Burgundy mixture is a simple diy copper fungicide that is effective against many fungi diseases in crops. It is a mixture of copper sulfate (CuSO4) and sodium carbonate (sodium bicarbonate, Na2CO3). It is also known as “sal soda Bordeaux”, not to be confused with Bordeaux mixture, which is a mixture of copper sulphate and hydrated lime (Ca(OH)2).

The chemicals listed here can be bought in places where Industrial or Chemistry lab chemicals are sold. But it is cheaper to buy from Industrial chemical sellers. In Anambra State, Nigeria, you can get them from Uga market, close to River Niger Bridge Head.

How to Make Burgundy Mixture

The amount of ingredients to use depends on the percentage of copper sulphate in the mixture. A 1% Burgundy mixture will contain 1% copper sulphate (that is, 1kg copper sulphate in 100 liters of water). Sodium bicarbonate is usually added at a higher amount than copper, else the sodium bicarbonate will crystallize out of solution within a short time. So NaHSO4 should be 1.25 times the weight of CuSO4 or more – the more the longer it will take for crystallization to occur.

To prepare 1% Burgundy mixture, you need 1kg CuSO4, 1.25kg NaHCO3 or more and 100L water. Mix the CuSO4 with 50L water in a plastic bucket and set aside. In another bucket, mix the NaCO3 with 50L of water and pour it into the CuSO4 solution. Stir very well while pouring using a wooden stick. Use immediately. You can prepare the CuSO4 and hydrated lime solution and store them indefinitely in airtight, glass/plastic containers till you need them.

Customizing: If 100L is too much or too small for your need, simply divide or multiply the quantities by a value to get what you want. E.g. if you just need 16L, do this calc: 100/16 = 6.25. Use this value to divide the quantities like this:

1/6.25 = 0.16kg or 160g CuSO4.

1.25/6.25 = 0.2kg or 200g NaHCO3

100/6.25 = 16L water.

If you need more than 100L, let’s say 245L. Do this: 245/100 = 2.45. Use this value to multiply the different quantities as follows:

1 x 2.45 = 2.45kg CuSO4

1.25 x 2.45 = 3.0625kg NaHCO3 or just 3.1kg

100 x 2.45 = 245L water

It is the percentage of CuSO4 in water that gives the percentage of burgundy mixture. E.g. 1% Burgundy mixture will contain 1kg CuSO4 in 100L water. 2% Burgundy mixture = 2kg CuSO4 in 100L water. 3% Burgundy mixture = 3kg CuSO4 in 100L water and so on. However, 1% mix is more commonly used.

Safety Precautions

1. Although the chemicals used here aren’t dangerous, it is still recommended that you wear protective equipment like goggles, mouth protection etc.
2. Don’t use metal while preparing or spraying this mix because of the dangers of CuSO4 reacting with metals. It can also damage the pumping system of motorize sprayers. Use only plastic sprayers.
3. Keep these chemicals well out of reach of children and pets

Fungi Diseases: It can help in controlling downy mildew, powdery mildew, potato blight, peach leaf curl and apple scab, Fire Blight, Black Spot, Downy Mildew, Powdery Mildew, Anthracnose, Rust, Blight

Advantages of Burgundy Mixture

1. It has a residual action that protects plants for a long time. Copper ions is slowly released every time the plant surface gets wet.
2. It is less toxic than other conventional fungicides, that is why it is approved for organic farming.

Disadvantages of Burgundy Mixture

1. To be effective, it has to be use preventively before signs of fungal disease appear. This is because it work by preventing fungal spores from germinating. Once fungi penetrate plant tissue, it will no longer be effective.
2. Using it for many years will lead to accumulation of free copper in this soil. This will have bad effects on plants. Modern copper fungicides contains copper in unreactive, chelated forms that will not harm plants.
3. It cannot be stored for a long time, else the sodium bicarbonate will crystalize out of solution, making the spray dangerous for plants. It is best to prepare it shortly before using.
4. Not compatible with most pesticides
5. It takes time to prepare

Correct use of Copper Fungicides

This applies to all copper-based fungicides, such as tribasic CuSO4, copper oxychloride, Cu hydroxide, Cu oxide, Cu ions linked to fatty acids etc. The above listed fungicides differs with burgundy mixture because they contain copper in fixed form. They cause less damage to plants, compatible with most pesicides etc.

1. Because they are protectant fungicide, they need to be applied regularly to cover new growth. But when there is no rain, copper ions will accumulate of the leaves, causing large amount of copper ions to be released whenever the leaves get wet. This will cause severe damage to leaves and fruits. Avoid repeated sprays when there is no rain.
2. Do not apply under slow drying conditions (cool wet weather, prolonged humid periods etc) to avoid damage to plants (phytotoxicity).
3. Don’t apply copper fungicides in acidic water because copper ions are more soluble in acidic solutions. This may damage leaves and fruits.
4. Before applying copper fungicides to all your plants, test it on few plants and observe them for 1-2 weeks. If nothing goes wrong you can then treat the rest. If something goes wrong, dilute it more and test.
5. Copper fungicides differs in their solubility. Hydroxides are more soluble than oxychlorides which are more soluble than tribasic copper sulphates and cuprous oxide. Less soluble formulations are usually more persistent on the plant surface and are less phytotoxic to plant tissues.
6. Thorough coverage of the spray on the plants is necessary to ensure proper protection. Cover both top and bottom of leaves. New growths have to be sprayed to protect them.
7. Although copper fungicides are approved for organic farming, they can still cause health problems or death when misused. Wear protective clothing when making or using them. This also applies to every other pesticides.
8. As you apply this mix, shake the sprayer from time to time to prevent settling.
9. Some plants don’t like copper or copper fungicides. They include cucumber

Ref

Naldc.nal.usda.gov dwarfing of cucurbits sprayed with bordeaux mixture