Extra-root topdressing technique of Fruit trees

Extra-root topdressing technique of Fruit trees

Extra-root topdressing of fruit trees is the assistant and supplement of soil fertilization, which can supply the nutrient elements and plant growth regulators that fruit trees lack in time, and can quickly promote or regulate the growth and development of fruit trees. It is a commonly used fertilization method in fruit tree production. It has the advantages of avoiding the adverse effects of soil on the substances applied, acting quickly, making up for root function, strong pertinence, and can be mixed with pesticides. The technique of topdressing outside the root of fruit trees is introduced below.

I. selection of foliar fertilizer

At present, the commonly used foliar fertilizers in fruit production are: nutritional foliar fertilizer, regulated foliar fertilizer, biological foliar fertilizer, amino acid foliar fertilizer, humic acid foliar fertilizer, compound foliar fertilizer and so on.

According to the growth and development of fruit trees, phenological period, natural environmental factors and types of deficiency diseases, suitable foliar fertilizer should be selected: when fruit trees grow too fast or weak, in addition to nutritional foliar fertilizer, it is also necessary to choose regulated foliar fertilizer to control or promote the growth of fruit trees; for fruit tree deficiency disease, choose nutritional or compound or amino acid foliar fertilizers containing missing elements. Foliar fertilizer sprayed mainly to promote growth in the early growth stage of fruit trees, foliar fertilizer which can increase fruit setting rate should be sprayed before and after flowering, and foliar fertilizer should be sprayed in the later growth stage to promote flower bud formation, improve fruit quality and increase tree nutrition reserve. To prevent the harm of disastrous weather (cold current, frost, waterlogging, etc.) to fruit trees, or to promote the growth and development of fruit trees after disasters and diseases and insect pests, you can choose to spray nutritious foliar fertilizer, combined with spraying regulated foliar fertilizer or compound foliar fertilizer to restore growth and improve resistance. Regulated or compound foliar fertilizers are often selected to spray love more, brassinolide, amino acids and humic acid foliar fertilizers and so on.

(2) concentration (amount) of foliar fertilizer application

Foliar topdressing must pay attention to spraying concentration, the concentration is too small to meet the requirements of fertilization, too high concentration is easy to harm or promote excessive control; the critical range of fruit trees from lack of fertilizer to excessive is very narrow, especially when spraying foliar fertilizer of growth regulators, it is more necessary to strictly control the concentration of spraying. The spraying concentration should be determined according to tree species (even varieties), tree age, tree potential, type of fertilizer deficiency, degree of fertilizer deficiency and so on. For example, if the plant growth inhibitor paclobutrazol is sprayed on prosperous fruit trees, when the concentration is too high, the tree will be dwarfed, the fruit will become smaller and the quality will decline.

III. Fertilization period

1. According to the characteristics of fertilizer requirement in each phenological phase, extra-root topdressing was carried out in the phenological phase of fruit trees. If the tree needs more boron fertilizer during the flowering period, the foliar fertilizer containing boron (such as borax, boric acid) or dipped in foliar fertilizer containing plant growth regulators (such as gibberellin, anti-falling hormone, etc.) can significantly increase the fruit setting rate.

two。 After the branches, leaves, flowers, fruits or roots of fruit trees are injured by disastrous weather or diseases and insect pests, foliar fertilizer can be applied outside the roots in time to help the affected fruit trees restore their growth and development.

3. When the occurrence of element deficiency disease, according to observation and diagnosis, to determine the types of nutrient elements that fruit trees lack (to determine the type of element deficiency disease), to achieve what is missing and what to make up, can be prevented before the onset of the disease or timely application of the missing elements in the early stage of the disease to achieve the purpose of prevention and treatment. If it is determined to be fruit tree yellow leaf disease (iron deficiency), foliar fertilizers such as ferrous sulfate and amino acid iron can be sprayed.

4. Prediction of missing element types ① predicts missing element types based on production experience. According to the types of nutrient deficiency diseases that often occurred in the park in the past, the missing elements and prevention period were determined, and the fertilizer spraying plan was made. Based on scientific theory, ② predicts the types of elements that are missing. Generally speaking, deficiency diseases rarely occur when fruit trees are planted in neutral soil, and they often occur when planted in acidic or alkaline soil, especially in alkaline soil with pH greater than 8. For example, yellow leaf disease, lobular disease and bitter pox disease caused by iron deficiency, zinc and calcium deficiency can be used as a basis to formulate preventive measures. If bitter acne disease is predicted, it can be in the young fruit stage. Spraying calcium-containing foliar fertilizer on young fruits and leaves, such as calcium nitrate and amino acid calcium, can effectively prevent bitter pox disease.

5. After spraying foliar fertilizer, the longer the leaves remain moist, the more nutrients absorbed by the leaves, and the better the effect, so it is necessary to choose a rainless morning (after dew drying) to spray before 10:00 or after 4 p.m., cloudy days without rain can be sprayed throughout the day, and the concentration of fertilizer solution should be appropriately reduced in case of rainfall within 5-6 hours after spraying.

In order to prolong the wetting time of foliar fertilizer solution on leaf surface, branch tip and other organs, and enhance the spreading force and permeability, appropriate amount of wetting agent, spreading agent and penetrating agent can be added when preparing foliar fertilizer, such as Shiliping, Zhuxiaoling, neutral detergent and so on.

4. Times of spraying

The concentration of foliar topdressing is lower, and the amount of fertilizer applied each time is less, generally spraying 1 or 2 times can not meet the fertilizer needs of fruit trees; moreover, the fertilizer effect period of foliar topdressing is short, generally only 6 ~ 7 days, especially when spraying nutritious foliar fertilizer, the amount of fertilizer applied is insufficient. Therefore, foliar topdressing is generally not less than 2 times, and the spraying times of nutrient elements (such as iron, boron, calcium, zinc, etc.) which are not easy to flow in the tree can be increased appropriately. When spraying foliar fertilizer containing plant growth regulators (such as gibberellin, ethephon, pyrifuron, etc.), it is generally sprayed twice, each time at an interval of about 10 days, to prevent improper regulation and cause harm.

5. Application method

1. Spray ① growth period. Foliar fertilizer was prepared into a certain concentration of solution and sprayed on various organs of the crown (mainly leaves). Nutrient elements or other substances were absorbed and infiltrated into the tree through stomata or intercellular space. Young leaves have stronger physiological activity and stronger ability to absorb and permeate nutrient elements than old leaves, so foliar fertilizer should be sprayed on young leaves. When spraying foliar fertilizer, both the front and back of the leaf should be sprayed; the back of the leaf is thinner than the front, with more stomata, loose spongy tissue and larger intercellular space, which is conducive to the absorption and infiltration of nutrients, so we should focus on spraying the back of the leaf. When spraying the nutrient elements which are not easy to move in the fruit trees, the foliar fertilizer solution can be sprayed directly to the organs that need the element, so that it can play a role quickly and effectively. When boron is sprayed in order to improve the fruit setting rate, the diluted boron fertilizer solution can be directly sprayed on flowers and young fruits. ② dormant period. Generally, the foliar fertilizer is sprayed on the crown before the fruit tree sprouts. For example, to prevent and cure the leaflet disease caused by zinc deficiency in fruit trees, spray 3%-4% zinc sulfate solution before germination, and then spray 0.3%-0.5% zinc sulfate solution on the crown after germination, the effect is excellent. When spraying branches, due to the poor absorption and permeability of branches, the effect of adding appropriate amount of wetting agent and penetrating agent will be better when preparing foliar fertilizer.

two。 Dipping method put the prepared foliar fertilizer solution in a large diameter container (such as a large tea jar), put the fruit tree organs that need extra-root topdressing into and soak for 3 minutes for 5 seconds, in order to achieve the purpose of fertilization. This method is often used in grape flower and fruit management, for example, in order to improve the fruit setting rate of grape, 20 mg / L gibberellin is dipped in inflorescence 3-5 days before flowering.

3. Trunk drip method this method is suitable for large trees with a trunk diameter greater than 10 cm. First punch a hole in the trunk, and then drip the foliar fertilizer into the hole. After the fertilizer enters the vessel tissue of the xylem of the branch, it can be transmitted to various organs with the movement of water in the tree. The use of this method is little affected by the external natural environment, the fertilizer utilization rate is high and the effect is fast. It can be divided into two categories:

① infusion method. It is similar to human transfusion. At the lower part of the trunk about 30 cm from the ground, drill a hole about 45 °upward, the hole diameter is consistent with the matching injection needle, drill 5 to 6 cm, remove the sawdust, screw the matching injection needle into the injection hole, tighten the liquid; hang the commercial nutrient solution bag (bottle) or self-made nutrient solution bag (bottle) on the tree, turn on the injection needle infusion. Self-made nutrient solution should use clean neutral water, preferably distilled water or pure water; foliar fertilizer should be of high purity and less impurities after dissolution. Simple infusion method: with medical infusion apparatus, fill with self-made foliar fertilizer liquid, punch and hang foliar fertilizer bottle as above, the hole can be slightly deeper; insert the needle into the hole, adjust the amount of drip, and seal with rubber mud. After the needle is inserted, the injection hole can also be blocked by a short branch segment which is equivalent to the caliber of the injection hole. Each tree with a trunk diameter of less than 10 cm can be punched 1 hole; for a tree with a trunk diameter of more than 10 cm, each tree can drill 2-3 holes.

② high pressure injection. The special trunk injection machine for fruit trees and trees is used to generate pressure through mechanical pumps or hand pumps to inject foliar fertilizer into the trees through needles, but this method is rarely used in fruit tree production at present.