What techniques are there for spraying foliar fertilizer on fruit trees?
Are there techniques for spraying foliar fertilizer on fruit trees? What should be noted when spraying foliar fertilizer on fruit trees? Is there anyone online who can help explain? Foliar spraying of fertilizer on fruit trees is the main form of root-outside topdressing, and it has advantages such as a small amount of fertilizer used, fast absorption, remarkable fertilizer effect, strong targeting, not being fixed by the soil, and not being restricted by the strength of root absorption function...
Foliar spraying of fertilizer on fruit trees is the main form of root-outside topdressing, and it has advantages such as a small amount of fertilizer used, fast absorption, remarkable fertilizer effect, strong targeting, not being fixed by the soil, and not being restricted by the strength of root absorption function. Zhongdiwang has compiled some techniques and precautions for spraying foliar fertilizer on fruit trees, listed below for netizens' reference.
Technique 1: Spray according to symptoms:
The principle of supplementing whatever is lacking should be followed. If young leaves, especially the young leaves at the top, die from the leaf tip and edges or along the midvein, it indicates calcium deficiency; if the leaf veins are green and the mesophyll is pale yellow or white, with symptoms developing gradually from young leaves to old leaves, it indicates iron deficiency; if the leaves show slight chlorosis and have wrinkles, sometimes abnormally thick and plump, and in severe cases the young branches die from the top downward, it indicates boron deficiency; if the plant's branches have excessively long internodes and the leaves are large, plump, and tender green, it indicates sufficient nitrogen fertilizer, and phosphorus and potassium fertilizers should be sprayed mainly, with an appropriate amount of trace element fertilizer also sprayed.
Technique 2: Choose the correct foliar fertilizer:
Ammonium bicarbonate among nitrogen fertilizers and phosphate rock powder among phosphorus fertilizers are ineffective or harmful when sprayed on leaves, and are strictly prohibited for spraying. Suitable for foliar spraying are urea, superphosphate, potassium sulfate, potassium dihydrogen phosphate, as well as boric acid (borax), zinc sulfate, manganese sulfate, ferric sulfate, ferric citrate, agricultural aspirin, calcium oxide, magnesium sulfate, limewater, etc.
If conditions permit, amino acid-based and humic acid-based biological micro-fertilizers can also be selected as much as possible, such as amino acid chelated calcium, black humic acid, brown humic acid, etc. They have effects such as improving fruit quality, highly efficient drought and cold resistance, and disease prevention and resistance.
Technique 3: Choose a suitable spraying time:
Root-outside topdressing mainly absorbs nutrients through plant stomata and the cuticle, and can be carried out throughout the entire growing season. Young leaves have vigorous physiological functions, a relatively large proportion of stomata, the strongest absorption capacity, and the most obvious effect. Fruit trees have different fertilizer requirement periods for different fertilizers, which should be flexibly grasped. For example, calcium fertilizer should be sprayed 40 days after flowering and 40 days before fruit harvest; iron fertilizer is suitable for spraying before bud break and during the vigorous growth period of autumn shoots; boron fertilizer should be sprayed at full bloom (50% of flowers open). Root-outside topdressing should be carried out on cloudy days without strong wind. If it is a sunny day, it should be sprayed before 9 a.m. and after 4 p.m.
Technique 4: Control the preparation concentration well:
Urea is 0.2%-0.5%, potassium dihydrogen phosphate is 0.3%-0.5%, superphosphate is 0.5%-1%, magnesium sulfate is 0.2%, potassium sulfate is 0.05%-0.1%, ferrous sulfate is 0.2%-0.5%, zinc sulfate is 0.5%-1%, boric acid is 0.1%-0.2%, ammonium molybdate or sodium molybdate is 0.01%, copper sulfate is 0.01%-0.02%, manganese sulfate is 0.05%-0.1%.
The concentration of foliar fertilizer spraying should generally be controlled below 0.5% to prevent fertilizer damage.
Technique 5: Choose the spraying parts of fruit trees well:
When spraying fertilizer, it should be sprayed onto the back of the leaves as much as possible, because the front side of the leaf has a cuticle layer, and water is not easy to enter, while the back of the leaf has no cuticle layer and has many stomata, so fertilizer is easily absorbed. In addition, foliar fertilizer spraying should not only spray the outer part of the tree canopy, but also the branches and leaves inside the canopy; not only the upper leaves, but also the middle and lower leaves.
Technique 6: Do not mix at will:
In order to improve work efficiency, foliar fertilizer spraying should use mixed solutions. Mixed solutions can be divided into: foliar fertilizer + insecticide, foliar fertilizer + plant growth regulator; foliar fertilizer + insecticide + fungicide; foliar fertilizer + insecticide + fungicide + plant growth regulator.
However, attention should be paid to the respective properties of these fertilizers and pesticides, and whether they can be mixed for use, otherwise it will reduce fertilizer and pesticide efficacy, and may even cause fertilizer damage and pesticide damage.
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