How to use Bordeaux mixture? A detailed guide to usage precautions

When using Bordeaux mixture, choose pure, high-quality white quicklime and pure blue copper sulfate, and prepare it in non-metal containers; the mixture prepared on the same day must be used up that same day. Use it during the fruit bunch closure and pit-hardening stage (late July to early August), and make sure the berries and fruit clusters are sprayed evenly. After harvesting the fruit, apply equal-lime Bordeaux mixture (1:1:200) for control.

The specific precautions for using Bordeaux mixture are as follows:

Bordeaux mixture was discovered by the French in the city of Bordeaux, hence its name. It is an inorganic copper-based fungicide. So, as a fungicide, what precautions should be taken when using it? And what are its preparation methods? Let us take a look together below.

As one of the fungicides, Bordeaux mixture requires close attention to the following points during use and preparation:

1. Preparation of the raw materials for Bordeaux mixture

Choose pure, high-quality white quicklime and pure blue copper sulfate, and prepare the mixture in non-metal containers; the mixture prepared on the same day must be used up that same day;

2. Timing of Bordeaux mixture use

Bordeaux mixture should be used after the rainy season arrives, that is, during the fruit bunch closure and pit-hardening stage (late July to early August). Make sure the berries and fruit clusters are sprayed evenly. After harvesting the fruit, apply equal-lime Bordeaux mixture (1:1:200) for control.

3. Crops suitable for Bordeaux mixture

In hot, humid weather, avoid applying Bordeaux mixture to crops such as potato, grape, cucurbits, tomato and pepper; use it with caution on crops such as peach, plum, apricot, Chinese cabbage, lettuce, soybean and common bean.

Preparation method of Bordeaux mixture:

Preparation of the copper sulfate and lime milk stock solutions

1. Stock solution I: 200 mL of 2% copper sulfate. Weigh out 4.0 g of copper sulfate, place it in a 250 mL beaker, first add a small amount of water, and after the copper sulfate crystals have completely dissolved, dilute to 200 mL and set aside.

2. Stock solution II: 200 mL of 2% lime milk. Weigh out 4.0 g of quicklime, place it in a 200 mL beaker, add a small amount of water, let it stand for 15 min without stirring so that it fully emulsifies into a paste, then add water to dilute, filter through gauze, transfer to a 250 mL beaker, and make 2% lime milk, set aside.

Dissolve the copper sulfate in half of the water and slake the quicklime in the other half. After they have completely dissolved, slowly pour both into a spare container at the same time while stirring constantly. Alternatively, slake the quicklime with 10%-20% of the water and dissolve the copper sulfate with 80%-90% of the water; after they have fully dissolved, slowly pour the copper sulfate solution into the lime milk while stirring to make Bordeaux mixture. Be sure never to pour the lime milk into the copper sulfate solution, otherwise the quality will be poor and the effect will be less effective.

The copper sulfate in Bordeaux mixture is toxic, so when applying it to crops, take care to avoid accidentally getting it into the mouth and causing poisoning. If someone accidentally swallows the solution, they can immediately eat a large amount of egg white, and at the same time contact a doctor for treatment right away.