Copper, predominantly in the form of Bordeaux Mix, is a time-tested and effective fungicidal spray for protecting fruit trees from a wide range of diseases. Its primary use on fruit trees is preventative, targeting fungal and bacterial pathogens during the dormant season.
The Role of Copper in Fruit Tree Health
Copper acts as a fungicide and bactericide, disrupting the cellular processes of many plant pathogens. When applied to fruit trees, it forms a protective barrier on the bark and dormant buds, preventing spores from germinating and infections from taking hold. This makes it invaluable for managing common fruit tree diseases such as peach leaf curl, apple scab, powdery mildew, and bacterial blight.
Preparing Bordeaux Mix for Fruit Trees
Bordeaux Mix is a classic copper fungicide made from copper sulphate and hydrated lime. It is crucial to prepare it correctly to ensure effectiveness and avoid tree damage.
Ingredients & Equipment
To prepare Bordeaux Mix, you will need:
- Copper Sulphate: (100g) - The active fungicidal component.
- Hydrated Lime: (100g) - Neutralizes the copper sulphate, preventing phytotoxicity (plant damage) and helping the mixture adhere to the tree.
- Water: (10 Litres total) - For dissolving the ingredients.
- Two large non-metallic buckets: For mixing.
- Stirring sticks: Non-metallic.
- Sprayer: A pump sprayer suitable for liquid solutions.
Step-by-Step Preparation
Follow these steps carefully to create your Bordeaux Mix:
- Dissolve Copper Sulphate: Take 100g of copper sulphate and dissolve it completely in 5 litres of warmed water in one of the buckets. Stir until all crystals are fully dissolved.
- Dissolve Hydrated Lime: In the second bucket, dissolve 100g of hydrated lime in 5 litres of water. Stir this mixture well to prevent the lime from settling at the bottom.
- Combine Solutions: Carefully and slowly pour the dissolved lime solution into the dissolved copper sulphate solution. It is crucial to add lime to copper, not the other way around, to ensure proper chemical reaction and stability. Continue to stir the combined mixture thoroughly.
- Test pH (Optional but Recommended): A simple test with a bright steel knife or nail can indicate proper preparation. Dip the knife into the mixture for a minute. If it shows a reddish deposit of copper, more lime is needed. A properly balanced mix will not coat the steel with copper.
- Use Promptly: The Bordeaux Mix should be used within a few days of preparation for optimal effectiveness. Its stability degrades over time.
Bordeaux Mix Recipe Summary
| Ingredient | Quantity | Purpose |
|---|---|---|
| Copper Sulphate | 100g | Fungicide/Bactericide |
| Hydrated Lime | 100g | Neutralizer, sticker, prevents phytotoxicity |
| Water | 10 Litres | Solvent, carrier |
Application Guidelines for Copper Sprays
Proper application is as critical as correct preparation for effective disease control and tree safety.
Best Practices for Spraying
- Timing is Key: For most fruit trees, the ideal time to apply Bordeaux Mix is during the dormant season. This typically means late fall after leaf drop, or early spring before buds begin to swell. Applying when trees are dormant ensures the spray covers all surfaces without damaging sensitive new growth.
- Thorough Coverage: Ensure complete coverage of all parts of the tree, including the trunk, branches, and any crevices where pathogens might overwinter. Spray until the solution drips from the branches.
- Crucial Precaution: Do not spray on emerging leaves as it will damage them. This includes budding leaves, blossoms, and young fruit.
Important Considerations
- Safety First: Always wear appropriate personal protective equipment (PPE) including gloves, eye protection, and a mask when preparing and applying any pesticide, including Bordeaux Mix. Copper can be an irritant.
- Environmental Impact: While copper is a natural element, excessive use can lead to accumulation in the soil, potentially harming beneficial soil organisms. Use only as needed and according to recommended guidelines.
- Read Product Labels: Always refer to the specific instructions on the packaging of your copper sulphate and hydrated lime products, as concentrations and recommendations can vary.
Using copper, particularly in the form of Bordeaux Mix, is a foundational practice in integrated pest management for healthy and productive fruit trees.
