First report of “Maladie des feuilles cassantes†(brittle leaf disease) of date palm in Algeria
*nduran@ivia.es
1 Laboratoire de Phytopathologie et Diagnostic, Institut National de la Protection des Végétaux, Biskra, Algerie
2 Institut National de la Recherche Agronomique de Tunisie, Centre de Recherches Phoenicicoles, 2260 Degache, Tunisie
3 UMR 1090, Institut National de la Recherche Agronomique, Villenave d'Ornon, France
4 Departamento de Proteccion Vegetal y Biotechnologia, Instituto Valenciano de Investigaciones Agrarias, Apartado Oficial, 46113 Moncada (Valencia), España
Accepted: 20 Feb 2006
In December 2003 symptoms, identical to those of Maladie des feuilles cassantes (MFC), or brittle leaf disease, of date palms in Tunisia were observed in the Biskra region of eastern Algeria. In Lichana, where the disease started in 1974, 29% of the trees were found to be affected, while in Farfar some farms had 100% of trees with MFC. The disease affects groves in traditional oases, as well as new, industrial plantations in the Bouchagroun and Dra Elbetikh areas. All cv. Deglet Nour samples from five areas (Vieux Zaatcha, Bouchagroun, Dra Elbetikh, and Farfar) tested positive for the MFC-specific double-stranded RNA (dsRNA) of host origin, which is present in leaflets from all MFC-affected trees but not in those from healthy trees (Fadda, 2001). The dsRNA is specific for MFC and is of diagnostic value, although not involved in the disease. All affected leaflets tested were also deficient in manganese (Mn; average 6.5 ppm dry weight, compared to 29 ppm for healthy leaves). MFC was first observed in the 1960s in the Nefta-Tozeur oases of Tunisia (Triki et al., 2003). Four to six years may elapse between the first symptoms (some fronds show chlorosis and have a dull, olive-green colour) and death of the tree. Leaflets become brittle and break easily. Necrotic streaks develop on the pinnae and many fronds acquire a jagged appearance. Leaflets are deficient in Mn and the symptoms are similar to those of frizzle-top of palms in Florida caused by deficiency of this mineral. Although no pathogen has yet been found associated with MFC, aspects of its epidemiology do not suggest a purely abiotic cause. Affected trees appear to cluster into foci and mineral analyses show no significant differences between the soils in which affected and unaffected trees are growing. This is the first report of this disease from Algeria. This disease is currently listed on the EPPO Alert list (www.eppo.org/QUARANTINE/Alert_List/viruses/brittleleaf.htm).
References
- Triki MA, Zouba A, Khoualdia O, Ben Mahamoud O, Takrouni ML, Garnier M, Bové JM, Montarone M, Poupet A, Flores R, Darós JA, Fadda ZGN, Moreno P, Duran-Vila N, 2003. “Maladie des Feuilles Cassantes†or Brittle Leaf Disease of date palms in Tunisia: biotic or abiotic disease? Journal of Plant Pathology 85, 71-79.
- Fadda ZGN, 2001. Identificación de caracterización de pequeños RNAs en palmera datilera y berenjena. Valencia, Spain: Universidad Politécnica de Valencia, PhD thesis.
This report was formally published in Plant Pathology
©2006 The Authors