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A survey carried out on vine stocks historically derived from a Gamay population known as ‘Plant Robert’ has allowed 13 clones free from major viral diseases to be introduced into a study collection. The agronomic and oenological performances of the three most promising candidates were studied in comparison with standard Swiss (RAC 10 and RAC 23) and French (ENTAV 565) clones as part of a trial conducted on the Agroscope experimental field in Pully from 2011 to 2015. The observations made have enabled the offering of a new clone (RAC 55) derived from the Gamay population known as ‘Plant Robert’, characterised by a moderate production potential and a high level of quality. This clone will be placed on the pathway to Swiss certification in spring 2017.

Keywords: grapevine, Gamay, Plant Robert, clonal selection, wine quality

E-Mail: jean-laurent.spring@agroscope.admin.ch

Adress: Agroscope, 1009 Pully

A trial was conducted on the cultivar Vitis vinifera Chasselas using two variables: 1) canopy height (90 or 150 cm), and 2) fruit load (5 or 10 clusters per vine). Isotopically labelled urea (10 atom % 15N) was applied at veraison with the aim of tracking nitrogen (N) distribution in the plant at harvest. The leaf-to-fruit ratio ranged from 0.4 to 1.6 m2/kg. Total and foliar N partitioning were mainly affected by canopy height: an oversized canopy (+31 % dry matter) led to a reduction in total N concentration throughout the plant (–17 %), and more especially in the yeast assimilable N concentration in the must (–53 %). Conversely, in a situation of insufficient leaf-to-fruit ratio, fruit maturity at harvest was affected.

Keywords: isotope labelling, yeast assimilable nitrogen, foliar fertilisation, partitioning, leaf-to-fruit ratio.

E-Mail: thibaut.verdenal@agroscope.admin.ch

Adress: Agroscope, 1009 Pully

The green splice graft has been experimented for top-grafting vines in the department of Herault. The vine stocks had been cut back in spring and the suckers grafted in July with shouts harvested the same day. The beginning of growth has proved to be rapid and homogeneous, the success rate is satisfactory (83.6 %) and the graft-union is completed. The tests realized in 2013 and 2016 has shown respectively, the importance of protection against fungus after grafting with downy mildew sensitive vine variety (Servant B) and the ability of resistant hybrid grape variety (Souvignier G) to spare this process.

Keywords: Splice graft, green grafting, top-grafting, resistant hybrid grape variety, vine, downy mildew, graft union

E-Mail: lepibiote@orange.fr

Adress:

At wine tastings doubts arise sometimes about the presence of volatil phenols, which are often the cause for barnyard, cloves, animal or stable odors. These odors are produced by Brettanomyces yeasts. Classic analysis methods include the counting of yeast cells after growth on agar medium. This analysis is not sufficient because Brettanomyces yeast may lose its ability to multiply all cells in response to stress but still remain viable. This viable but not cultivable (VNC) state is reversible. Tests were carried out in a red wine to find out if Brettanomyces yeasts, in the above mentioned state or exiting of it, retained their ability to produce volatile phenols. A stress factor of 30 mg/l free SO2 induced a VNC state. Brettanomyces yeasts lose the ability to degrade the wines but retrieve it as soon as the stress factor disappears and the yeast cells recover from their VNC state.

Keywords: Brettanomyces, Ethyl-phenol; Ethyl-gaiacol; VBNC; HPLC, EPF, Acridine orange, VBNC, VC, SO2

E-Mail: anne-claire.silvestri@changins.ch

Adress: School of Engineering at Changins

A rapid degradation of strawberries and raspberries is observed after harvest due to their fragility. The development of fungal diseases is the main cause of fruit losses and this is principally happening when storage conditions are not optimal. In this study, a treatment with gaseous ozone was tested with the aim to extend the storage life of the berries by reducing the losses caused by the development of rot. Results show that ozone is effective to slow down microorganisms growth without altering key fruit quality parameters (sugar, acidity and color) in most of the trials. In few experiments, a slight increase of strawberries softening caused by the ozone treatment was observed, but the difference with non treated fruits was not perceived by the panel of tasters.

Keywords: Strawberries, raspberries, ozone, fungal disease, quality

E-Mail: severine.gabioud@agroscope.admin.ch

Adress: Agroscope, 1964 Conthey

The stinkbugs Halyomorpha halys and Nezara viridula are two Pentatomidae that appeared recently in Switzerland and that become more and more problematic for fruit and vegetable production. In laboratory bioassays conducted at Agroscope Changins, residual effects of spinosad, chlorpyrifos, thiacloprid and azadirachtin A were tested on adults of the two pests at 0.5, 1, 2 and 4 times the doses recommended for field application in Switzerland. On H. halys, chlorpyrifos and spinosad showed the highest activity at recommended doses, with, respectively 50 % and 39 % mortality at 2 days after spraying (= DAS), and 100 % and 83 % mortality at 6 DAS, whereas thiacloprid had a very weak effect at all 4 tested doses. Comparatively, N. viridula was less sensitive to chlorpyrifos and spinosad, but slightly more susceptible to thiacloprid, though the latter induced a mortality of only 25 % at 2 DAS and 50 % at 6 DAS. Azadirachtin A was nearly ineffective on both species. Chlorpyrifos and spinosad might therefore be integrated in an “attract and kill” strategy against H. halys adults immigrating from hibernation sites and consequently decreasing the risk associated with the extensive application of phytosanitary products.

Keywords: residual effects, IPM strategy, brown marmorated stink bug, southern green stink bug

E-Mail: serge.fischer@agroscope.admin.ch

Adress: Agroscope, 1260 Changins/Nyon