1. When choosing a citrus orchard, you should choose a place without obvious freezing damage, which requires deep soil layer, good drainage and ventilation, rich organic matter, convenient irrigation and convenient transportation. The hills and mountains are below 800 meters above sea level and the slope is below 25. In areas with freezing injury in winter, the southeast slope should be chosen, and gardens should not be built in low-lying areas with poor drainage and valleys where cold air is easy to stagnate. When the garden is built on gentle slopes, rivers and paddy fields below 5, attention must be paid to drainage. Natural barriers and large water bodies can be used to adjust the temperature, and gardens can be built around them. Building a garden requires a lot of surrounding environment. It is required that the citrus produced should be robust and free from pests and diseases, and the surrounding air quality, irrigation water quality and soil environmental quality should be fully understood. The standard of pollution-free food formulated by 200 1 says that the environmental quality of production process should be considered.
The planting season of 1. 1 is generally from late February to mid-March, before the spring shoots germinate. In areas without frost damage in winter, it can be planted in 10 ~ 1 1 mid-autumn; In April-May of spring and summer, after the growth of spring shoots stops, the survival rate of summer bamboo shoots is also very high. Container seedlings can be planted all year round.
1.2 The most common spacing for citrus cultivation is 4x6m, but different planting methods tend to make the citrus grow intensively in the later stage, so the spacing of 4x3m or even 4X 1.5 is often adopted. Its planting density is usually 4 10 plants per hectare, and there are 800 plants or even 1600 plants per hectare in the case of close planting. Dig a planting pit according to the specification of 1× 1 m, and apply basic fertilizers such as weeds, garbage fertilizer, decomposed organic fertilizer and calcium superphosphate in the pit. Kechun can also be planted in autumn.
2. Management of citrus trees
2. 1 soil management soil is a loose layer on the land surface, which is composed of minerals, organic matter, water, air and organisms. It is fertile and can grow plants. Citrus grows well in light soil, but it can also grow in heavy loam if suitable rootstocks and good drainage conditions are used. The soil with pH over 8.0 is not conducive to the growth of citrus. Citrus is very sensitive to soil salt and boron (even in deep soil) and hardened soil. Citrus roots are mainly distributed in 0.90 m soil layer, which varies with irrigation conditions. The vast majority of aerobic active roots are distributed in the surface layer of soil 30 cm. In light soil, the recommended irrigation cycle is twice a week, and daily irrigation is better. Obviously, because water can easily penetrate below the active root zone in light soil, frequent and small irrigation will produce better results.
2.2 Fertilizer and water management Citrus needs irrigation in dry months, so it must be irrigated in winter when the temperature is above 13 degrees Celsius. In addition, dehydration is dangerous, which makes the fruit flow to the leaves and causes the fruit to wither. In the past, furrow irrigation or sprinkler irrigation was mainly used in the upper part of the crown, but sprinkler irrigation was at risk of salinization, and furrow irrigation would reduce soil permeability. At present, drip irrigation and micro-sprinkler irrigation are used under the canopy, which is strip irrigation and part of the soil surface remains dry. Orchards that have not fully applied phosphorus and potassium fertilizer before planting should increase the application amount of phosphorus and potassium fertilizer year by year; 1 After young trees are planted, new roots begin to move, and thin manure can be applied. The amount of fertilizer should be less than more, light, not thick, especially chemical fertilizer, and more attention should be paid not to hurt the roots. Quick-acting fertilizer should be applied 1 ~ 2 times before each new shoot sprouting and during the growth period, and new shoots germinate 3 ~ 4 times in 1 year, that is, spring shoot fertilizer should be applied from the end of February to the beginning of March, summer shoot fertilizer should be applied in the middle and late May, autumn shoot fertilizer should be applied in the middle and early July, and winter fertilizer should be applied in1/June. In areas prone to freezing injury, fertilization should be stopped from August to 65438+10 to prevent late autumn shoots and winter shoots from sprouting and avoid freezing injury caused by nutrient consumption. In the second year after planting, the amount of fertilizer should be gradually increased, combined with soil improvement, organic fertilizer should be applied, the amount of phosphorus and potassium fertilizer should be increased, and appropriate amount of lime should be added to acidic soil to cultivate dense root groups and strong autumn shoots, laying the foundation for the third year. For 2-3-year-old trees, topdressing should be applied continuously in each new shoot growth period, about half a month before the emergence of bamboo shoots, and topdressing 1 time for those with less bamboo shoots. After self-cutting or coring, topdressing 1 times of strong shoot fertilizer, and topdressing twice after autumn shoots turn green.
Pay attention to the difference between weak trees and strong trees when fertilizing. In order to ensure the normal growth of weak trees for three times and increase the number of new shoots, summer shoots can be popularized in the first year after planting. When the summer shoots grow to 7-8 leaves, they can be picked and fertilized, so that the fertilized summer shoots are full and strong. Fertilization can promote the early autumn shoots to be strong and can play the role of nourishing the strong shoots with small fertilizer. In the second year after planting, the summer shoots with weak branches should not be cut short. After cutting short, the growth potential of new shoots will be weak due to poor nutritional conditions.
2.3 plastic pruning plastic pruning is a technical measure to adjust fruit trees into a fairly stable tree shape and growth and development space through certain surgical methods according to the growth characteristics and cultivation purposes of trees, combined with natural conditions and management technology level. The purpose of citrus pruning is "early fruiting, multiple fruiting, good fruiting and long fruiting". Correct pruning can promote the growth of trees and make them take shape as soon as possible, especially the branches of fruit trees are distributed reasonably, the crown is ventilated and transparent, the fruit is stable, which is convenient for field management, improves production efficiency, reduces production costs and increases economic benefits. For trees of different ages, young trees should bear fruit and yield as soon as possible; Mature trees achieve high quality and high yield, and prolong the fruiting period; Aging tree species should be updated as soon as possible to promote growth and maintain yield.
2.4 Protection of Flowers and Fruits In view of the phenomenon of falling flowers and fruits, corresponding measures should be taken to protect flowers and fruits.
Measures: ① Cultivating vigorous tree vigor and accumulating sufficient nutrients are the basis of keeping flowers and fruits. ② Leaves must be preserved before flowers and fruits can be preserved. In the process of fruit growth and development, different citrus varieties have different requirements for the leaf-fruit ratio of their high-yield trees. (3) Plant growth regulators can be used to protect flowers and fruits, such as photosensitizer, nucleotide and cytokinin. ④ Control the spring shoots and erase the summer shoots. ⑤ Ring cutting: select vigorous trees, and ring cut the lateral branches with a diameter of 4-5 cm twice at the bifurcation of 4-5 cm from April to June. ⑥ flower thinning and fruit thinning: after the fruit is stable, the small fruit, the over-dense fruit and the hidden fruit near the ground are thinned several times to keep the fruit blue normally. ⑦ Auxiliary pollination: artificial pollination is carried out after dew dries on sunny days in full bloom.
2.5 The suitable period of fruits and vegetables is after physiological autumn, which can be carried out twice in the middle and late June and mid-July. The amount of fruits and vegetables can be determined according to the fixed yield and leaf-fruit ratio of trees. When harvesting fruits and vegetables, pests, deformed fruits and damaged fruits should be removed first, and then small fruits should be removed.
3. Main diseases and insect pests of citrus and their control
During the growth and development of citrus, due to the influence of harmful organisms or adverse environmental conditions, its normal growth and development are inhibited, and its metabolism changes, resulting in reduced yield, poor quality and even death, which brings huge losses to the economic value of citrus and seriously affects the economic income of growers. Therefore, it is the greatest gain for growers to clearly understand the main diseases and pests of citrus and take effective control measures. The following are the kinds of citrus diseases and insect pests and some effective control methods for reference.
3. 1 disease
3. 1 1 Citrus Huanglongbing, also known as yellow tip disease, is a plant quarantine disease in China. Seedlings and young trees died within 1~2 years after onset, and adult trees lost their fruiting ability within 2~3 years after onset. In the early stage, its symptoms were a few new buds in individual plants, and a few yellow buds were mixed in the dense green crown, commonly known as Jinhua or Jitouhuang. The leaves at the diseased tip become hard and brittle, and the mesophyll turns yellow from the base of the leaves, while the lateral veins of the main veins remain green and mottled yellow-green, and the veins are enlarged, and the local cork cracks or the whole leaves turn yellow evenly. Prevention and control measures: ① Strict quarantine, prohibiting the introduction of seedlings and scions from epidemic areas in new areas and non-epidemic areas; (2) cultivating disease-free seedlings and establishing disease-free nurseries in areas free of Huanglongbing and citrus psyllid, and selecting virus-free seedlings; (3) pest control, timely control of citrus psyllid; (4) Dig out the diseased plants, strengthen inspection and handle the diseased plants in time.
3. 12 Citrus canker is an object of plant quarantine at home and abroad. The seedlings and young trees are seriously damaged, resulting in fallen leaves and dead branches, weak trees, slightly damaged fruits with disease marks, reduced quality, and even fruit drop and yield reduction. The disease damages leaves, branches and fruits. At first, the lesion was needle-shaped, yellow and water-soaked, and later it expanded into a nearly circular lesion. On both sides of the leaf, it bulges, cork-shaped, rough, taupe, and cracks like a crater. Preventive measures: ① Strict quarantine, soaking introduced seedlings and scions in 0.3% ferrous sulfate 10 minute. ② Strengthen cultivation management and prune and clear the garden in winter. Do a good job of wiping and controlling buds to reduce the incidence. Rational fertilization to control seedlings with fertilizer. (3) spraying chemicals to protect shoots and fruits, and selecting 77% copper hydroxide wettable powder, 30% copper oxychloride suspending agent 800- 1000 times solution, 20% methyl dichloroisocyanuric acid wettable powder 1000- 1500 times solution or 20% quinconazole wettable powder/kloc.
3. 13 Citrus scab mainly harms leaves, branches and fruits, causing defoliation and fruit drop. The diseased fruit is small and deformed, with poor quality and poor growth of damaged new shoots. The disease can only infect leaves, shoots and tender tissues in fruit fields. The damaged leaves appeared water spots at first, and then gradually expanded, showing waxy yellow to yellowish brown, with a diameter of 0.3~2.0mm and cork. Prevention and control measures: ① Quarantine of seedlings, introducing seedlings and scions from other places in the newly-built garden for quarantine. Scions and seedlings from other places can be soaked in 800 times of 50% benomyl wettable powder and 800 times of 40% triadimefon carbendazim wettable powder for 30 minutes. (2) Strengthen cultivation management, combine pruning in winter, cut off diseased branches and leaves, collect ground branches and leaves, burn them together, and then spray chemicals under trees for prevention and control. Strengthen the management of fertilizer and water, promote the neatness of new shoots, shorten the tender period of young fruits and reduce the chance of pathogen infection. (3) Chemical spraying control to protect young leaves and young fruits. 600 times of 30% copper oxychloride suspension concentrate, 800 times of 40% triadimefon carbendazim wettable powder or 50% prochloraz manganese complex 1000 times can be selected for spraying.
3. 14 citrus anthracnose often causes a large number of fallen leaves, dead branches and fruit drops, which leads to the decline of tree vigor, products and quality, and even the death of branches and leaves. Prevention and control measures: ① Strengthen cultivation management, dig deep into the soil to avoid partial application of nitrogen fertilizer, increase application of organic fertilizer, phosphorus fertilizer and potassium fertilizer, timely drainage irrigation, and do a good job in preventing frost and other pests and diseases. (2) clear the garden in winter, cut off diseased leaves and dead fruits, remove fallen leaves and diseased fruits on the ground, and burn or bury them centrally. (3) Pesticide spraying control, that is, spraying pesticides at the tender leaf stage, young fruit stage and fruit expansion stage in spring, summer and autumn, and spraying 25% prochloraz EC, 24% benzoxazole SC, 43% mancozeb SC 1000 times or 25% bromocyanonitrile EC 500-800 times.
3.2 pests
3.2 1 citrus root-knot nematodes citrus root-knot nematodes mainly harm the roots of plants, and the plants are damaged, which may lead to the decline of tree vigor or the withering and death of the whole plant. The injured root tissue overgrows due to stimulation, forming nodules of different sizes with few root hairs. The leaves above the diseased plant become smaller and yellow. In severe cases, the leaves curl, dry and fall off, and the branches wither or even the whole plant dies. Prevention and control measures: ① Strict quarantine, it is forbidden to transport seedlings from wards. (2) Cultivate disease-free seedlings and use them as the ground of rice seedlings before selection. The rice nursery should be ploughed and sunned repeatedly, and the nematicide should be fumigated two weeks before sowing. ③ Treatment of diseased seedlings: soak the diseased root 15min with warm water at 48℃ or soak the root with 40% mirex 100 times solution to kill the root nematodes. (4) treat the diseased tree and dig out the root of the disease. From June 5438 to February, the diseased roots and fibrous roots on the surface of diseased plants were dug out and burned, and lime 1.5~2.5kg was applied to each plant, and more organic fertilizer was applied to promote root growth and tree potential recovery.
3.22 The red spider mainly harms the leaves, branches and fruits of citrus. When the leaves and fruits are seriously damaged, they will turn gray and lose their luster until they turn yellow and fall off. April-June and September-165438+10 are the peak periods. Control measures: ① Strengthen inspection, with an average of 5-6 insects per leaf, which should be controlled. (2) Do a good job in clearing the garden in winter, and spray oil emulsion 100 times or Pomei 0.8- 1.0 degree stone sulfur mixture before germination in the following winter. ③ When the insect population reaches the control index, acaricide can be used for control or selective treatment, and broad-spectrum household drugs should be used less to protect natural enemies.
3.23 Citrus leaf miner is commonly known as "ghost painting symbol". The insect dives into the epidermis of young leaves, twigs and fruits as larvae to feed, forming a white curved insect path, which makes the leaves curl and fall off, hard and fragile, leading to poor growth of new shoots and affecting tree potential and fruits. The damage of summer shoots began in late May after germination, with the greatest damage in July and August. Preventive measures: ① Combined with clearing the garden in winter, cut off the damaged branches and burn them. (2) Pick off the sporadic sprouting buds too early or too late, strengthen the management of fertilizer and water, and make the new buds sprout orderly. (3) When new buds germinate 50%, or most teeth are 2-3cm long, or the damage rate of young leaves reaches 5%, start spraying, continue spraying for 2-3 times, and spray once every 5-7 days.
3.24 Citrus rust ticks are mainly concentrated on the branches, leaves and fruits of citrus, and the damaged peel or the back of leaves turns dark brown. Control measures: ① Careful inspection: 5- 10 plants were randomly selected from each orchard, and each plant was examined with a magnifying glass for 10-20 leaves or fruits. When there are 2-3 insects per leaf and fruit on average or individual leaves and fruits are gray, control should be carried out immediately. (2) Spraying Pomei 0.8- 1.0 degree sulfur mixture from winter to early spring to eliminate overwintering insects. Spray Bomei 0.2-0.3 degree stone sulfur mixture in peak period. (3) Control or selective treatment shall be carried out after reaching the control index, with acaricide as the main component and spraying carefully and evenly.
3.25 scale insects scale insects harm the branches, leaves and fruits of citrus. Adults and nymphs suck the juice of tissues, and the damaged tissues can't fully develop, and the trees are weak, resulting in falling leaves and fruits, affecting the quality of fruits and inducing soot disease. There are mainly scale insects, scale insects and scale insects in Nanfeng orange area. Control measures: ① Strengthen inspection and spray in the whole incubation period and the first nymph period to effectively control nymph. Generally, it is sprayed twice from mid-May to mid-June, and sprayed 1-2 times from August to September for control. (2) Do a good job in clearing the garden in winter, cut off branches and dead branches and burn them all. Spray 8- 10 times of pine alkali mixture or 100 times of liquid engine oil emulsion and 3000 times of liquid organophosphorus pesticide in winter.
4. Looking forward to the prevention and control of citrus diseases and insect pests, it is necessary to establish a forecasting mechanism of diseases and insect pests. Blindly spraying pesticides, especially frequently using broad-spectrum pesticides to kill a large number of natural enemies, is extremely unfavorable for establishing a sustainable ecological park. The prevention and control of pests and diseases in citrus orchards should adopt comprehensive management, actively apply biological control technology and adopt chemical, biological and physical control measures based on agricultural control, so as to control the occurrence of pests economically, safely, effectively and simply. The level of citrus production and cultivation technology directly affects the income of fruit farmers. Scientific and technical personnel should fully help fruit farmers understand citrus, introduce the occurrence law of citrus, minimize the occurrence of diseases and pests, and produce good products with high quality, high yield and no pollution.