|Riassunto in Inglese:|
Downy mildew, caused by Plasmopara viticola, is one of the most dangerous grapevine diseases. In organic vineyards, downy mildew is mainly controlled with copper compounds. However, due to its accumulation in soil, the use of copper could create problems of environmental impact. To this aim, the Commission Regulation (EC) N. 889/08 imposed severe standards to limit the use of metal copper per hectare per year. In order to minimize the use of copper or to find appropriate alternative solutions in line with the principles of organic farming, experimental trials have been conducted during five years of activity. In particular, this study has evaluated the anti-grape downy mildew activity of cupric products characterised by low metallic content (Glutex Cu 90 and Labicuper), natural products in association with low rate copper formulations (Brotomax and Biplantol), and natural products tested alone (Croplife, EcoMate Armicarb “0” and Biplantol). The experimental design adopted has been composed by randomized blocks with 4 replications and plots consisting of 12 plants. The assessments to evaluate the anti-grape downy mildew activity have been carried out every week on the 10 central plants of each plot. One hundred leaves and one hundred bunches per plot have been observed and it has been estimated the percentage of affected organs (disease incidence) and the percentage of the infected area (disease severity). Obtained data have been subjected to statistical analysis. These trials allowed to evaluate the effectiveness of different products against P. viticola under different conditions of epidemic pressure. In conditions of low and medium epidemic pressure, it is possible to achieve a satisfactory protection against P. viticola both with the use of copper compounds, or alternatives to copper compounds; on the other hand, under a high pressure of disease, only copper compounds have been effective to control P. viticola. Finally, the outcomes of this study highlight the need to adopt flexible defensive strategies based on the seriousness of the disease.