Integrated control of Striga hermonthica (Del.) Benth. in Burkina Faso through host plant resistance, biocontrol and fertilizers

A two-year field study investigated integrated management of Striga hermonthica on sorghum through host crop resistance, biocontrol (Fusarium oxysporum isolate 34-FO), and fertilizer application. The experiment was conducted in a field with natural Striga infestation at Kouaré Research Station in Fada N’Gourma, Burkina Faso. Treatments combining sorghum resistance with Fusarium inoculum and N-fertilizer or manure significantly reduced emerged Striga plant number, plant vigour and dry biomass of Striga and the area under the Striga number progress curve (ASNPC) in 2002, as compared to the control. Integrated Striga Management (ISM) plots fertilized with urea, urea plus growth medium or urea plus manure associated with Fusarium inoculum resulted in improved sorghum grain yield of at least 15% in 2001 and of at least 97% in 2002. Economic analysis showed that the combination of sorghum resistance with fungal inoculum or urea at 200 kg ha-1 allowed for a significant financial profit in sorghum production. The results suggest that to reduce Striga infestation below economic threshold, ISM treatments should be consistently applied for several years without expecting very high returns.Keywords: Striga hermonthica, integrated control, Fusarium inoculum, Sorghum resistance, fertilization, Burkina Fas

Summary and conclusions

Climate variability is a reality that is affecting rural livelihoods in West Africa today and presenting a growing challenge in the region, as in many other parts of the African continent and elsewhere. Climate change will have far-reaching consequences for the poor and marginalized groups among which the majority depend on agriculture for their livelihoods and have a lower capacity to adapt. Weather-related crop failures, fishery collapses, and livestock deaths in addition to losses of property are already causing economic losses and undermining food security in West Africa. This situation is likely to become more desperate and to threaten the survival of the majority of poor farmers as global warming continues. Feeding the increasing populations in a subregion with one of the highest rates of population growth in the world requires radical transformation of a largely underdeveloped agriculture over the next four decades. A major challenge is increasing agricultural production among resource-poor farmers without exacerbating environmental problems and simultaneously coping with climate change..

Overview

The part of Africa designated as West Africa is made up of 16 countries— Benin, Burkina Faso, Cape Verde, Côte d’Ivoire, Gambia, Ghana, Guinea, Guinea-Bissau, Liberia, Mali, Mauritania, Niger, Nigeria, Senegal, Sierra Leone, and Togo. Its land area is about 5 million square kilometers, and its population in 2010 was about 290 million. With the exception of Mauritania, these countries are members of the Economic Community of West African States (ECOWAS). The subregion comprises a diversified agricultural base spread over a wide range of agroecological zones with significant potential for improved agricultural productivity. Agriculture is the major source of livelihood for the majority of West Africans. The agricultural sector employs 60 percent of the active labor force but contributes only 35 percent of gross domestic product (GDP). The disparity between contribution to GDP and share of population means that many West African farmers are very poor, producing close to subsistence levels and facing numerous constraints such as droughts, soil acidity, and nutrientdepleted and degraded soils that impinge on agricultural development. The most important foodcrops grown and consumed in West Africa are cereals— sorghum, millet, maize, and rice; roots and tubers—cassava, sweet potatoes, and yams; and legumes—cowpeas and groundnuts. Major cash crops are cocoa, coffee, and cotton..

Host resistance stability to downy mildew in pearl millet and pathogenic variability in Sclerospora graminicola

Downy mildew, caused by Sclerospora graminicola, is a major pathogen of pearl millet (Pennisetum glaucum) in Asia and Africa. So development of resistant cultivars has been a major goal of national and international breeding programs. Stability of resistance in pearl millet lines developed at ICRISAT was studied through a collaborative International Pearl Millet Downy Mildew Virulence Nursery (IPMDMVN). The reactions to downy mildew of 11 pearl millet lines at 17 locations in India, Burkina Faso, Mali, Niger, and Nigeria from 1995 to 1999 were recorded. Disease incidence varied significantly among lines, locations, and years. The tested pearl millet lines exhibited significant differential resistance. Resistance in lines IP 18292, IP 18293, 700651 and P 310-17 was most stable regardless of the location or season. Analysis of the variation in resistance also suggested that the resistance in IP 18292 and IP 18293 was variable and depended on the locations and years, while the resistance in 700651 and P 310-17 was highly stable across locations and over years. The latter two lines could prove to be the most valuable sources of downy mildew resistance. The results also revealed significant differences in S. graminicola populations at different locations, with the highest disease at Bagauda (Nigeria) and Durgapura (India) and lowest from Coimbatore and Aurangabad (India). Based on the reaction of the 11 pearl millet lines, the 17 S. graminicola populations were grouped into six putative pathotypes (undefined populations closer to races)

Effets de quatre huiles essentielles sur la croissance mycélienne radiale d’un isolat de <i>Alternaria sp.</i> au Burkina Faso

L’alternariose de la tomate est une maladie cryptogamique dévastatrice dans les zones maraichères du Burkina Faso. Tous les organes de la plante (tiges, feuilles, fruits) sont attaqués, entrainant une baisse importante du rendement et une dépréciation de la qualité de la production. Dans la présente étude, quatre huiles essentielles de plantes aromatiques locales (Cymbopogon schoenanthus, Lippia multiflora, Ocimum americanum, et Ocimum basilicum) ont été testées, pour évaluer leurs propriétés d'inhibition sur la croissance radiale du mycélium d’un isolat pathogène de Alternaria sp. Le test in vitro des doses de 100%, 50%, 10%, 5% et 1% a montré que toutes ces huiles essentielles possèdent une activité antifongique sur ledit isolat. Les taux d’inhibition des huiles essentielles sur la croissance du champignon étudié vont de 25,96% à 100%. La meilleure inhibition a été enregistrée avec l’huile essentielle de Cymbopogon schoenanthus, de Ocimum basilicum et de Lippia multiflora pour les concentrations supérieures à 1%. Il ressort donc de cette étude que trois huiles essentielles, stoppent la croissance mycélienne de l’isolat pour des doses allant de 5% à 100%. Ces huiles (Cymbopogon schoenanthus, Ocimum basilicum et Lippia multiflora) pourraient être utilisées pour la mise au point de phytopesticides afin d'atténuer l’utilisation intensive et hasardeuse des pesticides.Mots clés:  Alternariose, activité antifongique, plante aromatique, tomate.&#x0D; English Title: Effects of four essential oils on radial mycelial growth of an isolate of Alternaria sp. in Burkina Faso&#x0D; Early blight of tomato is a devastating cryptogamic disease in the vegetable gardens in Burkina Faso. All plant’s organs (stems, leaves, fruits) are attacked causing a significant decrease in the yield and a depreciation of the quality of the production in the field. In the present study, four essential oils of aromatic plants (Cymbopogon schoenanthus, Lippia multiflora, Ocimum americanum, and Ocimum basilicum) were tested to evaluate the inhibition properties of these oils on the radial growth of the mycelium of an isolated pathogen of Alternaria sp. In vitro tests at doses of 100%, 50%, 10%, 5% and 1% showed that all these essential oils tested have antifungal activity on said strain. The inhibition rates of essential oils on the growth of the fungus studied range from 25.96% to 100%. The best inhibition was recorded with the essential oil of Cymbopogon schoenanthus, Ocimum basilicum and Lippia multiflora for applied concentrations more than 1%. It therefore emerges from this study that three essential oils stop the mycelial growth of the isolate for doses ranging from 5% to 100%. These oils (Cymbopogon schoenanthus, Ocimum basilicum and Lippia multiflora) could be used for the development of phytopesticides in order to reduce the intensive and hazardous use of pesticides.Keywords: Early blight, antifungal activity, aromatic plant, tomato.&#x0D;  </jats:p