There are strange brown and black spots on the leaf surface of the vegetables, and the leaves are dry and the leaves are dry. The factors that eliminate all kinds of eubacteria are mainly caused by the excessive use of foliar fertilizer. Because the weather is still hot and dry in August and September, the concentration of foliar fertilizer used by vegetable farmers is too high and the density is too high. In addition, most of the greenhouse vegetable crops are still in the sensitive vegetative growth period, so it is easy to appear. The use of excess fertilizer to damage plants is a problem!
First, the types of foliar fertilizers There are many types of foliar fertilizers. According to their functions and functions, foliar fertilizers can be summarized into four categories: nutritive, regulated, bio- and composite.
Second, foliar fertilization technology (a) select the appropriate variety. In the early stage of crop growth, in order to promote its growth and development, regulated foliar fertilizer should be selected. If the crop is lack of nutrients or the root absorption capacity declines in the late growth stage, nutritive foliar fertilizer should be used. The chemical fertilizers commonly used in foliar application in production are urea, potassium dihydrogen phosphate, superphosphate, potassium sulfate and various trace element fertilizers.
(2) The spraying concentration should be appropriate. Within a certain concentration range, the speed and quantity of nutrients entering the leaves increase with the increase of the concentration of the solution, but the concentration is too high and it is easy to cause fertilizer damage, especially the trace element fertilizer, generally large and medium amount elements (nitrogen phosphorus potassium calcium magnesium sulfur) The concentration is 500-600 times, the trace elements iron, manganese and zinc are 500-1000 times, the boron is 3000 times or more, and the copper and molybdenum are 6000 times or more.
(3) The spraying time should be appropriate. When fertilizing leaves, the longer the wetting time, the more nutrients are absorbed by the leaves, and the better the effect. Under normal circumstances, it is advisable to keep the leaf wet time in 30-60 minutes. Therefore, foliar fertilization is best carried out in the windless weather in the evening; spraying fertilizer in the morning with dew will reduce the concentration of the solution and affect the effect of fertilization. Foliar topdressing can't be carried out on rainy days or before rain, because nutrients are easily leached and can't reach the desired effect. If it rains 3 hours after spraying, it should be sprayed once every day, but the concentration should be reduced appropriately.
(4) Spraying should be uniform, meticulous and thoughtful. Foliar fertilization requires fine droplets and uniform spray, especially when spraying the upper leaves and the back of the leaves.
(5) The number of spraying should not be too small, and there should be an interval. The concentration of crop topdressing is generally low, and the amount of absorption per time is very small, much lower than the demand for crops. Therefore, the number of foliar application should not be less than 2 to 3 times. At the same time, the interval should be at least one week, and the number of spraying should not be too much to prevent damage.
(6) Foliar fertilizer should be used properly. When foliar topdressing, two or more foliar fertilizers can be reasonably mixed, which can save spraying time and labor, and the yield increasing effect will be more significant. However, after the fertilizer is mixed, there must be no adverse reactions or no reduction in fertilizer efficiency, otherwise the purpose of mixing will not be achieved. In addition, the concentration of the solution and the pH should be paid attention to when the fertilizer is mixed. Under normal circumstances, the pH value of the solution is about 7, and the neutral condition is favorable for the absorption of the leaves.
(7) Add a wetting agent to the fertilizer solution. There is a layer of thick and thin stratum corneum on the leaves of the crop. It is difficult to infiltrate the solution. For this reason, an appropriate amount of humectant, such as neutral soap, good quality detergent, etc., can be added to the leaf fertilizer solution to reduce the solution. Surface tension increases the contact area with the blade and improves the effect of foliar topdressing.
(8) The period when foliar fertilizer is needed: 1. When encountering pests and diseases, the use of foliar fertilizer is beneficial to improve the disease resistance of the plant; 2. The soil is acidic, alkaline or salinity is too high, which is not conducive to the absorption of nutrients by plants. 3, fruiting period; 4, after the plant encounters gas damage, heat damage or frost damage, choose the right time to use foliar fertilizer to help relieve symptoms.
(9) It is best not to use foliar fertilizer: 1. Flowering period. The flowers are delicate and susceptible to fertilizer; 2, seedling stage; 3, high temperature and strong light period in one day.
Huaxian Liu Huimin
First, the types of foliar fertilizers There are many types of foliar fertilizers. According to their functions and functions, foliar fertilizers can be summarized into four categories: nutritive, regulated, bio- and composite.
Second, foliar fertilization technology (a) select the appropriate variety. In the early stage of crop growth, in order to promote its growth and development, regulated foliar fertilizer should be selected. If the crop is lack of nutrients or the root absorption capacity declines in the late growth stage, nutritive foliar fertilizer should be used. The chemical fertilizers commonly used in foliar application in production are urea, potassium dihydrogen phosphate, superphosphate, potassium sulfate and various trace element fertilizers.
(2) The spraying concentration should be appropriate. Within a certain concentration range, the speed and quantity of nutrients entering the leaves increase with the increase of the concentration of the solution, but the concentration is too high and it is easy to cause fertilizer damage, especially the trace element fertilizer, generally large and medium amount elements (nitrogen phosphorus potassium calcium magnesium sulfur) The concentration is 500-600 times, the trace elements iron, manganese and zinc are 500-1000 times, the boron is 3000 times or more, and the copper and molybdenum are 6000 times or more.
(3) The spraying time should be appropriate. When fertilizing leaves, the longer the wetting time, the more nutrients are absorbed by the leaves, and the better the effect. Under normal circumstances, it is advisable to keep the leaf wet time in 30-60 minutes. Therefore, foliar fertilization is best carried out in the windless weather in the evening; spraying fertilizer in the morning with dew will reduce the concentration of the solution and affect the effect of fertilization. Foliar topdressing can't be carried out on rainy days or before rain, because nutrients are easily leached and can't reach the desired effect. If it rains 3 hours after spraying, it should be sprayed once every day, but the concentration should be reduced appropriately.
(4) Spraying should be uniform, meticulous and thoughtful. Foliar fertilization requires fine droplets and uniform spray, especially when spraying the upper leaves and the back of the leaves.
(5) The number of spraying should not be too small, and there should be an interval. The concentration of crop topdressing is generally low, and the amount of absorption per time is very small, much lower than the demand for crops. Therefore, the number of foliar application should not be less than 2 to 3 times. At the same time, the interval should be at least one week, and the number of spraying should not be too much to prevent damage.
(6) Foliar fertilizer should be used properly. When foliar topdressing, two or more foliar fertilizers can be reasonably mixed, which can save spraying time and labor, and the yield increasing effect will be more significant. However, after the fertilizer is mixed, there must be no adverse reactions or no reduction in fertilizer efficiency, otherwise the purpose of mixing will not be achieved. In addition, the concentration of the solution and the pH should be paid attention to when the fertilizer is mixed. Under normal circumstances, the pH value of the solution is about 7, and the neutral condition is favorable for the absorption of the leaves.
(7) Add a wetting agent to the fertilizer solution. There is a layer of thick and thin stratum corneum on the leaves of the crop. It is difficult to infiltrate the solution. For this reason, an appropriate amount of humectant, such as neutral soap, good quality detergent, etc., can be added to the leaf fertilizer solution to reduce the solution. Surface tension increases the contact area with the blade and improves the effect of foliar topdressing.
(8) The period when foliar fertilizer is needed: 1. When encountering pests and diseases, the use of foliar fertilizer is beneficial to improve the disease resistance of the plant; 2. The soil is acidic, alkaline or salinity is too high, which is not conducive to the absorption of nutrients by plants. 3, fruiting period; 4, after the plant encounters gas damage, heat damage or frost damage, choose the right time to use foliar fertilizer to help relieve symptoms.
(9) It is best not to use foliar fertilizer: 1. Flowering period. The flowers are delicate and susceptible to fertilizer; 2, seedling stage; 3, high temperature and strong light period in one day.
Huaxian Liu Huimin
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