The function of Bordeaux liquid and matters needing attention in use

Bordeaux liquid is an inorganic copper fungicide. The chemical composition of its active component is CuSO4 ·xCu (OH) 2 ·yCa (OH) 2 ·zH2O. In 1882, the Frenchman A. Migar found its bactericidal effect in Bordeaux, so it is called Bordeaux liquid. It is a sky blue colloidal suspension made of about 500 grams of copper sulfate, 500 grams of quicklime and 50 kilograms of water. The ingredient ratio can be increased or decreased according to the need. It is generally alkaline and has good adhesion properties, but the physical properties of long-term exposure are destroyed, so it is suitable to be used or made of dehydrated Bordeaux powder. Mix it with water when you use it.

Sterilization principle of Bordeaux liquid

Bordeaux liquid itself has no bactericidal effect, and when it is sprayed on the surface of plants, it is adsorbed on the surface of crops because of its adhesion. Plants secrete acidic liquids in the process of metabolism, coupled with the acidic substances secreted by bacteria when they invade plant cells, so that a small amount of basic copper sulfate in Bordeaux solution is converted into soluble copper sulfate, resulting in a small amount of copper ion (Cu2+). After Cu2+ enters the bacterial cells, the proteins in the cells solidify. At the same time, Cu2+ can also destroy some enzymes in its cells, so that the metabolism of bacteria can not be carried out normally. Under the influence of these two effects, bacteria can be poisoned and died.

The action object of Bordeaux liquid

To control early apple defoliation, anthracnose and ring disease, the apple can be sprayed with lime double Bordeaux solution 200 times 240 times, once a month, and alternately with other fungicides for 3 times 4 times. To prevent and cure apple fruit rot (ring rot, anthracnose), 200 times of lime or multi-dose Bordeaux solution can be sprayed 10 to 15 days before the occurrence of diseased fruit in previous years, once every 15 days, 3 times 4 times, and discontinued 25 days before fruit picking. In order to prevent and cure the mildew heart disease of apple, 200 times of lime Bordeaux solution should be sprayed at the bud stage of apple. To control apple and pear rust, spray lime equivalent Bordeaux solution 160 times on the juniper cypress around the apple orchard. To control grape anthracnose, anthracnose and downy mildew, a small amount of lime Bordeaux solution can be sprayed 160 times, once every 12 to 15 days, a total of 2 spray 4 times. After entering the rainy season, Bordeaux solution is effective in controlling grape diseases.

Points for attention in the use of Bordeaux liquid

1. Pay attention to the selection of raw materials: pure, high quality, white quicklime block and pure blue copper sulfate should be selected. Note that copper sulfate should not contain green and yellow impurities.

2. Master the preparation method: first, prepare the lime emulsion with the water of 1 beat 3, fully dissolve and filter it, and then prepare the copper sulfate solution with the water of 2 big 3, fully dissolve it and set aside. Slowly pour the copper sulfate liquid into the lime emulsion, stir or pour the copper sulfate liquid and lime emulsion into the same container at the same time, while stirring. The lime emulsion must not be poured into the copper sulfate solution, otherwise the prepared solution precipitates quickly and is prone to drug damage. Note that Bordeaux solution should be used with it, and the liquid prepared on the same day should be used up on the same day, not for a long time, not overnight, nor diluted. The preparation of Bordeaux liquid should not use metal utensils, especially iron, in order to prevent chemical reactions to reduce the efficacy.

3. Pay attention to the period of medication: after the arrival of the rainy season, it is generally used to control grape anthracnose, white rot, black pox, downy mildew and so on. 80% mancozeb should be sprayed before use, and a half-dose Bordeaux liquid should be sprayed 15 days after spraying. The spray must be uniform and meticulous, and the fruit and ear axis must be sprayed. After coloring with pollution-free pesticides, it is not suitable to spray Bordeaux solution. After fruit harvesting, lime equivalent Bordeaux solution (1-1-1-1-200) can be used for prevention and control.

4. Rational use of chemicals: Bordeaux solution is alkaline, and its effective ingredients are calcium and copper, which can not be mixed with fungicides and pesticides such as stone-sulfur mixture, carbendazim, mancozeb, etc. Bordeaux liquid, fungicides and insecticides must be used at intervals of 10 murals and 15 days respectively.

5. Timely safe spraying: use Bordeaux liquid to avoid high temperature and high humidity. If spraying Bordeaux liquid at hot noon or dewy morning, it is easy to cause rapid accumulation of lime and copper ions, resulting in burns of leaves and fruits. It is generally safer to spray after 15:00.

6. Different crops have different responses to Bordeaux solution: attention should be paid to the safety of copper sulfate and lime to crops. The crops that are sensitive to lime are potatoes, grapes, melons, tomatoes, peppers and so on. After using Bordeaux solution, these crops are prone to drug damage under high-temperature drying conditions, so lime equivalent, small or half-amount Bordeaux solution should be used, and seedlings are generally not used. Very sensitive to copper crops are peach, plum, apricot, cabbage, lettuce, soybeans, beans and so on, should be used with caution, can be tried before use.

Points for attention in the preparation of Bordeaux liquid

1. The preparation container should not use metal utensils (mainly metals with more active chemical properties than copper); the sprayed equipment should be washed in time to prevent corrosion (mainly for metals with more active chemical properties than copper). Metals with more active chemical properties than copper mainly include magnesium, aluminum, zinc, iron, tin and so on. The reason why utensils made of these metals cannot be held: Bordeaux liquid contains copper sulfate, and metals that are more chemically active than copper will replace it from the solution and deteriorate it. For example, iron: Fe+CuSO4===Cu+FeSO4; aluminum: 2Al+3CuSO4===3Cu+Al2 (SO4) 3

2, rainy days, foggy days, morning dew can not be used when it is not dry, so as to avoid drug damage. It can not be mixed with alkaline pesticides such as stone-sulfur mixture, and the interval between the two drugs is 15-20 days. Stop using the fruit 20 days before harvest. Some apple varieties (Golden Crown, etc.) after spraying Bordeaux liquid, the young fruit is easy to produce fruit rust, which can be changed to other pesticides.

3. It can not be diluted with concentrated Bordeaux solution and then diluted with water. The Bordeaux solution prepared at one time is a colloidal suspension, which is relatively stable. If you add water, it will form precipitation or crystallization and affect the quality, which is easy to cause drug damage.

4. Lime milk can not be poured into dilute copper sulfate, so the Bordeaux solution is extremely unstable and easy to precipitate.

5. Concentrated copper sulfate can not be poured into lime water, so the Bordeaux solution is unstable and the quality is poor.

6. The copper sulfate in Bordeaux liquid is highly poisonous. If you accidentally eat Bordeaux liquid, you should eat a lot of egg white.