Grapevine downy mildew control using reduced copper amounts in organic viticulture.

Area of Science:

• Agricultural Science
• Environmental Science
• Plant Pathology

Background:

• Copper is an essential micronutrient but its accumulation in soil from plant protection products poses environmental risks.
• Organic farming regulations limit copper use, prompting research into more sustainable alternatives.
• The European Commission is reassessing permitted copper quantities due to new evidence.

Purpose of the Study:

• To evaluate new copper formulations for reducing copper application rates in organic viticulture.
• To assess the impact of these new formulations on copper soil residues.
• To determine the efficacy of reduced copper dosages against Plasmopara viticola (downy mildew).

Main Methods:

• A two-year field trial was conducted using randomized block design with four replicates.
• New low-metallic copper formulations (Glutex CU 90, Labicuper) were tested against a standard product and an untreated control.
• Efficacy was evaluated by monitoring downy mildew on leaves and bunches; copper residues were analyzed in leaves, grapes, and soil at different depths.

Main Results:

• Tested copper formulations demonstrated effectiveness in controlling downy mildew at lower dosages than the standard.
• Annual copper input was substantially reduced: Glutex CU 90 by over two-thirds, Labicuper by four-fifths to five-sixths compared to the standard.
• Copper levels in grapes were below the residue limit (50 mg/kg), and no significant increase in soil copper residues was observed compared to the control.

Conclusions:

• New cupric formulations can significantly minimize the environmental impact of copper use in organic viticulture.
• Reduced copper application rates are achievable without compromising disease control efficacy.
• These findings support the adoption of innovative copper formulations for sustainable organic farming.