A: The yellowish walnut tree, also known as yellowing disease, white leaf disease, is a common disease in alkaline soils, mainly due to the alkaline soil of walnut seedlings or excessive calcium carbonate, which makes the ferritin in the soil soluble. Into the insoluble form, fruit tree absorption of ferritin is insufficient, the physiological state of the body is out of balance, chlorophyll synthesis is blocked, showing yellowing disease. In the onset of the spring growth period, 0.3% ferrous sulfate + 0.3% - 0.5% urea mixed liquor should be sprayed 2 or 3 times, or 0.5% iron fulvic acid solution 2 or 3 times, and ferrous sulfate added in the organic fertilizer. Crush coarse fat, mix well and apply under the tree tray. Generally 10 years old, the result tree can be applied to 250 g or so.
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What are the causes of the yellow and fallen leaves of the walnut trees?
The valve stem is an important part of the valve.
It is used to drive, connect the actuating mechanism or handle, and directly
drive the spool to move or rotate, so as to realize the function of valve switch
or regulation.Valve stem in the valve opening and closing process is not only
moving parts, stress components, but also seals. At the same time, it is
subjected to the impact and corrosion of the medium, and it also causes friction
with the packing. Therefore, in selecting the stem material, it must be
guaranteed that it has sufficient strength at the prescribed temperature, good
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vulnerable part, and the mechanical performance and heat treatment performance
of the material should be paid attention to when selecting.The valve stem in the
valve opening and closing process, under tension, compression and torsion force,
and direct contact with the media, as well as the relative motion between the
friction and filler, so in the choice of stem material, must ensure that it
provides adequate temperature strength, good impact toughness, abrasion
resistance and corrosion resistance of.