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A study on yield restriction was carried out on the new red wine Carminoir vine plant on the experimental estate at Gudo (Ticino, Switzerland) of the ACW Agroscope Changins-Wädenswil Research Station. A normal yield level, corresponding to a leaf-fruit ratio situated between 1.0 and 1.2 m2 of exposed leaf surface area per kg of grapes, was compared with a heavily restricted variant (50% of normal yield). The heavily restricted variant produced slightly sweeter and less acidic musts and wines richer in polyphenols, and with a deeper colour. Yield levels had no influence on vine strength and no notable differences were detected in the sensorial analysis of wines. Overall, the small qualitative differences measured in the present study did not justify very low yields, characterised by leaf-fruit ratios well higher than the value of 1.0 to 1.2 m2 of exposed leaf surface area per kg of grapes.

Keywords: grapevine, yield level, cluster thinning, must composition, wine quality.

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

Adress: Agroscope, 1009 Pully

One experiment of spacing between rows with different heights of the foliar hedge were started in 1986 in Pully (Switzerland) using Chasselas vines on the experimental estate of the Agroscope Changins-Wädenswil Research Station ACW. At the same shoot load and the same clusters number per vine, the increasing of the row spacing led to an increase of the yield per plant but to a strong decrease of the yield per square meter, without improvement of the sugar content in the must. The same observation was made for the total cane weight. The ratio of exposed leaf surface per kg of grapes (SFE/kg) was a valuable tool in explaining sugar content in musts. The row spacing had only little effect on must acidity, berry weight and bud fertility. With increasing vine spacing the number of roots per vine increased, but the root density per linear meter diminished.

Keywords: training system, vine spacing, yield, quality, roots distribution.

E-Mail: vivian.zufferey@agroscope.admin.ch

Adress: Agroscope, 1009 Pully

An analytical tool was built up to discriminate «wine in wood» from «wood in wine» practices. To this end, the pattern of empyreumatic xylovolatiles was studied by GC-MS in several commercial oak chips, laboratory oak chips and shavings from toasted staves. Red and white wines have been supplemented with these materials at 4 g/l, and their empyreumatic pattern measured after 3 to 6 weeks. The aromatic profiles of these wines were compared to those of wines raised in new oak barrels for up to 11 months, both groups forming a databank of more than 300 elements. Principal component analysis of raw data shows that wines in oak barrels are clearly discriminated from oak chip-treated wines. This difference in empyreumatic profiles proceeds from uneven impact of toasting on wood pieces of various thickness. Finally, bottledwines fromdifferent grape varieties and origins, were successfully confronted to the databank as well as a few «special cases».

Keywords: discrimination, oak, wine in wood, wood in wine, empyreumatic xylovolatiles, databank, principal component, analysis.

E-Mail:

Adress: Agora

The efficacy and the mode of action of various fungicides or elicitors (i.e. activators of defence mechanisms) were evaluated on the basis of grape resistance markers to downy mildew (Plasmopara viticola) developed at Agroscope Changins-Wädenswil ACW. These markers (rate of infection, quantification of sporulation, quantification of stilbenic phytoalexins and stomatal callose) are used both on single leaves and whole plants of Vitis vinifera cv. Chasselas. The results show that only two products (root extract of rhubarb Rheum palmatum and bark extract of glossy buckthorn Frangula alnus) out of 21 tested allow, at the same time, the elicitation of defence mechanisms in a prolonged way, particularly by stimulation of the _-viniferin synthesis (the most toxic stilben for P. viticola), and the inhibition of pathogen development at a significant degree. Gallic acid induced in the plants a massive production of stilbens for a short time, insufficient to inhibit the development of downy mildew. Nevertheless, it protects the plants by means of fungitoxic effect. On the contrary, copper treatments, tannic acid and extract of Chinese gall (Galla chinensis) showed important fungitoxic effects without induction of plant defence mechanisms. The described method allows a reliable evaluation of efficacy of elicitors or plant protection products against downy mildew of grapevine, based on objective analytical parameters.

Keywords: grape, defence mechanisms, stilbens, elicitors.

E-Mail: katia.gindro@agroscope.admin.ch

Adress: Agroscope, 1260 Changins/Nyon

Resistance detection tests were carried out by the topical application of discriminating insecticide doses on diapausing larvae of the codling moth C. pomonella collected in Swiss, Armenian and Bulgarian orchards. The level of resistance varied according to the origin of the populations and their history of pesticide treatment. Swiss strains were, in the worst cases, highly resistant to the insect growth regulators fenoxycarb, tebufenozide, methoxyfenozide and diflubenzuron, to deltamethrin as well as to the organophosphates phosalone and azinphos-methyl. They were a little less resistant to chlorpyrifos-methyl and chlorpyrifos-ethyl. Resistance to more recent products such as indoxacarb, imidacloprid, thiacloprid and spinosad was also very pronounced. The two strains coming from Armenia and Bulgaria were highly resistant to the organophosphates and pyrethoids whereas the efficacy of insect growth regulators and of the more recent products was clearly less affected. Only Emamectin, a new insecticide still in development, showed no signs of cross-resistance. The recommended strategy for resistance management, consisting of a combination of mating disruption technique and granulosis virus, improved efficacy of the majority of the products after few years.

Keywords: codling moth, Cydia pomonella, insecticides, resistance, Switzerland, Armenia, Bulgaria.

E-Mail: denis.pasquier@agroscope.admin.ch

Adress: Agroscope, 1260 Changins/Nyon

Horticultural Glasshouses are more and more often equipped with mist and fog systems. To appreciate the influence of air humidity on soilless culture of roses, the efficacy of biological control against mites (Tetranychus urticae) and white flies (Trialeurodes vaporariorum), the production of cut roses, their vase life and the emergence of diseases were analysed. In the treatment with regulation of air humidity, the development of mites during the hottest months in summer was limited compared to the treatment without fog system. On the other hand, the air humidity adjustment did not show significant effects on the development of the white flies, on the parasitism rate by Encarsia formosa, or on the yields. However, it allowed reducing the development of powdery mildew. The air humidity adjustment reduced the absorption of the nutrient solution, probably due to the lower transpiration rate and negatively influenced the vase life of the cut roses.

Keywords: air humidity, fog system, biological control, fertigation, glasshouse roses, production, vase life.

E-Mail: celine.gilli@agroscope.admin.ch

Adress: Agroscope, 1964 Conthey