Report on the coconut lethal yellowing mission in Mozambique, CIRAD-DNSA

Dollet Michel. 2007. Report on the coconut lethal yellowing mission in Mozambique, CIRAD-DNSA. Montpellier : CIRAD, 37 p.

Résumé : Coconut Lethal Yellowing (LY) and the Oryctes beetle are continuing their devastation in Zambezia, in the Quelimane region. The Madal Group has embarked upon the eradication of coconut palms affected by LY, in order to reduce Oryctes attacks. The variety performance trials (seednuts from Ivory Coast) testing reactions to LY were planted in March-April 2007. At the time of the visit, some seedlings were suffering from drought and scale attacks. An improvement in the watering system would not go amiss and would doubtless prevent losses. Analyses carried out by CIRAD in Montpellier show that it is doubtless still the same strain of phytoplasmas as in 2003 that is rife in Quelimane. In Cabo Delgado province, the oldest plantations are suffering from senility exacerbated by the lack of upkeep, nutritional deficiencies and Oryctes attacks. The coconut palms on smallholdings usually look much better. Sporadic Lethal Yellowing syndromes were identified from the South up to the Tanzanian border, but no disease foci as severe as those in Zambezia were ever seen. Analyses carried out in Montpellier show that there are two strains of phytoplasmas associated with these syndromes in Cabo Delgado. One corresponds to the phytoplasmas identified in Zambezia, associated with what is locally known as Lethal Yellowing. The other corresponds to the phytoplasmas known in Tanzania and Kenya associated with the Lethal Decline Tanzania syndrome (LDT). The different results recorded over the last 20 years on the performance of coconut varieties in relation to these syndromes, and the sequence differences for the rRNA gene between the two "strains" or "species" of phytoplasmas mean that there could be two diseases with different epidemiologies, and in particular different vectors. A pentatomid bug has been found to carry LY phytoplasmas. That bug might be the vector of LY in Cabo Delgado. It needs to be checked whether the bug is regularly associated with cases of LY and LDT. It would also seem important to have more exhaustive data on the distribution of the 2 syndromes in Cabo Delgado, or even in Nampula province, so as to more effectively define research strategies. Lastly, we recommend getting smallholders in the North of the province to abandon the practice of making holes in stems. Under the drought conditions persisting for the last 4-5 years in the North of the country, such large holes in the stem seem to considerably weaken the palms.

Mots-clés Agrovoc : Cocos nucifera, maladie bactérienne, phytoplasme, Oryctes, diagnostic, identification, PCR, épidémiologie

Mots-clés géographiques Agrovoc : Mozambique

Mots-clés complémentaires : Jaunissement mortel

Classification Agris : H20 - Maladies des plantes
H10 - Ravageurs des plantes

Auteurs et affiliations

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

Source : Cirad - Agritrop (https://agritrop.cirad.fr/543456/)

Métriques

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