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Orange leaf yellowing: cause analysis and treatment of orange leaf yellowing

Citrus can not only be used as cash crops, but also as potted plants to beautify the home environment and improve the air quality. Its flowers, leaves and fruits are very ornamental. At present, few people use orange as a pot culture, so there are frequent problems in the culture, such as the reason for the yellow leaves. In fact, the yellow leaves of orange may be caused by many reasons. Flower friends need to find the cause of the disease and criminal evidence to prescribe medicine.

The reason analysis and treatment method of orange leaves yellowing 1. There are many reasons for orange yellowing, which may be caused by the lack of some nutrients

1. Symptoms of nitrogen deficiency: leaves turn yellow, leaves turn light green evenly, with nitrogen transferred from leaves to maintain new growth.

Control methods: strengthen management, increase farmyard manure, combine with root topdressing, spray 0.2% urea and 0.3% potassium dihydrogen phosphate or nutrient liquid every 10 days, and add 0.2% borax spray to mountain orchards.

2. Symptoms of iron deficiency disease: generally, the young shoots show symptoms first, the leaves become thin and yellow, light green to yellow white, and the veins are green. The yellow leaves show obvious green reticulation, especially the leaves at the top of twigs. The branches of the diseased plant are delicate, and the leaves on the young branches are easy to fall off, and only sparse leaves are often left. After the leaves of the twigs fall off, the normal branches and leaves grow on the larger branches at the lower part, but the top branches die one after another. When the disease was serious, the leaves of the whole plant became orange yellow.

The main cause of Citrus iron deficiency is the lack of iron supply. It is reported that the lack of nitrogen fertilizer may also lead to iron deficiency. Iron deficiency often occurs together with zinc, manganese and magnesium deficiency.

Control methods:

(1) Change soil and apply fertilizer. The basic way to prevent iron deficiency is to improve the soil, improve the drainage and irrigation system, and prevent the occurrence of drought and flood. More organic fertilizer should be applied to alkaline soil, especially green fertilizer, miscellaneous fertilizer and other acid fertilizer.

(2) Apply ferric sulfate. On the basis of improving the soil and improving the drainage and irrigation system, apply ferric sulfate or spray 0.1% ferric sulfate solution; cut off part of the root to make it inhale ferric sulfate. However, the effect of using ferric sulfate without soil modification is not obvious.

(3) Apply 15-20 kg of sulfur yellow powder per mu, and apply ammonium sulfate, potassium sulfate, etc. to acidify the soil.

3. Symptoms of zinc deficiency: the leaves of new shoots turn yellow or yellow green, and the main and lateral veins and their adjacent tissues are still green. The main lateral vein of the old leaf has irregular green belt, and the rest is light green to orange yellow. Some leaves only show yellow and light yellow spots between the green main lateral veins, while others become smaller, narrower and greenless. When the zinc deficiency was serious, the top branches were short and the leaves were erect, the whole plant was erect and clumped, and then the twigs died.

Control method: spraying 0.4% - 0.5% zinc sulfate solution (adding 1% - 2% lime and 0.1% adhesive) before spring shoot growth can effectively treat zinc deficiency. In addition, 0.1% - 0.2% zinc oxide can also be sprayed for correction. For (ph5.5-6) slightly acidic soil, a small amount of zinc sulfate can also obtain good effect, but it is not effective for alkaline soil. If zinc deficiency is induced by lack of magnesium and copper, the effect of zinc salt application alone is not good, and the compound containing magnesium, copper and zinc must be applied at the same time to obtain good effect. Secondly, it is very important to increase the application of organic fertilizer.

Orange leaves turn yellow

4. Symptoms of boron deficiency disease: the leaves and old leaves turn yellow from vein to the whole leaf, with thick mesophyll and multiple backward curls of the tip; the veins are swollen, the main and side veins are corked and cracked in severe cases. The young leaves produce irregular water stained macula, which is distorted and deformed; some of them have water stained black spots at the base of the main vein on the back of the leaves, which are easy to fall off. On the skin of young fruit, there are milky white micro protuberances and small spots, in serious cases, there are sunken black spots, and the mesocarp and the core are filled with colloid, which often causes a large number of young fruit to fall off. The remaining fruit is small and hard, with a lump on the surface of the pericarp, thick pericarp, less seed abortion of juice, and medium pericarp and core filled with glue. When the orange garden is seriously lack of boron, a large number of leaves fall early, branches die, sometimes the whole plant is dry.

Control methods:

(1) Apply boron fertilizer. The boron fertilizer is mixed into human feces and urine, dug under the canopy and applied, covered with some organic fertilizer and then covered with soil. The amount of boron fertilizer applied to adult trees was 0.1-0.15 kg per time. Generally, it is applied once every 2-3 years.

(2) The roots were sprayed with boron. Generally, boron fertilizer (boric acid or borax liquid) is sprayed once in early spring and flowering period, which can effectively prevent and control boron deficiency. 0.5% - 0.8% in early spring and 0.3% - 0.4% later, but 0.2% - 0.3% in summer and autumn. In order to prevent drug damage, 0.5% quicklime can be added. The spray dosage should be used in cloudy days or in sunny days when the temperature is low and the humidity is high.

(3) Avoid excessive application of NPCA. Especially for the soil with low organic matter content, we should pay more attention not to apply too much nitrogen, phosphorus and calcium fertilizer, but to apply compost manure, or farmyard manure and green manure with high boron content. In acid soil, too much lime should not be used.

(4) In dry season, water should be kept and watered in time; in rainy season, waterlogging should be drained to prevent the loss of effective boron.

5. Damage of manganese deficiency disease: the leaves of young shoots are normal in size, yellow green, the main and lateral veins and their adjacent tissues are green, and the rest are yellow green, which is similar to the symptoms of zinc deficiency disease. However, the yellow part of zinc deficiency is very yellow, the green part of manganese deficiency is green, the tender leaves are small and narrow, the size and shape of manganese deficiency leaves are basically normal, and the old leaves also show symptoms. When it is serious, the leaves are aged and shed at the early stage, and the growth of new shoots is severely inhibited, some of them die. If manganese and zinc were deficient, the twigs would wither more.

Control methods:

(1) Manganese sulphate was applied. Acid soil can be applied with manganese sulfate mixed with other fertilizers. Lemon is easy to cause harm to manganese sulfate. The spraying times should be less and the concentration should be small. Attention should be paid. The alkaline soil can be sprayed with a mixture of manganese sulfate and quicklime (0.2% - 0.6% manganese sulfate and 1% - 2% quicklime), neutralized to (ph6-6.5), and the control effect is good.

(2) From May to August, spray with 0.6% manganese sulfate and 0.3 Baume's stone sulfur mixture, or spray with 0.3% manganese sulfate and equal amount of lime, or spray with 0.4% manganese sulfate and rosin mixture.

(3) More organic fertilizers such as composting manure or retting green manure should be applied.

2、 Another possibility is that the leaves turn yellow due to insect damage:

Yellow leaves caused by diseases and insect pests: the yellow and scorching parts of leaves are caused by citrus anthracnose, whether it is anthracnose or other diseases.

Control method: spray the leaves 500 times with 50% carbendazim (broad-spectrum bactericide) every 10 days, but it's too luxurious for a single bonsai.

Orange leaves turn yellow due to diseases. 1. Selection of flowerpot: the flowerpot of potted citrus should not only meet the growth of fruit trees, but also be beautiful and firm. Because of the large crown and many results, large flowerpots should be selected, and drainage holes should be provided, so as to timely discharge excess water and prevent ponding and rotten roots. Citrus is not very strict to soil, but potting should be reasonable allocation of potting soil.

2. Soil matching: 1 for garden soil, 1 for decomposed organic fertilizer, 0.5-0.8 for river sand, 0.5-0.2 for grass and wood ash. After mixing the basin soil, mix it well and finely, put it in a transparent plastic bag and expose it in the sun for a week for sterilization, and turn it frequently.

3. Citrus planting: after the soil in the flowerpot is ready, it can be planted. Place 1-2 thick broken slag, crushed stone or sand at the bottom of the flowerpot to drain water and ventilate the root. Before planting, the rotten organic matter basal fertilizer was applied in the basin. When transplanting, the root system of the seedlings did not contact the basal fertilizer, so as to avoid the death of the seedlings. Add a small amount of basin soil, put the seedlings in the center of the basin, so that the root system stretches around, and try not to bend the root. When transplanting, the plants should be drenched with water first, and a certain amount of root fixing soil should be reserved at the beginning of seedling, and the roots should be reduced, but a certain amount of lateral roots should be reserved, which is beneficial to absorption. Slowly add the basin soil, continuously lift the root, cover the soil to the root neck, and gently compact with hands to make the soil closely connected with the root, make the basin soil surface flat and water permeable. After 2-3 days of planting, the soil should be supported by poles to prevent the wind blown seedlings from hindering the growth of new roots and keep the soil moist.

4. Key points of watering: Citrus likes to be wet. To keep the basin soil wet, whether to water or not, the surface soil in the basin should be watered when it turns white. Tap the side of the basin, the sound is clear and crisp, indicating that the soil is dry and needs watering. The water should be well watered. It is advisable to let water seep out of the drain hole at the bottom of the basin. The soil is too wet, which is easy to cause rotten roots and needs to be drained.

5. How to apply fertilizer: because of the limitation of pot soil, the nutrition supply of potted orange is very limited, so we should apply more thin fertilizer at ordinary times. The plants were treated with liquid fertilizer once before germination, and then with liquid fertilizer mainly composed of nitrogen fertilizer once every 7-10 days to promote long branches, leaves and spring shoots. After each heartlifting, fertilizer should be applied in time to make the branches mature early. During the growth of oranges, you can sprinkle some cake fertilizer on the basin surface to make some fertilizer infiltrate into the soil every time you water it, so as to enhance the fertility. After autumn, fertilization was reduced to avoid over nutrition of plants, promote autumn shoots and compete with fruits for nutrients, resulting in fruit falling.

6. Pruning and basin changing: for potted citrus, due to the small soil and limited nutrition, necessary pruning work should be done. Through shaping and pruning, the reasonable distribution of nutrition in the tree body should be adjusted, so that the limited nutrients can be supplied to buds and leaves in a centralized way, and more fruiting branches can be formed, so as to reach the goal of full branches of flowers and fruits. About 2 years, it is necessary to change basin and soil, and at the same time, the root system should be dredged, pruned and rejuvenated.

Citrus fruits