What are the diseases and insect pests control of citrus?

Citrus pest control: 1. Canker is the object of plant quarantine at home and abroad. Oil-soaked spots with yellow needles appeared on the leaves, which gradually expanded, swelled and cracked. Finally, the lesion is cork-shaped, taupe, and nearly round, with yellow halo around it. The diseased spots on branches and fruits are similar to those on leaves. The pathogen survives in the diseased area for a long time, and spreads through wind and rain, insects and branches and leaves at short distance, and mainly through diseased seedlings, scions and fruits at long distance. Bacteria invade from stomata, lenticels and wounds, with an incubation period of 3 ~ 10 days, which is prevalent when it is hot and rainy. Sweet oranges are seriously ill, oranges and oranges are light, and kumquat is disease-resistant. Strict quarantine should be carried out and the diseased plants should be burned immediately. Clean the garden thoroughly in winter, control the leaf miner and avoid injury. Before and after flowering in summer and autumn, the shoots spread their leaves, and when the leaves turn green, they are sprayed with 200 times Bordeaux solution or 0.2% ~ 0.3% sulfur mixture. Su Ming-Bordeaux produces 500 times a day, 3% chlortetracycline 300 times (produced in Shanghai) and 50% chlorobromoisocyanuric acid (produced in Zhuji, Zhejiang) 1000 times, and the effect is good.

2. Root rot mainly harms root neck and root group. At first, it was soaked in water near the ground, and the cortex turned brown and smelled of distiller's grains. The enlarged lesion caused the root and neck ring to be cut off. The inner veins or lateral veins of diseased leaves are dark yellow, easy to fall off, with many flowers and early fall off. The remaining fruits are colored in advance, and the skin is rough and sour. The weather is hot and rainy, and the drainage is not smooth. Bark was seriously damaged, sweet orange rootstock was the worst, followed by red orange rootstock, and bitter orange and lime had strong resistance. It is the most economical and effective method to prevent foot rot by selecting disease-resistant rootstocks such as Fructus Aurantii and improving grafting parts appropriately. Scrape the diseased part, coat it with bordeaux pulp, and replace the rootstock when the condition is serious.

3. Scab disease, the damaged leaves began to appear small spots in the water, then turned waxy yellow, and became cork-like with the growth of leaves. The surrounding leaf tissue is conical, the other side is concave, and the leaves are twisted and deformed. Fruits undergo many tumor-like processes. Mycelia overwinters in epidemic areas, and wind and rain insects spread. The optimum temperature of pathogen development is 16 ~ 23℃, and the disease is prevalent in spring and autumn shoots, and the fruit is most affected from late May to early June. Oranges are the most susceptible to infection, followed by oranges, and sweet oranges have stronger disease resistance. Cut off diseased branches and leaves. When spring buds germinate and the bud length is less than one grain of rice, spray 200 times Bordeaux solution or 500 times 50% bactericide solution; Spraying 0.5% Bordeaux solution or 500 times acaricide and 2000 times mannan solution to treat mites in the second bud stage; Spray 0.6% Bordeaux solution when Sanhuaxie 1/2 ~ 2/3; Spraying 70% thiophanate methyl 600 times solution or 70% mancozeb 500 times solution 7 ~ 10 day after the fourth flowering; Continue spraying Tobuzine or Mancozeb for the fifth time.

4. Black spot disease, also known as scab, mainly harms fruits. At the beginning, there were reddish-brown spots on the surface of the fruit, which expanded into dark-brown circular spots with a diameter of 2 ~ 3 mm, slightly raised around, obvious boundaries, central depression, grayish brown and many small black spots. During storage and transportation, the diseased spots are dark brown, leathery and irregular, causing rot. The pathogen overwinters on fallen leaves, infects young fruits after falling flowers in the next spring, and the incubation period is very long, and it becomes ill after coloring. Ponkan, red orange, early orange, local early, lemon, etc. They are all seriously ill, but the sweet orange is light. It is necessary to do a good job in clearing the garden and remove fallen leaves, branches and diseased fruits. Reduce the wound, and spray it 2 ~ 3 times every 10 ~ 15 days within10.5 months and August after flowering. 600 times of 90% Sheng Da M-45 wettable powder, 500-600 times of 50% thiophanate-methyl, 800 times of 50% carbendazim, 300-400 times of crystal sulfur mixture or cycloserine and dijundan can be used alternately in due course.

5. Resin disease mainly damages branches, with cortex necrosis and xylem grayish brown. There is a yellowish brown or dark brown bacterial band at the junction of the diseased part and the healthy part, sometimes there is glue flowing from the diseased part and small black sticky spots under the skin. Pathogens overwinter in dead bark and dead branches, invade when wounds and freezing damage occur, and are suitable for onset in spring and autumn. Remove pathogens, scrape off diseased parts and wounds, and disinfect with 0. 1% mercuric chloride. Before the spring shoots germinate, spray 0.5% Bordeaux solution once at 2/3 of the flowering time and once at the young fruit stage.

6. Huanglongbing is a devastating disease. At the early stage of the disease, the tip of the blade yellowed and the leaves turned yellow evenly. Some leaves turn yellow from the base or edge of leaves near veins after turning green, and spread into irregular yellow-green spots. The diseased leaves fall early, the branches die, the flowers bloom early, and the fruit is small or deformed. The pathogen is rickettsia, which is spread by citrus psylla. Strict quarantine should be carried out and a disease-free nursery should be established. The rootstock seeds were pre-soaked in hot water at 50 ~ 52℃ for 5 minutes, then soaked in hot water at 55 ~ 56℃ for 2 hours, then grafted with clear water, and the grafted seedlings were treated with hot and humid air at 49℃ for 50 minutes. Strictly control citrus psylla. For lightly diseased trees, drill a hole at the base of the trunk to the depth of 2/3 of the diameter, and inject 2 ~ 5 kg tetracycline hydrochloride 1000 mg/L to completely remove seriously diseased trees.

7. Decline disease mainly harms grafted trees with lime as rootstock. The newly diseased branches do not germinate or germinate less, the old leaves lose their luster, the main lateral veins obviously turn yellow and fall off, and the diseased branches die from top to bottom. The pathogen is virus, which is spread by orange aphid, cotton aphid, orange aphid and Spiraea aphid. Eureka lemon and grapefruit can be used as indicator plants. Selecting disease-resistant rootstocks such as Fructus Aurantii, Fructus Citri Tangerinae, Lemon, Fructus Citri Tangerinae and Fructus Citri Grandis, and selecting nontoxic scions or heat treatment.

8. Cracking skin disease mainly harms rootstock grafting trees such as Fructus Aurantii and teak. At the early stage of the disease, the bark cracked longitudinally, part of the bark fell off, the crown was dwarfed, the new shoots were few and weak, some leaves were green near the veins, and the mesophyll was yellow, similar to zinc deficiency, some branchlets died, with many flowers and fruits, and the yield decreased. Viroid has strong heat resistance and can spread through contact with roots, tools and hands. The selection line of Etrog fragrant garden Arizona 86 1 can be used as an indicator plant for selecting non-toxic seedlings. After pruning infected plants, the pruning tools were disinfected with bleaching powder 10 times solution containing 5.25% sodium hypochlorite.

9. Bituminous coal disease, there are three kinds of bituminous coal disease, one is cinder, the moldy layer is black tissue paper, which is easy to tear off or fall off naturally, accounting for 55%; The second is Acanthopanax, the mold layer is like the bottom ash of a pot, which falls off in pieces when rubbed by hand, mostly on leaves, accounting for 30%; The third kind of small cinder, the mold layer presents radial small mold spots, which are scattered on the dry leaves and back of leaves and are not easy to peel off, accounting for 15%. The disease can occur in the field in May-165438+10, and it is the most serious in June and July, lasting for more than 7 months. Citrus overwinters indoors in the north, and bituminous coal disease is more serious. According to the investigation, bituminous coal disease is related to whitefly, so it can be controlled by 40% omethoate, 65,438+00% Dagong wettable powder 65,438+0000 times or 65,438+00% imidacloprid 3000 times. Bituminous coal disease can be sprayed with Koside 1000 times or Xinwansheng 500 times or 92% diesel emulsion 200 times.

10. Ralstonia solanacearum is a major disease of citrus, with acute wilting. When this disease occurs, all the leaves will wither and the whole plant will die. There are three types of chronic diseases: partial type, deciduous type (onset from late May to early June), late bud type and late flower type. The diseases of sour orange rootstock and bitter orange rootstock are serious, and fruit tree diseases are more common in red and yellow soil. At the early stage of the disease, roots and branches can be cut off, bran fertilizer and guest sand can be added to restore the tree vigor, and the wilting type is generally uncontrollable.

1 1. There are mainly four kinds of mites: citrus red spider, yellow spider, citrus rust tick and citrus tumor wall. Citrus red spider harms the front and back of leaves, making the leaves dim and gloomy, which mostly occurs in April-May, and can also bloom in September-65438+10. Orange spiders are mostly clustered on both sides of the main vein and lateral vein on the opposite side of the leaf. After the injury, a yellow depression covered with sparse net appeared, and the young leaves were deformed and curled after the injury. These two kinds of red spiders should spray the mixture of 1 pomeranite sulfur once before New Year's Day. After the spring seedlings germinate, when the tender leaves grow to 0.5 cm, 25% Kung Fu EC can be sprayed 2000 times. Protect natural enemies, such as black beetles, thrips, predatory mites and lacewings.

12. Whiteflies include whitefly, citrus whitefly, green whitefly, coral whitefly, Diptera and whitefly. Larvae suck juice from leaves and secrete honey dew, which causes tobacco diseases. There are four generations a year, the second and third instars overwinter on the back of leaves, pupate in mid-March and emerge in mid-April. The nymphae stage of each generation is mid-May, late June, mid-August and late June 10. It mainly protects natural enemies, such as ladybug with red lips, Chrysopa lacewing, wasp with few knots, wasp with whitefly, etc. The first generation 1 ~ 2 instar nymph (in the first half of May) can be sprayed with 40% quick-killing EC 1000 times, and other nymphs can be sprayed with 25% chlorpyrifos wettable powder/. 13. Scale insects. The scale insects of citrus include cyst scale insects, red scale insects, Japanese scale insects, red cap scale insects, China red scale insects, sand scale insects, arrow scale insects and black scale insects. It is necessary to protect natural enemies such as Lepidoptera angustifolia, Lepidoptera angustifolia, Lepidoptera angustifolia, Aphis nigricans, Aphis gracilis, Aphis wax. During the incubation period from May to June, the larvae were killed by spraying 800 ~ 1000 times of oil emulsion 200 ~ 250 times or 0.5% fruit juice agent 500 ~ 1000 times.