------------- 74
Species of Scale Insects Infected--------------------- --- 74
How to Apply the Fungus-------------------------------- 75
The White-Headed Fungus __--_------------- -------------_ 75
How to Apply the Fungus-------------- ------- ---------76
Species of Inscets Infected -------------------------77
The Black Fungus --- ------------ ---------------78
Scale Insects Attacked--------_------- ------------------- 78
How to Apply the Fungus ---- ---------- 79
The Red Fungus of the Whitefly----- ----------- ----79
How to Apply the Fungus --- ----------- ------ -80
The Yellow Fungus of the Whitefly ----------- ------------ 81
How to Apply the Fungus------------------ ---------- _---81
The Brown Fungus of the Whitefly --------------81
How to Apply the Fungus--------------------------- ---82
The Cinnamon Fungus-------------- ---------------- 82
How to Apply the Fungus-----------------------------------82










SUMMARY

. The climate of Florida is especially favorable to the development of fungus
diseases of insects.
2. The peculiar life habits of scale insects and whitefly larvae make them es-
pecially liable to attacks of fungus diseases.
3. Treating orchard pests by means of their diseases is the natural method, and
an economical one.
4. Spraying with insecticides to reduce the number of scale insects is recom-
mended for small and badly infested trees, or for older trees that have been
greatly neglected.
5. The six fungi discussed in this bulletin have been known for years and used
successfully.
6. These parasitic fungi have saved the Florida citrus-growers many hundreds
of thousands of dollars.
7. The Experiment Station is unfortunately financially unable to supply fungus
material, but this can be obtained from private parties. (See list on page
73.)




CONTENTS

Page
Favorable Conditions in Florida _.. ----------__ --_71
These Fungi Do Not Attack Trees------------------------------- 71
Care Necessary for Success -- -------- ----------------------- 72
Time Necessary to Secure Infection------------------- --------73
The Experiment Station Cannot Supply Fungi -------------_-----73
Where Fungi May Be Bought-------7---- ------------ 73
The Red-Headed Fungus --- ----_-------------------- 74
Species of Scale Insects Infected--------------------- --- 74
How to Apply the Fungus-------------------------------- 75
The White-Headed Fungus __--_------------- -------------_ 75
How to Apply the Fungus-------------- ------- ---------76
Species of Inscets Infected -------------------------77
The Black Fungus --- ------------ ---------------78
Scale Insects Attacked--------_------- ------------------- 78
How to Apply the Fungus ---- ---------- 79
The Red Fungus of the Whitefly----- ----------- ----79
How to Apply the Fungus --- ----------- ------ -80
The Yellow Fungus of the Whitefly ----------- ------------ 81
How to Apply the Fungus------------------ ---------- _---81
The Brown Fungus of the Whitefly --------------81
How to Apply the Fungus--------------------------- ---82
The Cinnamon Fungus-------------- ---------------- 82
How to Apply the Fungus-----------------------------------82











FUNGUS DISEASES OF


SCALE INSECTS AND WHITEFLY


BY P. H. ROLFS AND H. S. FAWCETT
REVISED BY P. H. ROLFS


FAVORABLE CONDITIONS IN FLORIDA

Nowhere else in the world have fungus diseases been employed
to combat scale insects and similar pests to so large an extent as
in Florida. This is largely due to the fact that our climatic condi-
tions are especially favorable to the spread of fungi. It happens
that Florida, in addition to having an abundant rainfall, has also a
moist atmosphere.
The use of fungi and bacteria to produce diseases of insects
has been advocated from time to time as a means of repressing
insect pests. The conditions, however, under which many species
live are such as to make it a difficult matter to apply the remedy.
Wherever species occur that are gregarious in their habits, the dis-
ease method of combating them can be used with advantage.
Many species of scale insects and similar insects in Flor-
ida suffer great annual diminution from fungus diseases. This
can be readily proved by simply treating a scale-infested plant with
a fungicide, such as Bordeaux mixture, which will then destroy
the fungi that kill the insects, and a great increase of the latter
will ensue. There are still many undiscovered species of fungus
which attack these forms of insects.

THESE FUNGI DO NOT ATTACK TREES
It is frequently asked whether it is not dangerous to introduce
these fungi into an orchard, the questioner fearing that they might
produce a disease of the trees, or attack the fruit. No such dan-
gers need be anticipated from any of the scale-destroying fungi that
we have so far discovered. As soon as these fungi have destroyed
the scale insects or other pests upon which they live there is no
more food for them to exist upon and consequently they must per-











FUNGUS DISEASES OF


SCALE INSECTS AND WHITEFLY


BY P. H. ROLFS AND H. S. FAWCETT
REVISED BY P. H. ROLFS


FAVORABLE CONDITIONS IN FLORIDA

Nowhere else in the world have fungus diseases been employed
to combat scale insects and similar pests to so large an extent as
in Florida. This is largely due to the fact that our climatic condi-
tions are especially favorable to the spread of fungi. It happens
that Florida, in addition to having an abundant rainfall, has also a
moist atmosphere.
The use of fungi and bacteria to produce diseases of insects
has been advocated from time to time as a means of repressing
insect pests. The conditions, however, under which many species
live are such as to make it a difficult matter to apply the remedy.
Wherever species occur that are gregarious in their habits, the dis-
ease method of combating them can be used with advantage.
Many species of scale insects and similar insects in Flor-
ida suffer great annual diminution from fungus diseases. This
can be readily proved by simply treating a scale-infested plant with
a fungicide, such as Bordeaux mixture, which will then destroy
the fungi that kill the insects, and a great increase of the latter
will ensue. There are still many undiscovered species of fungus
which attack these forms of insects.

THESE FUNGI DO NOT ATTACK TREES
It is frequently asked whether it is not dangerous to introduce
these fungi into an orchard, the questioner fearing that they might
produce a disease of the trees, or attack the fruit. No such dan-
gers need be anticipated from any of the scale-destroying fungi that
we have so far discovered. As soon as these fungi have destroyed
the scale insects or other pests upon which they live there is no
more food for them to exist upon and consequently they must per-







Florida Agricultural Experiment Station


ish. One of our best orchardists having extensive orchards in the
State, has frequently said that he would prefer to have always
two or three scale-infested trees in the orchard. As long as
he had these scale-infested trees he was sure of knowing just where
he could put his hand on fungus material to keep down the scale in-
sects in the other trees. The same speaker stated, that one among
the many regrets he had after the great freeze was that he had lost
not only a considerable amount of well-grown wood from his trees,
but had also lost all his friendly fungi; and that he was somewhat
perplexed to know just where to get these fungi again to protect
his trees against the scale insects.
It is nearly certain-one might say almost beyond question-
that for the most part the diseases of scale insects and whitefly are
native to Florida. While this cannot be stated with absolute cer-
tainty, still the fact that the different fungi appear spontaneously
in widely separated orchards, as well as in hammocks of the State,
rather confirms one in this opinion. In addition to this, quite a
number of the fungi which attack scale insects have been found on
seedling trees growing near hammocks in localities where it would
not be probable that they could have been carried from cultivated
orchards.
CARE NECESSARY FOR SUCCESS

To control scale insects and whitefly by means of the fungus
diseases one must pay close attention to minor details, and must
make intelligent observations. It is impossible to carry out this
work successfully without due regard to the needs of the fungus
and the peculiarity of the insect pest that is to be controlled. For
such work to be effective, it is necessary to make close observations
of the entire orchard; to find where the greatest amount of scale
or whitefly is located; and to introduce the fungi in such positions
as will give the best opportunity for the spores to spread from
one limb to another, and from one tree to another.
It sometimes happens that orchards become very badly in-
fested with scale insects before one is aware of the fact; or, stating
it in other words, the orchardist becomes careless and neglects to
make observations in his field as frequently as he should. When
such a condition has arisen, especially in connection with recently-
planted or scattered trees, it will be best to relieve the condition
temporarily by spraying with some contact insecticide; such as







Bulletin 19


whale-oil soap or kerosene emulsion, or some good proprietary
brand. This will give the trees relief by reducing the amount of
scale present; and then as soon as the insecticide has disappeared,
the fungi may be introduced. Spraying for scale insects in Florida
must be looked upon as merely an expedient for helping any one
out of a position into which carelessness has allowed him to fall.

TIME NECESSARY TO SECURE INFECTION

In treating any kind of an orchard with fungus to destroy
scale insects or whitefly, one should not lose sight of the fact that
it requires a certain time before the fungus can be sufficiently dis-
seminated throughout the tree, or throughout the orchard, to do ef-
fective work. During the most favorable weather it will require
about four weeks for the infection to make itself visible to the un-
aided eye. In the case of the red-headed fungus of scale insects
the minimum time is a little less than this. During dry weather in
summer, or during cold weather in winter, it will take much longer
for the fungus to make a visible infection. It should be said,
however, that many infections occur which are not visible to the
unaided eye. It not infrequently happens, especially in the case of
the San Jose scale, that the red-headed fungus kills off a very large
percentage of the scales without producing any of the red pustules.

THE EXPERIMENT STATION CANNOT SUPPLY FUNGI

The Experiment Station is maintained by funds received from
the Federal treasury. The laws and regulations under which the
money is expended are made by the Federal Congress. As the
collecting and distributing of fungus is not an experiment, it could
not justly be charged to this fund. Our State Legislature could
easily make provision for such work if it was considered desirable.
Fungus material, however, can readily be obtained from private
sources.
WHERE FUNGI MAY BE BOUGHT

F. P. Henderson, Gainesville, Fla.; Frank Stirling, DeLand,
Fla.; S. L. Story, Eustis, Fla.
The cost of the material will vary according to the season in
which it is to be used, and the amount needed. In general, it runs
from one to three dollars an acre of trees to be treated.







Bulletin 19


whale-oil soap or kerosene emulsion, or some good proprietary
brand. This will give the trees relief by reducing the amount of
scale present; and then as soon as the insecticide has disappeared,
the fungi may be introduced. Spraying for scale insects in Florida
must be looked upon as merely an expedient for helping any one
out of a position into which carelessness has allowed him to fall.

TIME NECESSARY TO SECURE INFECTION

In treating any kind of an orchard with fungus to destroy
scale insects or whitefly, one should not lose sight of the fact that
it requires a certain time before the fungus can be sufficiently dis-
seminated throughout the tree, or throughout the orchard, to do ef-
fective work. During the most favorable weather it will require
about four weeks for the infection to make itself visible to the un-
aided eye. In the case of the red-headed fungus of scale insects
the minimum time is a little less than this. During dry weather in
summer, or during cold weather in winter, it will take much longer
for the fungus to make a visible infection. It should be said,
however, that many infections occur which are not visible to the
unaided eye. It not infrequently happens, especially in the case of
the San Jose scale, that the red-headed fungus kills off a very large
percentage of the scales without producing any of the red pustules.

THE EXPERIMENT STATION CANNOT SUPPLY FUNGI

The Experiment Station is maintained by funds received from
the Federal treasury. The laws and regulations under which the
money is expended are made by the Federal Congress. As the
collecting and distributing of fungus is not an experiment, it could
not justly be charged to this fund. Our State Legislature could
easily make provision for such work if it was considered desirable.
Fungus material, however, can readily be obtained from private
sources.
WHERE FUNGI MAY BE BOUGHT

F. P. Henderson, Gainesville, Fla.; Frank Stirling, DeLand,
Fla.; S. L. Story, Eustis, Fla.
The cost of the material will vary according to the season in
which it is to be used, and the amount needed. In general, it runs
from one to three dollars an acre of trees to be treated.






Florida Agricultural Experiment Station


THE RED-HEADED FUNGUS
Figure 14 is from a photograph of the red-headed fungus
(Sphaerostilbe coccophila Tul.) growing on the purple scale on a
branch of an orange tree. The red color of the fungus shows whitish
in the illustration.
The writer was the first to call attention to the fact that the red-
headed fungus is parasitic on the San Jose scale. The discovery
was made at De Funiak Springs, Fla., in May, 1896. Immediately
after making this discovery steps were taken to find means of using
it in a practical way to control this pernicious scale. The results of
these experiments showed that it was not only easy to infect scales
that were previously free from the disease, but that the work could
be done profitably under field conditions.
An important fact brought out in the laboratory investigations
is that myriads of scales are infected and killed by this fungus with-
out its being externally visible. It therefore frequently happens
that a scaly tree may be thoroughly overrun with this fungus, al-
though no red pustules are visible. This point should be especially
remembered when one is introducing the red-headed fungus. There
can be no longer any question as to its efficiency in Florida, since
hundreds of acres have been treated in a practical way with complete
success.
SPECIES OF SCALE INSECTS AFFECTED
SA large number of scale insects are
IT known to be affected by this fungus. The
following list gives only those that are of im-
% portance in Florida:
(I) Purple Scale (Mytilaspis citricola),
occurring mainly on the branches and leaves
of citrus.
(2) San Jose Scale (Aspidiotus perni-
ciosus), occurring mainly
on the branches of peaches,
plums and pears.
(3) Long Scale (Myti-
laspis gloverii), occurring
mainly on the branches and
Fig. 14-Red-headed fruit of citrus. Fig. 15 P. rithe-
Fungus. Enlarged cium. Enlarged
twice. (4) Round Scale (As- 75 times.







Bulletin 119


pidiotus ficus), occurring mainly on the leaves and fruit of citrus.
(5) Chinaberry Scale (Aspidiotus nerii), occurring mainly on
the branches and leaves of chinaberry.
(6) Chaff Scale (Parlatoria pergandii), occurring mainly on
the trunk and larger branches of citrus.
(7) Water Oak Scale (Aspidiotus obscurus), occurring mainly
cn the smaller branches of water oak.
(8) Red Maple Scale (Aspidiotus tenebricosus), occurring
mainly on the larger limbs and trunk of red or swamp maple.
About a dozen other scale insects, that are not present in Flori-
da, or that occur only rarely, are also affected. The orange scale
cf California (Aspidiotus amrantii) is among those attacked by it.
HOW TO APPLY TIE FUNGUS

The simplest and also an economical way is illus-
trated by Figure 13. One simply chooses a portion of the
tree that is most severely affected by scale insects, and
then applies the "remedy," as shown in the illustration.
It is advisable to place the fungus-bearing material up-
permost, so moisture from dews and rains will carry the
spores (see Figure 16) over and among the healthy scales. Fig. 16
Ascus
This method of introducing the fungus may be success- and
fully applied at any time of the year. It is advisable to spores.
use one to a dozen pieces in every tree, according to the 200times.
size of the tree and the severity of infestation by scale insects. Place
the fungus so it will be shaded from the direct rays of the sun.
This fungus has been successfully applied by the spore-spray-
ing method. (See "Red Fungus of the Whitefly.") Each red pus-
tule produces thousands of spores. One or two hundred pustules
to the gallon of water would seem to give a sufficient number of
spores to each drop of water to make a good catch. It will be ad-
visable to employ this method when rains occur during the growing
season. This fungus is usually most abundant from April until
November, but may be found at any time during the year.

THE WHITE-HEADED FUNGUS

This fungus (Ophionectria coccicola E. and E.) appears to
have been first mentioned by Mr. H. G. Hubbard in his book "In-
sects Affecting the Orange," published by the U. S. Department of







Florida Agricultural Experiment Station


Agriculture; though its true value
was not suspected at the time. In
Fact, the fungus at that time was
thought to be an injurious para-
.site rather than a friendly one. It
is more thoroughly distributed
S throughout the citrus-growing
sections of Florida than any other
S species of fungus. Curiously
enough, it happens that the fun-
gus is not recorded as occurring e.
on any of our native scales. For I
keeping the long scale and the
purple scale in check it is proba-
bly much more effective in the :
citrus orchard than is the red-
Fig. 17.-White- headed fungus. It is much better Fig. 18.-White-
headed Fungus. known than the latter, and much headed Funeus.
Imperfect stage. Perfect stage.En-
Natural size. more commonly used. The writer large twice.
found the white headed fungus
present in all sections of the State where citrus groves occur. Some-
times small groves are found without this fungus. Under such
circumstances, the long scale and purple scale make unusual head-
way, and not infrequently kill large branches. Recently-set trees
are sometimes killed by these scales before the fungus has had an
opportunity to destroy the scale. Like the red-headed fungus, this
seems to be a tropical species, occurring in Java, South Africa, the
West Indies, and South America.
'Figure 17 is from a photograph of the white-headed fungus
growing on the purple scale on an orange tree.
Figure 18 is from a photograph of the perfect stage of the
white-headed fungus (enlarged twice) killing purple scale on an
orange twig.
HOW TO APPLY THE FUNGUS
The method of applying the fungus is exactly the same as
that for applying the red-headed fungus. The pustules which con-
tain the conidia are usually a little longer time in making their ap-
pearance than in the case of the red-headed fungus. The spore-
spraying method has not been employed extensively with this fun-
gus because the other method has been so satisfactory and effective.







Bulletin 119


SPECIES OF INSECTS INFECTED
In Florida this fungus has been re-
peatedly found by entomologists and
plant pathologists of the Experiment Sta-
tion during the last fifteen years. From
the literature at hand it would seem that
this fungus is much more effective in
the long scale and the pur- Fig. 19. Fig. 20.-Conidial
keeping down the long scale and the pur- A head spore. Enlarged
ple scale in Florida than in any other por- enlarged 130 times.
15 times.
tion of the world. Its usefulness with us,
seems, however, to be limited to these
two scale insects. Fortunately, it is very
effective on these two species, which are
the commonest and most destructive of
our scale insects when left uncontrolled.
'Figure 19 shows one of the conidia-
bearing heads of the white-headed fun-
Fig. 21.-Conidial spore ger-
minating. Enlarged gus, enlarged 15 times.
130 times. Figure 20 shows the peculiar tri-
dent conidial spore. The arms of the trident
close up on drying and open on becoming
damp, causing the spores to move about.
Figure 21 shows a trident co-
nidial spore germinating in water.
Figure 22 shows a perithecium
of the white-headed fungus in cross-
section. Enlarged 80 times.
Figure 23 shows an ascus with
Fig. 23. ascospores enlarged I o times.
Ascus. En-
rged 110 Figure 24 shows three asco- Fig. 22.-Perithecium.
times. spores enlarged 400 times. Enlarged 80 times.
Figure 25 shows the germination of an ascospore in water.



Fig. 24.-Asco-
spores. En-
larged 400
times.
Fig. 25.-Ascospore germi-
nating. Enlarged 180times.







Florida Agricultural Experiment Station


THE BLACK FUNGUS

The honor of discovering
and first experimenting with
this fungus (Myriangium du-
riaei Mont.) as a parasite of
scale insects belongs to Prof. t
W. M. Scott, who reported in
1898 successful experiments
with it in destroying the San
Jose scale. It had been collect-
ed many times previously, but
had always been considered as
m living on the bark of various
S plants. Its range of distribution
seems to be more northerly
Fig. 26-Imperfect than that of the white-headed Fig. 27- Perfect
stage. Natural stage. Natural
size. fungus, and it is probably not size.
so widely distributed as the red-headed fungus. For the most
Dart, the observations as to the scales upon which it lives have beer
less carefully made than in other cases. It occurs in all parts of
the State, and is probably more generally distributed throughout
Florida than either of the foregoing species.
Figure 26 is from a photograph of the immature stage of the
black fungus killing the chaff scale on an orange twig.
Figure 27 is from a photograph of the perfect stage of the
black fungus killing scales on an orange twig.
SCALE INSECTS ATTACKED
A fungus referred to by Professor
Hume in his book, Citrus Fruits and
Their Culture, is probably
this species. It occurs on the
chaff scale, the purple scale,
the long scale, and on the
San Jose scale in Florida. It
Fig. 28-Cross section of per- is especially useful in de- Fia 29.--Ascus
feet stage. Enlarged 70 times. stroking the chaff scale, times
which occurs so abundantly on the larger limbs and trunks of trees.
The peculiar habit of this fungus in forming a heavy black crust,
makes it more difficult to determine the species of scale parasitized.







Bulletin ni9


For this reason many of the records of its parasitism
are rather indefinite. Vhen this fungus destroys ,
scales located on citrus fruit it is more or less trou-
blesome. It sticks so firmly to the fruit that some
of the black spots do not wash off in passing through Fig. 30-Spores.
Fig. 30-Spores.
the washer. Enlarged 500
Figure 28 shows a cross section of the mature times.
fungus bearing the asci.
Figure 29 shows an ascus of the black fungus with spores.
Figure 30 shows spores of the black fungus.

HOW TO APPLY THE FUNGUS

This fungus occurs on any portion of the tree infested by the
scale affected. To apply the fungus, a small sprig three to six
inches long should be tied to the scale-infested portion of the tree.
It is best to put the fungus as nearly as possible in contact with
the scales we desire to infect. In some instances we have found
that the fungus was slow in killing the scales, especially in small
trees, but that finally the eradication was perfect. In one case
the fungus was a year and a half in killing off the last remnant of
the scale, but the same tree has remained free from scales down to
the present day-a period of over four years.


THE RED FUNGUS OF THE WHITEFLY


Fig. 31-Red Fungus of Whitefly. Natural size.







Florida Agricultural Experiment Station


This fungus (Aschersonia aleyrodis) was discovered by Dr. H.
j. Webber, and described by him in 1897. In Bulletin 103 of the
Florida Experiment Station will be found a full description of this
fungus and the methods employed for using it. The following are
brief directions based upon the information there contained.
HOW TO APPLY THE FUNGUS

Spore-Spraying Method.-Dr. E. W. Berger, while Entomolo-
gist of the Experiment Station, developed the spraying method for
applying this fungus. Up to that time various other less satisfacto-
ry methods had been employed.
Place from 25 to 50 leaves having an abundance of pustules on
them in a pail of water. More may be used if an abundance of ma-
terial is at hand. Allow these to soak from five to ten minutes or
longer, stirring the mixture from time to time. Then pour the mix-
ture into the tank of a spraying machine, passing it through cheese-
cloth or something else that will strain out the particles that might
clog the nozzle. The spraying mixture should be used soon after
having been prepared, though it may be allowed to stand for twelve
to fifteen hours without serious injury to the spray. Care should be
taken not to use any spraying machine for this purpose that has pre-
viously been used for spraying fungicides or insecticides. Some
such machines have been used successfully, but they were thoroughly
washed and scoured clean of the insecticide before being used.
Apply this mixture to the under sides of the leaves as far as
possible, giving special attention to the under sides of leaves borne
on water-sprouts.
The condition of the weather is a very important feature in get-
ting a good catch of this fungus. Some of the very best catches
that Dr. Berger made came from applications made during the rainy
season when the atmosphere was extremely humid. In fact, some
very good catches occurred from sprayings made during rain.
The Application of this Method.-A great many thousands
of trees have been treated in this way with the best of success. In
fact, it has gotten to be what we would call the practical way of com-
bating whitefly. Mr. Frank Stirling, of DeLand, has sprayed
thousands of trees belonging to scores of different owners; besides
this, he has furnished hundreds of thousands of leaves to people to
apply themselves. Mr. E. B. Stevens, formerly of Lakeland, has
also used it very extensively. Mr. S. L. Story, of Eustis, is another







Bulletin jp 81

person who has applied this to a great many different groves; and
like other people who are applying these spores, guarantees his work.
Leaf-Pinning Method.-This was employed to some extent in
the early days when the spore-spraying method was not well under-
stood. It consists merely in pinning leaves bearing a number of
pustules to the tree affected with whitefly, pinning them preferably
on water-sprouts and other places where the whitefly are likely to
occur in considerable abundance. This method, however, is slow,
and would not be considered economical on a grove scale.

THE YELLOW FUNGUS OF THE WHITEFLY
This fungus (Aschersonia flavo-citrina) was first described
from specimens collected in Brazil on guava leaves. It was discov-
ered in Florida in 1906. It resembles the red whitefly fungus in
habits and general appearance, except in the matter of coloring.
It is useful only in combating the cloudy-winged whitefly
(Aleurodes nubifera), and for this purpose it is probably no more
effective than the red whitefly fungus.
HOW TO APPLY THE FUNGUS

It may be applied in the same manner as the red whitefly fun-
gus.
THE BROWN FUNGUS OF THE WHITEFLY
I --I


Fig. 32-Brown Fungus of Whitefly. Natural size.







Bulletin jp 81

person who has applied this to a great many different groves; and
like other people who are applying these spores, guarantees his work.
Leaf-Pinning Method.-This was employed to some extent in
the early days when the spore-spraying method was not well under-
stood. It consists merely in pinning leaves bearing a number of
pustules to the tree affected with whitefly, pinning them preferably
on water-sprouts and other places where the whitefly are likely to
occur in considerable abundance. This method, however, is slow,
and would not be considered economical on a grove scale.

THE YELLOW FUNGUS OF THE WHITEFLY
This fungus (Aschersonia flavo-citrina) was first described
from specimens collected in Brazil on guava leaves. It was discov-
ered in Florida in 1906. It resembles the red whitefly fungus in
habits and general appearance, except in the matter of coloring.
It is useful only in combating the cloudy-winged whitefly
(Aleurodes nubifera), and for this purpose it is probably no more
effective than the red whitefly fungus.
HOW TO APPLY THE FUNGUS

It may be applied in the same manner as the red whitefly fun-
gus.
THE BROWN FUNGUS OF THE WHITEFLY
I --I


Fig. 32-Brown Fungus of Whitefly. Natural size.







82 Florida Agricultural Experiment Station

This fungus (Aegerita weebberi Fawcett) was discovered by Dr.
H. J. Webber. Its scientific position, however, was not known until
Professor H. S. Fawcett discovered its spores. Since that time the
fungus has been employed to a considerable extent, and gives ex-
tremely satisfactory results. In fact, some citrus growers con-
sider it better than all of the other natural agencies combined.

HOW TO APPLY THE FUNGUS
The spores of this fungus are not produced on the lower side
of the leaves where the pustules are, but occur on the upper side of
the leaves, and when the spore-bearing stage is reached, the leaves
show a cinnamon-brown color on the upper side. The spores can
usually be observed by the use of a strong hand-magnifier.
When the spores are found to be present, they are used in the
same way as is described for the Red Whitefly Fungus.

THE CINNAMON FUNGUS

This fungus (Verticillium heterocladum) occurs from time
to time upon the clear-winged whitefly, chaff scale, orange soft scale
(Lecanium hesperidum), and on the purple scale.

HOW TO APPLY THE FUNGUS
This fungus has not been found to be sufficiently active in hold-
ing the more serious scale insects in check to merit very much
study, consequently very little is known about the best ways of
applying it.




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