|Abstract in English:|
Downy mildew caused by Plasmopara viticola (Berk. & MA Curtis) Berl. & De Toni, is one of the most dangerous grapevine disease. In organic vineyards, grapevine downy mildew is mainly controlled with copper compounds. However, since of its accumulation in the soil, the use of copper may cause problems of environmental impact. To this regard, the European Union Regulation N. 889/08 imposed severe standards for the use of metal copper per hectare per year. This regulation specifically emphasizes the need to increase research efforts in order to minimize the use of copper or to find appropriate alternative solutions in line with the principles of organic farming.
In order to try to solve this problem, we conducted experimental trials during five years of activity. These trails were carried out in an organic vineyards in an area nearby the city of Rome (Italy). In details, this study evaluated ‘anti-grape downy mildew’ effectiveness of the following compounds: low-rate copper formulations (Glutex Cu 90 and Labicuper), copper compounds associated with natural products (Brotomax and Biplantol), and finally, natural products used alone (Croplife, Armicarb, Biplantol). These trials were carried out in compliance with the EPPO/OEPP PP 1/31 (3) guidelines. The experimental design adopted was that of randomized blocks with 4 replications and plots consisting of 12 plants. The assessmentS to evaluate the ‘anti-grape downy mildew’ effectiveness were performed weekly on the 10 central plants of each plot. We observed 100 leaves and 100 bunches per plot. The percentage of affected organs (disease incidence) and the percentage of the infected area (disease severity) were estimated. This last data was calculated through a scale of 9 classes of attack (0-8) with the formula of Townsend-Heuberger, and the degree of effectiveness according to Abbott was too included in this analysis. The obtained data were analyzed statistically according to the analysis of variance (ANOVA) using the statistical software Statgraphics. For the comparison of the average values we applied the Tukey's test (p ? 0.05). Finally, these trials allowed us to evaluate the effectiveness of different products against P.viticola under conditions of a different epidemic pressure. Specifically, a low infection pressure had characterized the trials which were conducted in 2006; while a high epidemic pressure had been the condition of 2008 experiments; finally, a medium infection pressure had characterized those experiments which were respectively undertaken in the years 2007-2009-2010. These studies showed that in conditions of low and medium epidemic pressure, it is possible to achieve a satisfactory protection against P.viticola with the use of either copper compounds, or alternatives to copper-compounds; conversely, under high pressure of disease, only copper compounds were effective for the control of P.viticola. Finally, the outcomes set forth by this study highlight the necessity to adopt flexible defensive strategies based on the seriousness of the disease. In fact, just such an appropriate form of intervention allows farmers to combine to a satisfactory ‘anti-downy mildew’ defense a reduced environmental impact.