Description succincte
(Anglais)
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This research project will investigate the efficacy and potential adverse impacts of alternative strategies to control soil-born deceases in strawberry production. Certain soil fungi such as Verticillium spp. represent a serious threat to various crops including strawberries. On the other hand beneficial soil fungi such as Trichoderma spp. are powerful biological control agents. Therefore, any control measure applied to reduce impact of soil-born pathogens should no affect beneficial soil microorganisms in the long term and thereby reducing soil quality. Methyl bromide has extensively been used for soil-born pathogen control, but in 2005 it has been banned in many countries due to its impact on stratospheric ozone. Alternative methods are being developed but the precautionary principle indicates that prior to routine application new technologies have to be evaluated for potential adverse effects on the environment. Therefore, this project aims at assessing efficacy and potential negative effects of two promising alternative control measures, i.e. 'biofumigation' (BF) and 'biological soil desivestation' (BSD). During a period of two years a postdoctoral research fellow will establish and if necessary improve or develop diagnostic tools for genetic analyses of Verticillium spp. and Trichoderma spp. in soil. These tools will be applied to assess the effects of BF and BSD on pathogenic, beneficial, and general soil microorganisms in pot and field experiments with strawberries. With these data we will be able: i) to assess efficacy and undesired non-target effects of these control measures and ii) to provide a validated set of tools for soil quality assessment. Both these deliverables are of great importance for sustainable agriculture, i.e. strawberry production, general soil-born pathogen control, and soil quality assessment.
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Partenaires et organisations internationales
(Anglais)
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AT, BE, BG, CH, CY, CZ, DE, DK, ES, ES, FI, FR, GR, HR, HU, IE, IL, IT, LT, LV, MK, NL, NO, PL, PT, RO, RS, SE, SI, SK, TR, UK
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Résumé des résultats (Abstract)
(Anglais)
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Verticillium wilt is a major concern in strawberry production systems, where the disease is caused by Verticillium dahliae and V. albo-atrum. High concentrations of chemical fumigants are required to suppress the long-term survival structures of the fungi, making the control of Verticillium wilt costly and environmentally damaging (Pegg & Brady, 2002). Moreover, banning methyl bromide, the most efficient chemical soil fumigant, induced a strong need for alternative control methods (Carpenter et al, 2000). Biofumigation and biological soil disinfestation are two methods compatible with organic production and promising results against Verticillium wilt (Goud et al, 2004; Debode et al, 2005). The first method is based on the release of isothiocyanates during the decomposition of some crucifers, while the second method acts through anaerobic soil conditions under the temporarily sealed soil surface. However, efficacy of soil-borne disease control may depend on the soil type (Michel & Mew, 1998). A molecular diagnostic tool for four economically significant Verticillium species was developed. A phylogenetic study of the genus Verticillium using a multi gene approach was firstly conducted. Cluster analyses revealed species-dependent clustering for the intergenic spacer (IGS) gene sequences and a large number of species-specific DNA sequence signatures. Therefore, the complete IGS region was isolated and sequenced from a collection of 45 fungal strains including Verticillium and closely related species. Species-dependent clustering was verified with a proteomic approach using Matrix Assisted Laser Desorption Ionization - Time Of Flight (MALDI-TOF) mass spectrometry. Based on this data, we designed species-specific PCR primers targeting the IGS of the four Verticillium species and tested them on the collection of 45 strains. Specificity and sensitivity of the primers will be tested on environmental samples and a quantitative PCR tool will be developed. This rapid and reliable detection method will be applied to assess efficacy of biofumigation and biological soil disinfestation against Verticillium spp. in a pot experiment conducted over a four month period. Samples were regularly taken, and inoculum concentration of Verticillium spp. in soil as well as microbial activity quantified. The newly developed molecular diagnostic tool will be applied to monitor Verticillium spp. during the different treatments and the impact on non-target microorganisms will be assessed.
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