Bordeaux Mixture vs Copper Oxychloride: A Practical Guide for Copper Fungicide Selection

Copper fungicides remain a backbone of disease management in many crops, especially where growers face downy mildew, leaf spots and bacterial diseases season after season. Among the classic options, Bordeaux mixture and copper oxychloride are two of the most recognized copper-based solutions.

On paper, they are both “copper fungicides”. In practice, they behave very differently in the field and in your product portfolio:

• Bordeaux mixture is a traditional copper–lime preparation with strong leaf adhesion and slow copper release.

• Copper oxychloride is a manufactured copper salt with more predictable formulation behaviour and broader fit with modern spray programmes.

For distributors, importers and brand owners, the key questions are:

• What is the real difference between Bordeaux mixture and copper oxychloride?

• For which crops, climates and customer segments does each one make more sense?

• How can you position both products in your portfolio without confusing your growers or cannibalising sales?

This article gives a structured comparison, from formulation chemistry to field behaviour and commercial positioning, so you can make informed and profitable decisions.

Quick Answer: What Is the Difference Between Bordeaux Mixture and Copper Oxychloride?

In simple terms:

• Bordeaux mixture is a suspension of copper sulphate and lime prepared in water. It forms an insoluble copper–lime film on plant surfaces with slow copper ion release and very good adhesion.

• Copper oxychloride is a manufactured copper compound formulated as a wettable powder or similar product. It provides more readily available copper ions, is easier to handle and store, and fits better into modern spraying and tank-mix practices.

Both deliver protective copper on the plant surface, but they differ in how they are prepared, how quickly copper becomes available, how they behave in the field, and how convenient they are for today’s growers.

What Are They? Composition and Formulation Chemistry

What Is Bordeaux Mixture?

Bordeaux mixture is one of the oldest fungicides still in use. It is not a single chemical but a mixture prepared by combining:

• Copper sulphate (often called “blue vitriol”), and

• Hydrated lime

in water, in defined proportions.

Key characteristics:

• The reaction between copper sulphate and lime forms insoluble copper compounds suspended in water.

• When sprayed, these particles adhere strongly to leaves, forming a protective film.

• Because the copper is relatively insoluble, copper ion release is gradual, reducing the risk of sudden phytotoxicity but requiring sufficient surface coverage.

In practice, Bordeaux mixture is often prepared close to the time of application, and quality depends on mixing discipline and water quality.

What Is Copper Oxychloride?

Copper oxychloride is a manufactured copper fungicide. It is a defined chemical compound produced industrially and then formulated into:

• Wettable powder (WP)

• Wettable granules (WG / WDG)

• Sometimes suspension concentrates (SC), depending on the market

Key characteristics:

• The copper is present as copper oxychloride crystals, ground to a defined particle size.

• When mixed with water, it disperses into fine particles that release bioavailable copper ions at the plant surface.

• Because it is produced in a controlled environment, particle size distribution, purity and surfactant system can be standardised.

From a product management perspective, copper oxychloride is a ready-made commercial formulation, whereas Bordeaux mixture is a field-prepared mixture.

Mode of Action: How Copper Controls Fungal and Bacterial Diseases

Both Bordeaux mixture and copper oxychloride ultimately rely on copper ions for their fungicidal and bactericidal activity.

• Copper ions interfere with enzyme systems and protein functions in fungal and bacterial cells.

• They disrupt membrane integrity, respiration and other essential metabolic processes.

• The result is multi-site protective activity on the plant surface, making copper fungicides valuable for resistance management.

Important point for your customers:

• Mode of action is essentially the same for both Bordeaux mixture and copper oxychloride.

• The real difference lies in how quickly copper ions are released, how well the spray deposits stick to the plant, and how convenient the products are to use.

Performance Differences: Solubility, Rainfastness, Longevity and Phytotoxicity

Solubility and Copper Release

• Bordeaux mixture

  • Contains copper in relatively insoluble forms bound with lime.

  • Copper ions are released slowly as the film weathers on the leaf surface.

  • This slow release can help reduce the risk of plant injury when used correctly, especially on sensitive crops, but requires good coverage and correct preparation.

• Copper oxychloride

  • Provides copper in a more readily available form.

  • Bioavailable copper ions are released more quickly at the plant surface.

  • This can deliver a stronger initial protective effect but demands careful attention to rates and timing to avoid unnecessary stress on sensitive crops.

Rainfastness and Film Persistence

• Bordeaux mixture is known for very strong adhesion to plant surfaces. The combination of lime and copper forms a persistent film which:

  • Adheres well to leaves and bark

  • Can withstand moderate rainfall better than some other copper formulations

  • Makes it particularly valued in regions with frequent rain during disease-prone periods

• Copper oxychloride also adheres to foliage but:

  • Its rainfastness is more dependent on formulation quality and adjuvants

  • Heavy or frequent rainfall may remove residues more readily than in well-prepared Bordeaux applications

  • In many programmes, re-application intervals are set accordingly in line with product labels

Phytotoxicity Considerations

Both products carry a risk of phytotoxicity if misused:

• Excessive copper on tender leaves or under certain environmental conditions can cause leaf burn or russeting.

• Bordeaux mixture’s lime component can buffer acidity, and slow copper release may reduce the risk in some situations, but incorrect preparation or rate can still damage plants.

• Copper oxychloride, with more immediate copper availability, requires precise adherence to label rates, timing and crop restrictions, particularly on sensitive varieties or during hot, bright conditions.

Your message to growers should be consistent:

Copper fungicides are powerful, non-selective protectants. Their value comes from correct use, not from pushing rates or shortening intervals beyond what labels and regulations authorise.

Pest Spectrum and Crop Application Differences

Both Bordeaux mixture and copper oxychloride are used against a wide range of fungal and bacterial diseases, for example:

• Downy mildews

• Anthracnose

• Leaf spots

• Certain bacterial blights

However, their typical crop positioning often differs.

Where Bordeaux Mixture Is Commonly Used

Bordeaux mixture has a long history in:

• Vineyards – especially for downy mildew and other fungal diseases on grapes

• Citrus orchards – for canker and other diseases, depending on local practices

• Tomatoes and vegetables – for early blight, leaf spots and bacterial problems in some systems

• Tree crops and orchards – as a dormant or pre-season spray in certain regions

Because of its history and composition, Bordeaux mixture is often considered attractive where:

• There is interest in traditional or organic-oriented production systems (within certified limits and national rules)

• Growers are accustomed to mixing and applying it themselves

• Strong leaf adhesion is a priority due to frequent rain

Where Copper Oxychloride Fits Best

Copper oxychloride is widely used across:

• Fruit trees – apples, pears, stone fruit and others, depending on registrations

• Vegetables – tomatoes, peppers, potatoes and various leafy or fruiting vegetables

• Plantations – coffee, cocoa and other perennial crops

• Row crops – where copper is part of an integrated disease management strategy

It is particularly attractive where:

• Growers want a ready-to-use, stable commercial formulation

• Spray programmes demand good compatibility and predictable behaviour in modern equipment

• There is a need to standardise copper products across multiple crops and regions

From a portfolio point of view:

• Bordeaux mixture often occupies a specialist or traditional niche.

• Copper oxychloride often plays the role of general-purpose copper fungicide across a wide crop base.

Field Behaviour: pH Sensitivity, Tank-Mix Compatibility and Spray Fit

pH and Mix Compatibility

• Bordeaux mixture

  • The presence of lime gives the mixture a alkaline pH.

  • This can make it incompatible with many other pesticides, especially products that are unstable under alkaline conditions.

  • As a result, Bordeaux mixture is often used alone, not as part of complex tank mixes.

• Copper oxychloride

  • Commercial formulations are usually closer to neutral pH in spray tank conditions, depending on water and adjuvants.

  • They are generally more compatible with a range of other fungicides and insecticides, within label restrictions.

  • This makes copper oxychloride more suitable for tank-mix programmes and integrated spray schedules.

Application Convenience and Operational Efficiency

• Bordeaux mixture

  • Often requires on-farm preparation, combining copper sulphate and lime in the right sequence and ratio.

  • Mixing quality, water pH and timing all affect performance.

  • This can be a challenge for larger operations or for growers with limited labour and training.

• Copper oxychloride

  • Arrives as a finished product in standard packaging.

  • Growers simply measure the product and mix it in the spray tank with water as directed.

  • This simplifies logistics, improves batch-to-batch consistency and saves time at farm level.

For modern distributors and brand owners, copper oxychloride offers a clearer path to professional, standardised product lines, while Bordeaux mixture often remains more artisanal and region-specific.

Cost, Availability and Market Positioning

Bordeaux Mixture – Low Material Cost, High Application Volume

From a cost perspective, Bordeaux mixture often appears attractive:

• The basic ingredients – copper sulphate and lime – are widely available and relatively low cost per kilogram of material.

• However, the application volume and frequency, as well as the labour for preparation, can be significant.

• The economic appeal is strongest in settings where labour costs are lower, growers are used to preparing mixtures, and markets value traditional copper protection.

Positioning:

• As a value option in specific, traditional crop segments (grapes, citrus, some vegetables).

• As a potential tool for lower-input or semi-organic systems, where regulations permit Bordeaux mixture within copper limits.

Copper Oxychloride – Controlled Cost, Broader Value

Copper oxychloride is typically:

• More expensive per kg of active ingredient compared with raw copper sulphate and lime

• Used at lower rates per hectare than traditional Bordeaux mixtures

• Delivered as a professional, standardised fungicide product with clear label directions

Positioning:

• As a modern copper fungicide that fits well into integrated programmes.

• As the default copper option in many dealer portfolios due to reliability, compatibility and broad crop registrations.

• As a fungicide that supports professional branding, consistent quality and export-oriented agriculture.

For a B2B audience, the trade-off is clear:

• Bordeaux mixture: low material cost, high handling cost, stronger traditional positioning.

• Copper oxychloride: more balanced combination of material cost, handling efficiency and market acceptance.

Safety, Residues and Environmental Profile

Both Bordeaux mixture and copper oxychloride involve copper, and therefore share key risk considerations:

• Copper can accumulate in soil when used excessively over many years.

• It can be toxic to aquatic organisms and certain soil micro-organisms at high levels.

• Residues on crops must comply with maximum residue limits (MRLs) in local and export markets.

Differences in formulation and release rate mean:

• Bordeaux mixture, with slower copper release from its film, may sometimes be perceived as “gentler” on the plant under certain conditions, but it still contributes copper to the environment over time.

• Copper oxychloride, with higher immediate copper availability, provides strong protection but requires strict adherence to recommended rates, intervals and pre-harvest intervals as per the label.

In all communications and programmes, it is essential to underline:

• Copper fungicides are protectant tools.

• Application must always follow product labels and local regulations.

• Risk management should follow the principle:

Risk = Hazard × Exposure.

By controlling dose, timing, number of applications and buffer zones, you can help growers benefit from copper fungicides while respecting long-term soil and environmental health.

Side-by-Side Comparison Table

The table below summarises the key practical differences that matter for B2B purchasing and product strategy.

This table can be used directly in catalogues, training materials and web content to support customer conversations.

Which One Should You Choose? A Decision Framework for B2B Buyers

When Bordeaux Mixture Makes Sense

Bordeaux mixture is a logical choice when:

• You serve traditional grape, citrus or vegetable markets where growers already know and trust Bordeaux.

• Labour for mixing and application is readily available, and growers are comfortable preparing mixtures.

• The market values a classic copper–lime solution, and regulations allow Bordeaux mixture within copper limits.

• You want to offer a value-tier product alongside more modern copper formulations.

When Copper Oxychloride Is the Better Anchor

Copper oxychloride is typically the stronger choice when:

• You manage a diversified portfolio across multiple crops and regions.

• Growers expect ready-made, stable and easy-to-use products that fit into planned spray schedules.

• You need good tank-mix flexibility with other fungicides and insecticides (within label constraints).

• Your customers supply export markets and require consistent performance and documentation.

In short, copper oxychloride is often your primary copper fungicide, while Bordeaux mixture becomes a specialised or traditional complement.

Using Both in One Portfolio

You do not necessarily need to choose one and abandon the other. A well-structured product line can include both:

• Bordeaux mixture-based products

  • For specific crops and regions where the traditional approach is preferred or where leaf adhesion in rainy conditions is critical.

• Copper oxychloride-based products

  • As your main copper fungicide range for fruits, vegetables and plantations with modern spraying practices.

The key is to avoid internal competition by:

• Defining clear use cases and target segments for each active.

• Communicating the practical differences in preparation, handling, rainfastness and crop fit.

• Training your sales teams to recommend the right product based on crop, climate, labour conditions and market requirements.

FAQ: Bordeaux Mixture vs Copper Oxychloride

Q1. Is copper oxychloride better than Bordeaux mixture?
There is no universal “better” option. Copper oxychloride is more convenient to handle, more compatible in tank mixes and better suited to modern spray programmes. Bordeaux mixture offers strong adhesion and a traditional profile that some growers prefer, especially in certain grape and citrus systems. The right choice depends on crops, climate, labour and regulatory context.

Q2. Can Bordeaux mixture replace copper oxychloride in my portfolio?
In some traditional segments, yes; Bordeaux mixture can provide effective copper protection. However, it is less convenient, less compatible with tank mixes and more dependent on correct on-farm preparation. For a broad, multi-crop portfolio, copper oxychloride is usually a more versatile primary product, with Bordeaux mixture as a complementary option.

Q3. Which product is more suitable for organic or low-input systems?
Bordeaux mixture has a long history in traditional and some organic-oriented systems, where local regulations permit its use within copper limits. Copper oxychloride is also used in various production systems, but organic certification and copper limits differ by country and scheme. For organic positioning, always check the specific certification rules and national regulations.

Q4. Does Bordeaux mixture stick better to leaves than copper oxychloride?
Bordeaux mixture is known for its very strong adhesion and persistent film on leaves and bark, which can be an advantage in rainy climates. Copper oxychloride also adheres well when formulated correctly, but its rainfastness depends more on the formulation system and application conditions. Product labels and local trial data should guide spray intervals.

Q5. How should I talk to growers about safety and residues for both products?
The message should be consistent: both products are copper fungicides and must be used with respect for soil health, water bodies and residue regulations. Emphasise that:

• Applications must follow label rates and intervals.

• The number of copper sprays per season should respect local limits and export MRL requirements.

• PPE, buffer zones and correct sprayer calibration are essential.

Position copper as a valuable but finite resource that needs to be managed responsibly.

Turn Copper Choices into Portfolio Value

The comparison “Bordeaux mixture vs copper oxychloride” is not just a technical debate. It is a portfolio and positioning decision:

• Bordeaux mixture can anchor your offer in traditional segments, especially where growers value long-standing practices and strong adhesion in rainy climates.

• Copper oxychloride can anchor your modern copper fungicide line, supporting diverse crops, tank-mix programmes and professional spray schedules.

If you align each product with the right:

• Crops and disease targets

• Climate and spraying conditions

• Customer profile and labour reality

you transform copper fungicides from commodity products into a structured, profitable and sustainable portfolio.