Towards a collaborative research: A case study on linking science to farmers' perceptions and knowledge on Arabica coffee pests and diseases and its management

The scientific community has recognized the importance of integrating farmer's perceptions and knowledge (FPK) for the development of sustainable pest and disease management strategies. However, the knowledge gap between indigenous and scientific knowledge still contributes to misidentification of plant health constraints and poor adoption of management solutions. This is particularly the case in the context of smallholder farming in developing countries. In this paper, we present a case study on coffee production in Uganda, a sector depending mostly on smallholder farming facing a simultaneous and increasing number of socio-ecological pressures. The objectives of this study were (i) to examine and relate FPK on Arabica Coffee Pests and Diseases (CPaD) to altitude and the vegetation structure of the production systems; (ii) to contrast results with perceptions from experts and (iii) to compare results with field observations, in order to identify constraints for improving the information flow between scientists and farmers. Data were acquired by means of interviews and workshops. One hundred and fifty farmer households managing coffee either at sun exposure, under shade trees or inter-cropped with bananas and spread across an altitudinal gradient were selected. Field sampling of the two most important CPaD was conducted on a subset of 34 plots. The study revealed the following findings: (i) Perceptions on CPaD with respect to their distribution across altitudes and perceived impact are partially concordant among farmers, experts and field observations (ii) There are discrepancies among farmers and experts regarding management practices and the development of CPaD issues of the previous years. (iii) Field observations comparing CPaD in different altitudes and production systems indicate ambiguity of the role of shade trees. According to the locality-specific variability in CPaD pressure as well as in FPK, the importance of developing spatially variable and relevant CPaD control practices is proposed. (Résumé d'auteur

A Comparison Among Various Robusta Coffee (Coffea canephora Pierre) Clonal Materials and their Seedling Progenies at Different Levels of Nitrogen

The propagation and distribution of robusta coffee (Coffea canephora Pierre), clonal selections in Uganda has been hampered by logistics. These clonal selections also exhibit a substantial degree of genotype-environmental interaction. Our objectives were to further elucidate the differences between these clones, the differences between individual clones and their corresponding seedling progenies and a farmer's elite entry and to define the nitrogen levels required for the optimal performance of the various clones and seedling progenies. A split-split plot, randomized complete block design with 4 replicates was used. Mean yield data for the years 1988 and 1989 are presented. There were significant differences in the response to nitrogen but a complete response curve was not established. Nevertheless, the data confirmed that it is highly profitable to apply nitrogen to robusta coffee. The differences between the yields of clonal cuttings and their corresponding seedling progenies were much higher for the erecta types of robusta coffee than for the nganda type. The nganda clones had a higher level of general combining ability than the erecta types. The correlations between the clonal parents and their corresponding seedling progenies were low for all entries but slightly higher for the nganda than for the erecta entries. Using clonal cuttings resulted in higher yields for the erecta entries compared to their corresponding seedling progenies. This was not necessarily so with the nganda material.Key words: Robusta coffee, erecta type, nganda type, clones, seedlings, nitrogen

Immunodiagnostic potential of a 27 kDa protein of Fusarium xylarioides, the cause of coffee wilt disease in Robusta coffee in Uganda

Several Fusarium species infect Robusta coffee; these Fusarium xylarioides Steyaert (Gibberella xylarioides Heim and Saccas) are the most virulent and responsible for the destructive Robusta coffee wilt disease in Uganda. To date, F. xylarioides has not been isolated directly from soil, though the pathogen can persist in soil for a short time. In this study, a promising diagnostic target which can be developed into a serological test for F. xylarioides in coffee plants and soil has been identified and validated for identification. Water-soluble extracts of mycelia from six Fusaruim species were resolved by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The different protein profiles from the other five Fusarium species were compared and contrasted with that of F. xylarioides. Protein bands that appeared peculiar to F. xylarioides were cut and injected into rabbits to produce polyclonal antibodies. Dot blot and Western blot analyses showed one immunodominant antigen (27 kDa) common to all F. xylarioides isolates analyzed. No cross-reactivity of anti-27 kDa antibodies were observed in the entire test Fusarium species. The results suggest that polyclonal antibodies raised against the endoantigens from F. xylarioides of 27 kDa, is a promising tool for the rapid, sensitive, and accurate detection of pathogen in soil and plant parts.Keywords: Gibberella xylarioides, coffee wilt disease, antigen, antibodies, Uganda.African Journal of Biotechnology, Vol 13(29) 2922-292

Preliminary report on the status and host plant utilization by the Black Coffee Twig Borer, Xylosandrus compactus (Eichhoff) (Coleoptera: Curculionidae) in Uganda

The Black Coffee Twig Borer, Xyalosandrus compactus (Eichhoff) is a new but rapidly spreading pest of coffee and other plant species. However, knowledge of its pest status, damage and host plant species utilization in Uganda is still limited. To ascertain its spread and impact, a survey was conducted on 250 farms in 25 districts in the 5 major coffee growing regions of Uganda. At farm level, 12 coffee trees were randomly sampled along a diagonal transect and assessed for X. compactus infestation. In addition, host plant utilization by the pest was determined through farmers’ interviews and direct search by researchers. Our data show that the pest is present in all the 5 districts (100%) sampled in central region viz:- Mukono, Luwero, Mityana, Mubende and Mpigi, and at least 50% of the districts in southwestern viz:- Bundibugyo, Kasese and Rubirizi. However, the beetle was not observed in northwestern (West Nile), northern and part of eastern (Mt. Elgon) regions. X. compactus prevalence (percentage of infested farms), incidence (percentage of infested trees) and damage (percentage of infested primary branches) were 58.1, 34.0 and 3.8% respectively in the central region whereas, 22.1, 7.7 and 0.8% respectively in the southwestern region. At district level, the highest prevalence (100%) was observed in Mukono and Luwero then Bundibugyo (62.5%), Mityana (50.0%), Rubirizi (40%) and Kasese (30%). Similarly, high incidence rates of 91.7, 73.3 and 44.8% were observed in Mukono, Luwero and Bundibugyo respectively. Likewise, high damage rates of 13.6, 5.2 and 4.8% were observed in Mukono, Luwero and Bundibugyo districts respectively. Further, our study identified and documented more than 30 plant species in 17 families as potential hosts for X. compactus. These include important commercial and food crops, forest, fruit and shade trees and shrubs. In conclusion, this study confirms earlier surveys and reports that the black coffee twig borer is fast and rapidly spreading away from its initial occurrence (southwestern Uganda) and epicenter (central Uganda) to new infestation areas, posing a big threat to coffee production in the country. Therefore, there is an urgent need to put in place comprehensive mitigation measures in order to prevent the pest from spreading to new areas and also to minimize its impact on coffee production within the already affected areas

Nucleotide diversity of genes involved in sucrose metabolism. Towards the identification of candidates genes controlling sucrosse variability in Coffea sp.

Quality and drought stress tolerance are two important targets for Coffea species cultivation. Currently, efficient genetic improvement of these traits is still hampered by the lack of early and cheap predictors. In this context, identification of molecular tools linked to these traits would significantly improve breeding efficiency. Based on the available literature, different metabolisms involved in the variability of both drought tolerance and coffee quality can be proposed. Based on this information, a study was initiated in Coffea species, aiming at estimating nucleotide diversity of four sucrose metabolism enzymes (Sucrose Synthase, Cell Wall Invertase, acid Vacuolar Invertase and Sucrose Phosphate Synthase). The two mains objectives of this work were i) to assess the level of variability of these genes within the whole area of distribution of Coffea canephora, and within 15 related Coffea species representing the four groups of diversity of this genus, and ii) to identify polymorphisms useful for mapping and association genetic studies. Almost 200 polymorphisms (SNP, INDELS, SSR) were identified through sequencing of Coffea canephora genotypes. In addition, analysis of the variability of these genes between different Coffea species allowed the identification of 300 additional polymorphic sites. Parallel in-silico analysis of EST resources confirmed the interest of this approach towards the identification of polymorphisms in Coffea sp. Identification of nucleotide polymorphisms will not only provide useful markers for traditional genetic studies (genetic mapping, population genetics, association studie) but also provide criteria to infer the evolutionary history of the analysed genes. Such information will be particularly relevant to select the best candidate genes to test in future association studies

Genetic characterization and relationships of Uganda wild, feral and cultivated Coffea canephora (Robusta) for future sustainable use.

The ability of crops to adapt to environmental changes such as the predicted climate change strongly depends on the genetic variation that exists within the crops