Analysis of Common Physiological Diseases of Over-summering Vegetables
Analyzing common physiological diseases of over-summering vegetables
Affected by high temperatures, over-summering vegetables often develop physiological diseases due to improper management such as watering, fertilizing and applying pesticides, for example tomato leaf curling, small leaves and yellow leaves, yellow cucumbers, and premature plant decline, etc.
Regarding these physiological diseases, many vegetable growers mistakenly regard them as infectious diseases and cannot treat them accordingly, which results in reduced yields and low benefits of over-summering vegetables.
In this issue, we will focus on the typical physiological diseases of over-summering vegetables for the reference of vegetable grower friends. One manifestation of physiological diseases: tomato leaf curling
Symptoms: leaves curl upward, and in severe cases curl into a tube shape, developing from the bottom upward.
Physiological leaf curling in tomatoes is intuitively analyzed as being caused by water deficiency. Under water-deficient conditions, the leaves self-regulate by closing their stomata to reduce water transpiration, which makes the leaves curl upward.
Perhaps some vegetable growers will ask: when growing over-summering tomatoes, we water once every three to five days, so how could there be water deficiency? Don't worry, this is exactly the topic we are going to analyze.
Apart from the problem of insufficient watering (that is, the amount of water applied cannot meet the evaporation of soil moisture and the transpiration of the plants), poor root development or root damage is the key cause of water deficiency in the plants. It should be specially pointed out that improper watering is very likely the chief culprit causing poor root development or root damage.
Therefore, over-summering tomatoes must be watered reasonably and scientifically.
One, watering must be carried out according to the characteristics of different growth stages.
Generally, 3-5 days after the tomato transplanting water, the seedling-establishing water should be applied, after which the soil should be kept appropriately dry to promote deep root growth and cultivate strong plants. In the early fruiting stage the plants are relatively small and ground evaporation is large, so watering can generally be done once every 5-7 days, followed by intertillage and hoeing. Afterward, as the plants grow and develop, their water requirement increases, so watering should be done in time to prevent alternating dry and wet conditions that affect the normal growth of the vegetables.
Two, water according to growth vigor.
Plants that are dark green with glossy leaves that are green and flat and with spreading heart leaves indicate that moisture is uniform and suitable. If the heart leaves are shrunken and do not spread, the leaf color is dark green, and there is slight leaf drooping on sunny days, this indicates water deficiency and water should be supplied in time. If the heart leaves spread excessively, the leaves are large and thin, and the leaf surface exudes too much water, this indicates excessive moisture, and water should be controlled to prevent excessive vegetative growth.
Three, the watering time within a day in the greenhouse.
In summer, never water at noon when the temperature is relatively high; generally it should be done before 10 a.m. and after 4 p.m.
Some vegetable growers do not understand why watering is not allowed at noon, but the reason is actually very simple. Because in summer the ground temperature is already very high, and after several hours of strong light in the morning, the ground absorbs even more heat, making the ground temperature higher, while the water used for irrigation is drawn from underground and its temperature is relatively much lower. Irrigating vegetables with such well water will cause the soil temperature to drop sharply, leading to weakened root metabolic activity and affecting water absorption. At the same time, because the air temperature is very high, the aboveground branches and leaves still have strong transpiration, so the water absorption rate of the roots cannot compensate for the water loss rate of the aboveground parts, causing the vegetables to lose a large amount of water in a short time, resulting in plant wilting and dry leaf edges and tips. Two manifestation of physiological diseases: premature plant decline
Symptoms: thin stems, small leaves, yellow leaves, weak growth vigor, few fruits set, poor fruit development, low yield, and weakened disease resistance and stress resistance.
There are many causes of premature plant decline, such as aggravation of pests and diseases, insufficient light, and root injury, but for over-summering vegetables, improper fertilization is the main cause of premature plant decline.
Some vegetable growers may say: for over-summering vegetables, we generally do not use organic fertilizer before transplanting, we only spread some chemical fertilizer before transplanting, and then flush some fertilizer with the water each time we irrigate, so how could root injury occur?
In fact, it is precisely these practices that cause root injury in vegetables.
One, not paying attention to the use of organic fertilizer before transplanting. Organic fertilizer is a slow-release and long-acting fertilizer. After application, it can not only improve the soil and enhance soil fertility, but more importantly, it can evenly and continuously supply the nutrients needed for vegetable growth. If organic fertilizer is insufficiently applied, it often leads to nutrient deficiency in the middle and late stages of plant growth and development and thus premature decline, and even applying more fertilizer later cannot save the plants from premature decline.
At the same time, if the use of organic fertilizer is neglected while chemical fertilizer is one-sidedly increased, it often causes soil compaction and reduced soil permeability, which easily causes poor root growth and development and leads to premature decline.
Two, excessive use of nitrogen fertilizer. Some vegetable growers, in order to promote crop growth, excessively flush nitrogen fertilizer, resulting in root injury, making the plants thin and weak with poor development and premature decline. In addition, excessive use of nitrogen fertilizer easily causes excessive vegetative growth of the plants and makes the crops age prematurely.
Three, flushing fertilizer excessively in a single application. Flushing an excessive amount of fertilizer at one time increases the concentration of the soil solution, forming salt damage, affecting root growth, and further leading to insufficient supply of water and nutrients needed for plant growth, thus causing premature decline.
In order to prevent vegetable roots from being injured, the above fertilization methods must be avoided and scientific fertilization must be achieved.
The scientific fertilization method is: on the basis of applying sufficient organic fertilizer (generally it is advisable to use more than 5000 kg of organic fertilizer per mu per year), use chemical fertilizer in an appropriate amount according to the growth needs of the crop, and do not one-sidedly apply nitrogen fertilizer. For example, for tomatoes in the fruiting stage, the most suitable ratio of nitrogen to potassium in the flushed fertilizer is 1:2, and flushing 60 jin of compound fertilizer per mu each time is sufficient.
After crops show premature decline, the combined method of spraying on the top and irrigating at the bottom should be used for remediation. Spraying on the top means foliar spraying of leaf fertilizer. Nitrogen-phosphorus-potassium nutrient-type leaf fertilizer mixed with cytokinin at 400 times can be used for foliar spraying to quickly supplement the nutrients needed for crop growth and delay plant aging. Irrigating at the bottom means applying rooting agents or microbial bacterial fertilizer to promote root growth and enhance the root system's ability to absorb water and fertilizer. After the plants return to normal, topdressing should be carried out in time according to the growth needs of the crop. Three manifestation of physiological diseases: tomato fruit rib blight
Symptoms: uneven fruit coloring, with blackening inside the skin and outside the flesh. In mildly affected fruits, some vascular bundles become brown and necrotic; although the fruit appearance does not change, the parts where the vascular bundles have turned brown do not turn red. In more severely affected fruits, all the vascular bundles in the flesh are dark brown, the placental tissue of the diseased fruit develops poorly, and some are accompanied by hollow fruit; the fruit surface shows obvious uneven red and green, and in severe cases the affected parts are light green and the surface becomes hard.
In tomato fruit rib blight, the most important manifestation is poor fruit coloring. Insufficient light, imbalance of nitrogen, phosphorus and potassium, and root injury can all cause poor fruit coloring. In summary, it is caused by unsuitable cultivation conditions.
Perhaps some vegetable growers will say: growing over-summering vegetables is like looking after a child, fearing they will get too hot, so we cover them with shade netting; fearing they will not have enough nutrition, we apply good fertilizer; fearing they will not have enough water, we water once every three to five days, so how could unsuitable cultivation conditions still occur?
Although vegetable grower friends do a lot, they may not always do it right.
One, covering with shade netting all day causes insufficient light. The purpose of setting up shade netting was originally to create a suitable growing environment for vegetables when the light is relatively strong at noon, but many vegetable growers often stop managing after covering the shade netting, resulting in insufficient light for the vegetables. When the number of light hours is insufficient, especially when the number of light hours is less than 7 hours, the incidence of fruit rib blight is relatively high. Light is the power source of photosynthesis. In this regard, it is suggested that vegetable grower friends cover with shade netting only at noon on sunny days, and remove it in time in the evening and on cloudy and rainy days, so as to ensure the light exposure time and light intensity for tomatoes.
Two, imbalance of the nitrogen and potassium ratio during fertilization. In the fruiting stage, tomatoes need a large amount of potassium fertilizer, about 1.8 times that of nitrogen fertilizer. If the amount of nitrogen fertilizer is too large and potassium fertilizer is insufficient during topdressing, the incidence of fruit rib blight is high. In addition, frequently applying manure that has not yet been fully decomposed will also aggravate the occurrence of this disease. Therefore, the ratio of nitrogen to potassium during topdressing should be coordinated, and Dayuan Meirida (17:5:28) or Fangrun (15:15:30) can be used for topdressing.
Three, root injury leads to a decline in the ability to absorb water and nutrients, and the incidence is high. At present, the temperature is relatively high and water evaporation is relatively large. Some vegetable growers water excessively in order to promote rapid tomato growth, resulting in root injury and promoting the occurrence of fruit rib blight fruit. Therefore, tomato watering should be based on "three observations": observe the sky, observe the ground, and observe the crops.
For greenhouse tomatoes that have already developed fruit rib blight, under the condition of enhancing light, foliar spraying of monopotassium phosphate at 200-300 times, or Leduo leaf fertilizer at 500-1000 times, or Fangrun leaf fertilizer at 800-1000 times can be used to quickly supplement nutrients and reduce the probability of fruit rib blight fruit appearing in the later stage. Four manifestation of physiological diseases: yellowing cucumber fruits
Symptoms: cucumber fruits turn yellow, but there are no disease spots on the fruits.
Yellowing cucumber fruits have no disease spots, so the possibility of infectious diseases can be ruled out and they can be judged as physiological diseases. Specifically, poor root development of summer cucumbers is the main cause of yellowing fruits; poor root development affects the growth and development of the entire plant, so the cucumber cannot obtain sufficient nutrition, which further causes the fruits to turn yellow.
Perhaps some vegetable growers will say: in order to give cucumbers sufficient nutrients, we have applied no small amount of fertilizer, so how could this situation still occur?
If the cucumber root system has not developed well, then no matter how much fertilizer is applied it will be of no help, because poor root development means the roots cannot fully absorb fertilizer to supply fruit growth, resulting in the phenomenon of yellowing fruits.
In fact, poor root development is mostly caused by improper subjective management by vegetable growers. In this regard, the management of over-summering cucumbers should focus on nourishing the roots.
One, change the planting method of watering after transplanting.
Many vegetable growers often plant dry first and then water during transplanting. The disadvantage of doing so is that the surface layer has sufficient water and fertilizer, and the roots develop horizontally in the shallow surface layer, which limits the future expansion of the root system; in addition, because the surface soil has high fertilizer efficiency, it is easy to produce excessive lush growth.
If the soil is watered thoroughly before transplanting, it can induce the root system to develop in depth. The deep soil has less fertilizer, and the vegetables absorb less fertilizer before flowering, which instead makes it less likely for the aboveground part to form excessive vigorous growth. At the same time, watering first can also lower the ground temperature, which is more conducive to root growth and seedling establishment.
Two, protect the leaves and promote rooting.
The nutrients needed by the root system are mostly provided by the middle and lower leaves, so the lower leaves should not be removed too early, and leaf diseases must be strictly controlled.
Three, fertilize reasonably and nourish and protect the roots.
A large amount of fertilizer can easily cause the capillary roots to age or be injured. Applying too much base fertilizer or applying organic fertilizer that is not fully decomposed can directly cause root burning and plant death; flushing too much chemical fertilizer at one time during the fruiting stage of vegetables, especially using too much nitrogen fertilizer, can also cause root burning.
The suitable fertilization method is: after applying an appropriate amount of base fertilizer in the shallow layer, then open a ditch at the transplanting position and apply biological fertilizer deeply, such as Dayuan Luodi Shenggen, etc., which can play multiple roles in improving the soil, preventing diseases, promoting new roots, and prompting the root system to develop in depth to form thick and strong roots. After vegetables enter the fruiting stage, vegetative growth and reproductive growth proceed simultaneously. When flushing fertilizer, while ensuring that the roots are not harmed, both plant growth and fruit development should be considered, so it is not suitable to apply too much nitrogen fertilizer, and an appropriate amount of high-quality compound fertilizer should be flushed. In addition, if the temperature is too high, the amount of chemical fertilizer should be reduced and more biological fertilizer should be applied to ensure normal root growth and development.
Regarding these physiological diseases, many vegetable growers mistakenly regard them as infectious diseases and cannot treat them accordingly, which results in reduced yields and low benefits of over-summering vegetables.
In this issue, we will focus on the typical physiological diseases of over-summering vegetables for the reference of vegetable grower friends. One manifestation of physiological diseases: tomato leaf curling
Symptoms: leaves curl upward, and in severe cases curl into a tube shape, developing from the bottom upward.
Physiological leaf curling in tomatoes is intuitively analyzed as being caused by water deficiency. Under water-deficient conditions, the leaves self-regulate by closing their stomata to reduce water transpiration, which makes the leaves curl upward.
Perhaps some vegetable growers will ask: when growing over-summering tomatoes, we water once every three to five days, so how could there be water deficiency? Don't worry, this is exactly the topic we are going to analyze.
Apart from the problem of insufficient watering (that is, the amount of water applied cannot meet the evaporation of soil moisture and the transpiration of the plants), poor root development or root damage is the key cause of water deficiency in the plants. It should be specially pointed out that improper watering is very likely the chief culprit causing poor root development or root damage.
Therefore, over-summering tomatoes must be watered reasonably and scientifically.
One, watering must be carried out according to the characteristics of different growth stages.
Generally, 3-5 days after the tomato transplanting water, the seedling-establishing water should be applied, after which the soil should be kept appropriately dry to promote deep root growth and cultivate strong plants. In the early fruiting stage the plants are relatively small and ground evaporation is large, so watering can generally be done once every 5-7 days, followed by intertillage and hoeing. Afterward, as the plants grow and develop, their water requirement increases, so watering should be done in time to prevent alternating dry and wet conditions that affect the normal growth of the vegetables.
Two, water according to growth vigor.
Plants that are dark green with glossy leaves that are green and flat and with spreading heart leaves indicate that moisture is uniform and suitable. If the heart leaves are shrunken and do not spread, the leaf color is dark green, and there is slight leaf drooping on sunny days, this indicates water deficiency and water should be supplied in time. If the heart leaves spread excessively, the leaves are large and thin, and the leaf surface exudes too much water, this indicates excessive moisture, and water should be controlled to prevent excessive vegetative growth.
Three, the watering time within a day in the greenhouse.
In summer, never water at noon when the temperature is relatively high; generally it should be done before 10 a.m. and after 4 p.m.
Some vegetable growers do not understand why watering is not allowed at noon, but the reason is actually very simple. Because in summer the ground temperature is already very high, and after several hours of strong light in the morning, the ground absorbs even more heat, making the ground temperature higher, while the water used for irrigation is drawn from underground and its temperature is relatively much lower. Irrigating vegetables with such well water will cause the soil temperature to drop sharply, leading to weakened root metabolic activity and affecting water absorption. At the same time, because the air temperature is very high, the aboveground branches and leaves still have strong transpiration, so the water absorption rate of the roots cannot compensate for the water loss rate of the aboveground parts, causing the vegetables to lose a large amount of water in a short time, resulting in plant wilting and dry leaf edges and tips. Two manifestation of physiological diseases: premature plant decline
Symptoms: thin stems, small leaves, yellow leaves, weak growth vigor, few fruits set, poor fruit development, low yield, and weakened disease resistance and stress resistance.
There are many causes of premature plant decline, such as aggravation of pests and diseases, insufficient light, and root injury, but for over-summering vegetables, improper fertilization is the main cause of premature plant decline.
Some vegetable growers may say: for over-summering vegetables, we generally do not use organic fertilizer before transplanting, we only spread some chemical fertilizer before transplanting, and then flush some fertilizer with the water each time we irrigate, so how could root injury occur?
In fact, it is precisely these practices that cause root injury in vegetables.
One, not paying attention to the use of organic fertilizer before transplanting. Organic fertilizer is a slow-release and long-acting fertilizer. After application, it can not only improve the soil and enhance soil fertility, but more importantly, it can evenly and continuously supply the nutrients needed for vegetable growth. If organic fertilizer is insufficiently applied, it often leads to nutrient deficiency in the middle and late stages of plant growth and development and thus premature decline, and even applying more fertilizer later cannot save the plants from premature decline.
At the same time, if the use of organic fertilizer is neglected while chemical fertilizer is one-sidedly increased, it often causes soil compaction and reduced soil permeability, which easily causes poor root growth and development and leads to premature decline.
Two, excessive use of nitrogen fertilizer. Some vegetable growers, in order to promote crop growth, excessively flush nitrogen fertilizer, resulting in root injury, making the plants thin and weak with poor development and premature decline. In addition, excessive use of nitrogen fertilizer easily causes excessive vegetative growth of the plants and makes the crops age prematurely.
Three, flushing fertilizer excessively in a single application. Flushing an excessive amount of fertilizer at one time increases the concentration of the soil solution, forming salt damage, affecting root growth, and further leading to insufficient supply of water and nutrients needed for plant growth, thus causing premature decline.
In order to prevent vegetable roots from being injured, the above fertilization methods must be avoided and scientific fertilization must be achieved.
The scientific fertilization method is: on the basis of applying sufficient organic fertilizer (generally it is advisable to use more than 5000 kg of organic fertilizer per mu per year), use chemical fertilizer in an appropriate amount according to the growth needs of the crop, and do not one-sidedly apply nitrogen fertilizer. For example, for tomatoes in the fruiting stage, the most suitable ratio of nitrogen to potassium in the flushed fertilizer is 1:2, and flushing 60 jin of compound fertilizer per mu each time is sufficient.
After crops show premature decline, the combined method of spraying on the top and irrigating at the bottom should be used for remediation. Spraying on the top means foliar spraying of leaf fertilizer. Nitrogen-phosphorus-potassium nutrient-type leaf fertilizer mixed with cytokinin at 400 times can be used for foliar spraying to quickly supplement the nutrients needed for crop growth and delay plant aging. Irrigating at the bottom means applying rooting agents or microbial bacterial fertilizer to promote root growth and enhance the root system's ability to absorb water and fertilizer. After the plants return to normal, topdressing should be carried out in time according to the growth needs of the crop. Three manifestation of physiological diseases: tomato fruit rib blight
Symptoms: uneven fruit coloring, with blackening inside the skin and outside the flesh. In mildly affected fruits, some vascular bundles become brown and necrotic; although the fruit appearance does not change, the parts where the vascular bundles have turned brown do not turn red. In more severely affected fruits, all the vascular bundles in the flesh are dark brown, the placental tissue of the diseased fruit develops poorly, and some are accompanied by hollow fruit; the fruit surface shows obvious uneven red and green, and in severe cases the affected parts are light green and the surface becomes hard.
In tomato fruit rib blight, the most important manifestation is poor fruit coloring. Insufficient light, imbalance of nitrogen, phosphorus and potassium, and root injury can all cause poor fruit coloring. In summary, it is caused by unsuitable cultivation conditions.
Perhaps some vegetable growers will say: growing over-summering vegetables is like looking after a child, fearing they will get too hot, so we cover them with shade netting; fearing they will not have enough nutrition, we apply good fertilizer; fearing they will not have enough water, we water once every three to five days, so how could unsuitable cultivation conditions still occur?
Although vegetable grower friends do a lot, they may not always do it right.
One, covering with shade netting all day causes insufficient light. The purpose of setting up shade netting was originally to create a suitable growing environment for vegetables when the light is relatively strong at noon, but many vegetable growers often stop managing after covering the shade netting, resulting in insufficient light for the vegetables. When the number of light hours is insufficient, especially when the number of light hours is less than 7 hours, the incidence of fruit rib blight is relatively high. Light is the power source of photosynthesis. In this regard, it is suggested that vegetable grower friends cover with shade netting only at noon on sunny days, and remove it in time in the evening and on cloudy and rainy days, so as to ensure the light exposure time and light intensity for tomatoes.
Two, imbalance of the nitrogen and potassium ratio during fertilization. In the fruiting stage, tomatoes need a large amount of potassium fertilizer, about 1.8 times that of nitrogen fertilizer. If the amount of nitrogen fertilizer is too large and potassium fertilizer is insufficient during topdressing, the incidence of fruit rib blight is high. In addition, frequently applying manure that has not yet been fully decomposed will also aggravate the occurrence of this disease. Therefore, the ratio of nitrogen to potassium during topdressing should be coordinated, and Dayuan Meirida (17:5:28) or Fangrun (15:15:30) can be used for topdressing.
Three, root injury leads to a decline in the ability to absorb water and nutrients, and the incidence is high. At present, the temperature is relatively high and water evaporation is relatively large. Some vegetable growers water excessively in order to promote rapid tomato growth, resulting in root injury and promoting the occurrence of fruit rib blight fruit. Therefore, tomato watering should be based on "three observations": observe the sky, observe the ground, and observe the crops.
For greenhouse tomatoes that have already developed fruit rib blight, under the condition of enhancing light, foliar spraying of monopotassium phosphate at 200-300 times, or Leduo leaf fertilizer at 500-1000 times, or Fangrun leaf fertilizer at 800-1000 times can be used to quickly supplement nutrients and reduce the probability of fruit rib blight fruit appearing in the later stage. Four manifestation of physiological diseases: yellowing cucumber fruits
Symptoms: cucumber fruits turn yellow, but there are no disease spots on the fruits.
Yellowing cucumber fruits have no disease spots, so the possibility of infectious diseases can be ruled out and they can be judged as physiological diseases. Specifically, poor root development of summer cucumbers is the main cause of yellowing fruits; poor root development affects the growth and development of the entire plant, so the cucumber cannot obtain sufficient nutrition, which further causes the fruits to turn yellow.
Perhaps some vegetable growers will say: in order to give cucumbers sufficient nutrients, we have applied no small amount of fertilizer, so how could this situation still occur?
If the cucumber root system has not developed well, then no matter how much fertilizer is applied it will be of no help, because poor root development means the roots cannot fully absorb fertilizer to supply fruit growth, resulting in the phenomenon of yellowing fruits.
In fact, poor root development is mostly caused by improper subjective management by vegetable growers. In this regard, the management of over-summering cucumbers should focus on nourishing the roots.
One, change the planting method of watering after transplanting.
Many vegetable growers often plant dry first and then water during transplanting. The disadvantage of doing so is that the surface layer has sufficient water and fertilizer, and the roots develop horizontally in the shallow surface layer, which limits the future expansion of the root system; in addition, because the surface soil has high fertilizer efficiency, it is easy to produce excessive lush growth.
If the soil is watered thoroughly before transplanting, it can induce the root system to develop in depth. The deep soil has less fertilizer, and the vegetables absorb less fertilizer before flowering, which instead makes it less likely for the aboveground part to form excessive vigorous growth. At the same time, watering first can also lower the ground temperature, which is more conducive to root growth and seedling establishment.
Two, protect the leaves and promote rooting.
The nutrients needed by the root system are mostly provided by the middle and lower leaves, so the lower leaves should not be removed too early, and leaf diseases must be strictly controlled.
Three, fertilize reasonably and nourish and protect the roots.
A large amount of fertilizer can easily cause the capillary roots to age or be injured. Applying too much base fertilizer or applying organic fertilizer that is not fully decomposed can directly cause root burning and plant death; flushing too much chemical fertilizer at one time during the fruiting stage of vegetables, especially using too much nitrogen fertilizer, can also cause root burning.
The suitable fertilization method is: after applying an appropriate amount of base fertilizer in the shallow layer, then open a ditch at the transplanting position and apply biological fertilizer deeply, such as Dayuan Luodi Shenggen, etc., which can play multiple roles in improving the soil, preventing diseases, promoting new roots, and prompting the root system to develop in depth to form thick and strong roots. After vegetables enter the fruiting stage, vegetative growth and reproductive growth proceed simultaneously. When flushing fertilizer, while ensuring that the roots are not harmed, both plant growth and fruit development should be considered, so it is not suitable to apply too much nitrogen fertilizer, and an appropriate amount of high-quality compound fertilizer should be flushed. In addition, if the temperature is too high, the amount of chemical fertilizer should be reduced and more biological fertilizer should be applied to ensure normal root growth and development.