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Contribution to the development of a biological control method against crown rot disease

Lassois L., De Lapeyre de Bellaire L., Busogoro J.P., Jijakli M.H.. 2004. In : Picq Claudine (ed.), Vézina Anne (ed.). First International congress on Musa: harnessing research for improved livelihoods, 6-9 July 2004, Penang, Malaysia. Abstract guide. Montpellier : INIBAP, p. 163-163. International Congress on Musa: Harnessing Research for Improved Livelihoods. 1, 2004-07-06/2004-07-09, Penang (Malaisie).

Crown rot is an important banana post-harvest disease infecting the pad of cut hands. The disease spreads rapidly during fruit ripening and contaminates the pedicel and ultimately the pulp. The disease is caused by a complex of fungi (occasionally bacteria) with one main pathogen: Colletotrichum musae. The aim of this study was to evaluate the antagonistic activity of two yeast strains against the parasitic complex in relation with their concentrations and their incubation period. The antagonistic activity of Pichia anomala strain K and Candida oleophila strain O, applied at three concentrations (106, 107 , 108 cfu/ml), have been evaluated on Colletotrichum musae (103 conidia/ml), Fusarium moniliforme (104 conidia/ml), Cephalosporium sp. (104 conidia/ml) or on a parasitic complex formed by the association of these three fungi. One hundred pl of the pathogen(s) were deposited on the crown of 4 'Grande naine' (AAA) hands. After 15 minutes, the crowns were soaked in a suspension of strain K or strain O for 10 seconds. Before the evaluation of the pathogen(s) progression into the crown, bananas were incubated for 13 days under conditions similar to exportation. Antagonistic effects have been observed on C. musae, F. moniliforme and the complex. Among the various treatments, the application of strain O at 108 cfu/ml showed the highest protective level (56%). This level was higher than those observed against the fungi separately inoculated. The influence of incubation period between strain O (108 ufc/ml) and complex inoculation has also been studied. Strain O was applied 24h before the complex, but also 15' or 3h after its inoculation. The highest protective level was observed when strain O was applied 24h before the complex. Finally, a correlation between symptom severity and protective level of strain O has been highlighted. When the severity of the disease increased, protection by the yeast decreased. In conclusion, both strains have showed antagonistic effects but str

Mots-clés : musa; ravageur des plantes; colletotrichum; contrôle de maladies; lutte biologique; parasite; colletotrichum musae

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