Report on the scientific and methodological support mission for coconut lethal yellowing research at Opri in Takoradi, Ghana, 7 to 14 March 2005

Dollet Michel. 2005. Report on the scientific and methodological support mission for coconut lethal yellowing research at Opri in Takoradi, Ghana, 7 to 14 March 2005. Montpellier : CIRAD, 32 p. N° de rapport : CP_SIC 1843

Résumé : This mission focused on 3 major components in the development of Cape St Paul Wilt (Lethal Yellowing) in Ghana: the coconut palm, the disease vector, the pathogen. The coconut palm: of the different coconut varieties planted since 1981, only the Sri Lanka Green Dwarf (SGD) and Vanuatu Tall (VTT) varieties had not succumbed to the disease by the end of the 1990s. At the beginning of that decade, replanting with a Malayan Yellow Dwarf (MYD) x VTT hybrid was recommended. Although the MYD did not prove resistant to CSPW, it was accepted that, given the precocity of the hybrids and with the contribution of VTT genes, Ghanaian farmers could count on yields that were ensured for at least 15 years. However, since 2000, it has turned out that VTT palms can be destroyed by CSPW (Axim performance trials). In addition, some of those hybrids are beginning to display CSPW symptoms in various plantations in the country (Fawomanye, Asebu), a diagnosis confirmed in the laboratory by PCR analyses. It has therefore become urgent to find a follow-on to this waiting solution, which has lasted more or less the expected time (10-15 years), particularly since CSPW is now attacking young MYD x VTT plantations (under 5 years old). Which new varieties (or hybrids) ought to be planted? SGD, which was long extolled as the saviour "variety", has in fact often proved to be a low yielder, completely stunted, or even sterile (Axim performance trial). Moreover, some of them carry the CSPW pathogen. Further varietal performance trials need to be planted with new varieties as soon as possible. Meanwhile, it will be necessary to diversify replantings and introduce the hybrid being studied, SGD x VTT, if the agronomic results in the Agona trial are good. The disease vector: None of the transmission trials conducted over the last 5 years have led to identification of the CSPW vector (trials finished at the end of 2004). New attempts need to be made, modifying various factors: - new trial sites, nearer active foci. One of those sites could be located in the Asebu region, - collection of insects then direct releases into cages on coconut palms (abandon intermediate "acquisition" periods on palms), - diversification of the released species (it is recommended that trials with Nzinga be hatted), - lowering of cage temperatures by any means (shading, spraying with water).

Auteurs et affiliations

• Dollet Michel, CIRAD-CP-UPR Etiologie dépérissements (FRA)

Source : Cirad - Agritrop (https://agritrop.cirad.fr/528843/)

Métriques

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