Abstracts
Résumé
Au Maroc, le sol et le climat sont deux facteurs ayant encouragé le développement des cultures ornementales. Or, la situation actuelle du secteur ornemental est telle que l'entretien et le diagnostic phytosanitaire sont loin d'être pratiqués régulièrement. Des isolements fongiques à partir des lésions foliaires de l'Hibiscus rosa-sinensis ont révélé pour la première fois la présence du Setosphaeria rostrata et du Cochliobolus spicifer. Ces deux espèces induisent des symptômes foliaires différents une fois inoculées aux plantes de l'Hibiscus rosa-sinensis. Le S. rostrata provoque des lésions de forme irrégulière et de couleur brun clair ou noirâtre et entraîne un dessèchement du limbe. Le C. spicifer est responsable de lésions foliaires de couleur brun clair qui apparaissent à la marge des feuilles puis se développent vers le centre et prennent un contour pâle. Le C. spicifer est l'agent pathogène le plus agressif (coefficient d'infection = 44).
Mots clés:
- Cochliobolus spicifer,
- Hibiscus rosa-sinensis,
- inoculation,
- pouvoir pathogène,
- Setosphaeria rostrata
Abstract
In Morocco, soil and climate are two factors that have fostered the development of ornamental cultures. However, the current situation in the ornamental sector is such that maintenance and plant health diagnosis are far from being implemented regularly. Fungal isolations from foliar lesions of Hibiscus rosa-sinensis revealed for the first time the presence of Setosphaeria rostrata and Cochliobolus spicifer. These two species induce different foliar symptoms when inoculated to Hibiscus rosa-sinensis plants. Setosphaeria rostrata clearly causes lesions of irregular forms, which are brown or blackish in colour, causing drying of the leaves. Cochliobolus spicifer causes brown foliar lesions that appear on the periphery of the leaves before developing towards the centre and becoming paler along the contour. Cochliobolus spicifera is the most pathogenic fungal species (coefficient of infection = 44).
Key words:
- Cochliobolus spicifer,
- Hibiscus rosa-sinensis,
- inoculation,
- pathogenic capacity,
- Setosphaeria rostrata
Appendices
References
- Alcorn, J.L. 1988. The taxonomy of Helminthosporium species. Annu. Rev. Phytopathol. 26 : 37-56.
- Anonyme. 1977. Alpha flore. Encyclopédie des plantes, des fleurs et des jardins. Vol. 1. Ed. Grammont, Lausanne. 300 p.
- Barrault, G. 1989. L’helminthosporiose de l’orge causée par Drechslera teres. Thèse de doctorat d’état. Institut national polytechnique de Toulouse, France. 435 p.
- Chuan, H. 2003. Ornamental Plant Disease Management Assistant. Virginica cooperative Extension. p. 450-802.
- Domsch, K.H., W. Gams et T.H. Anderson. 1980. Compendium of soil fungi. Vol. 1. Academic Press, London, UK. 859 p.
- Ehteshamul-Haque, S. et A. Ghaffar. 1994. New records of root infecting fungi from Pakistan. Pak. J. Phytopathol. 6(1) : 50-57.
- Ellis, M.B. 1971. Demataceous Hyphomycetes. Commonwealth Mycological Institue Kew, Surrey, England. 608 p.
- El-Morsy, M.A. 1999. Studies on certain fungal diseases of date palm in new Valley. Thesis (M. Sc.), Dept. of Plant pathology, Faculty of Agriculture, Assiut University. Egypt.
- Hill, J.P. et R.R. Nelson. 1983. Genetic control of two parasitic fitness attributes of Helminthosporium maydis race T. Phytopathology 73 : 455-457.
- Loegering, W.D. 1959. Method for recording cereal rust data. USDA Int. Spring Wheat Rust Nursery, Washington, DC, USA.
- McGinnis, M.R., M.G. Rinaldi et R.E. Winn. 1986. Emerging agents of Phaeohyphomycosis: pathogenic species of Bipolaris and Exserohilum. J. Clin. Microbiol. 24 : 250-259.
- Mullin, B.-A. C.G. Cook et R.L. Schading. 1993. First report of Exserohilum rostratum, Curvularia senegalensis and Nigrospora oryzae infecting kenaf in Texas. Plant Dis. 77(8) : 846.
- Perry Lawton, B. 2004. Heavenly hibiscus-long-lived, easy-care flowering beauties for every garden. Plants & Gardens News. Vol. 19, No 3. [http://www.bbg.org/gar2/topics/plants/2004fa_hibiscus.html] [consulté le 17 avril 2006].
- Pratt, R.G. 2000. Diseases caused by dematiaceous fungal pathogens as potential limiting factors for production of bermudagrass on Swine effluent application sites. Plant Dis. 92 : 512-517.
- Saeed, R.S., A.I.I. El-Fiki et A.M.M. Mahdy. 1992. Pectinolytic, cellulolytic and oxidative enzymes; activities in vitro and in vivo in relation to pathogenicity of some grapevine leaf spot pathogens. Ann. Agri. Sci. (Moshtohor) 30(2) : 711-730.
- Smiley, R.W., P.H. Dernoeden et B.B. Clarke. 1992. Compendium of turfgrass diseases, 2nd ed. American Phytopathological Society, St. Paul, MN. 98 p.