Citrus is an evergreen fruit tree, with a long growth period, many types of diseases and insect pests, and a large number of sprays throughout the year, which is easy to cause increased resistance, reduced natural enemies, and sharp increase in drug costs and pesticide residues. After the winter, all kinds of diseases and insects that harm citrus, such as scabs, anthrax, leafminer moths, mites, mesotopes and leaf curl moths, have entered the overwintering period of comprehensive decline from the peak period, and are also the weak links in the life history of various diseases and insects.
The main types of pests and diseases and control indicators
The main species of citrus winter pests and diseases are citrus red spider, rust tick, wood lice, whitefly, leaf curl moth, mesozoan, canker disease, anthrax, resin disease and so on. All localities should carry out targeted pest control in light of local actual conditions and according to the occurrence of diseases and insects.
1 pest article
Red spider: mainly harmful to leaves, branches and fruits, with pale spots on the front of the affected leaves and on the surface of the fruit. When there are 2-3 insects and eggs on each leaf (fruit), it is the key control period.
Rust ticks: mainly harmful to leaves and fruits. Commonly known as "black peel fruit". When there are 2 to 3 insects on the leaf back and fruit surface, or when gray mold is seen, spray control begins in time.
Mesophyllus: mainly harmful to branches and leaves, the affected leaves turn yellow, the branches are rough and uneven, when the nymphs, especially the first instar nymphs, are in full bloom, it is the appropriate period for control.
Whitefly: Mainly harmful to the leaves, larvae clustered on the back of the leaves to suck sap, after harming the young citrus shoots, induce bituminous coal disease. It causes the branches and leaves to turn black, die and fall off, affecting the tree posture and yield.
2 Diseases
Anthrax: mainly harmful to leaves, branches, spots on the black dots, winter attention to focus on the prevention and control of autumn shoots and late autumn anthrax.
Resin disease: mainly harmful to the branches and leaves of citrus, which occurs on the branches is called resin disease, and what occurs on the leaves and young fruits is called sharpened disease. After the damage of citrus trunks, it affects the tree potential, especially after being frost damaged, there is a risk of causing a large occurrence of resin disease, the loss is greater, the impact on the next year's yield is great, and the whole plant dies after spring in severe cases.
Canker disease: mainly harmful to the leaves, the spots penetrate the front and back sides of the leaves, forming a crater crack. The disease is very easy to invade from the wound, and the onset of spring shoots is the most serious.
Winter pest control time in citrus groves
The main period is from the citrus fruit harvest (November to early December) to March before the buds sprout in the following spring. In this period, the diseases and insect pests have entered the dormant period, the tree body resistance is extremely high, the resistance to diseases and insect pests is reduced, and through a variety of control methods and increased drug concentrations, the general control effect is good, which can greatly reduce the source of overwintering insects, and play a multiplier effect for the control of diseases and insects in the next year.
Suitable for winter prevention and control technology 1 clear garden
Doing a good job in clearing the garden in winter is an effective measure to remove the source of diseases and insects in the coming year and reduce the incidence of the next year. Combined with winter pruning, we cut off the branches and leaves of diseased insects, focusing on the removal of diseased leaves, dead branches and residual fruits of mesozoites, branch cattle, anthrax, canker disease. The diseased branches, leaves, and residual fruits that are removed should be burned in a concentrated manner. And remove the branches and moss and lichens on the ground. For Huanglong disease strains, all symptoms that are obvious should be resolutely removed to reduce the source of incidence in the next year.
2 trimming
Winter pruning work should be strengthened. The dead branches, diseased branches, and weak branches of the citrus tree are all pruned, and the cut branches are intensively treated and burned. For diseased insect branches that cannot be cut, such as resin disease and foot rot that occur on the trunk, tianniu and gidding insects are hidden under the trunk bark, and it is necessary to scrape, completely scrape the diseased skin and old bark, kill the tianniu and gidding insects with an iron hook, disinfect the wound with 75% alcohol, and coat it with Bordeaux liquid or stone sulfur compound for wound protection. Clay and water are used to form a mud mass and an appropriate amount of chemicals such as enemy insects are added to block the holes of borer pests such as tianniu.
3 trunks painted white
1.5 kg of lime, 0.2 kg of salt, 0.3 kg of sulfur powder, mixed into a paste, formulated into a whitening agent, painted on the trunk on a sunny day. The height of the brush is preferably under the first main branch, which can eliminate the diseases and insects hidden on the trunk of the tree for overwintering. After whitening, it can also use the reflection of light to reduce the temperature difference between day and night in the tree and avoid frost damage to the trunk.
4 The whole garden is deeply turned
By turning the whole garden deep, some larvae and pupae such as overwintering bud maggots, elephant beetles or large fruit flies can be killed in the soil. After clearing the garden in winter, combine the application of organic fertilizer to carry out a deep turn, turn 20-30 cm deep on the periphery of the canopy, cut off a small number of old roots, promote new roots, and loosen and mature the soil. For the red and yellow loam soils with acidic soils, 50-100 kg of lime per mu were sprinkled in the whole garden before deep turning, which neutralized the pH value and increased the calcium nutrients of the soil, effectively preventing the occurrence of physiological glue disease.
5 pharmaceutical control
The first time: rough garden, after fruit picking, spray 45% crystal stone sulfur compound 150 times liquid, sterilization and mites.
Second time: after pruning, you can choose 99% mineral oil emulsion, 95% motor oil emulsion 100 to 150 times liquid, pine resin compound 8 to 10 times liquid, or sodium thiolinate water agent, sprayed alone.
The third time: before the spring buds are about to germinate, they can be sprayed with 73% g mite emulsion 1200 to 1500 times liquid.
Precautions
(1) After spraying, the stone sulfur compound should be sprayed 15 days apart before the mineral oil agent can be sprayed.
(2) When clearing the garden, choose to carry out when the weather is clear, carefully and comprehensively spray the leaf back and shaded branches, and take personal protective measures to avoid drug poisoning.
(3) Orchards with more diseases should be added with other fungicides, and organophosphorus agents can also be added to prevent insect pests.
Ulcer disease is more serious: you can use zinc thiazole + zinc manganese zinc or imidamine + chlorpyrifos + foliar fertilizer, pay attention to first shear and then spray, if the incidence is more than 30%, it is recommended that the whole garden be destroyed.
Gravel disease and macular disease are more severe: phenyleth methylcyclazole propiconazole + zinc manganese + chlorpyrifos + ethanazole + foliar fertilizer can be used.
Moss and soot disease are more serious: allicin + permethrin agents + alkyne mite + foliar fertilizer can be used.
(4) In addition to the garden where ulcer disease occurs heavily, when clearing the garden, it is necessary to pay attention to spraying first and then cutting and then spraying to achieve the effect of completely clearing the garden.