Field Management of navel Orange Orchard in Spring and Summer

Gannan spring is early, warm and rainy. March to June is the spring shoot growth of navel orange, flowering and fruit setting, the first and second phenological periods of physiological fruit drop, and it is also a dangerous period for more than 10 kinds of diseases and insect pests, such as citrus bud maggots, mites, scale, leaf roll moth, longicorn beetles, anthrax, resin disease, canker and so on. At this time, the orange orchard management is good or bad, is the key period affecting the yield and quality of navel oranges, thousands of things, we should pay attention to the following three technical measures.

First, clearing ditches and drainage and storing water to prevent drought

Navel orange has poor stress resistance in flowering and young fruit stage, which is not only afraid of high temperature and drought, but also afraid of flood and waterlogging. Special attention should be paid to strengthening the management of water drainage and irrigation in orange orchards.

(1) ditch cleaning and drainage of navel orange orchard

According to meteorological data, the rainfall in southern Jiangxi has doubled since April, which is 203.5mm, and has entered the rainy season. The rainfall has further increased in May and June, reaching 256.6mm and 303.8mm respectively, and there are often torrential rains, which belong to the flood season. Therefore, seriously do a good job of terrace management, clear ditches and drainage, so that the ditches are connected, the drainage is unobstructed, and there is no stagnant water in the orange orchard after rain, so as to ensure the normal growth and development of navel orange roots and the strong ability to absorb fertilizer and water. Such as poor drainage of the orange orchard in the rainy season, resulting in soil anoxia, when the oxygen concentration in the soil drops below 2%, the navel orange root is black and mildew; under the anoxic condition, the substance in the soil is reduced to produce a large amount of hydrogen sulfide, methane and other toxic substances. When the concentration of hydrogen sulfide in the soil reached 3 × 10-6, the navel orange root system was poisoned and died. In addition, the stagnant water in the orange orchard will also form a high-temperature and humid microclimate environment. According to scientific research records, within the appropriate temperature of about 20 ℃, the incidence of anthracnose, resin disease and canker of navel orange is almost proportional to rainfall. Because the number of rainfall is more and the duration of rainfall is long, it is beneficial for a large number of spores to produce and spread widely, and the disease is prevalent. Light causes falling leaves, flowers and fruits of navel oranges, weakens the tree potential, reduces yield and reduces quality, while heavy ones cause rotten roots, dead branches, dead trees, and bad consequences of destroying the garden.

(2) storing water and preventing drought in the rainy season

While emphasizing the drainage and waterlogging prevention of orange orchards in the rainy season, we should also pay attention to introducing the surface runoff in the rainy season into pools, hills and reservoirs to prevent drought. According to scientific calculation, if we can store enough water for navel orange plants in southern Jiangxi, navel oranges can be used as supplementary irrigation water in dry season.

2. Flower and fruit protection and thinning

The navel orange has a large number of flowers, poor flower quality and serious drop of flowers and fruits. According to the survey and statistics, the fruit setting rate of navel oranges is only 0.2% per cent, 1.7% and 98% of flowers and fruits, respectively, falling off at bud stage, flowering stage, young fruit stage, and even mature stage, which shows how important it is to implement flower and fruit protection techniques for navel oranges.

(1) techniques for protecting flowers and fruits of navel oranges

1. Protect flowers and leaves first: the leaves of navel oranges are the production and storage organs of organic nutrients. The floral organ development, spring shoot growth, flowering and fruit setting and early development of young fruit of navel orange mainly depend on the nutrient supply of overwintering old leaves. Therefore, the more the over-wintering old leaves of navel orange are retained, the more nutrients stored in the tree, the more spring shoots germinate, the faster the growth, the better the flower quality, the higher the fruit setting rate, the faster the young fruit develops and expands, the higher the yield per unit area and the better quality. In cultivation, it is very important to reduce and delay the shedding in spring, that is, to prolong the leaf age through the safe overwintering of navel orange old leaves through reasonable soil fertilizer and water management.

2. control of diseases and insect pests: the harm of diseases and insect pests to navel oranges, one is to weaken the tree potential and reduce the fruit setting rate, such as soot disease, plaster disease, foot rot and mites, scale, leaf moth and so on. Second, it directly harms flowers and fruits, resulting in falling flowers and fruits. Such as canker, resin disease, flower bud maggot, leaf roll moth and fruit-sucking armyworm and so on. It is necessary to conscientiously implement the technical measures of "prevention first, comprehensive prevention and control" to achieve the purpose of protecting trees and fruits.

3. Ease the contradiction between shoot and fruit: for spring shoot, the first is to promote early application of spring fertilizer to strive for early occurrence of spring shoot, which is beneficial to reduce the second physiological fruit drop. If the spring shoot grows too much due to abnormal climate, late application of spring fertilizer or too much nitrogen fertilizer, the spring shoot can not be cut before flowering, it should be dealt with in time to restrain its overgrowth; when there are too many new leaves, part of the vegetative branches on the top of the crown and the leafy flower branches above four leaves should be wiped off, and the ratio of new to old leaves should be adjusted according to 1:1 for adult trees and 0.7 for young trees. But the spring shoot should not be smeared too much, otherwise it will aggravate the second physiological fruit drop, and hinder the individual development of fruit, small fruit, can not achieve the goal of high yield and high quality. The treatment of spring shoots should be completed 3-5 days before flowering, and the effect is not good if it is late.

The treatment of summer shoots: fruit trees should control summer shoots, and careful application of fruit protection fertilizer is the key. Adult trees should wipe off all summer shoots, which is an important measure to reduce fruit drop in June. Considering that the young tree expands the crown while bearing fruit, it only wipes off the middle and lower summer shoots, and the top summer shoots are coring.

4. balance of endogenous hormones: young trees have more vigorous branches and low fruit setting rate, so they can be bent and bound in September and October with a piece of straw. Due to the change of the top position of the strong branch, the level of promotive endogenous hormone in the whole shoot decreased by half, while the level of inhibitory endogenous hormone doubled, thus weakening the vegetative growth of the strong branch, promoting nutrient accumulation and beneficial to flower bud differentiation. After January of the following year, the straw was moldy and loosened by itself. if the branch posture was still upright, the growth was restrained by bending the branch for the second time before flowering in March or April, and the effect of flower and fruit preservation was very good.

5. Apply plant growth regulators to protect flowers and fruits:

① sprays 50 × 10-6 gibberellin + 0.2% urea + 0.2% potassium dihydrogen phosphate + 0.1% methyl topiramate to protect fruit when the navel orange Xiehua 2 is 3-3 / 4. For years or trees with a small amount of flowers, you can consider spraying them in advance to Xiehua 1 / 2.

7 days after flowering or young fruit stage of ② navel orange, spray type liquefied BA+GA (Chongqing Zhongtangsuo product, the same below), each bottle (10ml) mixed with 15 kg fresh water + 3 yuan (15 g) methyl topiramate; or in the young fruit stage, use smeared fruit type synergistic liquefied BA+GA, each bottle mixed with 1 kg of fresh water, select the young fruit that grows well, and apply dark green young fruit once, the fruit protection effect can reach 70-80%. In the middle of May, use yellowish ester, each bottle with 300 grams of water, apply liquid to the navel with a brush to prevent the umbilical yellow from falling fruit.

(2) Flower and fruit thinning techniques of navel orange

Navel orange hanging too much fruit, too much nutrient consumption, not only affect the full expansion of the fruit, but also inhibit autumn shoot germination and flower bud differentiation, the formation of large and small fruit; at the same time, it will also cause premature senescence and shorten the life span. In order to obtain high quality and stable yield and long-term economic benefits, navel orange should also promote reasonable burden. While protecting flowers and fruits, we should also promote flower thinning and fruit thinning, especially for those weak trees with large amounts of flowers, we should emphasize thinning flowers and fruits in stages and batches.

1. Pruning and thinning buds and flowers: when pruning in winter and spring, cutting and cutting some fallen flowers and fruit branches and sweeping branches will not only remove a large number of inferior flower buds, but also renew the fruiting mother branches and increase the reserve branches, which is beneficial to restore the tree potential and improve the flower quality, fruit setting rate and fruit quality.

2. Fruit thinning by stages and batches: in the whole process of fruit development, disease and insect fruits, deformed fruits, dense fruits, small fruits, coarse-skinned and large fruits are thinned out in stages and batches, and finally the fruit is determined according to the leaf-fruit ratio of 50-60:1, which is an economic and effective measure to strive for high yield, stable yield, high quality and high efficiency of navel orange.

III. Pest control and pollution-free food production

(1) Control techniques of diseases and insect pests of navel orange

The warm and rainy environment and rich food (spring shoots, young fruits) conditions are conducive to the breeding and breeding of citrus diseases and insect pests. The temperature in April and May, the incidence of canker, anthrax and resin disease is almost proportional to rainfall; the first generation of scale insects, whitefly and leaf roll moth control is good or bad, which determines the population density and damage degree of the whole year; from the first ten days of April, red spiders doubled and became popular in May, and rust wall lice transferred from old leaves to new leaves, and then brought fruit damage, forming the first peak. In addition, flower bud maggots and weevils flourished in early April, and Coleoptera pests such as beetles, longicorn beetles, gibberries and orange axes also emerged successively in May. In the face of more than 10 kinds of diseases and insect pests, if we adopt the method of medicine and chemical prevention, it will be empty talk for navel oranges to become pollution-free food. The policy of "giving priority to prevention and comprehensive prevention" must be carried out.

1. Strictly implement the plant quarantine system, and all seedlings, scions and fruits transferred in and out must go through quarantine, issue quarantine certificates, and block the transmission of dangerous diseases and insect pests.

2. Agricultural control: ① selects varieties and rootstocks with strong disease and insect resistance; ② builds shelterbelt, intercropping or grass cultivation in the garden to improve ecological conditions; ③ strengthens field soil fertilizer and water management, cultivates strong trees, improves navel orange disease resistance and insect resistance; ④ pruning directly removes part of the disease source and insect mouth, improves canopy ventilation and light transmission conditions, and inhibits the reproduction of diseases and insect pests ⑤ cleans ditches and drains to reduce the humidity of orange orchards and restrain the spread of diseases and insect pests.

3. Physical control: ① uses the phototaxis and chemotactic characteristics of pests to light black light, yellow light, poison erbium, trap and kill beetles and leaf roll moth adults; ② organizes labor to kill Coleoptera pests such as beetles, longicorn beetles, weevil and so on.

4. Biological control: first, interplanting plants such as patchouli thistle, castor, perilla and towel gourd in navel orange orchard to protect predatory mites, amblyseius mites, lacewings, ladybugs, parasitic wasps and other pest natural enemies; second, if there are conditions, they can also artificially introduce, reproduce and release pest natural enemies to eat insects. The third is to use biological pesticides to control insects with bacteria.

5. Chemical control: on the basis of strengthening the investigation, we should grasp the occurrence law of diseases and insect pests in orange orchards, make clear the objects of attending and concurrent treatment, grasp the weak links of diseases and insect pests, and use pesticides rationally. timely, accurate, economical and effective elimination of diseases and insect pests before causing losses. For example, at the end of April and the beginning of May, the first generation of larvae of cotton scale, sagittal scale, chaff scale and whitefly hatched or caused larval stage of 1-2. At the same time, the number of red spiders doubled, and rust wall lice transferred from old leaves to new leaves to fruit damage. During the period of fruit damage caused by deciduous anthrax, resin disease and canker, the mixture of 2000 can be sprayed at 1000 times, and then sprayed 8 times of Donin, 1000 times of water amine sulfur mixture and dimethoate mixture after 7-10 days. can receive the main treatment of scale, mites and bacterial, fungal diseases and other diseases and insect pests.

(2) production requirements of pollution-free fruits

In the process of pollution-free fruit production and processing, due to the pollution of air, water and soil in the environment, too many synthetic chemicals such as pesticides, chemical fertilizers and hormones are used, which is a serious threat to people's health. consumers require to eat high-quality, safe and pollution-free food, so organic food, green food and pollution-free food are used.

Organic food: it refers to the food which is completely free of synthetic pesticides, fertilizers and hormones. It is the safest and most high-end food for human beings.

Green food: it refers to the food that follows the principle of sustainable development, according to the specific mode of production and recognized by special agencies, which is licensed to use the green food logo trademark, which is divided into An and AA levels. Green food is pollution-free, safe, high-quality and nutritious food. Because of matters related to environmental protection, they are called "green". In order to highlight that this kind of food comes from a good environment, it is named green food.

Pollution-free food: refers to the food in which the environment of the place of origin, production process and end products meet the standards and norms of pollution-free food, and are approved by special agencies to use pollution-free labels.

In June and July this year, the Ministry of Agriculture held an important meeting in Ganzhou to formulate the "navel orange pollution-free fruit quality standard" and the "division of navel orange epidemic areas." The publication of these two documents indicates that the state has made two very important decisions on Gannan navel orange industry, which fundamentally solved the potential crisis and future worries of Gannan navel orange.