Gannan Navel Orange, a specialty of Ganzhou City, Jiangxi Province, is a national geographical indication product of China. At present, Ganzhou City, Jiangxi Province, where Gannan Navel Orange originates, has become the world's largest navel orange planting area, the third largest annual output in the world, and the largest navel orange producing area in the country. The main varieties of Gannan navel orange are Newhall navel orange varieties, which have the characteristics of beautiful appearance, excellent meat quality and commerciality, and the peel is smooth, with a rich citrus fragrance, the flesh is tender and crisp, the slag juice is juicy, the juice is sweet and sour, the flavor is rich and fragrant. As the saying goes, the fruit is delicious and difficult to plant, gannan navel orange planting faces many types of diseases and pests, especially yellow dragon disease, red spider, leaf fragment disease and other diseases and insect pests are the roadblocks to the development of Gannan navel orange, the following introduction of several major diseases and pests and control measures:
1. Citrus psyllids
Citrus psyllids are very harmful to navel oranges. Wood lice suck on navel orange shoots, young shoots, and young leaves, causing young shoots, young shoots and yellow flowers, shrinking and drying, and young leaves deforming and falling off. The biggest harm of wood lice to navel oranges is the transmission of yellow dragon disease. Wood lice is an important way to spread yellow dragon disease, adult lice and nymphs have the ability to spread yellow dragon disease, of which the 3-5 year old wood lice nymph has the strongest ability to spread yellow dragon disease. Wood lice mainly feed on navel orange shoots, control wood lice infestations, focusing on the prevention and control of wood lice in spring, summer and autumn. Ladybirds, aphid-eating flies, jumping wasps and praying mantises are natural enemies of citrus psyllids, and the cultivation of thistles and green manure in orange groves provides a habitat for natural enemies of psyllids and is beneficial to the control of pyllids. Doing a good job of clearing the garden in winter, reducing overwintering adults, and reducing the base number of insect mouths are very important for the control of citrus lice.
Citrus wood lice harm young leaves
2. Red Spider
The red spider, also known as the citrus full-clawed mite, is mainly harmful to the leaves, young branches and fruits of the navel orange. Adult mites, nymphs, and young mites suck juice on the leaves, young branches and fruits, and the leaves appear dense white spots and lose their luster, and in severe cases, they fall leaves and fruits, affecting tree potential and yield. In the Gannan region, there are two peak periods for the occurrence of red spiders: April-June and September-November[2]. The prevention and control of red spider insect pests should be carried out before the peak to reduce the insect population base and avoid large occurrences. Red spiders can be controlled by using the red spider's natural enemies six-point thrips, predators and mites. Red spiders have strong resistance to drugs, and when using drugs to control red spiders, it is necessary to pay attention to rotating drugs to avoid resistance.
Red spiders harm their leaves
3. Rust ticks
Rust ticks, also known as rusty spiders, are mites like red spiders. Rust ticks are mainly harmful to citrus fruits and leaf backs. The back of the affected leaf slowly turns brown, curls and deforms, and falls in severe cases; the epidermis slowly turns brown and rough, affecting the quality. Rust ticks are small, imperceptible to the naked eye, and parthenogenesis and fertility are strong, and can be flooded in a short period of time. The key to the prevention and control of rust ticks lies in early detection and early prevention. In the Gannan area, July to September is the peak period of rust tick hazards, and the monitoring of orchard insects should be strengthened in 5 to 7 months before the peak, early detection, and timely spray control. The iron wall lice prefer shade and fear light, and special attention should be paid to spraying the lower part of the canopy, the back of the leaf surface and the shade of the fruit when spraying control. High temperature drought is more conducive to the reproduction of rust ticks, and timely irrigation in the high temperature and drought midsummer can effectively control the occurrence of rust ticks.
Iron ticks
4. Whitefly
The main whitefeds that harm Gannan navel oranges are citrus whitefly and black spotted whitefly[3]. Adult whitefly and larvae gather on the back of young leaves to suck sap, inducing bituminous coal disease, which in severe cases causes leaf deformity and leaf fall, causing dead shoots. The control of whitefly should focus on the prevention and control of the first half of the year, focusing on the prevention and control of adult overwintering generations and nymphs of each generation. From April to May, the insect-like generation is relatively neat and the air humidity is large, which is conducive to the use of parasitic fungi, parasitic bees and other natural enemies to carry out centralized control of whitefly.
Whitefly
5. Huanglong disease
Xanthalobacterium is a disease that is devastating to citrus crops caused by the infestation of Phloem bacillus. Phloem bacilli infect the tree body, destroy cells, tissues, organs, the diseased tree shows leaf mottled yellowing, uniform yellowing, defiant yellowing, the fruit appears green fruit, red nose fruit. The bacteria are transported to the whole plant with the sieve tube, and the whole tree body decays, causing disease and death. Yellow dragon disease is mainly transmitted by citrus lice, but can also be transmitted by grafting and silk seeds. Gannan area is the Epidemic Area of Huanglong Disease, and the prevention and control of Huanglong disease is mainly based on prevention: strict plant quarantine, establishment of disease-free nurseries, cultivation of disease-free seedlings, strict prevention of disease-ridden seedlings and diseased fruit output; do a good job in prevention and control; timely inventory of orchards, discover the body of diseased trees, dig up in time, and prevent infection.
Mottled yellowish new shoots and blue-nosed red-nosed fruit
6. Ulcer disease
Canker disease is a bacterial disease, mainly harmful to the young leaves, young shoots and young fruits of the navel orange. The dorsal surface of the affected leaf first appears with a needle tip-sized thick yellow spot, and then the front and back surfaces bulge into a volcanic opening with a yellow-brown halo, nearly round, wood-bolted diseased spot. The spots on the treetops and fruits are similar to the leaves, but the degree of wood embolization is higher, and the central volcanic opening is more pronounced. When the damage is severe, the leaves and fruits fall and the treetops die. Ulcer disease may occur in all stages of the navel orange tap, especially in the summer and autumn stages. The best time for the prevention and treatment of umbilical orange canker disease is the greening period of spring shoot leaves, the leaf spreading period and the young fruit stage of summer and autumn shoots. The prevention and treatment of ulcer disease is mainly based on the spraying of chemical pesticides. In addition, it is very important to do a good job in the prevention and control of pests such as leaf-diving moths and mites, reduce wounds, and enhance tree potential, which is very important for the prevention and control of canker disease.
Canker disease harms foliar influence photosynthesis and harms fruit to reduce commerciality
7. Anthrax
Anthrax is a disease caused by fungal infection, which harms the leaves, branches, flowers, fruits and stalks of navel oranges, often causing a large number of leaves, fruit fall, and branch death, which can cause the death of the whole plant in severe cases. During the storage and transportation of fruits, it will also cause a large amount of fruit rot. Anthrax is spread by wind, rain and insects. Winter drought frost damage is more severe, early spring low temperature, rainy can easily cause anthrax, weak trees are prone to disease, overripe, wounded fruits are easy to infect. The prevention and control of anthrax is mainly based on prevention: strengthen cultivation management, enhance tree potential, and improve disease resistance; do a good job in clearing the garden in winter, mainly removing diseases and insect branches and leaves, dead branches and leaves; strengthen fertilizer management, strengthen plastic pruning, and reduce the occurrence of diseases and insect pests.
Anthrax diseased leaves
8. Sand skin disease
Sand skin disease, also known as resin disease, black spot disease, is a fungal disease. Sharpie disease is mainly harmful to the leaves and fruits of navel oranges. Small, protruding black-brown particles appear on the surface of the leaves and peel. Sandskin disease is spread by wind, rain, insects, etc. Sand skin disease occurs under rainy and moderate temperature conditions. In the Gannan area, april to June and August to September are the more frequent periods of sand skin disease. In order to prevent and control sandbar disease, attention should be paid to strengthening production management, enhancing tree potential, and improving the disease resistance of trees; pay attention to antifreeze, drought and flooding, and sunburn to reduce damage and reduce the infestation of pathogens.
Illustration
Nine, the big fruit fly
Citrus fruit fly is commonly known as "maggots, maggots, maggots" is called differently from place to place. Here, the Chongqing area is called maggots. It is an international and domestic phytosanitary pest. If the prevention and control is not in place, its occurrence area is large, the harm loss is heavy, and it has caused huge economic losses to fruit farmers, and has become the first major pest in citrus production. Citrus fruit fly focuses on prevention. Several key steps in control are because citrus fruit flies are migratory quarantine pests, which spread quickly and are highly harmful but preventable and controllable. Secondly, the citrus fruit fly is to lay eggs in the citrus larvae, the larvae hatch in the fruit inside the wearing of the petal caused by the harm, the adult stage fruit tree does not show any harm, the control strategy should be based on prevention, the control method is to trap the poisoning of adult insects before spawning, combined with maggot treatment to reduce the insect mouth base the following year. Citrus fruit fly is a suction mouthpiece, strong ability to migrate, in the selection of poisoning adult insects, should be prepared with stomach poisoning, fumigation, touch killing effect of chemical pesticides. Therefore, the following aspects are generally used for prevention and control.
1. Ground sealing: In the peak period of overwintering adult feathering (generally in early and mid-May), do a good job of ground sealing, and use ground spray (recommended as insecticide by relevant departments) on the ground in the canopy of citrus trees with a large amount of fruit fall to poison and kill the adult insects unearthed by feathering.
2, spray poisoning: according to the citrus fruit fly is a suction mouthpiece, feathering after the excavation needs to take food supplement nutrition and other living habits. In the selection of medicine, 2-3 kinds are also prepared for gastric poisoning, fumigation, and touch killing.
3, the treatment of unripe yellow fruit, ground fruit: from the end of September, to the orchard to remove the "unripe first yellow", "yellow with red" fruit and pick up the ground fruit, and then add 56% aluminum phosphide tablets with a large plastic bag sealed, time 2-3 months, kill the larvae in the fruit, pay attention to the plastic bag to paste a warning sign.
4. Winter ploughing, eliminating winter pupae: combined with winter pruning and clearing the garden, ploughing and fertilizing, deep ploughing of the garden soil in late winter and early spring, increasing the mechanical casualties of pupae or dying due to changing its overwintering position and not being suitable for survival; eliminate some of the overwintering pupae in the 10-15 cm tillage layer on the surface.
Diagram of the growth stages of the citrus giant fruit fly