Introduction. La micropropagation in vitro du bananier est habituellement réalisée à partir du bourgeon caulinaire, donc à partir d’un seul explant par rejet. Par ailleurs, la production de vitroplants est souvent limitée par la disponibilité en rejets et le pourcentage de variants somaclonaux augmente avec le nombre de subcultures. Il serait donc intéressant de disposer d’un plus grand nombre d’explants par rejet afin de produire un même nombre de vitroplants avec moins de subcultures. L’exploitation des bourgeons axillaires présents en grand nombre sur un rejet de bananier permettrait d’augmenter le nombre d’explants utilisables pour sa multiplication. L’objectif de nos travaux a donc été d’évaluer les capacités de prolifération in vitro des bourgeons axillaires en comparaison de celles du bourgeon caulinaire. Matériel et méthodes. Des bourgeons caulinaires et axillaires prélevés sur des rejets du cultivar Big Ebanga (AAB, plantain faux corne) ont été soumis à trois types de désinfection : une désinfection par flambage, une désinfection classique modifiée et une désinfection classique. Ils ont été ensuite ensemencés sur un milieu de culture. L’effet de plusieurs concentrations en benzylaminopurine (BA) a été étudié sur la précocité de la prolifération des bourgeons axillaires. Résultats et discussion. La désinfection classique a donné le plus faible taux d’infection (30 %) chez les bourgeons axillaires. Les bourgeons axillaires ont proliféré précocement et ont produit des bourgeons adventifs dès la première subculture, alors que les bourgeons caulinaires n’ont proliféré qu’à partir de la deuxième ou troisième subculture. Cette prolifération précoce a été accélérée en présence de (2 et 4) mg BA·L–1. Le nombre de pousses formées par chaque type de bourgeon n’a pas été significativement différent. Conclusion. Les bourgeons axillaires sont un bon matériel de départ pour la culture in vitro. Leur utilisation permet de régénérer un grand nombre de vitroplants à partir d’un seul rejet et augmente ainsi les potentialités de production in vitro de matériel végétal sain chez le bananier plantain. La conformité au champ des plants issus de ces bourgeons axillaires fera l’objet d’études ultérieures.

Introduction. La maladie du bout de cigare est provoquée par Trachysphaera fructigena Tab. et Bunt. ; cette maladie fongique est responsable de l’apparition de symptômes nécrotiques sur les fruits des bananiers et des plantains dans différentes régions de production en Afrique. Les conditions permettant un développement optimal de cette maladie sont très particulières car elles sont saisonnières et ne sont généralement réunies que dans certaines zones de production. La mise en œuvre de méthodes de lutte efficaces pour contrôler cette maladie est très difficile en raison de sa saisonnalité. Le travail réalisé a permis d’évaluer l’efficacité d’une technique de ligature des inflorescences du bananier pour lutter contre la maladie du bout de cigare en milieu paysan. Matériel et méthodes. Des plants du cultivar de plantain French clair (AAB) ont été utilisés dans un dispositif expérimental en blocs randomisés comprenant trois répétitions de deux traitements (zone d’Ekona à 400 m d’altitude, au Cameroun) : un traitement témoin non traité et un traitement de plants dont les inflorescences ont été ligaturées dès la floraison. Les comparaisons ont porté sur le pourcentage de régimes touchés par la maladie, le pourcentage de mains atteintes par régime et le pourcentage de fruits atteints par main et, enfin, le poids des régimes à la récolte. Résultats et discussion. Les plus faibles attaques ont été enregistrées sur les plantes ligaturées. Les taux d’infection ont alors été globalement de 3 % pour les régimes traités, de 12 % pour les mains par régime et de 1 % pour les fruits par main, alors que ces taux ont été de (73, 61 et 16) %, respectivement, pour les plantes témoins non traitées. La technique utilisée a aussi permis un gain supplémentaire de poids d’environ 2 kg par régime. Ces premiers résultats expérimentaux montrent que la technique de lutte est efficace pour contrôler les infections par T. fructigena. Des études complémentaires devront cependant être réalisées pour confirmer ces résultats avant d’envisager le transfert de cette technique en milieu paysan.

Introduction. Banana plants (Musa sp.) face problems caused by diseases such as Yellow Sigatoka (Mycosphaerella musicola), which is responsible for significant economic losses. Through micropropagation techniques, a somaclone variety called CIEN BTA-03 resistant to this disease was obtained. The purpose of this study was to compare fruits of somaclone CIEN BTA-03 and its parental clone Williams. Materials and methods. Fruits from both clones were studied, determining shape, weight, dimensions, proportions, pulp viscosity and consistency, total solids, soluble solids, pH, titratable acidity, sugars, ash, total phenolic content and crude fiber, and analyzing their color, odor and taste. Results and discussion. Clones differed in shape, weight and [pulp/peel] ratio. Pulps also differed in viscosity, pH, and soluble solids, sugars and phenolic compound contents. Differences between the two clones favored clone CIEN BTA-03, since it was better ranked for the color, odor and taste characteristics. Conclusion. Despite being resistant to Yellow Sigatoka, somaclone CIEN BTA-03 shows better sensory characteristics than its parental clone Williams.

Introduction. Damage of citrus fruits by the Mediterranean fruit fly Ceratitis capitata Weid. results in economic losses in Nigeria. The majority of the citrus producers are small-holders who are yet to adopt standard citrus production practices. A trial was therefore established in a savannah zone of Nigeria with a Southern Guinea agroecology to evaluate simple fruit fly control practices. Materials and methods. The efficacy of combining cultural practices such as removal of dropped fruits, changes of harvest period, and three applications of dimethoate/cypermethrine mixture in controlling fruit fly damage was tested on sweet orange Citrus sinensis (L.) Osbeck var. Valencia Late in 2000 and 2001. Results. Fruits attacked by C. capitata increased with fruit maturity and were positively correlated with the number of dropped fruits. Insecticide applications and removal of dropped fruits significantly reduced the number of fruits attacked by the fruit flies. Similarly, early harvesting at 50% fruit ripening significantly (P < 0.05) reduced the number of fruits attacked by the fruit flies when compared with the late harvesting at 90% ripening. The interactive effects of insecticide applications and the period of harvest significantly (P < 0.05) reduced attacks on fruits. Discussions. Judicious use of insecticides, periods of harvest and removal of fallen fruits reduce fruit fly damage. Late harvest and non-removal of fallen fruits constitute fruit fly reservoirs for the re-infestation of other clean fruits. Since the tested control methods were simple, they can be adopted by small-holders for the control of fruit flies.

Introduction. Sclerocarya birrea (A. Rich.) Hochst. is a common species in the dry zones of Africa. Although appreciated by the populations for its fruit, the subspecies birrea, present in Western Africa, remains not domesticated and under-utilized; the subspecies caffra, originating in Southern Africa, was recently domesticated there where it occupies a considerable economic role. Within the framework of a domestication programme led in Senegal, tests studied the development of the grafting applied to S. birrea subsp. birrea. Materials and methods. Scions taken from female mature trees were grafted on young rootstock plants at five periods during the year and according to three grafting techniques (tongue grafting, top grafting and side plate grafting). Results and discussion. The most favorable period for the grafting is at the end of the rain season; no significant difference was observed between the three types of grafting technique tested. Conclusions. The propagation technique highlighted could be developed for the ex situ conservation of the genetic diversity of Sclerocarya birrea subsp. birrea and also for the selection of varieties interesting for the criteria considered (yield and fruit quality, and rusticity). In time, S. birrea subsp. birrea could constitute in Western Africa a fruit tree crop for diversification.

Introduction. The lack of information in the literature regarding the most adequate sampling time and leaf for the assessment of the nutritional status of carambola trees limits the use of leaf analysis as a diagnostic method for this species. Therefore, we determined seasonal variations in the leaf mineral composition of carambola trees cultivated on acid soil and submitted to lime application in order to define criteria for the indication of the diagnostic leaf and the adequate sampling time. Materials and methods. The experiment was set up in a typic Hapludox in Bebedouro, São Paulo, Brazil, with lime doses of (0, 1.85, 3.79, 5.56 and 7.41) t·ha–1 applied in August 1999. Grafted carambola tree seedlings (cv. Malaysia) were planted in December 1999. To assess the nutritional status of the plants, the leaf’s macro- and micronutrient concentrations were determined in the third and sixth leaves, including the petiole, in flowering branches without fruits located in the middle third of the plant. Samples were collected throughout 2002, except for January and February due to the lack of flowers. Results and discussion. The results showed that the sixth leaf was more effective than the third leaf for the assessment of the nutritional status of carambola trees, with better differentiation of the lime effect on the levels of Ca, Mg, Mn, Zn, Cu and Fe, especially during the sampling period from August to October. Conclusion. In the area concerned with this study, the sixth leaf collected during the flowering peak from August to October appears ready to allow a nutritional diagnosis of carambola trees.

Introduction. Litter on the ground is a primary source of Botrytis cinerea inoculum in boysenberry (Rubus hybrid) gardens. The effect of litter management on primary inoculum production, and flower and berry infections was determined. Materials and methods. A series of experiments ranging from laboratory to large-scale field evaluations were conducted in New Zealand during 1997-2002 to evaluate litter management options for control of B. cinerea. The laboratory trial investigated the effect of litter size (shredded vs. unshredded litter) and debris amendments on tissue degradation and B. cinerea colonization. The field trial (four sites) investigated the effect of litter amendments (compost, urea and fungicide) and piling litter on B. cinerea sporulation. In the 4-year commercial-scale study (three properties), the effect of litter treatment (piling, compost and microbial extracts/suspensions) on primary inoculum, flower and berry infections was assessed. Results and discussion. The laboratory trial showed that bark + sewage sludge compost amendment enhanced litter decomposition and reduced B. cinerea sporulation on infected tissue after 8 weeks. The field trial indicated that piling of shredded boysenberry debris was more important than litter amendments in reducing the amount of B. cinerea harbored within the litter. Commercial field-scale evaluation of litter management options verified that piling of shredded litter is the most important step in B. cinerea inoculum control from debris. It also showed that microbial litter amendments (compost, solutions or extracts) can be beneficial. While B. cinerea inoculum control also reduced the amount of flower infections, berry infections at harvest were not affected, indicating that other sources of B. cinerea inoculum contribute to berry infection post-flowering.