When the relative humidity is high and there is dew or water film on the leaves, it is easy to cause phytotoxicity to plants with poor copper tolerance. It has a long duration and is widely used to control many diseases of vegetables, fruit trees, cotton and hemp.
The effective component is basic copper sulfate, which can effectively prevent spore germination, prevent bacterial infection, promote dark green leaves and healthy growth, and improve the disease resistance of trees. The preparation has the characteristics of broad bactericidal spectrum, long duration, no drug resistance of bacteria, low toxicity to people and animals, etc. , which has the longest application history.
Precautions: Pay attention to the selection of raw materials, such as pure, high-quality, white quicklime blocks and pure blue copper sulfate. Note that copper sulfate should not contain green and yellow impurities.
Master the preparation method, take 1/3 water to prepare lime emulsion, fully dissolve it and filter it for later use; Then take 2/3 of the water to prepare copper sulfate solution, and fully dissolve it for later use. Slowly pour the copper sulfate solution into the lime emulsion while stirring, or slowly pour the copper sulfate solution and the lime emulsion into the same container while stirring.
Never pour lime emulsion into copper sulfate solution, otherwise the prepared liquid medicine will precipitate quickly and be prone to phytotoxicity. Note that Bordeaux liquid should be prepared as needed, and the liquid medicine prepared on the same day is used up, so it is not suitable for long-term storage, and it is not allowed to stay overnight.
Refer to the above? Baidu Encyclopedia-Bordeaux Liquid