Résumé
Coffee wilt disease (CWD), which is caused by Fusarium xylaroides Steyaert, the conidial stage of Gibberella xylarioides Hem. & Saccas, is the most serious problem of Robusta coffee (Coffea canephora) production in Uganda, the Democratic Republic of Congo (DRC) and Tanzania. It is also affects Arabica coffee (Coffea arabica) production in Ethiopia. CWD spreads quickly and widely, thus it is a threat to coffee production in all continents. It can be controlled effectively by planting resistant varieties. In Uganda CWD was first observed on C. canephora in 1993, in areas bordering the DRC and by 2002 it had spread to many parts of the country, where it had destroyed 44.5% of the crop (Oduor, 2005). This reduced Uganda¿s coffee exports by nearly 50% and led to economic loss of US dollars 80-270 million annually between 1996 and 2007. Consequently, a search for CWD resistant C. canephora varieties was initiated at the Coffee Research Centre (COREC) in 1997. This involved screening C. canephora germplasm in naturally infected fields and in artificial inoculations carried out in the screen house for resistance. The C. canephora genotypes both in field and screen house studies, responded quantitatively to the disease, implying that CWD resistance in C. canephora is controlled by many genes. 1519 completely resistant genotypes were identified through large scale germplasm screening in artificial inoculations at COREC and these were planted in mother gardens and thereafter they were cloned and planted in field evaluation trials. 167 of the clones underwent preliminary evaluation and four (4) were selected for being resistant to leaf rust and red blister disease and having good cup and bean qualities. The four selected clones were planted in on-farm multi location evaluation trials, en route to being recommended for commercial cultivation. Similarly, four (4) CWD resistant clones were selected from among many genotypes screened in naturally infected fields at COREC and were also planted on-farm multi location trials, en route for recommendation for farmer cultivation. (Résumé d'auteur)