Developing shoots of grapevine ( Vitis vinifera cv. Kerner) were inoculated with conidia of the powdery mildew, Uncinula necator , at well-defined phenological stages of the host to provoke the development of flag shoots in the field and to investigate these shoots as early as possible in the following growing season for the presence of the pathogen. The disease progress was monitored and fungal growth and development on samples from a field trial were analysed by means of low-temperature scanning electron microscopy (LT-SEM). Mycelium was detected on the surface and in the interior parts of buds. The suitability of the field plot to analyse flag shoots was proven by the occurrence of such shoots in the following spring. Furthermore, early stages of cleistothecia development on berries were described for the first time. Establishment of U. necator in dormant buds of grapevine, giving rise to flag shoots in the following spring, is considered to play a significant role in overwintering of the pathogen in the vineyards of southern Germany.

No abstract

Grapevine downy mildew is one of the major diseases in viticulture. To control this disease, a more effective strategy has been developed and established based on growth and model data as well as on a combination of fungicides. For this purpose, the systemic plant protection product potassium phosphonate (PP) was combined with two contact fungicides. Treatments were carried out according to the different experimental conditions after the growth of 400 cm2, 600 cm2, and 800 cm2 leaf area per primary shoot. PP increased the effectiveness of the preventive fungicides whenever high infection pressure was the case. The experiments also show that it is possible to extend the treatment intervals from 400 cm2 to 600 cm2 new leaf area when PP was added. However, none of the tested treatments were sufficient for the extension to intervals of 800 cm2. These data show that PP can be a key factor in the reduction of the application of synthetic or copper-based fungicides.

The negative effects of plant protection products on the human health and the environment have become a major concern for consumers and politics in Europe. In the last years new policies for risk mitigation and reduction of use of synthetic pesticides has been enforce in Europe and Switzerland. A possible strategy to reduce the use of plant protection products is to spray according to the epidemic of diseases and pests by following decision support systems (DSS). The platform VitiMeteo offers a wide set of forecasting models for viticulture including downy and powdery mildew, black rot, grape berry moth and rust mite. Two research institutes the Staatliches Weinbauinstitut Freiburg (Germany) and Agroscope (Switzerland) developed VitiMeteo jointly. A consortium was built with the company Geosens (Germany) which is in charge of the programming of the different forecasting software. Each institute is running his own internet website with specific tools and feature for each country but the core of the system is the same. The combination of these different DSS allows a significant reduction of plant protection products used. All these forecasting systems and tools are freely available for the winegrowers on the platform www.vitimeteo.de and www.agrometeo.ch. The use of these platforms helps the winegrowers to meet current society's expectations.

Black rot on grapevine is a fungal disease c a u s e d b y P h y l l o s t i c t a a m p e l i c i d a (s y n. Guignardia bidwellii) affecting grape leaves as well as clusters. A novel black rot decision support system termed VitiMeteo Black rot was assembled based on existing sub-models and incorporated into the established VitiMeteo forecast and decision support platform. Based on local weather data and a 5-day weather forecast, VitiMeteo Black rot simulates the relative susceptibility of grape clusters, the occurrence