What is the reason for the yellow leaves of the apple tree? Thank you!

Yellow leaf disease of apple trees is also known as white leaf disease, or iron deficiency green fading. It occurs in all apple producing areas in China, especially in saline-alkali soil and areas with high limestone. In the year when there is more rain in spring, seedlings and young trees are seriously damaged.

Identification characteristics] Yellow leaf disease of apple trees is mainly manifested in the young leaves of new shoots, and the symptoms of vigorous growth of new shoots are the most obvious. At the beginning of the disease, the mesophyll first began to turn yellow, the leaf veins and main veins remained green, and the leaf surface was green reticulated and lost green. In severe cases, the whole leaf turns white and the leaf margin is scorched, resulting in early defoliation and even death of the top of the new shoot.

The fruit of the diseased tree is still green.

Causes and characteristics of the disease].

Yellow leaf disease in apple trees is mainly caused by iron deficiency in apple trees. Due to the severe influence of iron on the function of chlorophyll, the leaves show yellowing. Iron in the tree is not easily transferred, so the symptoms of vigorous young leaves are the most obvious.

In general, the soil is rich in calcium carbonate, too alkaline, too much soil moisture and partial application of available nitrogen fertilizer, which will affect the iron uptake of fruit trees.

Comprehensive control] 1) Improve soil: Do not choose saline-alkali land and soil with too high alkalinity for new orchards. If it is unavoidable, soil improvement should be strengthened, organic fertilizer or intercropping green manure crops should be added, soil structure should be improved, soil humus should be increased, and the occurrence of diseases should be reduced.

2) Strengthen orchard management: Reasonable fertilization, avoid partial application of nitrogen fertilizer, properly control the load of fruit trees, and pay attention to drainage in the rainy season.

3) Increase the application of iron fertilizer: In orchards where yellow leaf disease occurs severely, spray ferrous sulfate solution before germination, or inject with ferrous sulfate tree trunks, and can also use 1% 3% ferrous sulfate solution to pour into the rhizosphere soil.

4) Growing season control: when the top 3 leaves of the short branches lose green, spray 200 300 times of fulvic acid diferlamine every 10 days, or urea plus ferrous sulfate dilution, a total of 3 times, can significantly increase the iron content and chlorophyll content of the leaves, and can effectively control the occurrence and development of iron deficiency yellow leaf disease.

There are two reasons for the yellow leaves of apple trees, one is the yellow leaves caused by excessive branches, and the other is that the yellow leaves are easy to appear due to fertilization.

Due to the small spacing of fruit trees and the large number of crown branches, the inner chamber and lower leaves of the crown can not photosynthesize to produce dry matter, and such leaves become consumables for the growth of fruit trees, and physiological yellowing and defoliation naturally occur.

Summer pruning should be carried out in time to ensure ventilation and light in the canopy, which is the best way to prevent this from happening.

The fertilization time interval is long, in the spring budding and leaf flowering period, autumn branch and leaf growth and fruit expansion period, the tree consumes a large amount of nutrients, if it is not replenished in time, there will be defertilization, and the leaves will appear yellow flowers.

The nutrient content of organic fertilizer is comprehensive, and the soil can be improved after application, and the soil fertilizer is easy and slippery, and the fertilizer effect period is long and stable. It is especially used in orchards where the goldenrod phenomenon occurs, which is conducive to the recovery of leaf green.

The reasons for answering the yellow leaves of apple trees are generally as follows: in the process of growth, the fruit tree lacks iron and the soil is alkaline; Fruit trees infected with mosaic virus; Excessive or too little fertilization and watering, and untimely drainage in rainy weather; The operation is not standardized during ring stripping; The canopy of fruit trees is too dense, which hinders the photosynthesis of the foliage inside.

1. What's going on with apple trees with yellow leaves?

1. After entering the rainy season, the lack of iron in the growth process of apple trees, especially the young trees that have just been planted for 1-2 years on alkaline soil, and the yellow leaves are more serious.

2. The apple tree is infected with the apple mosaic virus, which causes the leaves to turn yellow.

3. The management method of the grower is inappropriate, the fertilization and water application are unreasonable, and the drainage is not timely, resulting in the yellowing of the leaves caused by poor root respiration.

4. During this period of about 10-15 days, the leaves will have a period of yellowing, which is a normal phenomenon, but if the ring stripping is not standardized, the yellowing time of the leaves will be prolonged and more serious.

5. There are too many branches and leaves at the top of the apple tree, resulting in the leaves inside not getting enough light, and the phenomenon of physiological yellowing and defoliation occurs.

6. Pests on apple trees cause yellowing of leaves.

2. What to do if the apple tree has yellow leaves

1. Spray ferrous sulfate solution on the branches and leaves of the yellow leaf part, or urea plus ferrous sulfate mixture, or fulvic acid diferamine 200-300 times liquid and other organic iron fertilizers, or compound iron fertilizer with citric acid and ferrous ammonium sulfate preparation solution (50kg of water + 50g of citric acid + 150g of ferrous sulfate + 100g of urea).

2. Around the middle of July, spray 300-450 times of "Virus II", pure milk that can be added to the solution. Or spray with 1000 times of morphinguanidine hydrochloride copper acetate or phytolingl emulsion, spray once every 10-15 days, a total of 2-3 sprays.

3. If there is continuous rainy weather, drain the water in time to avoid water accumulation in the orchard, which will affect the breathing of the roots of the apple tree, and loosen the soil in a timely manner. If the weather is dry, water in time to ensure that the soil is well hydrated.

4. After ring stripping, check the healing of the fruit tree every once in a while, if there is a wound that has not healed, smear mud on the wound in time and then wrap the wound with plastic film to promote wound healing, and at the same time you can spray urea 300 times, spray every 7 days, or 1000 times of Green Fenwei No. 2.

5. When the top branches and leaves are too lush, prune the apple tree in time to ensure the ventilation and light transmission of the leaves inside.

6. Dig a ring ditch around the crown of the tree, the ditch is 50cm deep and 60cm wide, and then dissolve ferrous sulfate with 10 times the water, and then mix it according to the ratio of ferrous sulfate: humus organic fertilizer = 1:15, and apply it in the annular ditch, if it is a tree of more than 10 years, apply 80-100kg, and apply 30-50kg for less than 10 years.

1. Lack of nutrients.

Lack of nutrients is the first factor that many fruit farmers think of, in the actual planting process, the lack of nutrients will indeed cause the fruit trees to lose green and yellow, such as nitrogen deficiency, the leaves turn yellow and fall off; When magnesium is deficient, the middle leaf veins lose green and turn yellow; When zinc is deficient, there will be green loss and spots; When boron is deficient, the leaves curl up, turn yellow and lose green, and have yellow spots, but other elements can also cause green loss.

This situation can be alleviated by timely fertilizer supplementation, and it is better to combine top dressing and foliar fertilization.

2. Soil problems.

When there is a problem with the soil itself, it will also cause the fruit tree to turn yellow and lose green, such as when the pH value in the soil is too high or too low, it may cause this phenomenon, under normal circumstances, when the pH value is greater than or less, it will affect the normal growth of the fruit tree, resulting in nutritional imbalance of the fruit tree.

In this case, it is necessary to "repair" the soil, which is a long-term process, such as applying farm fertilizer, reducing the amount of agricultural inputs, and applying different fertilizers according to the specific pH level of the field.

3. Temperature. When the fruit tree is in a high temperature state for a long time, the respiration of the fruit tree will be greater than that of photosynthesis, and the root system will do anaerobic respiration, resulting in a decrease in the absorption capacity of the root system, affecting the synthesis of chlorophyll, and then the leaves will show yellowing and green loss.

On the contrary, when the fruit tree is in a low temperature state for a long time, it will also affect the growth of the fruit tree, such as in early spring, the ground temperature rises slowly, and the leaf part has begun to grow, but the underground part is not enough to ensure the growth of the aboveground part, which is easy to cause insufficient nutrition and water, and finally the leaves appear yellow and green.

4. Moisture. If there is too much water in the orchard, there is water in the field, after the waterlogging, the roots are hypoxic, and they are forced to carry out anaerobic respiration, which will form toxic substances and affect the normal metabolism, and at the same time, some trace elements in the fruit tree will also be lost, resulting in the yellowing and loss of green leaves, pay attention to the drainage measures in the orchard to avoid long-term water accumulation.

5. Pests and diseases.

In the process of fruit tree growth, the invasion of pests and diseases will also cause the leaves to turn yellow and lose green, some pathogens and pathogens will invade the leaves, destroy chlorophyll, in addition to fruit trees, the loss of green caused by viruses is also more common, and the harm of red spiders and aphids will also cause the leaves to lose green and yellow, pay attention to timely spraying of pesticides for prevention.

Summary. The yellow spots on apple leaves can be caused by a variety of reasons, including pathogenic bacteria, malnutrition, abnormal climate, etc. Some common pathogens, such as sheath rot, rust, anthrax, etc., can cause yellow spots on apple leaves, and these pathogenic bacteria can multiply and cause damage to the leaves.

Malnutrition can also lead to yellow spots on apple leaves, and a lack of iron, zinc and other elements can lead to yellowing of leaves. In addition, climate anomalies such as drought, overwatering, and sun exposure may also be responsible for the yellow spots on apple leaves.

The yellow spots on apple leaves can be caused by a variety of reasons, including pathogenic bacteria, malnutrition, abnormal climate, etc. Some common pathogens such as resistant sheath rot, rust fungus, anthracnose, etc., can cause yellow spots on apple leaves, and these pathogens can multiply and cause ear damage to the leaves. Malnutrition can also lead to yellow spots on apple leaves, and a lack of iron, zinc and other elements can lead to yellowing of leaves.

In addition, climate anomalies such as drought, overwatering, and sun exposure may also be responsible for the yellow spots on apple leaves.

Any questions, dear.

1. Insufficient light.

1.Causes: There may be a large number of branches and lush leaves in the canopy, resulting in insufficient sunlight in the inner cavity of the canopy or the lower leaves, resulting in yellowing of the leaves.

2.Treatment: Prune the yellowed leaves in time, reasonably relax the canopy with dense branches and leaves, open up the internal space, and increase the light and ventilation inside the plant.

Second, there is a lack of iron.

1.Causes: In the growth of apples, the most common element deficiency yellow leaf disease is caused by iron deficiency.

When there is a shortage of finch-source iron, the leaves near the top of the shoots turn completely yellow, and some of the leaves are scorched and gradually begin to shed their leaves. 2.Solution:

If there is a lack of iron, it is necessary to deal with the yellowed branches and leaves. Mixed iron fertilizer solutions, citric acid, and ferrous sulfate should be used appropriately and sprayed on the leaves before 10 a.m. or after 4 p.m. The fog should be fine, and the spray should be even and thoughtful.

3. Improper fertilization.

1.Reason: If the fertilization is done for a long time, it is easy to lose fertilizer, and the leaves will turn yellow.

During the period of growth, flowering, fruiting, etc., the tree consumes a large amount of nutrients. If it is not replenished in time, there will be problems of defertilization and yellowing of leaves. 2.

Treatment method: If there is a long-term lack of fertilizer, it should be supplemented immediately, increase the number of fertilization, speed up the frequency of fertilization, and appropriately use compound fertilizer to supplement various elements. Do not overfertilize until the leaves are better, then return to normal fertilization.