Why do navel oranges get sunburn? How to prevent it?

It is related to the variety, the growth environment, the resistance to itself, the weather, and the bacterial infection.

I think this is related to weather reasons, soil reasons, fertilization reasons, planting reasons and temperature reasons, so if you want to prevent and control sunburn, then you must choose more fertile and wide land when planting, and you must use farmhouse fertilizer when fertilizing, never use fertilizer bought outside, but also often water the plants, but also to prevent the occurrence of pests and diseases, if there is a situation of small insects, then you must spray insecticides in time.

Because there were no insects, the weather was too hot. Pay attention to sun protection, spray the trees with more water, pay attention to the soil, and improve the environment of the orchard.

Symptoms: First the fruit is cracked near the top, then the peel is longitudinally cracked and opened, and the petals are also correspondingly ruptured, revealing the juice cells, some of which are transversely or irregularly cracked, resembling cracked pomegranates, and finally fall off.

It is best to take the disease-free mother tree and disease-free area, soak it with 1000 times tetracycline hydrochloride for an hour before grafting, and then rinse it with water before grafting. The disease is currently transmitted only by the citrus psyllid, the only insect vector, in close proximity, and by scion and seedlings in long distances. Therefore, the prevention and control work mainly does the following points, strictly inspects the vaccine wood, controls the transportation of diseased seedlings and scions, and burns them immediately as soon as the diseased seedlings are found;

Some of the new shoots are yellowed and "yellow shoots" appear, the yellow shoots initially appear at the top of the canopy, and then gradually expand, after 1 or 2 years of the whole plant onset, the spring shoots symptoms mostly appear after the leaves turn green, first at the base of the leaf veins turn yellow, then part of the mesophyll fades green, the leaf veins gradually yellow, the leaves are now irregular yellow-green patches, shortening the tip pulling period. When the new shoots are pumped to 1 2 cm, spray the insecticide 1 2 times. In winter, citrus psyllids prefer to fly to the left of the orchard to overwinter on the bougainvillea.

Spraying insecticides on bougainvillea has a certain effect on reducing the number of psyllids.

In addition, strict quarantine should be implemented for citrus seedlings and scion transferred to the new area. Second, establish a relatively isolated disease-free seedling breeding base. The base must be located in a non-diseased area, and it is required to be free of poison-transmitting insects - psyllids; The rootstock seeds should be harvested from disease-free trees and soaked in 50 52 hot water for 5 minutes, and the leaves of young trees and diseased trees in summer and autumn should be uniformly light yellow-green.

Mottled yellowing leaves. Yellowing begins near the veins, base or edge of the leaf, and then spreads to form uneven patches of yellow and green. Element-deficient yellowing leaves.

It is called mosaic leaves. > it is only the leaves that change at first, but in severe cases, the roots of the fruit tree will begin to rot, and the degree of decay will spread with the disease. Huanglongbing disease starts from the top leaves and then spreads downward, so it can be treated and prevented by daily observation of fruit trees.

First of all, pesticides must be sprayed, and photosynthesis must be carried out more, and more ventilation must be done, and stagnant water must be cleaned up in time.

Usually we must ventilate more, and we must spray more pesticides, and we must choose high-quality varieties, and we must clean up the stagnant water in time.

If you want to prevent and control the physiological diseases of navel oranges, you should apply pesticides regularly and quantitatively to control pests and diseases.

At present, it is the peak period of the occurrence of scale insects, black-thorned whiteflies and leaf rollers, and the prevention and control should be strengthened. Due to the lower temperature than usual, the occurrence of red and yellow spiders is heavier than in previous years, so it is necessary to strengthen the control of red and yellow spiders.

The following high-efficiency, low-toxicity, and residue-free pesticides are recommended:

For the prevention and control of blackthorn whitefly, scale insects and leaf rollers, 48% Lesben emulsifiable concentrate is diluted 800 1000 times; Spray again every 20 days.

For the prevention and control of anthracnose and soot disease, 80% Dasheng m-45 wettable powder is diluted 600 800 times and sprayed, and sprayed again every 15 days; Dasheng M-45 has a special effect on soot disease, and it can effectively remove soot disease by spraying it 3 times in a row.

Red and yellow spiders can be sprayed with mites, i.e. dead emulsifiable concentrate, 1500 times. First of all, we should start from cultivating healthy trees, and appropriately increase nitrogen fertilizer to improve the nutritional level of trees. Secondly, before flowering, the strong and prosperous autumn shoots are pulled into a drooping or horizontal state, so that most of the flowers are facing down when they open, reducing the sun-facing fruit and preventing the production of navel yellow; Again in the early to mid-June to mid-to-late July combined with the fruit, spray 30 40 milligrams of "92O" solution, spray twice, late July to late August with 600 times of "flantin" solution to spray the fruit umbilicus, in order to inhibit the occurrence and spread of umbilical yellow disease.

Good evening! Navel orange fruit cracking, sunburn and navel yellow are the three major physiological diseases.

Fruit cracking: It is necessary to strengthen scientific management, enhance tree potential, especially in the dry period after the plum rain to before the autumn rain, we should do a good job in water management, so as to irrigate or water in time, keep the soil moist frequently, and promote the normal growth and development of fruits.

During the rapid fruit expansion period, foliar potassium fertilizer was sprayed 2 or 3 times. Foliar potash fertilizer can be used as potassium dihydrogen phosphate or potassium sulfate compound fertilizer.

Sunburn: Do not spray pesticides such as engine oil emulsion and stone sulfur mixture in the high temperature season, so as not to aggravate the occurrence of sunburn.

In the early stage of sunburn disease, paste white paper on the surface of the sunburn fruit, and pull the branches and leaves to cover the fruit to reduce direct sunlight.

For the teacher's reference only.

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