Apple deficiency
Symptoms In the spring and summer, when fruit trees grow vigorously, nitrogen deficiency occurs. Mature leaves at the base of new shoots gradually turn yellow and develop towards the top, so that new shoots also turn yellow.
The young leaves are small, the leaves are upright, the leaves are grayish green, purplish, the veins and petioles are red, the cortex is reddish-brown, petiole clings to the branches, and is easy to fall off.
The branch shoots were thin and weak and reddish-brown. The bark is yellow, the result is small but early, early fall, and flower buds are significantly reduced.
Diagnostic points:
Careful observation, if gradually yellow from the lower leaves, may be nitrogen deficiency.
Yellowish outward curling of leaves is the lack of other nutrients.
Although the leaves are yellow, but they are wilting during the day, it can be considered for other reasons (such as drought, root disease, etc.).
Diagnostic index: Nitrogen content in leaves less than 1.5% is nitrogen deficiency; normal values ​​are 2.2% to 2.6%.
Easy to happen conditions:
The soil is thin and there is no normal fertilization.
Extensive management, overgrown with weeds.
The saplings on sandy soil encountered heavy rain during the growing season.
Correction method:
In the middle or late September, organic fertilizer is applied in the ring or in the ditch. There are 3,000 to 5,000 kilograms per year per mus of Lin Youling orchard, and more than 5000 kilograms of mature orchards. In combination with autumn basal fertilizer, inorganic nitrogen fertilizer (urea, ammonium sulfate, ammonium nitrate) is mixed in the base fertilizer. Etc) or topdressing. The amount of pure nitrogen used was as follows: Unsuccessful trees were planted with strains of 0.25-0.45 kg; the initial fruit trees were 0.45-1.4 kg; fruit trees were 1.4-1.9 kg or more.
During the growth period of fruit trees, topdressing and flower buds are topdressed with nitrogenous fertilizers before they are differentiated. The young trees have 5-8 kg of pure nitrogen and 10 to 12 kg of mature trees. During the growth period, 0.5% urea can be sprayed on the leaves for 2 to 3 times ( Single spray can also be mixed with pesticides).
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