Thin-shelled pecans are the main pests and pests and their comprehensive prevention and control technologies
Yang Yanzhong Yang Xutao
Carya illinoinensis is a species of pecan in the walnut family, which is a well-known high-grade dried fruit, oil tree species and wood fruit combined with excellent tree species, because of its tall and straight tree body, beautiful tree shape, but also has the potential for development of urban landscaping tree species. The thin-shell pecan industry in Chuzhou City has developed rapidly, but diseases and insect pests such as Tianniu, scarab beetle and black spot disease have occurred one after another, which has seriously affected the yield, quality and efficiency of thin-shelled pecans. In order to effectively carry out the green prevention and control work of thin-shelled pecan orchards, this paper discusses its occurrence law and green prevention and control methods.
1 Types and quantities of major pests and diseases
Relevant reports show that the thin-shelled pecan pest totals 60 species in 6 orders and 34 families, with the most abundant leaf-eating pest species and the second dry moth pest. Among them, Phylloxera notabilis Pergande, Anoplophora chi⁃nensis, and Sphecodoptera sheni (Sphecodoptera sheni) are the main pests of thin-shelled hickory seedling, juvenile and large tree stages, respectively. From 2013 to 2018, the author conducted a pest survey of 2-5 year old thin-shelled pecan forests and scattered trees in Chuzhou City, Anhui Province, and found that six kinds of diseases and insect pests, including black spot disease, brown spot disease, scarab beetle, stinging moth, American white moth, and Xingtian cow, were more harmful.
2 Major diseases
2.1 Nigra
2.1.1 Symptoms Black spot disease mainly harms the leaves, fruits and shoots of thin-shelled pecans. When the black spot disease harms the young fruit, the surface of the diseased fruit produces small black-brown spots, the spots gradually sink and expand, turn into a near-circle irregular shape, the color gradually deepens, and the water-stained halo appears on the periphery of the spots, rotting from the inside to the outside; when the black spot disease harms the leaves, small black spots will appear at the forks of the leaf veins and leaf veins, gradually expanding, and the outer edge of the spots is translucent halos.
2.1.2 Occurrence Of black spot disease usually occurs under conditions of high temperature and humidity. Pathogenic bacteria mainly overwinter in diseased branches, fruits, germs and insects, and produce spores on diseased spots when the temperature rises in mid-to-late March. Germs emerge in the following spring and spread to the leaves, fruits and branches through wind, rain, insects, diseased pollen and human activities. Germs invade natural orifices such as stomata, skin pores, honey glands, stigmas, etc., and can also invade from various wounds.
2.1.3 Prevention and control measures Select fine varieties with strong disease resistance, and have been approved (identified) by the Forest Tree Seed Approval Committee and are suitable for planting in the region, such as Boni, Mahan, Huangbo No. 1, Huangbo No. 2, YLJ023, YLJ042, etc. Chemical control is generally sprayed from mid-April to mid-June, with mild diseased strains sprayed 1 to 2 times and moderate diseased strains 2 to 3 times. The selected agents are pentrazole, humus, etc., and other triazole fungicides and their compounds can also be selected.
2.2 Brown spot disease
2.2.1 Symptoms The occurrence of brown spot disease mainly harms leaves, young shoots and fruits. At the beginning of leaf infection, there will be nearly round or irregular gray-brown spots, and when the diseased leaves are severe, they will scorch and die, and the leaves will fall early. When the young shoots are onset, long or irregularly shaped slightly sunken brown spots appear, and in severe cases, the spots surround the branches and cause the upper part to die. At the time of victimization, the epidermis first appeared small and slightly raised brown soft spots, which then rapidly expanded and gradually became black, and the kernels became black and decayed.
2.2.2 Occurrence Of pathogenic bacteria overwintering in conidia on the leaves and branches of the affected thin-shelled pecan. Leaves and shoots can still produce spores under suitable temperature and humidity conditions after overwintering, and they are spread with wind and rain. The fruit is susceptible to infection by pathogens before forming a hard core, and the onset of disease is more severe during the rainy season.
2.2.3 Prevention and control measures Before the onset of illness, dilute and spray with 500 to 800 times of origacin, and use the drug once every 15 days. At mild onset, spray with Auric Liangguoan 500 times liquid, spray once in 7 to 10 days. If the condition is severe, spray with 300 times the liquid of the fast net and take the drug once in 3 days.
3 Major pests
3.1 Scarab beetles
3.1.1 Life history and occurrence of scarab beetles belong to the insect family Coleoptera, the most common is the patina (Anomala corpulenta), the larvae are called grubs, commonly known as silkworms, about 3 to 4 mm long, milky white, body fat, and bent into a "C" shape to the ventral surface. Normally, one generation occurs every year, with larvae overwintering in the soil, emerging as adults in early May of the following year, peaking in late May. Usually, trees are damaged at dusk, and after midnight they leave one after another, dive into grass or loose soil, and lay eggs in the soil. Adult insects are clustered, suspended to death, phototropic, and are most harmful on sweltering and windless nights. The adults feed on the leaves of the leaves, and at the peak of the occurrence, all the leaves are eaten, and only the reticular veins remain. The larvae can directly bite off the roots and stems of thin-shelled pecan seedlings, resulting in dead seedlings; or nibble on the thin-shelled hickory root system, making the plant growth weak.
3.1.2 Prevention and control measures Booby traps using night lights. Or use the adult pseudo-death to beat the trunk at 7-9 o'clock in the evening to shock the insects, and use plastic sheets under the tree to concentrate on eliminating the insects. Spray the foliage with 0.4% of the insects in the evening during the peak of adult pests (June-July). After mixing 50 kg of seeds with 50% octyl thiophosphate emulsion oil or mixing 1 kg of slag, the 5% poisonous sand made is sprinkled into the sowing ditch with the seeds to poison the larvae.
3.2 Thorn moths
3.2.1 Life history and occurrence of thin-shelled pecans are mainly caused by three species, including the yellow-spined moth (Cnidocampa flavescen), the brown thorn moth (Setora postorna⁃ta) and the two-toothed green thorn moth (Latoia hilarata Staudinger), which are mainly damaged by larvae. Holes, missing or only petioles and main veins may appear on the leaves, affecting tree growth potential and fruit yield. The stinging moth generally occurs in 2 generations per year, and the old mature larvae overwinter in the soil near the trunk, branches and trunks of the host tree. Mid-June is the peak of feathering of the first generation of adult insects, and early to mid-August is the peak of feathering of the second generation of adult insects. The first generation of larvae is harmful from late June to early July, and the second generation of larvae is at its peak from mid-August to mid-September.
3.2.2 Prevention and control measures Using the phototropism of adult insects, black light lamps are used to trap adult insects during the feathering of adults to reduce the density of insect populations. In the late June and mid-August larval infestation periods, spray 25% urea no. 3 1500 to 2000 times liquid, 4.5% cypermethrin 2000 times liquid or 10% insecticidal 4000 times liquid to control larvae. In winter, combined with plastic pruning and whitening of the trunk, the overwintering cocoons in the soil near the trunk, branches and trunks are manually uprooted to reduce the source of insects.
3.3 American white moth
3.3.1 Life history and occurrence of the American white moth (Hyphantria cunea (Drury)) also known as autumn curtain caterpillar, mesh curtain caterpillar, belongs to the lepidoptera lamp moth genus, generally occurs in 3 generations a year, to pupate under the bark or the ground where the dead branches and leaves overwinter. Adults are pure white and have a body length of 9 to 15 mm. The mature larvae are 28 to 35 mm long and have a wide longitudinal band of dark brown to black on the back. Adult insects feather in Chuzhou City around April 20 every year, and the larvae appear in early May, because the first generation of insects is relatively neat in age, which is the best control period for the American white moth. After the larvae hatch, they spit out a silk knotted net, and the cluster net feeds on the leaves, like a layer of white yarn wrapped around the leaves, and after the leaves are eaten, the larvae move to the branches and other parts of the young branches to weave a new net. The larvae encroach on the leaves, leaving only the veins of the leaves, causing the tree to grow poorly, or even the whole plant to die.
3.3.2 Prevention and control measures Strengthen plant quarantine and increase the re-inspection of the transfer of diseased wood from the white moth-infected areas of the United States. Taking advantage of the phototropism of adult insects, 1 insecticidal lamp is hung every 100m to trap adult insects. From late April onwards, 1 sex trap is suspended every 100 m to trap the overwintering adults. And the insecticidal lights should be staggered apart to hang, so as not to affect the effect of insect attraction. Using the characteristics of clusters of 1-3 instar larvae, they have been manually cut off from May and burned intensively behind the scenes. From late May to early June, larval urea or 20% chlorhexabenzamide (Kangkuan) were sprayed in the form of aircraft control or ground control to control the 1st generation of 3-4 instar larvae.
3.4 Star Celestial Bull
3.4.1 Life history and occurrence rules Anoplophora chinen⁃sis belongs to the insect family Coleoptera, Chuzhou City generally occurs in 1 generation per year, the larvae normally overwinter in the xylem; adults begin to appear in late April, and June is the peak period; adults begin to lay eggs in early June, and late June to mid-July is the peak spawning period. The hatching larvae begin to moth into the tree from late June to July, overwinter from late September to early October, and the larvae begin to pupate and feed in late March of the following spring. After feathering, the adults bite the petioles, leaves, and twig cortex of thin-shelled pelars, and the damaged areas are black-brown, discharging brown powdery feces and wood chips, which gradually moth into the xylem. The older larvae feed mainly on the trunk and roots near the ground, blocking the nutrient delivery of the tree, and the tree body declines, which can cause the death of the whole plant in severe cases.
3.4.2 Prevention and control measures (1) Whitening of the trunk. Taking advantage of the spawning habit of adult Xingtian cattle in the lower part of the main trunk, the preparation of lime sulfur whitening agent or stone sulfur compound quicklime whitening agent is applied to the thin shell pecan trunk below 100 cm until the ground. (2) Artificial hunting. Using adult habitat and suspended animation habits, adult insects are often checked to kill when they stop in the forest during the adult peak period from May to July. Branches can be shaken violently, and adults can fall off by suspending death. Regular inspections from July to September found that the cattle were carved into grooves or reddish-brown feces, scraped with a sharp knife or struck with a hammer or hooked with wires to kill the larvae. (3) Poisoning with drugs. From October to April of the following year, the inspection found that reddish-brown fecal debris and moth holes appeared around the trunk, and poison sticks were inserted into the borer holes or infused with inhalatory insecticides such as oxidized Leguo to kill the larvae in the moth tunnel. From the beginning of June to the end of August, the trunk and branches of the tree are sprayed with 100 to 200 times the liquid of green weer (cypermethrin microcapsules) to kill adult insects that supplement nutrition or lay eggs.
4 Comprehensive prevention and control technology
4.1 Agricultural measures Keep trees strong in accordance with the principle of suitable land for trees. Reasonable dense planting in the field, strengthen winter shaping and pruning, form a suitable forest stand closure, improve inter-forest ventilation and light transmission conditions, and establish a stand ecosystem with strong self-control ability. Timely clean up the field of diseased branches, zombie fruits, fallen leaves, fruit, etc., to reduce the source of field infestation.
4.2 Physical measures Use pests to booby trap or artificially capture light, color, taste, etc. The whole park is evenly arranged according to every 6670 ~10000m2 standard 1 frequency vibration insecticidal lamp or black light, according to every 667m2 standard evenly arranged 5 ~ 6 plates of sweet and sour liquid or white moth trap; between June and August to check whether there are carved grooves and wood chips or insect droppings in the lower part of the trunk, after finding, you can use a knife to scrape or wooden hammer to kill the Tianniu larvae; in August, cut the branches that do not die normally and destroy them; cut off the branches of diseased insects, sick fruits, scrape off the spots and warped skins in winter; artificially capture adult insects such as scarab beetles and tianniu at night or early in the morning In winter and in May-June, the lower part of the trunk is coated with stone sulfur compound or whitening to prevent pests from laying eggs on the tree and the tianniu.
4.3 Biological measures A control method of using beneficial organisms or other organisms to suppress or eliminate pests. After investigation, the natural enemies of pests and insects distributed in the thin-shelled hickory forest in Chuzhou City mainly include natural enemies such as the Lady beetle family, the step beetle family, the parasitic fly family and the ant family. Plant legumes or grasses such as clover, alfalfa, rye grass and other legumes or grasses in the garden to provide a habitat for natural enemies; raise poultry such as native chickens and ducks in an appropriate amount to feed pests such as scarab beetles, celestial cows, snails, and slugs; spray biological agents such as white zombie bacteria during the rainy season to achieve bacteriological control of insects; release parasitic and predatory natural enemies such as swollen leg bees, flower velvet parasitic nails, and Chinese knife mantises to control pests in the field.