Development of a long term strategy based on genetic resistance and agroecological approaches against Coffee Wilth Disease in Africa : First annual report : covering period 1/11/2001 to 31/10/2002

Bieysse Daniel. 2003. Development of a long term strategy based on genetic resistance and agroecological approaches against Coffee Wilth Disease in Africa : First annual report : covering period 1/11/2001 to 31/10/2002. s.l. : s.n., 100 p. N° de rapport : CIRAD-AMIS N° 08/2003

Note générale : INCO : International Scientific Cooperation Projects. Contract number ICA-CT-2001-10006

Résumé : Coffee Wilt Disease due to #Fusarium xylarioides# is currently a major problem especially for Robusta coffee in DRC and Uganda. This vascular disease induces the death of the coffee tree within 9 to 15 months, depending on the susceptibility and on the agro ecological conditions. Replanting is impossible, due to the soil being infested for several years. Genetic resistance seems the only solution to fight the disease; indeed it is investigated by the COWIDI INCO DEV Project. The objectives of the Project are: 1- Study of the genetic diversity of the pathogen, 2- Characterisation of the host/pathogen interaction, 3- Identification of tolerant/resistant varieties, analysis of inheritance, elaboration of a breeding strategy, 4- Factors influencing the development of the disease. In order to study the genetic diversity of the pathogen, a collect of strains has been realised by CORI and CIRAD in the representative coffee areas in Uganda, and a collection has been initiated by CABI with a central data base regrouping baseline information on each isolate. A preliminary analysis of molecular variability using variable number tandem repeat (VNTR) has commenced. Initials tests give rise to almost identical fingerprint profiles for all strains. However ISSR PCR primers demonstrate some level of intraspecific variability. A conventional genetic approach involving assessment of Vegetative Compatibility Groups has been initiated by CABI. The sexual life cycle is in progress in UCL. To study the aggressiveness and of the host pathogen/interaction, a standardised inoculation method by syringe injection of a calibrated suspension of conidia in the stem of young plantlets 8 to 10 months old is in progress at CORI, CIRAD, and UNIKIN. A protocol is experimented with a statistic design. Specific techniques adapted to the local constraints are also experimented by every partners. A ring test to compare results will be developed during the next year. The first results at CIRAD show a variation in the aggressiveness of the isolates. These results permitted to earmark tester isolates for routine tests in CIRAD (CAB003). Work at CORI is in progress. CIRAD made a first series of tests to evaluate the susceptibility of Coffea canephora. Representatives of the five genetic groups of the species expressed various levels of resistance with isolate CAB003. Populations 1160, 1173, 1219, and 1230 look resistant (To be confirmed). For some populations the response is clear, namely 1213, 1153, 1191, 1236 (susceptible). For others the rate is intermediate, around 50%. These results can be considered as a trend. At CORI, clones and local germplasm have exhibited field resistance and will be included in a hybridisation scheme. Collection of seeds from genotypes representative of the available germplasm and rooting of cuttings has started. An MTA (Material Transfer Agreement) has been signed between CORI and partners via CIRAD. At UNIKIN field evaluation in Yangambi Station is in progress. The 7 Robusta clones (L36, L48, L93, L147, L215, L251, and SA158) currently released to the farmers in Orientale, Nord- and Sud- Kivu Provinces, and the clones recommended for the Bas Congo region (LAF93, LAF159, S9, S19, S23) will be dispatched to the partners. In DRC the survey in Bas Congo, Bandundu and Kasai Provinces indicated that no case of the disease could be find in any of the sites visited. An epidemiological survey is planned in Northern and North Eastern Province for December 2002. In Uganda, a base line survey conducted between March and May 2002, established that, in the districts of Mukono, Bundibugyo, Rukungiri, Kayunga, Kibale, Hoima, Kiboga, Mubende, Luwero, Wakiso, Mpigi, there are coffee farms which are nearly 100% devastated. In Uganda, four sites in small holders farms, have been selected for epidemiological observations in Mayuge and Iganga districts (Eastern Uganda) where disease pressure is low. For comparison purpose, four sites are selected in Masakai and Rakai districts. Disease recording is palnned every 4 weeks.

Mots-clés Agrovoc : Coffea canephora, Fusarium, variation génétique, résistance aux maladies, pouvoir pathogène, épidémiologie, organisation de la recherche, coopération internationale

Mots-clés géographiques Agrovoc : Afrique, Ouganda, Cameroun, Congo

Mots-clés complémentaires : Fusarium xylarioides

Classification Agris : H20 - Maladies des plantes

Editeurs scientifiques et affiliations

• Bieysse Daniel, CIRAD-AMIS-PROTECTION DES CULTURES (FRA)

Source : Cirad - Agritrop (https://agritrop.cirad.fr/513573/)

Métriques

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