During the Spring Festival, many people must have orange trees in their homes, but there will inevitably be some problems in the breeding process. If the leaves are yellow, there are several reasons. Let's take a look at them!
An analysis of the causes of yellow leaves of "Nianju" orange trees: first, the lack of disease elements causes yellow leaves of orange trees;
1. Symptoms of nitrogen deficiency in Orange: leaves turn yellow, leaves turn light green evenly, with nitrogen transferred from leaves to maintain new growth.
Control measures: 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 in oranges: generally, the young shoots show symptoms first, the leaves become thin and yellow, light green to yellow white, the veins are green, the yellow leaves show obvious green reticulation, and the leaves at the top of twigs are more obvious. 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 iron deficiency of orange is mainly caused by the lack of iron supply. It is reported that iron deficiency may also occur due to insufficient nitrogen fertilizer. 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.
Orange tree leaves yellow
3. Symptoms of zinc deficiency of Orange: yellow or yellow green leaves of new shoots, and green main and lateral veins and their adjacent tissues. 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.
4. Symptoms of Citrus boron deficiency disease: the leaves and old leaves begin to turn yellow from vein to the whole leaf, with thick mesophyll and multi-directional back curl of leaf tip; the veins are swollen, the main and side veins are corked, and cracked seriously. 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 orange manganese deficiency disease: the leaf size of young branch is normal, yellow green, main and lateral veins and their adjacent tissues are green, the rest is yellow green, 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、 Diseases and insect pests cause orange leaves to turn yellow;
In April June and September November, the occurrence peak of red spider is mainly harmful to citrus leaves, branches and fruits. When the damaged leaves and fruits are serious, they turn gray white and lose luster until they are yellow and fall off.
terms of settlement:
1, 75% grams of mite 3000 times liquid, or 15% scavenging net 1000 times liquid spray (for the treatment of rust ticks); 2, recommended 5000 times of 24% mite suspensions produced by Bayer in Germany, the effect is outstanding.
Orange tree leaves yellow orange tree maintenance experience: fertilization precautions:
1. Heavy application of winter fertilizer
Before and after fruit picking, combined with deep ploughing to change soil and heavy application of organic fertilizer, it has a significant effect on restoring tree vigor and promoting flower bud differentiation. The specific method is: in the first ten days of November to December, the deep ditch can be opened outside the tree crown, and the base fertilizer (peanut bran, bone meal, soil and miscellaneous fertilizer, pig and cattle manure, compost, manure, phosphate rock powder, superphosphate, etc.) can be applied again. Heavy application of winter fertilizer is the basis of high yield in the next year. However, it should be noted that the winter fertilizer must be applied early and more frequently (accounting for 50% of the annual fertilization), and mainly organic fertilizer.
2. Early application of spring fertilizer
The application of available nitrogen and phosphorus fertilizer before the sprouting of orange tree (from late February to early March) can strengthen the shoots and improve the quality of flower branches (increase the number and area of leaves of flower branches), which can promote the normal germination of new shoots and supply nutrients for fruit development.
3. Applying fruit fertilizer skillfully
The application of quick acting nitrogen fertilizer in the middle and last ten days of may can compensate the nutrients consumed in flowering and make the young fruit get enough nutrition, reduce the falling fruit and improve the fruit setting rate. From July to September, the fruit grows rapidly, and a large number of autumn shoots are drawn out. As the fruiting mother branch of the next year, the conflict between nutrition growth and fruit development often arises between competing for nutrients and water. At this time, the application of quick acting nitrogen fertilizer combined with phosphorus and potassium fertilizer can accelerate the growth of fruit, improve the quality of fruit and promote the occurrence of autumn shoots. However, it must be noted that the type, concentration and method of fertilization should be determined according to the growth of trees, soil and weather conditions. In the dry season, we should first water the soil to keep it moist, then apply fertilizer, which is conducive to root absorption and achieve the effect of "water promoting fertilizer". Applying fertilizer and water simultaneously is a method of skillfully applying fertilizer, which can make the same fertilizer play a greater role. For vigorous fruit trees, it is not suitable to apply too much nitrogen fertilizer, otherwise, excessive spring and summer shoot pumping will also cause fruit falling.
4. Fertilization outside the root
The application of fertilizer outside the root is a kind of top dressing method which uses the stoma and cuticle of leaves to infiltrate nutrients directly. It has the advantages of quick effect and high absorption and utilization rate. In the bud stage, flowering stage and young fruit stage, applying water-soluble quick acting fertilizer outside the root can improve the fruit setting rate and facilitate the fruit expansion and development.