Introduction. Black Leaf Streak Disease (BLSD) is regarded as the most economically important threat that the banana industry has to face. Effectively, this foliar disease affects leaf photosynthesis but, above all, reduces the greenlife of fruits, that cannot be exported in cases of severe infestation. Main characteristics of Black Leaf Streak Disease. More than 20 Mycosphaerella species have been described on bananas. Leaf spot diseases of bananas are caused by some species of this complex, of which M. fijiensis (BLSD) and M. musicola (Sigatoka disease) are the most important. M. fijiensis is an invasive species that has totally replaced M. musicola in most banana-exporting countries, which was conducive to increasing difficulties in banana leaf spot control. BLSD causes increasing difficulties for control. Since all banana cultivars grown in the banana industry are highly susceptible to BLSD, the control of this disease relies on aerial applications of fungicides according to either systematic frameworks (mostly contact fungicides) or forecasting strategies (mostly systemic fungicides). In a banana-exporting country where M. fijiensis has been reported, BLSD control becomes increasingly more difficult. This evolution is essentially due to the rapid emergence of fungicide resistance, and is conducive to a significant increase in the cost of disease control but, above all, to increasing negative environmental effects. Challenges for the banana industry. Because of the rapid adaptation of M. fijiensis, the banana industry must be prepared for significant evolution. We propose various parameters that should be monitored at different levels (disease assessment parameters, evaluation of chemical control efficiency, global evaluation of BLSD economic incidence) to rationalize such evolution. The modelization of BLSD effects on bunch mass and greenlife should enable defining acceptable disease thresholds and optimizing bunch weight and harvest stage according to agronomic practices. On the other hand, fungicide use is conducive to significant environmental impact and must be limited. Forecasting strategies should be used wherever systemic fungicides are still efficient. Finally, the predominance of a unique type of susceptible cultivar is unsustainable and the recourse to resistant varieties in an integrated strategy is undoubtedly the future of BLSD control.

L’arbre. Les arbres du genre Carapa (Meliaceae) sont présents dans toutes les forêts d’Afrique tropicale au niveau de l’équateur, du rift d’Albertine jusqu’au Sénégal et au Mali pour sa distribution la plus septentrionale. En Afrique comme en Amérique tropicale, le carapa est une source importante de Produits Forestiers ligneux (bois) et Non-Ligneux (PFNL). Le fruit et les graines. Le fruit typique de carapa est une capsule à quatre ou cinq valves qui renferment chacune deux à cinq graines, soit un total de huit à vingt graines par fruit. L’extraction de l’huile. Les villageois ramassent les graines tombées au sol avant qu’elles ne soient parasitées ou germées, ce qui est défavorable à la production d’une huile de qualité. L’extraction de l’huile se fait par ébouillantage des graines. L’huile extraite, polyvalente, est la substance issue de la plante qui est la plus utilisée devant les extraits de feuilles, d’écorce et de racines. Le marché. En Afrique, le commerce de l’huile de carapa est essentiellement local et reste une activité très marginale. Une demande accrue émane toutefois de l’utilisation de cette huile comme insecticide naturel dans la culture du coton biologique. Discussion. Compte tenu du potentiel économique de l’huile de carapa, sa commercialisation devrait respecter une rétribution équitable des paysannes afin de mieux rentabiliser la production. Des mesures de protection des arbres de carapa et de leur habitat doivent également être prises pour permettre une gestion de la production d’huile à long terme. La plantation semble être une option durable en vue de la conservation des peuplements naturels de carapa.

Introduction. A study of accessions from the major production areas of Dacryodes edulis (Don) Lam. (Burseraceae) in Cameroon was carried out in order to assess the impact of pedoclimatic parameters and genetic factors on the characteristics and the classification of the fruits. The work focused on statistical analysis of fruit morphological and chemical parameters to distinguish accessions. Materials and methods. The fruits were collected from five localities of Cameroon (Obala, Boumyebel, Makenene, Njombe and Kekem). Twenty-six characters, among which were eleven quantitative morphological, nine qualitative morphological and six chemical characters, were the object of a correlation analysis, a principal component analysis and hierarchical classification. Results. Among the twenty-six characters studied, eighteen presented interesting morpho-chemical characters to discriminate the accessions. The fruit quantitative morphological characters were not significantly different, while the qualitative morphological and chemical characters showed significant differences for the localities concerned. A principal component analysis and hierarchical classification distinguished three major groups at a genetic distance of between 5.70 and 6.92: group I consists of accessions from Makenene and Kekem, discriminated by five characters (lipids, protein, grain colour, texture and colour of the mesocarp); group II consists of accessions from Njombe and Obala and was discriminated by six characters (weight of fruits, amino acids, sugars, phenols, epicarp colour and shape of grains); group III consists of the accession from Boumyebel and was discriminated by seven characters (fruit length and diameter; [fruit diameter / fruit length] ratio; weight of fruit, mesocarp and grain; and mesocarp thickness). Discussion and conclusion. Like agro-forestry species such as Ricinodendron heudelotii and Irvingia gabonensis, D. edulis presents intra-specific variations that are related to pedoclimatic conditions and genetic factors.

Introduction. Canada is an important avocado importer from Mexico. For most of the harvest season, fruit reach adequate pulp dry matter content, ripen properly and, consequently, quality and shelf life are excellent. However, after January, fruit dry matter content increases and blackened skin occurs. Shipments to Canada containing blackened fruit are rejected because this characteristic is wrongly associated with low pulp firmness and short shelf life. The objective of our research was to determine the effect of harvest time and ripening degree on initial quality and shelf life of Hass avocado. Materials and methods. Fruit were harvested from October 2007 to April 2008, and grouped into five ripening categories according to the degree of blackened skin. Fruit were then refrigerated for 7 d to simulate shipment to Canada. Thereafter, fruit were stored under simulated market conditions until they reached the edible ripening stage. Dry matter content was calculated only at the beginning of the storage period while quantification of weight loss, fruit with blackened skin, pulp firmness, and pulp color was done at the beginning of the storage period, at the end of the refrigeration period, and every three days during market conditions. Results and discussion. Dry matter content, skin color and pulp hue angle significantly increased with harvest date and ripening degree. Weight loss decreased with harvest date but increased with ripening degree, while firmness was affected by harvest date but was not associated with ripening degree. Conclusion. There is no reason to reject or downgrade blackened fruit, since quality and shelf life are not affected.

Introduction. Tamarind (Tamarindus indica L.) belongs to the Fabaceae family; it is a multipurpose tree with slow growth. In order to help improve its growth and development, we assessed mycorrhizal diversity of tamarind parklands in Senegal. Materials and methods. Three sites of tamarind populations were sampled for each agro-ecological zone in Senegal: the Sahelian zone (i), Sahelo-Sudan zone (ii) and Sudan zone (iii). Soil and root samples were collected in each site and used for arbuscular mycorrhizal (AM) spore isolation and root colonization assessment. We identified the mycorrhizal fungi from spore collections and evaluated the root mycorrhization rate, defined as percentage of roots colonized according to agro-ecological zones. Results and discussion. The results did not reveal a specific AM fungal strain associated with tamarind plants. Three arbuscular mycorrhizal fungi (AMF) were identified from spores on the genus level: Glomus, Scutellospora and Acaulospora. Tamarind sites with sandy soil texture (70–90%) and located in dry areas (Sahel and Sudano-Sahel zones) were shown to be rich in mycorrhizal propagules. High densities of soil AM propagules evaluated with the Most Probable Number method (MPN) were found in Niokhoul (1100 propagules per 50 g of soil), Sakal (790 propagules per 50 g of soil) and Mbassis (780 propagules per 50 g of soil). However, higher mycorrhizal colonization (11%) was observed in the Sahel agro-ecological zone compared with the Sudano-Sahelian and Sahelian zones (3%) of Senegal. Conclusion. Our study explored natural AMF diversity as a starting point to develop inocula to be used in commercial nursery production of tamarinds.

Introduction. During maturation, vanillin is accumulated in green vanilla beans as glucovanillin; it is hydrolyzed to free vanillin by endogenous glucosidases during curing and gives the characteristic flavor of vanilla. The objective of our study was to investigate methods of curing that could greatly reduce the time to complete the process and yield cured beans that retain high concentrations of vanillin and other flavor compounds with high sensory quality rating. Materials and methods. Mature green beans were obtained from a commercial grower (Cairns, Queensland, Australia). One batch of beans was continuously sweated at 35 °C at high relative humidity (RH) for 12 d. Two further batches were blanched in water at 67 °C for 3 min, and then sweated at 45 °C at high RH for 4 d or at 35 °C for 5 d. The beans were sweated until they turned brown. Three methods of drying were evaluated: a heat pump dryer at 40 °C and RH 15%, tunnel dryer at 60 °C and RH 20%, and tunnel dryer at 60 °C and RH 10%. Vanillin was extracted from powdered samples of beans with n-pentane and dichloromethane (1:1 v/v) and assayed by HPLC. Glucovanillin was measured as total vanillin after acid hydrolysis of powdered samples of beans. Results and discussion. About 90% of the glucovanillin was converted to vanillin in non-blanched beans continuously sweated at 35 °C, but there was only 70% conversion in beans blanched at 67 °C for 3 min and sweated at 45 °C for 4 d or at 35 °C for 5 d. The sensory quality of cured beans was assessed by untrained panelists. Profiling showed that the beans sweated continuously at 35 °C had superior aroma compared with beans blanched in hot water and sweated at 45 °C or at 35 °C but the appearance of non-blanched beans was less attractive. Conclusion. The study revealed that a mild hot water blanching treatment followed by sweating at 35–45 °C and rapid drying is required to produce cured beans with excellent appearance and attractive aroma.