(1) Symptoms At the beginning, the whole plant leaves are dark green, which is often mistaken for excessive nitrogen application; if the temperature is low at this time, the veins of the petiole or leaf back are reddish-brown or purple, and then the front of the leaves is reddish brown.
(2) Diagnostic indicators When the phosphorus content in the middle part of the new shoots is less than 0.1% in July-August, it is deficient in phosphorus.
(3) Conditions of occurrence
a. The soil itself contains 0.1% of total phosphorus and the average available phosphorus is below 10 mg.
b. The alkaline soil contains more calcareous matter, and the phosphorus is fixed and cannot be absorbed by the fruit trees.
c. Partial application of nitrogen fertilizer, too little phosphorus.
(4) Correction method
a. Based on organic fertilizer, inorganic phosphate fertilizer or phosphorus-containing compound fertilizer.
b. Foliar surface spraying 0. 2% - 0.3% potassium dihydrogen phosphate aqueous solution; can also spray 1% ~ 3% calcium superphosphate water solution clear solution or 0.6% ~ 1.0% ammonium phosphate aqueous solution.
Huaxian Agricultural Technology Promotion Center Lu Shuguang
(2) Diagnostic indicators When the phosphorus content in the middle part of the new shoots is less than 0.1% in July-August, it is deficient in phosphorus.
(3) Conditions of occurrence
a. The soil itself contains 0.1% of total phosphorus and the average available phosphorus is below 10 mg.
b. The alkaline soil contains more calcareous matter, and the phosphorus is fixed and cannot be absorbed by the fruit trees.
c. Partial application of nitrogen fertilizer, too little phosphorus.
(4) Correction method
a. Based on organic fertilizer, inorganic phosphate fertilizer or phosphorus-containing compound fertilizer.
b. Foliar surface spraying 0. 2% - 0.3% potassium dihydrogen phosphate aqueous solution; can also spray 1% ~ 3% calcium superphosphate water solution clear solution or 0.6% ~ 1.0% ammonium phosphate aqueous solution.
Huaxian Agricultural Technology Promotion Center Lu Shuguang
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