Wheat diseases D. Schultz, R. Symptoms Black spot affects citrus foliage and fruits. There are several fruit symptoms that may overlap. Typical symptoms consist of hard spots that begin as small orange or red lesions with black margins and enlarge to become necrotic lesions. These blemishes of the rind (black spots, Fig. 1 & 2) make the fruits unfit for fresh market. Early virulent spots may coalesce to cover a large portion of the fruit. Other symptoms include speckled blotch or false melanose where the fruit is covered by tiny spots in absence of any other symptom. Severe disease causes extensive premature fruit drop. Tan Spot PLPA-Cit013-01 Department of Plant Pathology and Microbiology 6500 Amarillo Blvd. W., Amarillo, TX 79106 http://sickcitrus.tamu.edu Citrus Black Spot Figure 1: Typical black spots on Valencia orange, top left, and Ellendale mandarin, top right. Details of the lesions with pycnidia, in Nova mandarin (bottom, left & right) and in orange (bottom, center). Photos: Myrian Rybak. Summary Citrus Black Spot is a fungal disease that causes early fruit drop, reduces yield and makes the fruit unfit for fresh market. Spores produced on foliage are the main inoculum source, and the movement of sick plants or foliage the means of dispersion. The disease occurs in subtropical regions worldwide. In the US, Citrus Black Spot is only present in South Florida, where it was detected in 2010.
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Wheat diseases D. Schultz, R.
Symptoms
Black spot affects citrus foliage and fruits. There are several fruit symptoms that may overlap. Typical symptoms consist of hard spots that begin as small orange or red lesions with black margins and enlarge to become necrotic lesions. These blemishes
of the rind (black spots, Fig. 1 & 2) make the fruits unfit for fresh market. Early virulent spots may coalesce to cover a large portion of the fruit. Other symptoms include speckled blotch or false melanose where the fruit is covered by tiny spots in absence of any other symptom. Severe disease causes extensive premature fruit drop.
Tan SpotPLPA-Cit013-01
Department of Plant Pathology and Microbiology6500 Amarillo Blvd. W., Amarillo, TX 79106http://sickcitrus.tamu.edu
Citrus Black Spot
Figure 1: Typical black spots on Valencia orange, top left, and Ellendale mandarin, top right. Details of the lesions with pycnidia, in Nova mandarin (bottom, left & right) and in orange (bottom, center). Photos: Myrian Rybak.
Rybak, M. A., Canteros, B. I., Soliz, J., Hermosis, F., Benitez, R. Momento de Pulverización y Productos para el Control de Mancha Negra en Mandarina NOVA. XXXII Congreso Argentino de Horticultura. 23 al 26 de septiembre de 2009 Ciudad de Salta, Salta. Asociación Argentina de Horticultura. ASAHO. Libro de Resúmenes XXXII Congreso Argentino de Horticultura. Sección Fruticultura (FR-S4). Pag. 181
Rybak M.A., Canteros B. I. Soliz J., Benitez R., Hermosis F. Momento de aplicación para control de Black spot con bencimidazol y aceite en mandarina Nova. XIXº Reunión de Comunicaciones Científicas y Técnicas y Reunión de Extensión.Corrientes Argentina. FCA - UNNE. 6 y 7 de Agosto de 2008. CD Resumen Sanidad Vegetal _14. http://agr.unne.edu.ar/Extension/Res2008/SanVegetal/SanVegetal_14.pdf
Naranja Valencia
Fig. 1. Hard spots with black pycnidia caused by Guignardia citricarpa
Phyllosticta citricarpa (imperfect stage)
Rybak, M. A., Canteros, B. I., Soliz, J., Hermosis, F., Benitez, R. Momento de Pulverización y Productos para el Control de Mancha Negra en Mandarina NOVA. XXXII Congreso Argentino de Horticultura. 23 al 26 de septiembre de 2009 Ciudad de Salta, Salta. Asociación Argentina de Horticultura. ASAHO. Libro de Resúmenes XXXII Congreso Argentino de Horticultura. Sección Fruticultura (FR-S4). Pag. 181
Rybak M.A., Canteros B. I. Soliz J., Benitez R., Hermosis F. Momento de aplicación para control de Black spot con bencimidazol y aceite en mandarina Nova. XIXº Reunión de Comunicaciones Científicas y Técnicas y Reunión de Extensión.Corrientes Argentina. FCA - UNNE. 6 y 7 de Agosto de 2008. CD Resumen Sanidad Vegetal _14. http://agr.unne.edu.ar/Extension/Res2008/SanVegetal/SanVegetal_14.pdf
Naranja Valencia
Fig. 1. Hard spots with black pycnidia caused by Guignardia citricarpa
Phyllosticta citricarpa (imperfect stage)
Guignardia citricarpa Asci of Guignardia citricarpa with ascosporis.
! Frutos de Nova con diferentes grados de intensidad de black spot
Típicas manchas duras en mandarina Nova
Lesiones de manchas duras con picnidios en el centro del tejido necrótico (20x) G. mangiferae
G. citricarpa G. citricarpa Guignardia citricarpa en CHA Crecimiento de Guignardia en medios diferenciales Cherry agar y Oatmeal agar
G. citricarpa con un halo amarillo en medio Oatmeal Agar Frutos de mandarina Nova con síntomas de mancha negra
Summary
Citrus Black Spot is a fungal disease that causes early fruit drop, reduces yield and makes the fruit unfit for fresh market. Spores produced on foliage are the main inoculum source, and the movement of sick plants or foliage the means of dispersion.The disease occurs in subtropical regions worldwide. In the US, Citrus Black Spot is only present in South Florida, where it was detected in 2010.
Prepared by Dr. Diana Schultz1, Dr. Myrian Rybak2 y Dr. Ronald D. French3
1 Plant Pathologist, Fort Myers, Florida, 2 Plant Pathologist, Instituto Nacional de Tecnología Agropecuria (INTA), Estación Experimental Agropecuaria, Cerro Azul, Misiones, Argentina, 3Assistant Professor and Extension Plant Pathologist (Amarillo, TX)
Texas A&M AgriLife Extension Service; The Texas A&M SystemMarch 1, 2013
The information given herein is for educational purposes only. References to commercial products or trade names are made with the understanding that no discrimination is intended and no endorsement by Texas A&M AgriLife Extension Service personnel is implied.
Educational programs of the Texas A&M AgriLife Extension Service are open to all people without regard to race, color, sex, disability, religion, age, or national origin.The Texas A&M University System, U.S. Department of Agriculture, and the County Commissioners Courts of Texas Cooperating
Guignardia citricarpa Asci of Guignardia citricarpa with ascosporis.
! Frutos de Nova con diferentes grados de intensidad de black spot
Típicas manchas duras en mandarina Nova
Lesiones de manchas duras con picnidios en el centro del tejido necrótico (20x) G. mangiferae
G. citricarpa G. citricarpa Guignardia citricarpa en CHA Crecimiento de Guignardia en medios diferenciales Cherry agar y Oatmeal agar
G. citricarpa con un halo amarillo en medio Oatmeal Agar Frutos de mandarina Nova con síntomas de mancha negra
Guignardia citricarpa Asci of Guignardia citricarpa with ascosporis.
! Frutos de Nova con diferentes grados de intensidad de black spot
Típicas manchas duras en mandarina Nova
Lesiones de manchas duras con picnidios en el centro del tejido necrótico (20x) G. mangiferae
G. citricarpa G. citricarpa Guignardia citricarpa en CHA Crecimiento de Guignardia en medios diferenciales Cherry agar y Oatmeal agar
G. citricarpa con un halo amarillo en medio Oatmeal Agar Frutos de mandarina Nova con síntomas de mancha negra
Figure 2: Hard spots on mature and green mandarin fruits. Photos: Myrian Rybak. Causal agent
Black spot is caused by Guignardia citricarpa (asexual stage Phyllosticta citricarpa). Spores of the sexual stage, ascospores, develop on dead leaves (Fig. 3). Conidia-containing Pycnidia (asexual stage, Fig. 4) develop in the center of fruit lesions, and can be seen as small black dots (Fig. 1). The disease is widespread to most humid subtropical regions of the world.
Figure 3. Sexual stage fruiting body (left) and asci with ascospores (right). Photos: Myrian Rybak.
Inoculum source and conditions
Ascospores are carried from dead leaves into air currents. Conidia (Fig. 4) from fruit lesions are disseminated by rain. Conidia and ascospores (Fig. 3) are responsible for the local spread of the disease. Long distance dispersion occurs via infected nursery stock. Under favorable conditions spores germinate and infect young tissues. Although infection takes place in young tissues, lesions will not develop completely until fruits mature (Fig. 1 & 2).
Rybak, M. A., Canteros, B. I., Soliz, J., Hermosis, F., Benitez, R. Momento de Pulverización y Productos para el Control de Mancha Negra en Mandarina NOVA. XXXII Congreso Argentino de Horticultura. 23 al 26 de septiembre de 2009 Ciudad de Salta, Salta. Asociación Argentina de Horticultura. ASAHO. Libro de Resúmenes XXXII Congreso Argentino de Horticultura. Sección Fruticultura (FR-S4). Pag. 181
Rybak M.A., Canteros B. I. Soliz J., Benitez R., Hermosis F. Momento de aplicación para control de Black spot con bencimidazol y aceite en mandarina Nova. XIXº Reunión de Comunicaciones Científicas y Técnicas y Reunión de Extensión.Corrientes Argentina. FCA - UNNE. 6 y 7 de Agosto de 2008. CD Resumen Sanidad Vegetal _14. http://agr.unne.edu.ar/Extension/Res2008/SanVegetal/SanVegetal_14.pdf
Naranja Valencia
Fig. 1. Hard spots with black pycnidia caused by Guignardia citricarpa
Phyllosticta citricarpa (imperfect stage)
Figure 4. Pycnidia (left) and its conidia (right). Photos: Myrian Rybak.
Management
• Removal of dead leaves in groves to reduce the primary inoculum.
• Application of fungicides. Programs with three applications of Copper plus oil offer good protection. First application at 2-3 cm fruit diameter, second one month later (at 3-4 cm fruit diameter) and a third in another month (at 4-5 cm fruit diameter). In Argentina, a post infection application with Benomyl, Carbendazin or Thiophanate methyl, together with a second application at 4-5 cm fruit has resulted in good disease control. In Florida, protective treatments using either Copper, Strobilurin fungicides, Mancozeb, Carbendazim or Thiophanate methyl are recommended.
References
• Dewdney M.et al. 2012. Florida Citrus Pest Management Guide: Citrus Black Spot (http://edis.ifas.ufl.edu/cg088 )
• Dewdney M.et al. 2012. Citrus Black Spot (http://edis.ifas.ufl.edu/pp274 ).
• Kotze, J. M. 2000. Black spot. Page 23-25. In: Compendium of Citrus Disease. APS Press.
• Rybak, M. A. et al. 2009. Momento de Pulverización y Productos para el Control de Mancha Negra en Mandarina NOVA. XXXII Congreso Argentino de Horticultura (FR-S4). Pag. 181.
• Rybak M.A. et al. 2008. Momento de aplicación para control de Black spot con bencimidazol y aceite en mandarina Nova. XIXo Reunión de Comunicaciones Científicas y Técnicas y Reunión de Extensión.Corrientes ␣ Argentina. FCA - UNNE. http://agr.unne.edu.ar/Extension/Res2008/SanVegetal/SanVegetal_14.pdf
• USDA Citrus Health Response Program, Black Spot http://www.aphis.usda.gov/plant_health/plant_pest_info/citrus/black_spot.shtml
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