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Nine insecticides were incorporated at different concentrations in artificial diet to determine their larvicidal effectiveness on grape berry moth Eupoecilia ambiguella from a laboratory strain originally collected in the region along the Lake of Geneva. A first evaluation was made after 14 days of rearing. Surviving individuals were then kept until adult emergence. Dose-mortality curves have been established. Efficiency varied widely among the tested insecticides. Seven out of nine products had a good potential to control grape berry moth as their LC50 values ranged from 0.02 to 1 ppm: methoxyfenozide, spinosad, flufenoxuron, tebufenozide, indoxacarb, chlorpyrifosmethyl and teflubenzuron. Concerning chlorpyrifos-ethyl (Pyrinex), its high LC50 of approximately 100 ppm can be attributed to the microencapsulated formulation that probably does not allow a good diffusion of active ingredients into the diet. Diflubenzuron does not present any interest for controlling grape berry moth. Methoxyfenozide and tebufenozide are potentially a little more effective on grape berry moth than on grapevine moth. Spinosad is appreciably more active on grape berry moth whereas teflubenzuron is clearly more effective on grapevine moth.
Key words: grape berry moth, insecticides, artificial diet, Eupoecilia ambiguella.

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Adress: Agora

The pear leaf blister mite can cause severe damage to pear leaves and young fruits in some regions. Due to hidden living inside leaf blisters, the mites are largely protected against the impact of plant protecting agents. Until now, treatments with mineral oil in early spring, during the time when the mites leave their hibernation sites under the bud scales to invade the young leaves and blossoms, were the only possibility to control these mites in Swiss organic fruit growing. The aim of this study was to examine the effects of sulphur, mineral oil and Surround®WP applied after harvest, at the time when the mites leave their blisters and migrate to their hibernation sites. These different treatments were applied shortly after harvest to benefit of mild temperatures of September. Counting the number of mites after dissection of the buds in laboratory in autumn and spring showed a good efficacy for all treatments. But at visual spring control during bloom, these results could not be verified for all treatments. Only the sulphur-treated trees were virtually free of blisters at spring time. With an efficacy of 95% (one application) or 100% (three applications), even heavily infested orchards may be cleaned-up.
Key words: organic orchards, pest management, fruit growing, Pear leaf blister mite, Eriophyes pyri, sulphur.

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Adress: Agora

Important diseases of apple and pear are caused by apple stem pitting foveavirus (ASPV) and the related pear vein yellows virus (PVYV). The fast diagnosis of these diseases by enzymelinked immunosorbent assay (ELISA) became possible thanks to the development of the first monoclonal antibodies (Mab’s). The validation of the procedure was achieved with samples of various species, varieties and organs, at different vegetative states. The results have been compared to the biological indexing and molecular detection by RT-PCR assays (reverse transcription polymerase chain reaction). A total concordance has been observed between the results obtained by ELISA and the biological indexing. The applied RT-PCR protocol did not detect all origins of the viruses. Virus detection by ELISA revealed particularly reliable with samples of wood scrapings. Wooden material is usually used in the distribution of varieties. The virus control within selection and plant propagation programs will therefore be facilitated. The mono-specificity of these monoclonal antibodies also allowed to confirm the close serological relationship between ASPV and PVYV.
Key words: monoclonal antibodies, apple stem pitting virus, ASPV, pear vein yellows virus, PVYV, ELISA, detection, fruit viruses.

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Adress: Agora

Scatella tenuicosta Collin (often misidentified as S. stagnalis) is a very common commensal diptera of greenhouses, especially in hydroponic systems, feeding on algae. It does not cause any direct damage, but depreciates vegetable leaves by its faeces. It can also transmit pathogenic fungi. Biological parameters of each immature stage of this species were studied in the laboratory at constant temperatures (12, 15, 20, 25 and 30 °C). Biotests were conducted on cubes of stone wool at different doses of the insecticide diflubenzuron, the entomopathogenic nematode Steinernema feltiae and a preparation based on spores of Bacillus thurniginesis var. israelinesis (BTi). Development time from egg to adult requested from 7,4 days at 30 °C to 43 days at 12 °C, resulting in a thermal threshold of 8,2 °C and a thermal constant of 156,3 day-degrees. At 12 °C, gross mortality was the highest, affecting 65% of the immature stages. At 20 °C, females lay in average 31 eggs per day, and 515 eggs during the whole lifespan. S. tenuicosta has therefore a high potential of reproduction. In biotests, diflubenzuron caused almost total mortality, even at half the dose registered against fungus gnats. S. feltiae is not adapted to live in stone wool and caused only 53% mortality at twice the recommended dose. BTi showed no larvicidal activity. Management of the pest and possible biological control are discussed.
Key words: Scatella tenuicosta, shore flies, biology, biocontrol, IPM, greenhouse.

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

Adress: Agora

The incidence of cluster sun exposure on the quality of grapes and wines was studied in a trial set up with the cv. Chasselas on the experimental vineyard of Agroscope RAC Changins at Pully (VD). The interaction between the rows orientation and a permanent grass cover (60-70% of the surface) was also studied. The second part of the study presents the agronomic results and the wine and grape qualiy. The exposed leaf area per kg grape ratio and the sugar level of the must were strongly influenced by the manipulation of the leaves of the cluster zone. Titrable acidity, malate, formol index and the rate of Botrytis decreased when the bunches were exposed to the sun. The values of these parameters were also lower for the East-West orientation and the plots with permanent grass cover. The wine tasting did not highlight big organoleptic differences between the different treatments; only some tendencies could be observed at the time of a tasting of the wines after a few years in the bottle.
Key words: grapevine, defoliation, cluster microclimate, must composition, wine quality.

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E-Mail: dominique.maigre@bluewin.ch

Adress: Agora

In this article, the concepts of physiological, phenolic and aromatic compounds ripeness are approached. Whereas the follow up of physiological maturity (sugar concentration, acidity) is currently employed, it is not yet the case with the phenolic and aromatic compounds. Methods based on sensorial analysis of berries are proposed to gather added information. This will help to make the appropriate enological choices in order to produce the quality of wines expected by the consumer.
Key words: grape testing, physiological maturity, phenolic maturity, aromatic maturity.

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E-Mail: christian.guyot@eichangins.ch

Adress: Agora

Monitoring of usual maturation parameters (sugar content, total acidity) as well as of phenolic compounds is achieved during 2003 on fifteen plots throughout the French speaking part of Switzerland. In four of them berries are subject to sensory analysis and vinification at three to four successive harvest dates. Chemical and sensory analyses are carried out on each wine after eight months of aging. Flash profiling is used to determine the influence of berries ripening state on organoleptic characteristics of the wines. This method will help to clarify their sensory position compared to the measures obtained along maturation. During ripening, no relation is found between usual parameters and phenolic compounds evolution. Flash profiling designates the wines issued from the latest harvests as more complex and more harmonious, although technical ripeness (sugar content, acidity) was obtained much earlier. In three cases, a period of 16 to 17 days separated the time when phenolic compounds maturation curve reached a maximum and the harvest date of the most harmonious wines. Additional references should be gathered to confirm these trends.
Key words: ripening, maturation, phenolic compounds, anthocyanin.

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Adress: Agora