In the jujube area of ​​Zhangzhou, there have been many cases of phytotoxicity caused by the improper use of Bordeaux liquid in recent years. Especially for the continuous rainfall on August 18-22, 2010, the jujube trees suffering from Bordeaux liquid phytotoxicity are very large. Through investigation, the author found that all the jujube trees using Bordeaux mixture, regardless of time and time, suffered from different degrees of damage, especially the jujube and non-nuclear dates were the most seriously damaged. The jujube fruit hardened and began to appear water-stained, and then reddish. It turns into brown spots or blocks. After the phytotoxicity occurred, the majority of the jujube farmers had the phenomenon of not using Bordeaux liquid. Here, the author wrote this article for reference by the farmers.
Bordeaux mixture is the broadest-spectrum protective fungicide on the fruit tree with the longest application time, the widest range, the most stable drug effect, and no drug resistance. Its active ingredient is basic copper sulfate. In the production practice, some jujube farmers often cause phytotoxicity due to improper preparation or use, and should pay attention and prevent.
First, the symptoms of phytotoxicity
The symptoms of Bordeaux liquid phytotoxicity fall into two categories: one is the phytotoxicity caused by copper ions, which gradually darkens from the tip of the leaf and spreads to the leaf stalk to half of the blade, resulting in necrotic spots and even perforation. The phytotoxicity of the fruit is red spots, rust spots, and plaques. The other type is phytotoxicity caused by lime, the leaves grow abnormally, thick and rough, and the fruit hardens.
Second, the cause
1. When the Bordeaux mixture is prepared, the copper sulfate is not completely dissolved. When the medicine is sprayed on the fruit together with the dregs, the fruit will appear reddish brown stains and reduce the commercial value of the fruit.
2. Bordeaux mixture is used under high temperature conditions, which may cause phytotoxicity caused by lime. The copper ions in the Bordeaux mixture are in a complex state. After spraying on the foliage and the fruit surface, the copper ions are usually released slowly, and the bactericidal effect is exerted, which is safe for the fruit trees. However, when the dosage is too large, or the climatic conditions are favorable for the rapid release of copper ions, the copper ion concentration on the surface of the crop is too large, causing phytotoxicity to the leaves and fruit surfaces. For example, in the case of high temperature and rain in summer and autumn, especially when the continuous rainfall time is too long, the water droplets on the surface of the leaves and fruits are kept for a long time, and more carbon dioxide can be dissolved in the water droplets to promote the release of copper ions in the drug spots. The concentration of copper ions on the surface of leaves and fruits is too high, causing phytotoxicity, which causes so-called wind and rain damage.
3. The use of Bordeaux mixture in the young fruit stage and the fruit near maturity will cause rust spots on the fruit surface, rough skin and reduced smoothness, resulting in a decrease in the appearance quality of the fruit.
4. When the amount of lime in Bordeaux liquid is lower than the double amount, the use of Bordeaux liquid is prone to copper ion phytotoxicity, leading to defoliation and fruit drop.
5. Bordeaux mixture is mixed with or mixed with stone sulphur mixture, bacteriostatic, mancozeb, etc., and the interval is too short, which is easy to produce phytotoxicity.
Third, avoid measures
1. To select the preparation of raw materials. When preparing Bordeaux liquid, high-quality, pure, white, light-weight lump lime should be used; copper sulfate should be blue crystal, if it is yellow or green powder, it should not be used.
2. Strictly follow the preparation procedure. When dispensing, firstly use copper sulfate in a non-metallic container with appropriate amount of hot water, then filter, add 90% of the total water volume, and then filter out the residue after the opening, and must be fully dissolved. Pour the filtered lime liquid (with 10% water) into a large tank or a vat, then slowly pour the copper sulphate solution into the lime liquid in the tank or the vat, and stir vigorously while pouring. Stirring is continued for another 2 to 3 minutes. Never pour the lime liquid into the copper sulfate solution, otherwise the prepared liquid will precipitate quickly and is prone to phytotoxicity. In addition, it is best to use the drug immediately after it is formulated. It should not be used for a long time.
3. Use lime or multi-type ratio. When preparing, the less lime, the stronger the bactericidal ability, the higher the drug effect, the weaker the anti-raining ability, the shorter the residual effect period, and the phytotoxicity. On the contrary, the more lime, the weaker the bactericidal ability, the lower the efficacy, the stronger the anti-raining ability, the longer the residual effect period, and the less harmful to the phytotoxicity.
4. Reasonably mixed. Bordeaux mixture can not be mixed with stone sulfur, antibacterial and so on. Bordeaux mixture should be used with organic phosphorus pesticides carefully and can be used with mixing. It is only 10 days after spraying the stone sulphur mixture to spray the Bordeaux mixture. After spraying the Bordeaux mixture, it can be sprayed for 20 to 30 days.
5. Pay attention to the changes in the weather. Spraying Bordeaux mixture should be done in a clear, dew-free weather. Spraying in summer should avoid the high temperature noon, so as to avoid the damage of lime at high temperature. Spray in the rainy season, try to avoid the wind and rain, and at the same time, properly increase the amount and proportion of lime in the dispensing.
Fourth, remedies
In the early stage of phytotoxicity, spraying 0.5% to 1% of lime water solution can alleviate the release rate of copper ions and reduce the phytotoxicity to a certain extent. After the victim, spray 0.3% potassium dihydrogen phosphate solution or fertilization solution every 10 to 15 days, or spray humic acid foliar fertilizer to help the jujube restore growth and reduce the damage of phytotoxicity.
Bordeaux mixture is the broadest-spectrum protective fungicide on the fruit tree with the longest application time, the widest range, the most stable drug effect, and no drug resistance. Its active ingredient is basic copper sulfate. In the production practice, some jujube farmers often cause phytotoxicity due to improper preparation or use, and should pay attention and prevent.
First, the symptoms of phytotoxicity
The symptoms of Bordeaux liquid phytotoxicity fall into two categories: one is the phytotoxicity caused by copper ions, which gradually darkens from the tip of the leaf and spreads to the leaf stalk to half of the blade, resulting in necrotic spots and even perforation. The phytotoxicity of the fruit is red spots, rust spots, and plaques. The other type is phytotoxicity caused by lime, the leaves grow abnormally, thick and rough, and the fruit hardens.
Second, the cause
1. When the Bordeaux mixture is prepared, the copper sulfate is not completely dissolved. When the medicine is sprayed on the fruit together with the dregs, the fruit will appear reddish brown stains and reduce the commercial value of the fruit.
2. Bordeaux mixture is used under high temperature conditions, which may cause phytotoxicity caused by lime. The copper ions in the Bordeaux mixture are in a complex state. After spraying on the foliage and the fruit surface, the copper ions are usually released slowly, and the bactericidal effect is exerted, which is safe for the fruit trees. However, when the dosage is too large, or the climatic conditions are favorable for the rapid release of copper ions, the copper ion concentration on the surface of the crop is too large, causing phytotoxicity to the leaves and fruit surfaces. For example, in the case of high temperature and rain in summer and autumn, especially when the continuous rainfall time is too long, the water droplets on the surface of the leaves and fruits are kept for a long time, and more carbon dioxide can be dissolved in the water droplets to promote the release of copper ions in the drug spots. The concentration of copper ions on the surface of leaves and fruits is too high, causing phytotoxicity, which causes so-called wind and rain damage.
3. The use of Bordeaux mixture in the young fruit stage and the fruit near maturity will cause rust spots on the fruit surface, rough skin and reduced smoothness, resulting in a decrease in the appearance quality of the fruit.
4. When the amount of lime in Bordeaux liquid is lower than the double amount, the use of Bordeaux liquid is prone to copper ion phytotoxicity, leading to defoliation and fruit drop.
5. Bordeaux mixture is mixed with or mixed with stone sulphur mixture, bacteriostatic, mancozeb, etc., and the interval is too short, which is easy to produce phytotoxicity.
Third, avoid measures
1. To select the preparation of raw materials. When preparing Bordeaux liquid, high-quality, pure, white, light-weight lump lime should be used; copper sulfate should be blue crystal, if it is yellow or green powder, it should not be used.
2. Strictly follow the preparation procedure. When dispensing, firstly use copper sulfate in a non-metallic container with appropriate amount of hot water, then filter, add 90% of the total water volume, and then filter out the residue after the opening, and must be fully dissolved. Pour the filtered lime liquid (with 10% water) into a large tank or a vat, then slowly pour the copper sulphate solution into the lime liquid in the tank or the vat, and stir vigorously while pouring. Stirring is continued for another 2 to 3 minutes. Never pour the lime liquid into the copper sulfate solution, otherwise the prepared liquid will precipitate quickly and is prone to phytotoxicity. In addition, it is best to use the drug immediately after it is formulated. It should not be used for a long time.
3. Use lime or multi-type ratio. When preparing, the less lime, the stronger the bactericidal ability, the higher the drug effect, the weaker the anti-raining ability, the shorter the residual effect period, and the phytotoxicity. On the contrary, the more lime, the weaker the bactericidal ability, the lower the efficacy, the stronger the anti-raining ability, the longer the residual effect period, and the less harmful to the phytotoxicity.
4. Reasonably mixed. Bordeaux mixture can not be mixed with stone sulfur, antibacterial and so on. Bordeaux mixture should be used with organic phosphorus pesticides carefully and can be used with mixing. It is only 10 days after spraying the stone sulphur mixture to spray the Bordeaux mixture. After spraying the Bordeaux mixture, it can be sprayed for 20 to 30 days.
5. Pay attention to the changes in the weather. Spraying Bordeaux mixture should be done in a clear, dew-free weather. Spraying in summer should avoid the high temperature noon, so as to avoid the damage of lime at high temperature. Spray in the rainy season, try to avoid the wind and rain, and at the same time, properly increase the amount and proportion of lime in the dispensing.
Fourth, remedies
In the early stage of phytotoxicity, spraying 0.5% to 1% of lime water solution can alleviate the release rate of copper ions and reduce the phytotoxicity to a certain extent. After the victim, spray 0.3% potassium dihydrogen phosphate solution or fertilization solution every 10 to 15 days, or spray humic acid foliar fertilizer to help the jujube restore growth and reduce the damage of phytotoxicity.
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