Standard preparation procedure (1% solution)
- Copper sulphate solution: Dissolve 1 kg of copper sulphate crystals in 50 litres of clean water in a plastic or wooden vessel (never use iron or zinc containers).
- Slaked lime solution: In a separate container, slake 1 kg of fresh good-quality quicklime or chemical-grade hydrated lime with 50 litres of water to form a uniform milk of lime.
- Mixing process: Pour the copper sulphate solution slowly into the milk of lime while stirring continuously (never pour lime into copper).
- Neutrality test: Test acidity by dipping a clean, polished iron knife blade for one minute; if a reddish copper deposit forms, add more lime solution until neutral.
Target diseases in orchards and plantations
- Citrus: Citrus canker (Xanthomonas axonopodis) and gummosis / phytophthora foot rot.
- Grapes: Downy mildew (Plasmopara viticola) and anthracnose.
- Arecanut and coconut: Koleroga / Mahali (fruit rot caused by Phytophthora meadii) and bud rot.
- Rubber and coffee: Black stripe, abnormal leaf fall, and coffee rust.
Application precautions and shelf life
Bordeaux mixture must always be applied fresh on the day of preparation, as the active colloidal copper hydroxide precipitates out and loses fungicidal efficacy upon standing. Strain the mixture through muslin cloth to prevent sprayer nozzle clogging, and avoid spraying during extreme midday heat.
Official source
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Central Insecticides Board & Registration Committee ↗Related on KisanPe
Common questions
What is the standard ratio for preparing 1% Bordeaux mixture?
The standard ratio is 1 kg copper sulphate, 1 kg slaked lime, and 100 litres of water (1:1:100).
Why should metal vessels not be used for mixing copper sulphate?
Copper sulphate reacts corrosively with iron, galvanized steel, and aluminium containers; only plastic, earthen, or wooden vessels should be used.
Can Bordeaux mixture be stored overnight for next-day spraying?
No, it must be sprayed fresh on the day of preparation because the protective colloidal copper complex deteriorates within hours.
General guidance, not personal advice. For your farm, ask your local Krishi Vigyan Kendra or agriculture officer.
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