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Effectiveness of leaf oil of Pimenta racemosa (Mill) J.W. Moore on R. solanacearum population and bacterial wilt of tomato

Deberdt P., Davezies I., Coranson-Beaudu R.. 2014. In : Book of abstracts of the 2nd Congrès International Natural Products and Biocotrol. s.l., p. 16-16. Congrès International Natural Products and Biocotrol. 2, 2014-09-24/2014-09-26, Perpignan (France).

Bacterial wilt caused by Ralstonia solanacearum is the most widespread plant disease in tropical and subtropical regions. In Martinique (French West Indies), the bacterial wilt situation changed dramatically after 1999 with the emergence of strains of R. solanacearum assigned to a new genotype, phylotype IIB/4NPB, which is highly pathogenic for solanaceous crops, especially tomato. Due to the limited efficacy of current strategies for the management of bacterial wilt, new control strategies such as biorational soil treatments are required. We investigated the effects of three differently scented chemotypes of essential oils of Pimenta racemosa var. racemosa (lemongrass, aniseed and clove scents) on the emerging strain of R. solanacearum (phylotype IIB/4NPB), their potential use as biofumigants to reduce bacterial wilt disease of tomato, and their effect on tomato growth. Three concentrations of the oils (0.04, 0.07, and 0.14% vol/vol) were evaluated by in vitro culture amendment assays and in vivo experiments in a greenhouse. In the culture amendment assays, with lemongrass scented and aniseed scented oil chemotypes at concentrations of 0.04% and 0.07% respectively, both oils significantly reduced the growth of R. solanacearum compared with the control, and at 0.14% they completely inhibited bacterial growth. With the clove scented chemotype, complete inhibition of R. solanacearum growth was achieved at all the concentrations tested. No incidence of tomato bacterial wilt was observed after treatment with the clove scented chemotype of Pimenta racemosa when the tomato plants were planted in essential oil-treated soil. In the untreated control soil, bacterial wilt affected 64% of the tomato plants whereas with the clove scented chemotype at a concentration of 0.14%, no bacterial wilt was observed on tomato. Treatment with the clove scented chemotype significantly increased the growth of tomato plants compared with the untreated control. These results suggest that esse

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