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Sooty Mold Environmental Protection and Growth Management Department Air Quality Program Ambient Monitoring Section
What is it? n 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. n 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 n To determine if the material in question is of anthropogenic origin. n To determine the source of the material. n To assuage the concerns of the residents in affected areas.
Collecting Samples for Microscopic Analysis n Collection of affected biota/material in clean plastic baggies. Sirchie Evidence Vacuum Sweeper n Collection of material by scraping a sample it off the affected surface into a clean Petri dish. n 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 n n n n n 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. – – 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 n n n 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 n Several organic fuel and solvent standards were analyzed: § § § n 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 n 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. n 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. n 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 n 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. n Some species of sooty molds grow as a thick, spongy mass that encases the needles of conifers or the twigs of deciduous trees. n Insect activity may or may not be apparent. n Sooty molds may persist long after the insects themselves have disappeared.
The Effects of Sooty Mold on Plants n 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. n 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. n Fruits or vegetables covered with sooty molds are edible after removal of the mold with a solution of mild soap and warm water. n 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. – Pruning out dead and dying branches helps prevent infection by secondary pathogens.
The Link Between Insects and Sooty Mold n Although a few sooty mold fungi grow on plant substances exuded by the leaves, most grow on the honeydew produced by certain sucking insects. n Especially important are: – Whitefiles – Aphids – Mealy Bugs – Scale Insects
Whiteflies n n 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. – n Common species of whiteflies are: – – n n 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. – – – 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 n n 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. – – – (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). – n 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 n n n n 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 n n n 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. – – n The developmental stages of scale insects are: – – – n n egg (or live nymph), nymph (females, three instars; males, five instars), and adult. Scale insect development from egg to adult is: – – n 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 n n 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. – – n Ant management is an important consideration in managing sooty mold. – – – n n n 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 n n 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) n n Scientific name: Paratachardina lobata First collected in Florida on August 25 th 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 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 n Best-known species: Kerria lacca – n n (Photo by : F. W. Howard, University of Florida) n Used with permission from the University of Florida, Institute of Food and Agricultural Sciences (IFAS) Extension, Lobate Lac Scale, Paratachardina lobata (Chamberlin)(Hemiptera: Sternorrhyncha: Coccoidea: Kerriidae (reference no. 11). n These true lac scale insects have been utilized for centuries in making lacquer. Most species of the family, including P. 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 n n n n n 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 n n n 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 in Florida These include 39 plant species native to Florida (see adjacent table).
Hosts Highly Susceptible to the Lobate Lac Scale 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. n Sooty mold covers the branches, the insects themselves, and occurs in patches on the foliage. n Dense infestations are associated with branch dieback of some plant species and in severe cases, highly infested shrubs and small trees have died. n Certain native species appear to be highly susceptible: n Used with permission from the University of Florida, Institute of Food and Agricultural Sciences (IFAS) Extension, Lobate Lac Scale, Paratachardina lobata (Chamberlin)(Hemiptera: Sternorrhyncha: Coccoidea: Kerriidae (reference no. 11). – wax-myrtle, cocoplum, buttonwood, strangler-fig, myrsine, red bay, and wildcoffee n 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. n Scale insects rely mostly on passive dispersal of the crawler stage via air currents. n A key factor in spreading scale insect pests in urban areas is the movement of infested host plants from one location to another. n 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. n From the TAME Melaluca website: http: //tame. ifas. ufl. edu
Managing Lobate Lac Scale – The Difficult Task Ahead n n n 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. 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/pn 74801. 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 -618 W, 2000. http: //www. ext. vt. edu/pubs/plantdiseasefs/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/l 2315. htm Texas Nursery and Landscape Association, Texas A & M University System, College Station, Texas Agricultural Extension Service, Departments of Entomology and Horticultural Sciences, Pest Profiles: Aphids. http: //hortipm. tamu. edu/pestprofiles/sucking/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 SP 125, 1992. http: //edis. ifas. ufl. edu/BODY_IN 024 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/IN 156 S. H. Futch, C. W. Mc. Coy, 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/CH 195 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. Mc. Lean, and J. Wofford, University of Florida, Institute of Food and Agricultural Sciences (IFAS), Extension, Lobate Lac Scale, Paratachardina lobata (Chamberlin)(Hemiptera: Sternorrhyncha: Coccoidea: Kerriidae, Document EENY-276, 2002. http: //edis. ifas. ufl. edu/IN 471 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. Mc. Crone and J. G. Delly, The Particle Atlas: An Encyclopedia of Techniques for Small Particle Identification, Edition Two, Ann Arbor W. C. Mc. Crone and J. G. Delly, The 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 ENY 292, 1997. http: //edis. ifas. ufl. edu/In 043 Karen L. Snover, Director, Plant Disease Diagnostic Clinic at Cornell University, Sooty Mold http: //www. plantclinic. cornel. edu/Fact. Sheets/sootymold. htm Stephen Nameth, Jim Chatfield, and David Sheltar, 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 PP 24, 1993. http: //edis. ifas. ufl. edu/BODY_VH 049 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 Resources, The http: //www. ctahr. hawaii. edu/noni/sooty. Mold. 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. 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 (Hemiptera: Kerriidae), Florida Robert W. Pemberton, Potential Kerriidae), Entomologist 86(3), pp 353 – 360, September 2003. http: //www. fcla. edu/Fla. Ent/fe 86 p 353. pdf#search='control%20 of%20 P. %20 lobata%20 india ‘ 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