In Africa, synthetic pesticide applications are overly frequent and above labelled rates. We assessed the efficacy of an insect net physical control system on field cabbage (Brassica oleracea var. capitata) production in France and Benin. Various mesh sizes and netting removal frequencies were compared under contrasting climatic conditions. Studies under Mediterranean climatic conditions (spring season) compared two mesh sizes (0.73 mm and 1.6 mm). Studies under subequatorial climatic conditions (cool and hot seasons) tested nets of mesh size 0.4 mm and 0.9 mm used either as permanent cover, removed daily, or 3 days per week. The results showed that a fine mesh did not improve the netting efficacy against pests but had a major impact on the microclimate. In Mediterranean climatic conditions, the netting efficacy and beneficial microclimate improved crop yields. In subequatorial conditions, crop yields were lowest with permanent net protection due to high temperatures under the nets and poor aphid and Spodoptera littoralis control. Removing the nets 3 days per week was a good technical/economic trade-off, ensuring acceptable efficacy with minimal effects on the microclimate. (Résumé d'auteur

Background: Environmental heterogeneity, emerging pathogens and limited access to financial and agricultural inputs prevent farmers from producing consistent crop yields in many developing countries. Yield instability impedes establishment of processing and export industries, thereby inhibiting economic development. Modern varieties offer significant increases in yield stability. Results:A deeply collaborative, multi-national germplasm trialing network was established in West Africa to identify tomato varieties well adapted to each country and mobilize those varieties into local seed distribution networks alongside an integrated pest management program. Research partners in seven West African countries evaluated over 100 tomato varieties for resistance to tomato leaf curl disease (ToLCD). Using biotechnology, the identity and distribution of the key viruses (begomoviruses) causing ToLCD in these countries were identified, and a vector-independent inoculation method (agroinoculation) was developed. The trials identified a set of high-performing varieties with resistance. Agroinoculation with the three prevalent begomoviruses confirmed resistance. Conclusions:These trial results fulfill the new Economic Community of West African States harmonized seed regulation policy, which requires at least 2 years of national performance trials prior to commercialization of a tomato variety. To compete with a rapidly expanding canned tomato import industry, West African growers need to increase productivity and processing capacity; therefore, we also assessed processing and export trade data for fresh and processed tomatoes from each of the seven countries.

Cet article est distribué suivant les termes et les conditions de la licence CC-BY (http://creativecommons.org/licenses/by/4.0/ deed.fr) Introduction. Les cultures maraichères occupent une place importante pour l'alimentation humaine et contribuent significativement aux revenus des familles en Afrique de l'Ouest, mais leur production est confrontée à une pression des bioagresseurs qui limite leur productivité. Littérature. Cette revue, basée sur des publications scientifiques, a pour objectif d'évaluer le potentiel des plantes pesticides comme alternative à l'usage des pesticides de synthèse pour lutter contre les bioagresseurs des cultures maraichères en Afrique de l'Ouest. Elle montre que le principal moyen actuel pour combattre ces bioagresseurs repose essentiellement sur les pesticides de synthèse. Cependant, compte tenu de leur nocivité sur l'homme et l'environnement, en plus de la sélection de populations résistantes chez les bioagresseurs, la recherche de solutions alternatives s'impose. Les plantes pesticides se présentent comme une alternative prometteuse dans le contexte ouest-africain. En effet, diverses espèces de plantes pesticides peuvent être utilisées comme extraits de plantes ou en association avec d'autres cultures pour le contrôle des bioagresseurs. Celles-ci sont présentées dans le présent article de synthèse. Conclusions. Les plantes pesticides peuvent être une alternative prometteuse pour la gestion des bioagresseurs des cultures maraichères. Cependant, la plupart d'entre elles ne sont pas cultivées. Explorer les capacités biocides de plantes d'intérêt comme le genre Ocimum, connu pour ses usages thérapeutique, médicinal et alimentaire pourrait être intéressant pour le producteur. Toutefois, les populations doivent être sensibilisées sur les avantages à long terme des produits traités avec les pesticides à base de plantes pour faciliter leur utilisation. Mots-clés. Plante pesticide, extrait d'origine végétale, culture maraichère, lutte antiravageur, Afrique au Sud du Sahara. Pesticidal plants and vegetable crop protection in West Africa. A review Introduction.Vegetable crops play a leading role in human nutrition and contribute significantly to the incomes of families in West Africa. However, their production is hampered by pressure from pests, which limits their productivity. Literature. This review, based on scientific publications, aims to evaluate the potential of pesticidal plants as an alternative to the use of synthetic pesticides to control vegetable crop pests in West Africa. It shows that the primary current method used to control these pests is mainly based on synthetic pesticides. However, in view of their harmful effects on humans and the environment, in addition to the range of resistant pest populations, the search for alternative approaches is needed. Pesticidal plants are a promising alternative in the West African context. Indeed, various species of pesticidal plant can be used as plant extracts or in association with other crops in pest management. These plants are present...

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Aims: This research aims at evaluating the effect of salt stress on plant growth, Na+, K+, proline and soluble sugars contents in leaves and roots of local cultivar of African basil in Republic of Benin. Study Design: The experiment was laid out in a Completely Randomized Design (CRD) having five treatments and three replications. Place and duration of Study: The experiment was carried out in screening house under natural conditions at the Center of Agricultural Research of Agonkanmey, Commune of Abomey-Calavi, Republic of Benin from January to February, 2020. Methodology: Five salt concentrations (0, 30, 60, 90 and 120 mM) were used to irrigate three weeks old plants for two weeks. After two weeks, plant growth, sodium (Na) and potassium (K), proline, and soluble sugars contents of leaves and roots were determined. Results: Salt stress induced a significant reduction (p = .05) in shoot growth from 60 mM NaCl but had no impact on the number of leaves and shoot water content. Root growth was significantly reduced (p = .05) already at 30 mM NaCl. Leaf and roots Na+, proline and soluble sugars contents significantly increased (p = .05) under salt stress whereas K+ content decreased significantly (p = .05) only in root. Conclusion: Salt stress reduces the growth of African basil plants due mainly to Na+ ion toxicity. The ionic selectivity ratio (K+/Na+) rather than the K+ ion content plays an important role in the response of basil plants to salt stress, while both proline and soluble sugars accumulation may contribute to osmotic adjustment.