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In 2011, the efficacy of two insecticides registered in Switzerland for chemical control of the European cherry fruit fly (Rhagoletis cerasi), thiamethoxam (Actara) and acetamiprid (Gazelle SG), was compared to the former standard dimethoat (several products) in commercial orchard trials on 20 Swiss fruit farms. Dimethoat and thiamethoxam were each applied once three weeks before harvest. Acetamiprid was applied twice at an interval of 14 days and with a waiting period of again two weeks. All three insecticides resulted in a sufficient efficacy and thereby damage was below the limit required in practice. Insect exclusion netting (1.3 mm net) was equally effective in protecting the crop from damage if the nets were kept closed from colour change of the fruit (from yellow to pink) until harvest. Additional phenological experiments showed that eggs were laid on the fruit only from colour change on but also from then until harvest.

Keywords: european cherry fruit fly, chemical control, efficacy trials, insect exclusion netting, phenology, oviposition

E-Mail: heinrich.hoehn@acw.admin.ch

Adress: INRAE, UMR LAE, 68000 Colmar

The strawberry blossom weevil Anthonomus rubi is an important pest in open field raspberry crops of Switzerland. Today growers tend to deploy insecticides against this pest without applying the established economic thresholds since their assessment is judged to be too complicated and too labour-intensive. In order to simplify the process, the Nachmann function was used for studying the relationship between the number of clipped flower buds per inflorescence and the percentage of inflorescences damaged. The correlation obtained was excellent (r2 = 0.91) between these two parameters using a long-term data set collected on different floricane-fruiting cultivars and the current threshold of 1 to 5 % clipped flower buds equals 10 to 35 % inflorescences having at least one bud damaged. We therefore propose to redefine the economic threshold to 10 % of inflorescences being damaged before bloom and to control 100 inflorescences per 1000 m2 once the week from the stage of flower petals elongating until the beginning of full bloom. This method reduces significantly the time for assessing damage and should consequently offer an effective alternative to the systematic application of insecticides.

Keywords: Curculionidae, Rubus idaeus, pest monitoring, economic threshold

E-Mail: christian.linder@acw.admin.ch

Adress:

There is currently no disinfection method for organic seeds of aromatic and medicinal plants. From 2009 to 2011, Mediplant tested the disinfection with aerated steam (DAS) on seeds of common mallow (Malva sylvestris L.), marsh mallow (Althaea officinalis L.), thyme (Thymus vulgaris L.) and burnet saxifrage (Pimpinella peregrina L.). The DAS showed a partial efficacy on various pathogens on the seeds of common and marsh mallow. The best disinfection was achieved at 68 °C for 120 seconds. The DAS significantly improved the germination rate. The breaking of dormancy, and thus an improved germination rate could also be achieved by exposing the seeds to 68 °C during two to five minutes without steam. For the thyme and burnet saxifrage, the efficiency of the DAS could not be tested because the disease pressure was too low. Furthermore, the germination rate of the seeds of these two species was negatively affected by the DAS by treatments with longer duration and higher temperatures: for thyme seeds, when the treatment exceeded 60 seconds at 68 °C, and in any case for burnet saxifrage seeds. The drying of the seeds at 37 °C after DAS treatment is recommended to avoid the risk of too early germination immediately after the disinfection.

Keywords: Malvaceae, seed disinfection, aerated steam treatment, germination

E-Mail: sarah.sigg@acw.admin.ch

Adress: Médiplant, 1964 Conthey

An agronomical trial was conducted at the Research station Agroscope Changins- Wädenswil in Nyon (VD) in order to evaluate the effects of infections with GLRaV-1 or/and GFkV on the grape and wine production. In a ten-year study (2001–2010), effects of virus infection were measured on the main parameters of vines, musts and wine. The effects of GLRaV-1 with or without GFkV co-infection were a reduction of vine vigour and production potential of the vine, a decrease of the leaf mineral content (nitrogen, calcium and magnesium) but an increase of the leaf potassium content. No difference was observed between vines infected by GFkV alone and healthy ones. On the other hand, the presence of GFkV in mixed infections with GLRaV-1 contributed to increase the negative effects associated with GLRaV-1: reduction of the sugar and nitrogen contents in musts and reduction of the wine quality measured by sensory analysis.

Keywords: grapevine, GLRaV-1, GFkV, agronomical features, mineral nutrition, wine quality

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

Adress:

VitiMeteo-Plasmopara is an expert system to forecast the biological development of downy mildew using relevant weather data. It has been developed jointly by Agroscope Changins- Wädenswil ACW and the Weinbauinstitut of Freiburg in Breisgau. It is currently used over all vineyards of Switzerland, Germany, Austria and parts of northern Italy. Model validation for nine years in Changins (VD) has shown its reliability. The model allows to better control downy mildew and to decrease the number of fungicide applications.

Keywords: Plasmopara viticola, Decision Support System, weather data, forecasting, precision viticulture

E-Mail: pierre-henri.dubuis@acw.admin.ch

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