Epidemiology of black Sigatoka of banana (Musa spp.) in ecological zone IV of Togo

La banane est le fruit le plus consommé au monde et aussi en Afrique de l’Ouest. Cependant, les plantations de bananiers sont souvent attaquées par un champignon ascomycète appelé Mycosphaerella fijiensis M., responsable de la maladie des raies noires (MRN) ou cercosporiose noire avec des pertes de rendement supérieures à 50%. L’objectif de cette étude est d’identifier les variétés de bananiers résistantes, tolérantes et sensibles à la MRN. Cette étude a été menée dans quinze (15) plantations de bananiers et plantains dans la zone écologique IV du Togo. Les résultats nous ont montré que l’incidence de la maladie (IM) varie de 91,0 ± 21,6 à 100% ± 0,00 dans les champs et l’indice de sévérité (IS) varie de 94,0% ± 23,5 pour la variété Dankodu à 145,0% ± 96,4 pour la variété Agbavé, ce qui indique que toutes les variétés de cette zone seraient très sensibles. Nos travaux de sélection en serre, nous permettrons d’identifier les variétés sensibles et d’envisager les voies de stimulation de la défense naturelle de ces variétés par inoculation d’un éliciteur. Mots clés: bananier, cercosporiose noire, incidence, TogoBananas are the most consumed fruit in the world and in West Africa. However, banana plantations are often attacked by an ascomycete fungus called Mycosphaerella fijiensis M., responsible for black leaf streak disease (BLSD) or black Sigatoka with yield losses greater than 50%. The objective of this study is to identify varieties of bananas that are resistant, tolerant or susceptible to BLSD. This study was carried out in fifteen (15) plantations of bananas and plantains in ecological zone IV of Togo. The results showed that the disease incidence (IM) varies from 91.0 ± 21.6 to 100.0% ± 0.00 in the fields and the severity index (IS) varies from 94.0% ± 23.5 for the Dankodu variety to 145.0% ± 96.4 for the Agbavé variety, which indicates that all varieties found in this zone would be very sensitive. Our selection work in the greenhouse will allow us to identify the susceptible varieties and to consider ways of stimulating the natural defense of these varieties by inoculation with an elicitor. Keywords: banana, black Sigatoka, incidence, Tog

Assessment of major cassava diseases in Togo in relation to agronomic and environmental characteristics in a systems approach

A cassava disease survey was conducted in four agroecological zones of Togo. High incidences of cassava bacterial blight, cassava mosaic disease and cercosporioses were observed across ecozones, while anthracnose disease was rare. Bacterial blight field incidences of 90.5% in the dry savanna zone, 70% in the forest savanna transition zone, 64% in the wet savanna zone and 52.6% in the forest zone, were recorded, with plant incidences ranging from 27.4% in the forest zone to 72.7% in the dry savanna zone. Mosaic disease field incidences were nearly 100% in all the ecozones and high plant incidences up to 86.9% were found. Cercospora leaf diseases brown leaf spot, blight leaf spot and white leaf spot occurred in all the ecozones with incidences ranging from 68 to 100%. Negative correlations between bacterial blight and mosaic disease, and between mosaic disease and white leaf spot were found, while brown leaf spot and blight leaf spot, brown leaf spot and white leaf spot, and blight leaf spot and white leaf spot were positively correlated. Field incidence of bacterial blight was positively correlated with plant age, ecozones higher severity in dryer ecozones (P < 0.01), and weed density (P < 0.05). Further significant, but negative correlations occurred between bacterial blight and cercospora brown leaf spot on the other hand and vegetation type in the surroundings field (number of trees) (P < 0.05). Cercosporabrown leaf spot was also significantly negatively associated with the number of crops in a field (intercropping) (P < 0.05), and Cercospora white leaf spot with sandy soils (P < 0.01). Results indicate that agroecological factors such as ecozone, plant age, weed density, vegetation type, intercropping and soil type and moisture influence disease occurrence and should be considered when developing integrated control measures

Inventaire des maladies de l’anacardier (Anacardium occidentale L.) dans la préfecture de Tchamba au Togo

L’anacardier (Anacardium occidentale L.) est d’une grande importance socio-économique. Malheureusement, il est attaqué par bioagresseurs dont les maladies fongiques et bactériennes. La présente a pour but d’inventorier les maladies majeures de cette culture, d’évaluer leur prévalence, incidence et sévérité, et d’identifier les pathogènes associés dans 5 des 10 cantons de la préfecture de Tchamba au Togo. Trois vergers par canton ont été évalués par rapport aux symptômes de maladies. Les résultats ont révélé 7 maladies : dessèchement des bourgeons (DB), anthracnose, jaunissement foliaire, rouille noire, gommose, chancre bactérien et rouille rouge. Le DB a donné les taux d’incidence et de sévérité respectifs de 15,99% et 19,19%, supérieur à ceux des autres maladies (p = 0,03). La prévalence des maladies a varié de 20% à 100%. Les pathogènes associés identifiés sont Colletotrichum gloeosporioides pour l’anthracnose, Cochliobolus sp. pour le jaunissement foliaire, Cephaleuros virescens pour la rouille rouge, Lasiodiplodia theobromae pour la gommose et Xanthomonas sp. pour le chancre bactérien. Il ressort de ces résultats que l’anacardier est la cible de pathologiesaussi bien fongiques que bactériens et que de stratégies de lutte adaptées doivent être déployées. &nbsp; English title: Cashew (Anacardium occidentale L.) diseases’ inventory in the prefecture of Tchamba in Togo Cashew (Anacardium occidentale L.) is an important tropical crop worldwide. However, it is attacked by several bioagressors among which fungal and bacterial diseases. The present study aimed to survey the major diseases of cashew tree, assess their prevalence, incidence and severity, and to identify the associated pathogens in five from the ten districts of the prefecture of Tchamba in Togo. Three cashew plantations per district were visited and fungal and bacterial disease symptoms evaluated. The results revealed seven diseases occurring in the surveyed area: Dieback of buds, anthracnose, leaf yellowing, black rust, gum disease, bacterial canker and red rust. Dieback of buds recorded significantly higher disease incidence of 15.99% and severity of 19.19% than the other diseases (p = 0.03). The prevalence of the diseases varied from 20% to 100%. The associated pathogens of the diseases were Colletotrichum gloeosporioides for anthracnose, Cochliobolus sp. for leaf yellowing, Cephaleuros virescens for red rust, Lasiodiplodia theobromae for gum disease and Xanthomonas sp. for bacterial canker. These results revealed the importance of fungal and bacterial diseases occurring in the studied area, thus appropriate control measures must be developed