Effets de quatre huiles essentielles sur la croissance mycélienne radiale d’un isolat de Alternaria sp. 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. English Title: Effects of four essential oils on radial mycelial growth of an isolate of Alternaria sp. in Burkina Faso 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.

Isolement, Identification Et Activite Antifongique De Deux Sesquiterpenes D’asteriscus Graveolens Subsp. Odorus (Schousb.) Greuter

Two sesquiterpenes of Asteriscus graveolens subsp. odorus, have been extracted, separated, purified and identified by NMR and IR: the naupliolide and asteriscunolide 3c. The valuation of these compounds is part of the search for a preventive approach of integrated control to reduce significantly the use of pesticides and especially the fungicide ones. The results revealed a strong inhibitory effect on naupliolide against Botrytis cinerea, Penicillium digitatum and Penicillium expansum dice concentration of 200 ppm. The asteriscunolide 3c showed a remarkable effect against Botrytis cinerea from the concentration of 150 ppm.

Activite Antifongique Des Flavonoïdes Isoles De La Plante Asteriscus Graveolens Subsp. Odorus (Schousb.) Greuter

A phenol acid and three flavones isolated from the plant Asteriscus graveolens subsp. odorus were tested against three fungi: Botrytis cinerea, Penicillium digitatum and Penicillium expansum. Using the method of incorporation of products in a PDA, a high sensitivity of Botrytis cinerea to caffeic acid and nevadensine was observed. Penicillium digitatum is the sensitive to luteolin, as to Penicillium expansum, it marks a sensitivity to artemetin. The efficacy of the tested molecules could be the subject of an investigation and exploitation in the integrated fight against the three tested fungi that cause a lot of damage to fruits and vegetables post-harvest.