How to prevent the leaves of mandarin trees with melasma spots and then leaf shedding?

The use of disease-free seedlings must be the first step, followed by the protection of each batch of buds and the prevention of harmful insects such as leaf miners, mites, leaf beetles, snails, etc. In addition, wind and rain are necessary for the epidemic of diseases, so we should pay attention to the protection of medicine before and after the rain.

Some drugs can be sprayed, and at the same time attention should be paid to watering, but also to fertilization, and at the same time the characteristics of growth should be observed.

It is necessary to spray some pesticides, and the diseased leaves should also be pruned. Top dressing should also be carried out in a timely manner. And it is also necessary to water reasonably, and spray some special agents scientifically. In this way, the disease can be prevented.

First of all, you should spray some antibacterial and insect control drugs, and secondly, you should also water more and fertilize more, and you must cut off useless branches and leaves, and at the same time, the broken branches and leaves should also be removed.

If this happens, then we can sprinkle lime on the trunk of these trees to prevent insect pests, or we can sprinkle lime into the soil, which can also play the same role, and then we can also go to the agricultural department to buy some relevant pesticides, spray them in advance, or we can turn over the soil and let the sun shine to remove the pests and diseases inside.

Branches and leaves die and fall off, which is obviously unmanaged or poorly managed for a long time, resulting in soil compaction, lack of fertilizer, coupled with nutrient consumption of flowering and fruiting, serious nutritional deficiencies, and inadequate pest control and pruning lead to more dead branches and leaves. The third is pest control. The tree potential is poor, often serious pests and diseases, a comprehensive comprehensive pest control of fruit trees, fungicides + insecticides + acaricides are mixed, the base of pests and diseases is reduced, and then targeted prevention and control is carried out in the later stage.

Boron fertilizer is applied, boron fertilizer is mixed into human manure and urine, a trench is dug under the canopy and applied, covered with part of the organic fertilizer and then covered with soil. Adult trees should be treated with boron fertilizer kilograms each time, and lightly diseased trees can be reduced as appropriate. Generally, it is applied once every 2 to 3 years.

The tips of the old leaves of citrus potassium deficiency first turned yellow, and the leaves shrivelled slightly, and with the aggravation of potassium deficiency, the leaves gradually turned from twisting, curling and shrinking to a cup-shaped. The new leaves are generally normal green, but the tips of the current year's leaves will also be noticeably yellowish in the later stage of fruiting, especially in high-yielding navel oranges.

It can cause the leaf edge to dry up, soil analysis should be carried out to further judge whether the soil is deficient in potassium, if necessary, the root can be applied to the foliar potassium fertilizer, caused by pesticide damage. Due to the excessive concentration of pesticides, the slow-release agent should be sprayed in time, and the appropriate top dressing should be used to restore the tree potential. The most suitable soil pH for the growth of citrus roots is that when the soil acidity is large, the effective activity of medium and trace elements such as magnesium, iron, calcium and zinc in the soil is low, resulting in black roots, rotten roots, and the nutrient absorption function of the root system is reduced, which may also cause yellowing of the tree.

You can consider that the soil is saline-alkali, pay attention to drainage, expand the hole and turn the soil, increase the soil permeability, increase the application of organic fertilizer, it is recommended to choose a little better water-soluble fertilizer when topdressing, quickly improve the soil, dry with amino acid stock solution, combined with foliar fertilizer. Generally, the aboveground and underground growth is not coordinated due to the high grafting of Wenzhou tangerine, sweet orange and other varieties, resulting in the obstruction of nutrient and water transport, and the yellowing of the aboveground part gradually occurs (for example, sweet oranges with lime as rootstock generally begin to yellowish in June and the disease is serious).

Yes, molybdenum deficiency leaves have yellow spots on the surface, and we should give it proper fertilizer and nutrients.

It's true, and he should be sick like this, now he must go to prune in time, and then he must be well sunned and watered, and then let him take care of some fertilizer, and he must ensure that the time is longer.

Yes, so you can also buy more chemical fertilizers to apply in this area to ensure the normal growth of this plant.

Yes, when this happens to citrus trees, it is necessary to add some phosphorus-containing fertilizers, which will be remedied in time.

It may be that the root system is damaged and the soil needs to be loosened, and the rooting agent can help the new roots stretch, which may improve the growth of mandarins.

The main reason for the yellowing of the leaves and the loss of leaves is that the roots are weak and unable to absorb sufficient nutrients** plant growth and development needs. If necessary, apply deep and heavy bacterial fertilizer, improve the soil, make the soil deep, loose soil, fertile soil, lead deep roots, cultivate developed root groups, enhance the ability to absorb, absorb sufficient comprehensive nutrients ** Aboveground growth and development needs, you can make the aboveground branches luxuriant, the leaf color is dark green, there is no leaf yellowing, in addition, to strengthen management, to prevent waterlogging and drought.

1.Wet yellow. Due to excessive soil moisture, the soil is hypoxic, the roots are difficult to breathe, the root system is hindered in water absorption and fertilizer absorption, and the growth can not be carried out normally, resulting in the pale yellow leaves of the branches and the old leaves, and then withering and dying.

At this time, the soil should be loosened and drained in time to control the amount of irrigation.

2.Dry yellow. Drought can wilt citrus.

At this time, photosynthesis decreases, growth is stopped, the transportation of photosynthetic products is blocked due to lack of water, and a large amount of organic matter in the plant is hydrolyzed, and respiration is enhanced, thus consuming a large amount of organic matter. Due to the redistribution of water in the plant, the new leaves take water from the old leaves, causing the old leaves to fall off. Irrigation can be done in time according to the degree of dryness of the soil and the change of leaves, and watering is thorough.

3.Dull yellow. The normal growth of plants requires more than twice the light intensity of the light compensation point, and the organic matter produced by plant photosynthesis can meet the normal needs in addition to compensating for the respiration consumption.

If the light is insufficient, it will lead to smooth differentiation under the plant cells, the seedlings will have weak stems and branches, and the leaves will yellow. The preventive measure is to increase the light in time, greenhouse plants can be artificially supplemented, and different colors of plastic films can be selected to adjust the light quality, so as to increase yield, improve quality or reduce pests and diseases.

4.Worm yellow. In the process of citrus cultivation, it is often attacked by pests, especially all kinds of pests that eat leaves and stinging mouthparts, harm the leaves or suck the juice of the leaves, causing the leaves to shrink and curl, and make the leaves appear spotted and yellow.

Attention should be paid to observation, early prevention, and timely and appropriate symptomatic spraying for insect pests.

5.Sick yellow. Citrus cultivation often occurs with some diseases, such as:

Therefore, it is necessary to observe the branches, leaves and growth of citrus branches, leaves and growth, and regularly disinfect the soil with pesticides to eliminate pathogenic bacteria in the soil. It is extremely important to control the onset of the disease, and once the disease is found, it is necessary to prevent and treat it in time. <>

Plain yellow. In addition to being indispensable to a large number of elements such as nitrogen, phosphorus, potassium, etc., citrus is also very sensitive to some trace elements, and the lack of it will cause the disorder of seedling physiology, resulting in various symptoms of seedlings, which are also manifested in leaf color, such as iron, zinc, magnesium, sulfur, manganese, etc., which will cause the leaves to lose green and turn yellow. The micronutrient deficiency is mainly the result of long-term non-soil replacement or long-term single application of nitrogen fertilizers.

Therefore, it is necessary to improve the guest soil of the seedbed every other year, and pay attention to the application of organic fertilizer. Fat yellow. Too much fertilizer and too little fertilizer will have a bad effect on citrus, when the fertilizer is too thick and too much, it will cause the plant to be hindered by infiltration and transportation, and the new leaves will be thick, the leaves will be wrinkled but not stretched, and the old leaves will turn yellow and not fall off.

When fertilizer is lacking, it will cause thin branches, long internodes, thin leaves and yellowing. Therefore, proper fertilization can improve the photosynthesis of plants. For example, nitrogen and magnesium promote the growth of branches and leaves, expand the photosynthetic area, increase the chlorophyll content, and increase the photosynthetic rate.

Nitrogen, calcium, and zinc extend leaf life, which in turn prolongs photosynthetic time. Phosphorus, potassium, and boron improve the transport and distribution of photosynthetic products. In addition, reasonable fertilization can improve the soil and create a good living environment for plants.

The main reasons for the yellowing of the leaves of mandarin oranges:

It is the growth and development needs of the root worm that is weak and unable to absorb sufficient nutrients. It is necessary to apply deep and heavy bacterial fertilizer, improve the soil, make the soil layer deep, loose soil, fertile soil, lead deep roots, cultivate developed root groups, enhance the ability to absorb, absorb sufficient comprehensive nutrients ** Aboveground growth and development needs, can make the aboveground branches luxuriant, the leaf color is dark green, and there is no yellowing of leaves.

In addition, it is necessary to strengthen the management of fertilization, timely apply nitrogen, phosphorus and potassium water-soluble fertilizer to the roots, and spray 2 3 times of potassium dihydrogen phosphate on the foliar surface, once every 7 10 days, so as to improve the nutritional level of the plant and promote the growth of the tree.

Hello friends, in general, the humidity is high, pay attention to ventilation, pay attention to dry watering, do not dry and do not water.

Due to the symptoms of citrus brown spot disease, some fruit farmers call it black scar disease, which will cause citrus leaf loss, fruit drop, withered shoots, and reduce the commerciality of fruits with disease spots, and if the prevention and control is not timely, it will cause great losses.

Brown spot disease can be the most serious damage to citrus varieties throughout the growth period, with new shoots and young fruits being the most affected. When the new shoot is sick, many pin-shaped black-brown dots will emerge, slightly concave, and as the disease worsens, the lesion will gradually expand, and eventually the entire shoot will die in black-brown color.

Prevention and control of brown spot disease.

1. Agriculture and physical control: do a good job in the field, cut off diseased branches and leaves, so as to reduce the source of primary infection. Pay attention to strengthening the management of the growing period, such as scientific fertilizationWater-soluble fertilizer for sea meals,Promote the growth of shoots, improve the tree potential and disease resistance and stress resistance; For orchards with severe shade, large branches should be pruned to facilitate ventilation and light; Drain water to reduce humidity, shorten the duration of foliar water film, and reduce the chance of pathogenic bacterial infection.

2. Pharmaceutical prevention and control: seize the spring shoots, young fruit stage and fruit expansion period and other periods of drug protection, spring shoots after a grain of rice and flowers must be prevented. The agent can be used, pay attention to the combination of protection and the best agent.