1. Citrus lack of manganese symptoms
The young leaves showed obvious symptoms, the diseased leaves turned yellow-green, and the main and lateral veins and nearby leaves were green to dark green.
Mild Mn-deficient leaves can return to normal after they grow. Severe or continued Mn deficiency gradually enlarges the part of yellowing between lateral veins. Finally, only the main vein and some lateral veins remain green and the diseased leaves become thin.
The size of diseased leaves lacking manganese, the shape is basically normal, and some parts of yellowing are greener. Manganese deficiency is different from zinc deficiency and iron deficiency. Zinc deficiency has small, sharp leaves and yellowish yellow color; iron deficiency yellows yellowish white.
2. Causes of manganese deficiency in citrus
Manganese in alkaline soils tends to be insoluble, with less substitution and available manganese, and prone to deficiency of manganese. The effectiveness of iron and zinc in alkaline soils is also low, so it is often accompanied by iron deficiency and zinc deficiency.
In acidic soils with large organic matter, although the substitutional or effective manganese content is high, manganese is easily lost and manganese deficiency is prone to occur. In the strongly acidic sandy soil, zinc, copper, and magnesium are also easily lost, and zinc deficiency, copper deficiency, and magnesium deficiency disorders often occur.
Excessive application of nitrogen fertilizer or excessive copper, zinc, and boron in the soil affects the absorption and utilization of manganese and induces manganese deficiency.
Manganese in cold and wet soils tends to be inactive, but at higher temperatures and in more droughty soils, manganese tends to become effective, resulting in increased manganese reduction and excess manganese formation.
3. Methods for correcting manganese deficiency and manganese deficiency
Foliar spraying May-June leaf spray 1-2 times 0.05%-0.1% of chelated manganese or manganese sulfate, need to be sprayed every year.
Application of manganese fertilizer to soils such as purple soils is not effective, and organic fertilizers may be added or sulphur powder may be added to increase the dissolution of manganese in the soil and increase the absorption of manganese by citrus and cure manganese deficiency.
4. Citrus manganese excess disease
Symptoms: On the leaf surface of mature leaves, red-brown sag spots occur, starting from the tips of the leaves and margins, and spreading to the entire leaf as the symptoms develop. It usually takes place in the fall and there is a lot of fallen leaves in the late winter. It is prone to "purple blood disease", that is, the green spot of the fruit coloring period turns to purple brown by the mature period.
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