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Anthurium Diseases: Identification and Control in Commercial Greenhouse Operations
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 Material Information
Title: Anthurium Diseases: Identification and Control in Commercial Greenhouse Operations
Physical Description: Fact Sheet
Creator: Norman, David J.
Ali, Gul Shad
Publisher: University of Florida Cooperative Extension Service, Institute of Food and Agriculture Sciences, EDIS
Place of Publication: Gainesville, Fla.
Publication Date: 2012
 Notes
Abstract: Because of its attractive, long-lasting flowers, Anthurium is popular as both an exotic cut-flower crop and as a flowering potted-plant crop. Growers most often report two bacterial diseases and three fungal diseases in their commercial greenhouse environments. This article provides guidelines to identify and treat diseases that may be encountered during commercial greenhouse production of Anthurium.
Acquisition: Collected for University of Florida's Institutional Repository by the UFIR Self-Submittal tool. Submitted by Diana Hagan.
Publication Status: Published
General Note: "Publication #PP292"
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Source Institution: University of Florida Institutional Repository
Holding Location: University of Florida
Rights Management: All rights reserved by the submitter.
System ID: IR00000847:00001

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PP292 Anthurium Diseases: Identication and Control in Commercial Greenhouse Operations1David J. Norman and Gul Shad Ali2 1. This document is PP292, one of a series of the Plant Pathology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date March 2012. Visit the EDIS website at http://edis.ifas.u.edu 2. David J. Norman, associate professor, and Gul Shad Ali, assistant professor, Plant Pathology Department, University of Florida Institute of Food and Agricultural Sciences, Mid-Florida Resesarch and Education Center, Apopka, FL 32703 The use of trade names in this publication is solely for the purpose of providing specic information. UF/IFAS does not guarantee or warranty the products named, and references to them in this publication do not signify our approval to the exclusion of other products of suitable composition. All chemicals should be used in accordance with directions on the manufacturers label. Use pesticides safely. Read and follow directions on the manufacturers label.The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or aliations. U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A&M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Millie Ferrer-Chancy, Interim DeanIntroductionBecause of its attractive, long-lasting owers, Anthurium is popular as both an exotic cut-ower crop and as a owering potted-plant crop. Growers most oen report two bacterial diseases and three fungal diseases in their commercial greenhouse environments. is article provides guidelines to identify and treat diseases that may be encountered during commercial greenhouse production of Anthurium .AnthuriumCommonly known as amingo ower, Hawaiian love plant, cresta de gallo, or tongue of re, Anthurium has nearly 1,000 species, making it the largest genus in the plant family Araceae. Anthurium is native to tropical America, Mexico, Costa Rica, Cuba, and Brazil. Growth habits vary depending on species; some are terrestrial, others are epiphytic (Chen et al. 2003). Most cut-ower Anthurium cultivars are selections of Anthurium andraeanum an epiphytic-growing plant native to Columbia and Ecuador. e large red owers produced by Anthurium andraeanum cultivars are very recognizable to consumers (Figure 1). Breeding has introduced such ower colors as pink, orange, white, green, purple, and combinations of these colors. Florida is now leading the nation in owering potted Anthurium production. Cultivars for potted plant production have been derived from crosses of A. andraeanum with dwarf species, such as A. amnicola and A. antioquiense. Compact, hybrid varieties of potted Anthurium released by the University of Florida Plant Breeding Program include Red Hot (Henny, Chen, and Mellich 2008a), Orange Hot (Figure 2) (Henny, Chen, and Mellich 2008b), and Southern Blush (Henny, Poole, and Conover 1988). Figure 1. Anthurium Kozohara used in cut-ower production Credits: D. Norman, UF/IFAS

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2 Anthurium is very susceptible to bacterial and fungal diseases that can seriously limit commercial production. Bacterial blight caused by Xanthomonas is probably the most serious. Root rots caused by Rhizoctonia Pythium and Phytophthora also occur in Anthurium production. It is therefore important to be able to identify and eliminate these diseases.Bacterial Diseases of AnthuriumBacterial Blight Symptoms: e rst visible symptoms are yellowed (chlorotic), water-soaked lesions along the leaf margins that grow rapidly to form dead (necrotic) V-shaped lesions characteristic of this disease (Figure 3). e bacteria infect Anthurium plants by entering pores (hydathodes) along the leaf margins (Figure 4). Bacteria may also enter if leaf tissues become torn through pruning, or if leaf tissues are punctured by insects. When owers are harvested, bacteria can enter via wounds. Figure 3. Xanthomonas bacterial blight exhibits characteristic V-shaped, water-soaked lesions forming along the edges on Anthurium leaves. Credits: D. Norman, UF/IFAS Figure 4. Xanthomonas bacteria enter the leaf margins via pores (hydathodes) where guttation droplets form. Credits: D. Norman, UF/IFAS Figure 2. Anthurium Orange Hot used in owering potted plant production Credits: R. J. Henny, UF/IFAS Figure 5. Extensive necrosis develops on Anthurium plants that are systemically infected with Xanthomonas bacterial blight. Credits: D. Norman, UF/IFAS

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3 Guttation droplets form at night when humidity is high and potting soil is warm and wet. Amino acids found in this guttation uid are a source of food for the invading bacteria. Some infected plants are asymptomatic (do not show any disease symptoms) for months as the bacteria multiply. Bacteria in the guttation uid from these asymptomatic infected plants can infect adjacent plants. Invading bacteria quickly spread throughout the plant (Figure 5). Leaves of systemically infected plants may exhibit a bronzed appearance. Floral quality may be reduced and/or owers may become unmarketable (Figure 6). Eventually, plants wilt and die. Causal Agent: Xanthomonas axonopodis pv. dieenbachiae e species of Xanthomonas that infects Anthurium has a very broad host range and is able to infect most aroid species; therefore, Anthurium plants may get blight when grown in close proximity to other aroids, such as Dieenba chia Aglaonema and Spathiphyllum Factors Favoring the Disease: Bacteria can swim across wet surfaces; therefore, it is very important to keep the foliage dry. e most eective way of accomplishing this is through drip irrigation. Control and Treatment: Lower greenhouse humidity and temperature by increasing air circulation and venting the production facility. Allow space between the plants on the bench. Warm temperatures, high humidity, and saturated soils contribute to the formation of guttation droplets. Only clean, tissue-cultured plantlets should be used when establishing new plantings. Because Xanthomonas bacteria can enter the plant through any wound or tear in the stem or foliage, the disease is easily spread if propagation is done via cuttings or division. e disease can be spread when harvesting owers or removing old foliage. Sterilize knives and clippers by dipping cutting tools in a disinfectant between plants. e most eective disinfectants are the quaternary ammonium compounds. It is also good practice to have two knives or shears in a dip bucket so they can be alternated, thus extending time in disinfectant and allowing for better coverage of the cutting surface. When infected plants are found, they should be discarded immediately. Products containing copper (CuPro, Phyton 27, Camelot), mancozeb (Protect T/O, Dithane), and Bacillus subtilis (Cease, Companion) are eective against Xanthomonas .Bacterial WiltSymptoms: Leaf yellowing (chlorosis) is usually the rst symptom observed. e disease spreads rapidly throughout the vascular system of the plant, turning veins in the leaves and stems a brown, bronze color (Figure 8). Bacterial ooze (brown slime) will be present if cuts are made into the stems of highly infected plants. Plants will exhibit wilt symptoms even though adequate soil moisture is available. Figure 6. Xanthomonas bacterial blight lesions can also appear on the owers. Credits: D. Norman, UF/IFAS Figure 7. Ralstonia bacterial wilt causes yellowing (chlorosis) of Anthurium leaves. Credits: D. Norman, UF/IFAS

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4 Causal Agent: Ralstonia solanacearum Ralstonia is known to infect several hundred plant genera. is bacterial disease is an opportunistic pathogen that colonizes soil and can remain viable for years without a host plant. Factors Favoring the Disease: Cool greenhouse temperatures may temporarily mask symptoms and give bacteria time to spread. Symptoms appear rapidly during hot weather. Control and Treatment: A strict sanitation program is the most successful way to stop the spread of this pathogen and eventually eradicate it from a production facility. Fungi cides that contain phosphorous acid have also been shown to be eective in preventing infection; however, they do not cure systemically infected plants (Norman et al. 2006). Bacterial wilt is spread via contaminated soil, water, tools, or worker contact. Use disease-free propagation material. e bacterial wilt pathogen is easily spread via infected cuttings. Because the bacteria survive well in soil, both contaminated plant material and the supporting soil should be discarded. If pots and trays from contaminated infected plants are to be reused, they should be scrubbed free of adhering soil and then soaked in a disinfectant to kill the remaining bacteria. Knives and clippers should be sterilized between plants with a disinfectant containing a quaternary ammonium compound (Physan 20, Green-Shield) or diluted solution of bleach to prohibit spread.Fungal Diseases of AnthuriumRhizoctonia Root RotSymptoms: e term damping-o is used to describe these classical symptoms. Young, tender stems are girdled, become water soaked, and are unable to support the weight of the plant (Figure 9). Rhizoctonia attacks the roots and Figure 8. Wilt symptoms are the byproduct of Ralstonia bacteria clogging the vascular system of the plant. Credits: D. Norman, UF/IFAS Figure 9. Anthurium wilt caused by Rhizoctonia root rot. Credits: D. Norman, UF/IFAS Figure 10. Discolored brown roots are one of the symptoms observed with Rhizoctonia infections. Credits: D. Norman, UF/IFAS

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5 lower stems of plants (Figure 10), but under wet conditions it can also attack and spread in the upper leaf canopy. Causal Agent: Rhizoctonia solani Rhizoctonia can survive within soil for years without a host plant. e fungus produces small mats of tightly woven mycelia called sclerotia. Sclerotia are irregular in shape, brown in color, and resemble particles of soil. Sclerotia provide a seedlike mechanism for the fungus to survive unfavorable conditions, such as drought or cold weather. ese small sclerotia stick to trays and pot surfaces and are one of the ways the fungus spreads through nurseries. Factors Favoring the Disease: Water-saturated soils are conducive to disease development. Control and Treatment: Never incorporate native soils into media mixes without steam sterilizing. Use well-drained soil mixes. Never store peat moss, sphagnum moss, chips, or potting media mixes directly on soil surfaces where they can be colonized by the fungus. Plants should be cultivated on raised benches to limit root contact with soil. Rhizoctonia frequently gains access to production facilities via infected propagation material. Many fungicides are eective against outbreaks of Rhizoc tonia Examples include Clearys 3336, Fungo/Allban (thiophanate methyl), Medallion (udioxonil), and Contrast (utolanil).Phytophthora/PythiumBoth Phytophthora and Pythium are called oomycetes, commonly known as water molds. e control, spread, and management recommendations for Phytophthora and Pythium infestations are the same. Plants infected with either of these pathogens exhibit wilting, leaf yellowing (chlorosis), and root dieback (Figure 11). Symptoms: Phytophthora and Pythium infections primarily attack root systems. Plants will wilt even though adequate soil moisture is available. Root sloughing is the primary diagnostic tool (Figure 12). Under severe conditions, the foliage may exhibit black to brown leaf lesions. ese symptoms are similar to symptoms caused by Rhizoc tonia ; however, fungal strands (mycelial growth) are rarely observed with Phytophthora or Pythium infections. Causal Agents: Phytophthora nicotianae var. parasitica and Pythium splendens Phytophthora and Pythium species cause substantial damage to Anthurium and numerous tropical foliage crops. Factors Favoring the Disease: Water-saturated soils are conducive to disease development. ese diseases can usually be avoided by using light, well-drained soil mixes. Control and Treatment: Use well-drained, synthetic soil mixes. Use disease-free stock plants. Plants with symptoms of disease should be discarded and the rest of the production facility should be treated with a fungicide drench. If potting containers are reused, they should be scrubbed and sterilized. Cutting shears, knives, and tools should be dipped in an appropriate disinfectant between plants. Figure 11. Anthurium wilt caused by Phytophthora. Credits: D. Norman, UF/IFAS Figure 12. Pythium and Phytophthora cause root sloughing. Credits: D. Norman, UF/IFAS

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6 Fungicides such as mefenoxam (Subdue Maxx) and aluminum tris/Fosetyl-al (Aliette WDG), dimethomorph (Stature), uopicolide (Adorn), and phosphorous acid (Alude, K-Phite, Vital) may be used to control Phytoph thora and Pythium .Black Nose DiseaseSymptoms: Black nose can cause havoc in cut-ower and potted-plant production. Flowers and owering potted plants cannot be sold with this condition. e rst symptoms observed are small, brown to black ecks on the oral spadix (nose) (Figure 12). ese spots rapidly enlarge, become watery, turn brown to black, and may totally encompass the spadix. e spadix may eventually fall o. Growers may also observe black, sporecontaining structures (acervuli) on dead leaves and stems. Causal Agent: Colletotrichum gloeosporioides e fungus Colletotrichum gloeosporioides attacks many temperate and tropical crops and can cause damage to roots, stems, leaves, and owers. However, in Anthurium the pathogen is highly specic, only attacking the spadix portion of the ower (the nose). Factors Favoring the Disease: is disease is most severe during humid, warm conditions. Colletotrichum readily invades plant tissues previously damaged by pesticides, fertilizer, or bacterial blight (Xanthomonas ). Control and Treatment: e Colletotrichum fungus produces thousands of small hot-dog-shaped spores that can readily be moved by splashing water, air movement, and workers. A strict sanitation program is crucial to control the spread of this pathogen in a production facility. Fungicides containing mancozeb (Protect T/O, Dithane) are eective. Fungicide applications are usually discouraged because chemical residues diminish the marketability of owers and plants. Anthurium plant breeding programs both in Hawaii and Florida have incorporated disease resistance into many of the current cultivars. Newer cultivars are highly resistant to this pathogen and rarely exhibit black nose.ReferencesChen, J., D. B. McConnell, R. J. Henny, and K. C. Everitt. 2003. Cultural Guidelines for Commercial Production of Interiorscape Anthurium. ENH956. Gainesville: University of Florida Institute of Food and Agricultural Sciences. http://edis.ifas.u.edu/EP159. Henny, R. J., J. Chen, and T. A. Mellich. 2008a. New Florida Foliage Plant Cultivar: Red Hot Anthurium. ENH1009. Gainesville: University of Florida Institute of Food and Agricultural Sciences. http://edis.ifas.u.edu/EP363. Figure 13a. Black nose disease on Anthurium causes spadix darkening. Credits: D. Norman, UF/IFAS Figure 13b. Credits: D. Norman, UF/IFAS

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7 Henny, R. J., J. Chen, and T. A. Mellich. 2008b. New Florida Foliage Plant Cultivar: Orange Hot Anthurium. ENH1100. Gainesville: University of Florida Institute of Food and Agricultural Sciences. http://edis.ifas.u.edu/EP364. Henny, R. J., R. T. Poole, and C.A. Conover. 1988.Southern Blush Anthurium . HortScience 23(5): 922. Norman, D. J., J. Chen, A. Mangravita-Nova, and J. M. F. Yuen. 2006. Control of Bacterial Wilt of Geranium with Phosphorus Acid. Plant Dis 90(6): 798.