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The American walnut husk fly (Rhagoletis completa), recently invasive to Switzerland, is not the only cause of black-stained walnuts - which can be hardly separated from their sticky, rotten husk. Both bacterial blight (Xanthomonas arboricola pv. juglandis) and Marssonina-fungi (Marssonina juglandis) can also lead to similar symptoms. Walnut varieties prove to be very differently affected by these plant diseases. The same kind of variability is now also confirmed for walnut husk fly by new results of Agroscope Changins- Wädenswil ACW together with Mexican specialists. These recent results lead to recommend robust varieties for replanting in order to allow pesticide-free and still effective walnut production in the North-alpine regions. To fulfill plant protection issues, but also to benefit of other good characteristics, following varieties are recommended: Sheinovo, Rainuss Kläusler, Fernette, Scharsch, Geisenheim 26, Meylannaise, Fernor, Ronde di Montignac, Wirz, Ferjean, Geisenheim 1247 and Parisienne. Among those, Meylannaise, Ronde di Montignac and Geisenheim 26 are very robust selfpollinating varieties.

Keywords: Juglans regia, pest, disease, invasive species, walnut husk fly

E-Mail: joerg.samietz@acw.admin.ch

Adress: INRAE, UMR LAE, 68000 Colmar

The efficiency of addition of amino acids to musts poor in nitrogen was tested in 2009 and 2010 on Chasselas, Chardonnay and Sauvignon from experimental vineyards of Agroscope Changins-Wädenswil in Changins (VD). By considering the specificity of the nitrogen composition of the vines, the addition of amino acids allowed to improve slightly the gustative quality of Chardonnay and Sauvignon wines contrary to additions of mineral nitrogen or certain nutriments for yeasts. On the other hand, this source of nitrogen was ineffective for Chasselas wines quality.

Keywords: : nitrogen composition, amino acids, stress, wine quality

E-Mail: fabrice.lorenzini@acw.admin.ch

Adress:

The optimal harvest window (sugar, firmness, starch, malic acid and ripening index) for a long term storage of Jazz® apples was analysed and adapted. Several storage trials showed that a stepwise decrease in temperatures from 3.5 to 1.5 °C increased the soft scald damages on the fruits. Cooling the apple at 3.5 °C and then storing them at 3 °C under controlled atmosphere avoided this disease without any negative effects on fruit quality. Different conditions of controlled atmosphere CA (2.5 % CO2 and 2 % O2) and ultralow oxygen conditions ULO (2.5 % CO2 and 1 % O2) gave good results for a eight months storage. For longer conservation, ULO conditions are recommended. Jazz® apples showed very high firmness after storage as well as under ambient temperature. In general, this apple cultivar offers outstanding high tolerance to storage diseases.

Keywords: storage, controlled atmosphere, ultra low oxygen (ULO), firmness, quality, soft scald

E-Mail: danilo.christen@acw.admin.ch

Adress:

This study aimed to follow up the in orchard physiological ripening evolution of Luizet apricots using visible and near infrared spectroscopy. The potential of development of a decision support tool for the harvest of Luizet dedicated to distillation was assessed with non-destructive measurements on fruits harvested every day. Physicochemical parameters evolved as expected on the trees, showing increasing soluble solids content and ground color and decreasing firmness and acidity. The visible spectroscopy (DA-meter) allowed to predict harvest date with a precision of one day and near infrared spectroscopy (Phazir) with a precision of three days. Both portable devices allowed good monitoring of fruit ripening on the trees and can be considered as reliable decision support tools for optimal harvest time of Luizet dedicated to distillation.

Keywords: decision support tools, optimal harvest time, vis /nir spectroscopy, apricot distillate

E-Mail: danilo.christen@acw.admin.ch

Adress:

3D plant models of 13 to 14 year-old apple trees were created with computer programs, considering the variety Golden Delicious and three training systems (Vertical Axis, Drilling, Ycare). These models helped calculating light conditions within a tree and consequently their influence on sugar content of individual fruits. Within a tree, the sugar content was related to the STAR (Silhouette to Total Area Ratio, i.e. the ratio of exposed to total leaf area during a day) of the leaf area near the fruit. High correlation coefficients (r2 = 0.75 in 2004 and > 0.88 in 2005) could be achieved between STAR categories and sugar content of the respective fruits. However, for individual fruits the correlation coefficients were rather low (r2 < 0.2 for over a half of the trees in 2004 et 2005), suggesting that light conditions nearby fruit were not sufficient to explain alone its sugar content. Other factors, such as shoot lengths which affects the leaf area, may also play a role. This information is useful for trailing and pruning the trees to improve fruit quality. Differences in average sugar content of the fruits between training systems and apple trees could not be related to light conditions. The fruit to leaf area ratio was better suited to explain those differences in fruit sugar content between the trees.

Keywords: Malus domestica, three-dimensional, plant digitising, modelling, tree training

E-Mail: philippe.monney@acw.admin.ch

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