Introduction. Le plantain constitue une importante denrée alimentaire pour de nombreuses populations au sud du Sahara. Sa production dans les systèmes traditionnels de culture par les petits paysans est menacée par la maladie des raies noires, une maladie foliaire due à Mycosphaerella fijiensis Morelet responsable de pertes importantes de récolte. Pour faire face à cette maladie, des hybrides tétraploïdes de type plantain, résistants à la maladie, ont été créés au Cameroun puis sélectionnés à l’issue d’une première phase d’évaluation. Après multiplication végétative, les hybrides ainsi sélectionnés ont été évalués en station de recherche afin de déterminer leurs caractéristiques agronomiques et leur rendement potentiel en conditions de culture semi-intensive. Matériel et méthodes. De 1996 à 2000, trente hybrides sélectionnés ont été évalués, en comparaison avec leurs parents femelles, sur deux cycles de production à la faveur de trois essais mis en place suivant un dispositif expérimental en blocs de Fisher complètement randomisés avec deux répétitions de 10 bananiers chacun. Chacun des bananiers a été étudié à partir de caractéristiques agronomiques portant sur la croissance et la production. Résultats et discussion. Sept hybrides ont été sélectionnés sur la base de leur rendement potentiel élevé, de leur précocité de floraison et de leur pouvoir rejetonnant. Cependant, ce matériel végétal tétraploïde présente plusieurs défauts qui constituent un frein à leur diffusion. Certains de ces hybrides sont utilisés comme produits intermédiaires dans un nouveau schéma d’amélioration variétale au CARBAP.

Introduction. Citrus canker, caused by the bacterium Xanthomonas axonopodis pv. citri, is a serious disease of most commercial citrus cultivars and some citrus relatives. Surveys were conducted in small-scale farms, commercial plantations, backyard orchards and nurseries in order to quantitatively study the occurrence and distribution of the disease and determine the intensity and field host range. Materials and methods. Seventeen locations in four regional states of Ethiopia were surveyed. Incidence on leaves was determined by counting total number of leaves and expressed as a proportion of leaves with at least one lesion. Incidence on fruits was determined on attached fruits, recorded as presence or absence of the symptoms. Severity was also measured on leaves and fruits. The identity of the pathogen was confirmed by morphological, biochemical and physiological characterization and detached leaf tests of representative isolates. Results. The surveys indicated the occurrence of citrus canker in Ethiopia. Overall incidence on leaves was 71.4% of leaves with at least one lesion and severity was 26.8% of leaf area infected. Incidence on fruits was 30% of fruits infected and severity was 21.25% fruit area infected. Morphological, biochemical and physiological characterization and detached leaf tests of isolates indicated characteristics similar to X. axonopodis pv. citri. The host range for citrus canker in Ethiopia was limited to Mexican lime (C. aurantifolia) and sour orange (C. aurantium). Based on the field host range and detached leaf tests, it appears that the X. axonopodis pv. citri variant that occurs in Ethiopia has similar host ranges to that of atypical Asiatic (Xac-A*) form. Canker severity significantly correlated with temperature but not with rainfall, elevation or tree age. Conclusion. This is the first confirmed report of the disease in Ethiopia.

Introduction. Citrus is the most important fruit crop widely grown by small-scale and commercial farms in Ethiopia. However, productivity of citrus in many parts of the country is threatened by Phaeoramularia leaf and fruit spot disease caused by Phaeoramularia angolensis. Surveys and field experiments were conducted to map the geographical distribution, and to study the efficacy of different fungicides for the control of this disease. Materials and methods. Surveys were conducted in the major citrus-growing areas (south, south-west and north-west) of Ethiopia. Random sampling techniques were used for sample collection. The efficacy of different fungicides against P. angolensis was studied under a hot-spot area, based on disease incidence and severity, and marketable fruit yield. Results and discussion. Phaeoramularia leaf and fruit spot disease of citrus has been widespread throughout the south, south-west, and north-west of Ethiopia, causing complete crop failure. This disease was more severe in smallholder farmers' fields as compared with the commercial orchards. The severity of P. angolensis was varied between different citrus species and areas with different agro-ecologies. The south and south-west part of the country, characterized by high and frequent rainfall with high humidity, were severely affected by the disease. Field application of Benlate, Score and Cuproxat significantly reduced the incidence and severity of the disease and, thereby, increased marketable fruit yield. Conclusion. Phaeoramularia leaf and fruit spot disease of citrus has become widespread in many parts of Ethiopia within a short period. Further investigation on P. angolensis biology and detailed epidemiological studies are mandatory to develop a model, and, thereby, to facilitate forecasting systems for effective and sustainable management of leaf and fruit spot disease of citrus in Ethiopia.

Introduction. The grapefruit tree has a long production period. In the Jordan Valley, harvest lasts from November to March. Many Jordanian farmers tend to harvest their fruit early to get high prices, regardless of its quality. Thus, the effect of the harvesting date on fruit quality of grapefruit cv. ‘Red Blush’ was evaluated under Jordan Valley conditions for two seasons, 2002 and 2003. Materials and methods. Fruit quality of uniform 25-year-old grapefruit cv. ‘Red Blush’ trees budded on sour orange rootstock was studied during the 2002 and 2003 seasons. Fruits were harvested from October 15 in both seasons with 15-day intervals with a total of eight harvests. The studied data were total soluble solids (TSS), titratable acidity (TA), the [TSS/TA] ratio and juice percentage. Results and discussion. Fruit total soluble solids and fruit juice percentages were at a minimal level during early harvesting dates and increased with time, reaching the maximum level on January 1 for TSS and January 15 for fruit juice percentage in the first season and on December 15 and February 1, respectively, in the second season, after that TSS decreased. Fruit titratable acidity values were at maximal levels during early harvesting dates (October 15) and decreased with time, reaching the minimum level on February 1 in the first season and on January 15 in the second season. The [TSS/TA] ratio ranged from 5.5 to 6.0 between January 1 and February 1 in the first season, and between December 1 and January 15 in the second season. Conclusion. Our study displayed that Jordan Valley growers are harvesting their grapefruits much too early to provide acceptable eating quality fruits to local markets.

Introduction. L’olivier (Olea europaea L.) est la principale espèce fruitière exploitée au Maroc. L’embryogenèse somatique de la Picholine marocaine a été jusqu’à présent très peu étudiée malgré l’importance de cette variété au Maroc. L’objectif de nos recherches a été d’étudier les effets de divers milieux de culture sur l’induction et le développement d’embryons somatiques chez cette variété. Matériel et méthodes. Des cotylédons entiers de graines d’olivier ont été excisés après désinfection et mis en culture. L’initiation des cals embryogènes a eu lieu sur un milieu de culture de Murashige et Skoog, solidifié par de l’agar et contenant 0,5 mg de zéatine·L–1 combinée à différentes concentrations en acide naphtalène acétique (ANA) [(1, 2, 5, 10 et 40) mg·L–1], les cultures témoins étant sans régulateurs de croissance. Après 3 semaines, les cals ont été transférés dans un milieu soit liquide, soit solidifié par de l’agar ou de la gélerite. Après 6 semaines sur le milieu d’induction, les cals ont été transférés sur un milieu maintenu liquide ou solidifié par de l’agar ou de la gélerite, et contenant 0,5 mg·L–1 de zéatine, afin de favoriser le développement des embryons somatiques et, par la suite, leur régénération en plantules. Le taux de cals induits et le poids moyens des cals formés sur les différents milieux ont été mesurés après 6 semaines de culture sur le milieu d’induction. Une analyse histologique des cals embryogènes et non embryogènes a été effectuée. Résultats. L’induction des cals a significativement été influencée par la concentration en ANA. Les meilleurs résultats ont été obtenus avec 2 mg ANA·L–1 pour l’induction des cals (82,3 %) et 5 mg ANA·L–1 pour le développement de ces cals (150 mg). Le milieu liquide s’est révélé être le meilleur pour l’induction des cals et le milieu avec agar a favorisé le développement des cals et la régénération de plantules par embryogenèse somatique. L’utilisation de la gélerite n’a permis aucune morphogenèse. Les plantules régénérées et acclimatées ont présenté une croissance normale en serre. Conclusion. L’embryogenèse somatique serait exploitable pour la micropropagation de l’olivier au Maroc.

Introduction. Two Turkish fig cultivars, Alkuden and Bursa Siyahi, were propagated by meristem culture to eliminate the fig mosaic virus. The technique of dsRNA analysis was conducted on the in vitro propagated plants to test for virus-free status. Materials and methods. Four different Murashige and Skoog (MS) media complementedwith different concentrations of growth hormones (GA3, BA and IBA) were compared to study the cultured meristems’ survival rate, shoot formation and rooting. Short- and long-term thermotherapy treatments were also applied. Results. For survival rate, 0.2 mg GA3·L–1 + 0.5 mg BA·L–1 gave the most favorable results; for shoot formation, it was the medium with 0.2 mg GA3·L–1 + 2.0 mg BA·L–1 which was the best, while rooting rate was the highest for meristems cultured on MS medium with only 0.1 mg GA3·L–1. Conclusion. Meristem culture, together with thermotherapy treatment, is recommended to obtain virus-free fig plant material. Although cultured plants seemed to be very healthy, dsRNA virus tests are recommended for sensitive evaluation of the sanitary status of the plants obtained.