Recently, users from Shijiazhuang City asked in the "Q&A" column: What is the situation, citrus yellowing is serious?
As shown in the following figure
Diagnosed by a specialist
Xia Yingsan (Qingyun Town, Linshu County, Shandong Province, Agricultural Technology Station)
Poor soil environment, caused by lack of nutrients, pay attention to balanced fertilization, foliar spraying of green protection and medium and trace element foliar fertilizer.
Changsheng (Shaoguan City, Guangdong Province, specializing in the prevention and control of diseases and insects in southern fruit and vegetable cultivation)
Magnesium deficiency, increase the application of organic fertilizer plus magnesium sulfate, leaf spray suspension of magnesium.
Wang Gang (Weifang City, Shandong, Shouguang Tailai Plant Protection, good at plant protection technology)
Magnesium deficiency disease foliar spray boiling magnesium fertilizer to alleviate.
Liu Fenghua (Heze City, Shandong Province, member of China Cotton Association, good at plant protection technology)
Magnesium deficiency fertilizer, spray magnesium sulfate supplementation.
After the experts look at the picture to identify the disease, the preliminary confirmation is that the citrus magnesium deficiency, if there is any doubt, please continue to read down.
Knowledge Classroom:
1. Harmful symptoms
1. When citrus is deficient in magnesium, the leaves and old leaves near the fruit first show symptoms.
2. In the early stage of magnesium deficiency, the leaves first produce irregular yellow patches along both sides of the leaf veins, which gradually expand to the sides, so that the leaf veins are ribbed yellowing. The posterior macula is united with each other, the leaves are mostly yellow, and only the leaf tissue of the midrib and its base maintains an inverted "V" shaped green area.
3. When there is a serious lack of magnesium, the whole leaves turn yellow, easy to fall off when encountering bad conditions, and the deciduous branches often die in the spring of the following year.
4. Symptoms can occur throughout the year, but the most occurs in late summer or autumn when the fruit is near ripe.
Second, the cause of the disease
1. Magnesium in acidic soils and light sand soils is easily lost, especially in hillside land, and the exchange magnesium content in the soil is reduced.
2. Excessive application of potassium fertilizer and phosphate fertilizer affects the absorption of magnesium by citrus trees, which is easy to cause magnesium deficiency.
3. Excessive use of sulfur and stone sulfur compound agents in orchards can easily make the soil appear acidic, resulting in magnesium deficiency.
3. Prevention and control measures
1. From the young fruit stage to the expansion stage of the fruit, spray 0.1% magnesium nitrate or 0.2% magnesium sulfate solution, once every 7-10 days, 3-5 times continuously.
2. When the acid soil is deficient in magnesium, calcium, magnesium and phosphorus fertilizer are selected as phosphate fertilizer and applied together with organic fertilizer.
3. Potassium and magnesium sulfate are selected as fertilizer sources for potassium fertilizer. Fourth, each mu of magnesium oxide 10-20Kg or magnesium-containing lime 50-60Kg.
After discernment and recognition of illness, do you have a good idea in mind?