Rice pathogens intercepted on seeds originating from 11 African countries and from the USA

1,916 rice seed samples from 11 African countries and the USA were tested for the presence of pathogenic microorganisms or those affecting seed quality. Bacillus spp., Pantoea spp., Sphingomonas sp. and the fungi Acremoniella sp., Alternaria sp., Aspergillus flavus, A. fumigatus, A. niger, Chaetomium sp., Curvularia sp., Fusarium oxysporum, F. solani, Fusarium sp., Helminthosporium sp., Microdochium oryzae, Nigrospora oryzae, Penicillium sp., Pestalotia sp., Phoma sp., Magnaporthe oryzae, Rhizopus sp., Sarocladium sp. and Tilletia barclayana were isolated. The highest incidence values were obtained with Curvularia sp., Microdochium oryzae, A. flavus, F. solani and Nigropora sp. In contrast, these fungi were not isolated from seeds of many countries with Togo having the least affected seeds (nine out of the 24 potential organisms diagnosed). The highest frequencies of these organisms were found on seed samples from Benin (20/22), Burundi and Tanzania (19/24), and Senegal (18/24). Across countries, A. flavus, A. fumigatus, Curvularia sp., F. solani, Nigropora sp., Rhizopus sp. and Microdochium oryzae were the most frequently isolated organisms. Concerning the major diseases, blast was diagnosed only once despite the high number of samples tested

Combining High Yields and Blast Resistance in Rice (Oryza spp.): A Screening under Upland and Lowland Conditions in Benin

The future security of the supply of rice for food in Africa depends on improving the level of local production to achieve self-sufficiency. In order to cope with the existing gap between production and actual demand, combining a high level of rice blast tolerance and a high-yield potential is necessary. The current study was conducted under upland and lowland conditions in Benin to gain insight into the performance of selected blast-resistant accessions along with some currently grown varieties. This study revealed a high phenotypic variability among these accessions. Furthermore, differences in the performance of these accessions under lowland and upland conditions were observed. Principal component analysis showed their grouping in three clusters. The analysis also demonstrated a high yield potential among the blast-resistant rice accessions whether they were Oryza sativa or O. glaberrima. Furthermore, there was a significant correlation between yield and both spikelet fertility and growth cycle duration. In conclusion, the present study identified promising rice accessions for future breeding. High phenotypic variability in combination with interesting traits can help to develop new resilient varieties. Finally, when the traits correlate with yield, they can be used as markers for an early screening method for identifying promising accessions at an early stage

Analyse de la rentabilite economique des systemes de production a base d’Igname : cas des sites de Leo et Midebdo au Burkina Faso

La production de l’igname est confrontée à plusieurs contraintes dont la baisse de la fertilité des sols. Pour améliorer le rendement de leurs cultures, les producteurs d’igname ont alors adopté plusieurs méthodes de gestion. Cette étude a pour objectif d’analyser la rentabilité économique des systèmes de production à base d’igname en relation avec les méthodes de gestion de la fertilité des sols par les exploitants agricoles des communes rurales de Léo et Midebdo au Burkina Faso. Un essai de typologie des systèmes de production à base d’igname a été fait à l’aide d’une analyse en composante Principale (ACP) appliquée à un échantillon de 100 exploitants agricoles. Les résultats montrent qu’il existe deux systèmes de production : i) un système semi-intensif et ii) un système extensif et itinérant. L’analyse de rentabilité économique par les indicateurs tels que la marge brute et le ratio bénéfice/coût, montre que le système de production semi-intensif semble plus rentable que le système extensif. Le ratio bénéfice/coût obtenu avec chacun des systèmes de production est inférieur à 1, ce qui signifie que la production de l’igname dans ces conditions n’est pas économiquement rentable. Une politique de promotion de la culture de l’igname par l’adoption de fertilisants (organiques ou minérales) dans les systèmes de production pour compenser la baisse de la fertilité des sols permettrait aux producteurs d’accroître leurs productions et revenus.Mots clés: Dioscorea, système de production, rentabilité, Burkina FasoEnglish Title: Analysis of the economic profitability of yam-based production systems: the case of Leo and Midebdo sites in Burkina FasoEnglish AbstractFace to the problem of soil infertility, several methods of soil fertility management are used by yam producers to improve their production. This study aims to analyze the economic profitability of yam production systems in relation to soil fertility management methods by farmers in the rural communes of Leo and Midebdo in Burkina Faso. A typology test of yam production systems was carried out using a statistical method based on multivariate analysis. The analysis was applied to a sample of 100 smallholders. The results showed that there were two production systems: i) a semi-intensive system and ii) an extensive and itinerant system. The economic profitability analysis by indicators such as gross margin and the cost/ benefit ratio indicated that the semi-intensive production system was more profitable than the extensive one. The cost/benefit ratio obtained with the two production systems was inferior to 1 indicating that yam production activity under these production systems conditions, was not economically profitable. A policy of promoting yam cultivation through the adoption of fertilizers (organic or mineral) in production systems to compensate for declining soil fertility would allow producers to increase their production and income.Keywords: Yam, production system, profitability, Burkina Fas

Evaluation in vitro et in vivo de trois fongicides de synthese et d’un fongicide biologique sur la croissance et la severite de Colletotrichum gloeosporioides et de Pestalotia heterornis, champignons...

Full French Title: Evaluation in vitro et in vivo de trois fongicides de synthese et d’un fongicide biologique sur la croissance et la severite de Colletotrichum gloeosporioides et de Pestalotia heterornis, champignons responsables de maladies foliaires de l'anacardier (Anacardium occidentale L.) en Côte d’IvoireL’anthracnose, maladie fongique, cause d’importantes baisses de rendements des anacardiers (Anacardium occidentale L.) dans certains pays producteurs. En Côte d’Ivoire, l’anthracnose est l’une des maladies les plus répandues dans le verger anacardier et se développe sur tous les organes de la plante. Cette étude a été conduite dans le but d’évaluer et de proposer des fongicides de synthèse et un fongicide biologique efficaces contre Colletotrichum gloeosporioides et Pestalotia heterocornis. L’étude a été réalisée in vitro sur la croissance de ces champignons et en serre sur le contrôle de l’anthracnose par l’aspersion foliaire des fongicides sur des jeunes feuilles préalablement inoculées avec l’agent pathogène. Cette étude a permis de confirmer l’efficacité in vitro du Carbendazime à 1 ppm et du Prochloraze à 10 ppm contre C. gloeosporioides et P. heterocornis, les pathogènes fongiques les plus disséminés dans les vergers d’anacarde de Côte d’Ivoire. Le fongicide biologique NECO s’est également montré efficace in vitro en inhibant totalement la croissance mycélienne de C. gloeosporioides et de P. heterocornis respectivement à la concentration de 300 ppm et de 200 ppm. Le Propiconazole s’est montré le moins efficace. Carbendazime et NECO ont été les meilleurs fongicides contre C. gloeosporioides, en inhibant totalement l’expression des symptômes de l’anthracnose en serre, aux concentrations de 50 et 3000 ppm, respectivement. Ces fongicides peuvent constituer une base pour la lutte intégrée contre l’anthracnose de l’anacardier.Mots clés: Anacardium occidentale, anthracnose, contrôle, fongicide de synthèse, NECOEnglish Title: Chemical and biological control of cashew (Anacardium occidentale L.) anthracnose in Côte d’IvoireEnglish AbstractAnthracnose, a fungal disease, causes significant declines in yields of cashew trees (Anacardium occidentale L.) in some producing countries. In Côte d’Ivoire, anthracnose is one of the most common diseases in the cashew tree orchard and attacks all organs of the plant. This study was conducted with the aim of selecting and proposing integrated control methods through the use of synthetic fungicides and an effective biological fungicide against Colletotrichum gloeosporioides and Pestalotia heterocornis. The study was carried out in vitro and in a greenhouse by foliar spraying of fungicides on young leaves previously inoculated with the pathogenic agent. This study confirmed the in vitro efficacy of Carbendazim  at 1 ppm and Prochloraz at 10 ppm against C. gloeosporioides and P. heterocornis, the most common fungal pathogens found in cashew orchards of Côte d’Ivoire. NECO, a Biological Fungicide was also effective by completely inhibiting the in vitro growth of C. gloeosporioides at the concentration of 300 ppm and P. heterocornis at 200 ppm. Propiconazole was less effective than the other fungicides. Carbendazim and NECO were the best fungicides against C. gloeosporioides, completely stopping the expression of symptoms of anthracnose in the greenhouse, at concentrations of 50 and 3000 ppm, respectively. These fungicides provide a basis for integrated control of cashew anthracnose.Keywords: Anacardium occidentale, anthracnose, control, synthetic fungicide, NEC

First report of Rice stripe necrosis virus infecting rice in Benin

International audienc

Differential responses of Brassica oleracea and B. rapa accessions to seven isolates of Peronospora parasitica at the cotyledon stage

Nineteen accessions of Brassica oleracea var. italica (broccoli), 31 of B. oleracea var. boirytis (cauliflower), two of B. oleracea var. capitata (cabbage), three of B. rapa subsp, rapifera (turnip), one of B. rapa subsp, pekinensis (Chinese cabbage), and three of Raphanus sativus (radish) were tested for their response to isolates of Peronospora parasitica (downy mildew) at the cotyledon stage. Of the seven isolates tested, four were from crops of cauliflower in France, two from oilseed rape (B. napus subsp, oleifera) in the UK, and one was from mustard (B. juncea) in India. Twenty-one differential responses to P. parasitica isolates from B. oleracea and two from B. rapa were identified. All Raphanus sativus accessions were resistant to all seven isolates. Accessions for which seedling populations exhibited a heterogeneous reaction to some isolates were classified in a separate category. The differential resistance to P. parasitica identified in B. oleracea and B. rapa can be used for future studies of the genetics of the host-pathogen interaction and for breeding for disease resistanc

Evaluation de l’effet repulsif d’extraits de neem (Azadirachta indica A. Juss., 1830) sur le charançon de la patate douce (Cylas puncticollis Boheman, 1833) en condition de laboratoire a Korhogo, nord de la Cote d’Ivoire

Une stratégie de gestion intégrée des insectes nuisibles à la culture de la patate douce a été élaborée pour réduire les pertes dues à ceux-ci. Ainsi, les propriétés répulsives des extraits de feuilles et d’amandes de neem ont été évaluées sur Cylas puncticollis, un charançon de la patate douce. Pour ce faire, quatre concentrations d’extraits ont été préparées à raison de quatre répétitions par concentration. Le test a consisté à la détermination du pourcentage de charançons présents dans la zone traitée. Chacune des concentrations d’extraits a été appliquée sur la moitié d’un papier buvard placé dans une boite de Pétri de 9 cm de diamètre et sur lequel 10 charançons ont été posés. Les effets répulsifs des extraits ont été comparés à ceux d’un insecticide chimique et l’eau distillée. Le test avec 20 cL/L d’extraits de feuilles a causé 85 % de répulsion contre 45 % pour les amandes à 25 g/L. Les extraits ont significativement causé plus de répulsion que l’eau distillée et l’insecticide chimique. Les tests ont révélé un potentiel plus répulsif des extraits de feuilles comparé à celui des amandes. Les extraits de neem pourraient constituer une alternative crédible à la lutte chimique pour la protection de la patate douce contre ce charançon. English title: Evaluation of the repellent effect of neem extracts (Azadirachta indica A. Juss., 1830) on the sweet potato weevil (Cylas puncticollis Boheman, 1833) under laboratory conditions in Korhogo, northern Côte d’Ivoire Abstract An integrated pest management strategy for sweet potatoes has been developed to reduce pest losses. Thus, the repellent properties of neem leaf and kernel extracts were evaluated on Cylas puncticollis, a sweet potato weevil. For this purpose, four concentrations of extracts were prepared with four replicates per concentration. The test consisted of determining the percentage of weevils in the treated area. Each of the extract concentrations was applied to half of a blotting paper placed in 9 cm diameter Petri dishes on which 10 weevils were placed. The repellent effects of the extracts were compared to those of a chemical insecticide and distilled water. Test with 20 cL/L leaf extract caused 85% repellence compared to 45% for almonds at 25 g/L. Compared to the chemical insecticide and distilled water, the extracts caused significantly more repellence. The tests revealed a higher repellent potential of the leaf extracts compared to those of almonds. Neem extracts could be a credible alternative to chemical control for the protection of sweet potato against this weevil. Keywords: Neem extracts, Repellent effect, Sweet potato, Cylas puncticolli

High sensitivity of mobile phone microscopy screening for Schistosoma haematobium in Azaguié, Côte d'Ivoire

Schistosomiasis infections continue to impact African settings disproportionately, and there is an urgent need for novel tools to evaluate infection control and elimination strategies at the community level. Mobile phone microscopes are portable and semiautomated devices with multiple applications for screening neglected tropical diseases. In a community-based schistosomiasis screening program in Azaguie, Cote d'Ivoire, mobile phone microscopy demonstrated a sensitivity of 85.7% (95% CI: 69.7-95.2%) and specificity of 93.3% (95% CI: 87.7-96.9%) for Schistosoma haematobium identification compared with conventional light microscopy, and 95% sensitivity (95% CI: 74.1-99.8%) with egg concentrations of five or more per 10 mL of urine. Mobile phone microscopy is a promising tool for schistosomiasis control and elimination efforts

Limited efficacy of repeated praziquantel treatment in Schistosoma mansoni infections as revealed by highly accurate diagnostics, PCR and UCP-LF CAA (RePST trial)

BACKGROUND: Most studies assessing praziquantel (PZQ) efficacy have used relatively insensitive diagnostic methods, thereby overestimating cure rate (CR) and intensity reduction rate (IRR). To determine accurately PZQ efficacy, we employed more sensitive DNA and circulating antigen detection methods. METHODOLOGY: A sub-analysis was performed based on a previously published trial conducted in children from Cote d'Ivoire with a confirmed Schistosoma mansoni infection, who were randomly assigned to a standard (single dose of PZQ) or intense treatment group (4 repeated doses of PZQ at 2-week intervals). CR and IRR were estimated based on PCR detecting DNA in a single stool sample and the up-converting particle lateral flow (UCP-LF) test detecting circulating anodic antigen (CAA) in a single urine sample, and compared with traditional Kato-Katz (KK) and point-of-care circulating cathodic antigen (POC-CCA). PRINCIPAL FINDINGS: Individuals positive by all diagnostic methods (i.e., KK, POC-CCA, PCR, and UCP-LF CAA) at baseline were included in the statistical analysis (n = 125). PCR showed a CR of 45% (95% confidence interval (CI) 32-59%) in the standard and 78% (95% CI 66-87%) in the intense treatment group, which is lower compared to the KK results (64%, 95% CI 52-75%) and 88%, 95% CI 78-93%). UCP-LF CAA showed a significantly lower CR in both groups, 16% (95% CI 11-24%) and 18% (95% CI 12-26%), even lower than observed by POC-CCA (31%, 95% CI 17-35% and 36%, 95% CI 26-47%). A substantial reduction in DNA and CAA-levels was observed after the first treatment, with no further decrease after additional treatment and no significant difference in IRR between treatment groups. CONCLUSION/SIGNIFICANCE: The efficacy of (repeated) PZQ treatment was overestimated when using egg-based diagnostics. Quantitative worm-based diagnostics revealed that active Schistosoma infections are still present despite multiple treatments. These results stress the need for using accurate diagnostic tools to monitor different PZQ treatment strategies, in particular when moving toward elimination of schistosomiasis. CLINICAL TRIAL REGISTRATION: www.clinicaltrials.gov, NCT02868385