Sooty
Mold
Environmental Protection and Growth Management Department
Air Quality Program
Ambient Monitoring Section
What is it?
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Residents of several cities in
Broward county have
complained of finding a
dark, sooty material on
surfaces in their yards, such
as picnic tables, leaves, and
cars.

The residents were
concerned that the material
was from anthropogenic
sources, specifically,
airplane or vehicular
emissions.
Purposes of studies performed by
the Air Quality Program

To determine if the material in question is of
anthropogenic origin.
 To determine the source of the material.
 To assuage the concerns of the residents in
affected areas.
Collecting Samples for Microscopic
Analysis

Collection of affected biota/material in clean
plastic baggies.
Sirchie
Evidence Vacuum Sweeper

Collection of material by scraping a sample it off
the affected surface into a clean Petri dish.
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Collection of material with an evidence vacuum
sweeper.
Microscopes used for Particle
Identification
Stereomicroscope Images of Sooty
Material
PLM Images of Sooty Material
Sooty Mold
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The material was identified as sooty mold.
Sooty mold is a black coating of fungal
growth on leaves, branches, and fruit.
The fungus is usually powdery and dark
colored, hence the name - sooty mold.
The fungi associated with this condition are
do not feed on live plant tissue, but rather
on insect secretions with a high content of
sugars (honeydew).
If the honeydew is light, the mold may
appear only in spots.
As a general rule, sooty mold can usually
be rubbed off easily from the surface of
leaves, fruit, or branches.
After some time, the fungus may dry-off,
become flaky, and fall off.
Generally, the amount of sooty mold will
decrease if the insect population decreases.
If no insects are present to cause a reinfestation, rains will usually wash off most
of the sooty mold.
There are two types of sooty mold.
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A deciduous growth on leaves, which lasts
for the life of the leaf.
A persistent growth on stems and twigs of
woody plants, and on human-made
structures
Chemical Analysis of Sample
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To make certain the material was correctly identified as sooty mold and no anthropogenic
emissions were present, the material was analyzed by GC/FID.
Gas Chromatography with Flame Ionization Detector (GC/FID) is used in the
identification of organic compounds. Standards and samples are run on the instrument with
the same settings.
Identification and quantification of the materials are made by comparing the standard and
sample spectra.
Results of GC/FID Analysis of Sooty Material
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Several organic fuel and
solvent standards were
analyzed:
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Broward County EPD/Environmental Monitoring Division (EMD)
GC/FID
Analysis results.
Diesel fuel
Jet fuel
Kerosene
Mineral spirits
Unleaded gasoline
The material on found on
various plants in Broward
County was sooty mold
and no evidence of any
hydrocarbon-based fuels
was found in the samples.
Conclusions

Based upon the microscopic observations, all the samples collected from
plants contain sooty mold on their surfaces. Although the extent of
coverage and insects present varied among the different samples analyzed.
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The possibility of the substance being a petroleum based-fuel from the Ft.
Lauderdale Executive Airport is not likely, as demonstrated by the analysis
of the sample by gas chromatography with flame ionization detector.
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Additionally, despite the different varieties of plants present on the
complainants’ properties, the black substance was only present on certain
plants. Some plants were not affected at all by the material. If this were
truly an inert substance such as combustion emissions, it would be on
nearly everything in the yard not certain plants only.
Additional Information on
Sooty Mold
Identification, Causes, and
More…
The Symptoms of Sooty Mold

The presence of a black, soot-like
fungus, frequently appearing as a
thin crust over the surface of
leaves, is the best indicator of this
problem.
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Some species of sooty molds
grow as a thick, spongy mass that
encases the needles of conifers or
the twigs of deciduous trees.
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Insect activity may or may not be
apparent.
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Sooty molds may persist long
after the insects themselves have
disappeared.
The Effects of Sooty Mold on Plants

Since sooty molds are not parasitic organisms
and do not penetrate the plant tissue, there is
no direct injury to the plant from the sooty
mold.

Severely affected plants may be yellowed and
suffer defoliation from the combined effects
of insect feeding and the reduction in
photosynthesis that results from the blockage
of sunlight by the fungus.

Fruits or vegetables covered with sooty molds
are edible after removal of the mold with a
solution of mild soap and warm water.
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Although sooty mold usually does not cause
dieback or mortality, the insect feeding which
attracted the sooty mold infestation may have
been severe enough to weaken or kill portions
of infested plants.
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Pruning out dead and dying branches helps
prevent infection by secondary pathogens.
The Link Between Insects
and Sooty Mold
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Although a few
sooty mold fungi
grow on plant
substances exuded
by the leaves,
most grow on the
honeydew
produced by
certain sucking
insects.
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Especially
important are:
– Whitefiles
– Aphids
– Mealy Bugs
– Scale Insects
Whiteflies
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Whiteflies are tiny (about 1/16 of
an inch in length), white moth-like
insects.
Both adult and nymph stages feed
by sucking plant juices.
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Common species of whiteflies are:
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Heavy feeding can give plants a
mottled look, cause yellowing,
and may eventually cause death to
the host plant.
greenhouse,
silverleaf.,
sweet potato, and
banded wing,
Whiteflies attack a wide variety of
plants including bedding plants,
cotton, strawberries, vegetables,
and poinsettias.
Whiteflies are difficult to control.
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Chemical control programs often
have limited success.
The egg and pupa stages are
tolerant of most insecticides.
Whiteflies cling to the undersides
of leaves, making them difficult to
reach with chemicals or oil
sprays.
Aphids
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Aphids are soft-bodied insects with piercing
sucking mouthparts that feed on plant sap.
Aphids usually occur in colonies on the
undersides of tender new growth.
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(Photo by : J.L. Castner, Department
of Entomology and Nematology,
IFAS, University of Florida)
Used with permission from the University of
Florida, Institute of Food and Agricultural
Sciences (IFAS) Extension Ornamental
Insect Sheet 2 (reference no. 7).
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Heavily-infested leaves can wilt or turn
yellow because of excessive sap removal.
Aphid-feeding generally will not seriously
harm healthy, established trees and shrubs.
Some plants are very sensitive to feeding by
certain aphid species and can become
severely distorted, even if only a few aphids
are present.
Feeding on flower buds and fruit can cause
malformed flowers or fruit.
Aphids produce large amounts of honeydew.
Mealybugs
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Soft-bodied insects about 1/8"
long.
White to pinkish-white in color.
Several pairs of legs.
A mealy bug’s body is covered
with a waxy substance making
chemical control difficult.
Mealybugs tend to hide out in the
tight crevasses of the plant nodes.
Nearly any foliage plant can be
susceptible to this insect.
Mealybugs are hatched from
eggs.
– A female mealy bug can lay up
to 300 eggs with or without a
male.
– Nymphs or crawlers mature in
about 2 weeks.
Scale Insects
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Scale insects have piercing, sucking
mouthparts.
Feeding by scale insects weakens
and may kill plants.
Scale insects are classified as being
either armored or soft scale insects.
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The developmental stages of scale
insects are:
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egg (or live nymph),
nymph (females, three instars;
males, five instars), and
adult.
Scale insect development from egg
to adult is:
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Soft scales produce honeydew.
Armored scales do not produce
honeydew.
about 60 days for soft scales, and
about 180 days for armored scales,
but can vary widely with individual
species.
Adult males do not look like
females, but rather resemble small
midge-like insects.
Females of some species reproduce
without mating (parthenogenesis).
Managing Sooty Mold
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Most plants will tolerate a small insect population and light amounts of sooty mold.
Control of sooty molds begins with management of the insects creating the honeydew.
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Ant management is an important consideration in managing sooty mold.
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In some situations they can be dislodged with a strong stream of water.
Fertilizing and watering to keep plants healthy but not excessively vigorous also helps.
Ants are attracted to and use honeydew as a source of food.
Because of this, they will protect honeydew-producing insects from predators and parasites in order to
harvest the honeydew.
Keep ants out of trees and away from honeydew-producing insects by applying a sticky compound
around the trunk and trimming limbs touching buildings or other access points.
Baits, such as ant stakes placed under trees and shrubs, may help reduce ant foraging in some cases.
In many cases, predators and parasites are sufficiently abundant and quickly begin feeding on and
reducing populations of scale insects, aphids, whiteflies, or mealybugs once ants have been
eliminated.
If populations fail to decline, apply horticultural oils or insecticidal soap to suppress the
problem insects. One or more applications may be needed.
Sometimes prudent pruning can be helpful in removing most of the infested plant parts.
Once the honeydew-producing insects are suppressed, sooty molds will gradually weather
away.
A New South Florida Pest:
The Lobate Lac Scale
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Used with permission from the Florida Department of
Agriculture and Consumer Services, Florida State College
of Arthropods, Division of Plant Industry (FSCA-DPI)
(reference no. 10)
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Scientific name: Paratachardina
lobata lobata
First collected in Florida on August
25th 1999.
Native to India and Sri Lanka.
Pest to several tropical and
subtropical fruits and ornamentals
– Including hibiscus, coco plum,
black olive, weeping fig, wax
myrtle, buttonwood, sand live
oak, and fichus
P. lobata lobata is difficult to control.
It is the pest largely responsible for
the sooty mold on the large fichuses
in this area.
The Lac Scale Family: Kerriidae
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Best-known species: Kerria lacca
lacca
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(Photo by : F.W. Howard, University of Florida)
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Used with permission from the University of Florida,
Institute of Food and Agricultural Sciences (IFAS)
Extension, Lobate Lac Scale, Paratachardina lobata
lobata (Chamberlin)(Hemiptera: Sternorrhyncha:
Coccoidea: Kerriidae (reference no. 11).

These true lac scale insects have
been utilized for centuries in
making lacquer.
Most species of the family,
including P. lobata lobata, do not
produce any material of known
commercial value.
No species of Kerriidae is native to
Florida and adjacent land areas.
The Kerriidae is confined mostly
to the tropics.
The majority of the species of this
family of scales are distributed in
the eastern hemisphere.
Appearance of the Lobate Lac Scale
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Mature females are 1.5 to 2 mm long and
about the same width.
The body has two pair of prominent lobes
giving the body a unique x-shaped
appearance.
As the scale matures, individuals tend to
merge and may loose this distinctive shape.
The outer covering is very hard, glossy, and
dark reddish-brown.
Coloring may appear black because of the
coating of sooty mold.
The first instars (crawlers) are elongate-oval,
deep red, and about 0.2 mm long.
The characteristic lobate pattern develops in
the second instar.
The second instar female presumably molts to
the adult female as in other scale insects.
Males of this species have not been observed
in Florida.
Host Plants of the Lobate Lac Scale
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Lobate Lac Scales
have primarily
been found on
woody
dicotyledonous
plants, but have
also been found on
one coniferous
species (southern
red cedar) and on a
palm (Phoenix
roebele).
As of October
2002, more than
120 species in 44
families of woody
plants have been
determined to be
hosts of P. lobata
lobata in Florida
These include 39
plant species
native to Florida
(see adjacent
table).
Hosts Highly Susceptible to the Lobate Lac Scale
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On highly susceptible hosts, the Lobate
Lac Scale insects crowd on twigs and
branches of trees or shrubs forming a
contiguous mass that appears as a dark,
lumpy crust.
 Sooty mold covers the branches, the
insects themselves, and occurs in patches
on the foliage.
 Dense infestations are associated with
branch dieback of some plant species and
in severe cases, highly infested shrubs
and small trees have died.
 Certain native species appear to be
highly susceptible:
Used with permission from the University of
Florida, Institute of Food and Agricultural
Sciences (IFAS) Extension, Lobate Lac Scale,
Paratachardina lobata lobata
(Chamberlin)(Hemiptera: Sternorrhyncha:
Coccoidea: Kerriidae (reference no. 11).
– wax-myrtle, cocoplum, buttonwood,
strangler-fig, myrsine, red bay, and wildcoffee

Certain popular exotic ornamental plants
also appear to be highly susceptible:
– black-olive, Indian laurel, Benjamin fig,
and fruit trees (e.g., lychee, mango, and
star-fruit)
Spread of Lobate Lac Scale

Since the mature females of scale
insects are wingless, they play no role
in the dispersal of populations to
occupy new host plants.
 Scale insects rely mostly on passive
dispersal of the crawler stage via air
currents.
 A key factor in spreading scale insect
pests in urban areas is the movement
of infested host plants from one
location to another.
 Melaleuca serves as a good host for
the Lobate Lac Scale. Infested trees
can act as breeding grounds where
large numbers of larvae are free to
spread onto native and non-native
trees and plants.
From the TAME Melaluca website: http://tame.ifas.ufl.edu
Managing Lobate Lac Scale –
The Difficult Task Ahead
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The Lobate Lac Scale has rapidly become a major pest in
southeastern Florida.
There is no evidence that this scale insect species has natural
enemies in Florida.
Studies are being conducted to test horticultural oils and
additional chemical control methods.
Because it is predicted that with time a very large percentage of
trees and shrubs in both the urban and natural areas of Florida
will become infested with this scale insect, biological control is
being investigated as the only viable option for control in the
long term.
The United States Department of Agriculture – Agricultural
Research Service’s Invasive Plant Research Laboratory in
Davie, Florida is conducting extensive research on this scale
insect.
References
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
Kenneth J. Kessler, Principal Plant Pathologist. U.S. Department of Agriculture, Forest Service, North Central Research Station, How to
Recognize Sooty Mold, 1992.
http://www.na.fs.fed.us/spfo/pubs/howtos/ht_sooty/ht_sooty.htm
F.F. Laemmlen, University of California, Cooperative Extenion, Santa Barbara Co., Pest Notes: Sooty Mold, UC ANR Publication 74108, 2003.
http://axp.ipm.ucdavis,edu/PMG/PESTNOTES/pn74801.html
Mary Ann Hansen and Eric Day, Virginia Polytechnic Institute and State University, Virginia Cooperative Extension, Plant Disease Fact Sheet,
Sooty Mold of Conifers and Hardwoods, Publication No. 450-618W, 2000.
http://www.ext.vt.edu/pubs/plantdiseasefs/450-618/450-618.html
Jose M. Amador, Extension Plant Pathologist, Texas A& M University System, Texas Agricultural Extension Service, Diseases Affecting
Localized Parts of Trees
http://aggie-horticulture.tamu.edu/citrus/l2315.htm
Texas Nursery and Landscape Association, Texas A & M University System, College Station, Texas, Texas Agricultural Extension Service,
Departments of Entomology and Horticultural Sciences, Pest Profiles: Aphids.
http://hortipm.tamu.edu/pestprofiles/sucking/bartaphid/bartaphid.html
U.S. Department of Agriculture, Whitefly Knowledgebase (Developed at the University of Florida in cooperation with scientists at Texas A&M
University, the University of California, and Cotton Incorporated), 1995.
http://whiteflies.ifas.ufl.edu
D. E. Short and J. L. Castner, University of Florida, Institute of Food and Agricultural Sciences (IFAS) Extension, Ornamental Insect Sheet 2,
Document SP125, 1992.
http://edis.ifas.ufl.edu/BODY_IN024
M.A. Hoy, A. Hamon, and R. Nguyen, University of Florida, Institute of Food and Agricultural Sciences (IFAS) Extension, Pink Hibiscus
Mealybug, Maconellicoccus hirsutus (Green), Document EENY-029, 2002.
http://edis.ifas.ufl.edu/IN156
S. H. Futch, C. W. McCoy, and C. C. Childers, University of Florida, Institute of Food and Agricultural Sciences (IFAS) Extension, A Guide to
Scale Insect Identification, Document HS-817, 2001.
http://edis.ifas.ufl.edu/CH195
Florida Department of Agriculture and Consumer Services, Florida State College of Athropods, Division of Plant Industry (FSCA-DPI)
http://www.doacs.state.fl.us/pi/enpp/ento/paratachardina.html
F. H. Howard, R. Pemberton, A. Hamon, G. S. Hodges, B. Steinberg, C.M. Mannion, D. McLean, and J. Wofford, University of Florida, Institute
of Food and Agricultural Sciences (IFAS), Extension, Lobate Lac Scale, Paratachardina lobata lobata (Chamberlin)(Hemiptera:
Sternorrhyncha: Coccoidea: Kerriidae, Document EENY-276, 2002.
http://edis.ifas.ufl.edu/IN471
L. Williams, Department of Horticulture, Okaloosa County Cooperative Extension Service, University of Florida, Sooty Mold: Control Sooty
Mold on Plants by Stopping it Before it Starts, 2002.
http://okaloosa.ifas.ufl.edu/sootymold.html
References (Continued)
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
W. C. McCrone and J. G. Delly, The Particle Atlas: An Encyclopedia of Techniques for Small Particle Identification, Edition Two, Ann Arbor
Science Publishers, Inc., Ann Arbor, MI, 1973.
S.C.E.P.M.A.B., S.C.C.E.S. AND S.C.M.C.D., University of Florida, Institute of Food and Agricultural Sciences (IFAS) Extension, What’s
Bugging Me?- A Guide for Environmental Landscape Pest Control by Homeowners, Document ENY292, 1997.
http://edis.ifas.ufl.edu/In043
Karen L. Snover, Director, Plant Disease Diagnostic Clinic at Cornell University, Sooty Mold
http://www.plantclinic.cornel.edu/FactSheets/sooty/sootymold.htm
Stephen Nameth, Jim Chatfield, and David Sheltar, Ohio State University, Ohio State University Extension Fact Sheet, Plant Pathology, Sooty
Mold on Trees and Shrubs Fact Sheet, Document HYG-3046-96, 1996.
www.ohioline.osu.edu/hyg-fact/3000/3046.html
Ken Pernezny and R.B. Marlatt, University of Florida, Institute of Food and Agricultural Sciences (IFAS) Extension, Some Common Diseases of
Tahiti Lime in Florida, Document PP24, 1993.
http://edis.ifas.ufl.edu/BODY_VH049
Scott C. Nelson, Ph.D. Associate Specialist in Plant Pathology, University of Hawai’I at Manoa, College of Tropical Agriculture and Human
Resources, The Noni Website, Pest and Diseases, Noni Sooty Mold. 2005
http://www.ctahr.hawaii.edu/noni/sootyMold.asp
Agricultural Research Organization, The Volcani Center, Israel Department of Entomology, The United States Department of Agriculture,
Systematic Entomology Laboratory, Agriculture & Agri Food Canada, Eastern Cereal & Oilseed Research Centre, and the United States-Israel
Binational Agricultural Research and Development Fund, Scale Net (This is a site about scale insects), 2005
http://www.sel.barc.usda.gov/scalenet/scalenet.htm
Minnesota Department of Natural Resources, Sooty Mold website, 2005
http://www.dnr.state.mn.us/fid/july 98/07319801.html
University of Florida, Institute of Food and Agricultural Science Extension, TAME Melaluca Project
http://tame.ifas.ufl.edu
Robert W. Pemberton, Potential for Biological Control of the Lobate Lac Scale, Paratachardina Lobata Lobata (Hemiptera: Kerriidae), Florida
Entomologist 86(3), pp 353 – 360, September 2003.
http://www.fcla.edu/FlaEnt/fe86p353.pdf#search='control%20of%20P.%20lobata%20lobata%20india‘
United States Department of Agriculture – Agricultural Research Service’s Invasive Plant Research Laboratory website.
http://www.ars.usda.gov/main/site_main.htm?modecode=66-29-00-00