More years of field trials against Plasmopara viticola in organic viticolture.

The organic viticulture assumes a decisive role in the national agricultural sector. More impelling problems in the management of organic vineyards are represented by the plants pathology defence and particularly by Plasmopara viticola containment. Copper represents one of the few usable fungicides in the organic farming and the only one effective against downy mildew. The EC Regulation n. 473/2002 fixed the maximum usable quantity of copper compounds, owing to the environment problems due to the copper accumulation in the soil. To reduce quantity of metal copper or replace it with natural products, field trials with copper compounds at a low rate or with alternative copper products have been conducted in organic farms located near Rome. Besides, we have also estimated the possibility of reducing the operations against P. viticola optimizing fungicidal treatments. Guidelines EPPO/OEPP PP 1/31 (3) have been carried out. The results of the trials have shown that, using cupric products with low metallic content, to reduce copper quantities used, always allowed to respect the limits established by EC Regulation . The alternative products that were investigated have not guaranteed, instead, an adequate protection in high pressure of grapevine downy mildew. It was possible to reduce treatments against P. viticola through the control of different environmental parameters. The trials confirm that copper is indispensable for plant protection in organic farming, as it is not possible to replace it and no alternative substances from natural extracts exist. We can instead reduce the applied copper quantities using new products with low quantity of metal copper or trough the evaluation of climatic and pedologic data that allow to rationalize the fungicidal treatments.