Several common diseases and insect pests of sweet-scented osmanthus and their control knowledge

In the natural environment, sweet-scented osmanthus trees planted sporadically rarely have serious diseases and insect pests, so some people mistakenly think that sweet-scented osmanthus trees do not need plant protection. This is a wrong view. Although the species of diseases and insect pests that can cause the death of sweet-scented osmanthus trees are still not common, the diseases and insect pests that affect the growth of sweet-scented osmanthus and the yield of flowers are gradually increasing. Now many areas have listed sweet-scented osmanthus as a key economic tree species, the cultivation scale is getting larger and larger, people not only pay attention to its ecological benefits in landscaping, but also pay more attention to the economic benefits of its fresh flower production. Therefore, enough attention must be paid to the prevention and control of sweet-scented osmanthus diseases and insect pests.

(1) Diseases and their control

1. Sweet-scented osmanthus brown spot

The disease is caused by Cercospora of rhinoceros. Distributed in Shanghai, Jiangsu, Zhejiang, Guangdong, Shaanxi and other places.

(1) symptoms: at the beginning of the occurrence, there are some small maculae on the leaves, scattered, and gradually become yellowish brown to grayish brown near round spots, or irregular spots limited by the veins of the leaves, 2-3 mm in diameter, without obvious edges. There is a yellow halo on the outer edge. A large number of small gray-black mildew spots are produced on the front of the leaf. Disease spots can merge with each other to form large spots, resulting in leaf death.

(2) Control methods: select disease-free plants as breeding plants, strengthen cultivation management and enhance tree potential. Eliminate diseases and insects and reduce the source of infection. When the seedlings in the serious disease area come out of the nursery, 1000 times potassium permanganate solution can be sprayed for disinfection. During the onset of the disease, the patients were either sprayed with 1-200 Bordeaux solution, or treated with 1000-1500 times of 50% benzoate wettable powder, or 1000 times of 50% benzoate wettable powder, or 65% of Dysen zinc wettable powder.

two。 Osmanthus fragrans leaf spot

The disease is caused by the leaf spot mold of the mignonette. The disease occurred in various producing areas of sweet-scented osmanthus, such as Jiangsu, Zhejiang, Shanghai, Hubei, Guangxi and other provinces and cities.

(1) symptoms: the pathogen mostly invaded from the leaf edge or leaf tip, and the spot was yellowish green at first, then gradually expanded, grayish brown to gray, irregular or nearly round in shape, and the edge was obvious. In the later stage, there are many black spots on the disease spot, that is, the conidium of the pathogen. The damage of the lower part of the crown is often more serious than that of the top, and the disease of the old leaf is more serious than that of the new leaf.

(2) Prevention and control methods: remove diseased leaves in winter, burn and bury them, clean the countryside, and reduce the source of overwintering disease. Strengthen cultivation management and increase fertilizer application. When the weather is dry and hot, it should be properly watered to strengthen the tree potential and improve disease resistance.

3. Sweet-scented osmanthus coal pollution disease

The disease is caused by a variety of fungi, including citrus soot, stinging soot and Butler small soot. The disease is widely distributed, almost everywhere, not only to sweet-scented osmanthus, but also to citrus, tea and many other plants.

(1) symptoms: the symptoms caused by different pathogens of coal soot of sweet-scented osmanthus are also different. For example, the coal stain of soot is black thin paper, which is easy to tear off or fall off naturally; the coal stain of soot is black like pot bottom ash, and if it is wiped off with fingers, the leaf surface is still green; the mildew layer of small soot is radiant mildew spot, scattered on the leaf surface and leaf back, because its hyphae can absorb spores and can be attached to the host surface, so it is not easy to fall off. When the coal pollution disease is serious, the thick black mildew layer covers the mature leaves and branches of the whole tree, hinders the photosynthesis of leaves, inhibits the growth of new shoots, turns diseased leaves into yellow wilt, falls leaves early, and reduces ornamental value and flower yield.

(2) Control methods: the key to the prevention and control of this disease is to control pests (see pest section for specific methods). In the maintenance and management, it is necessary to prune properly, remove weeds, improve ventilation and light transmission, and enhance the tree potential in order to reduce the degree of disease. Chemical control: 2% ferrous sulfate solution or 50% carbendazim 1000-15000 times, 50% carbendazim wettable powder 1000 times solution have good control effect. For coal pollution caused by soot, copper soap solution (0.5 kg of copper sulfate, 2 kg of turpentine mixture and 200 kg of water) can be sprayed 2-3 times from June to July.

4. Osmanthus fragrans algal spot

(1) symptoms: the disease spot can appear on both positive and negative sides of the leaf, but mainly in the front. At first, white to yellowish-brown needle-sized dots are produced on the leaf surface. Sometimes the dots are arranged in a cross shape, and then radiate around to form a near-round or irregular slightly raised felt, with a fibrous texture, irregular edges, grayish green or yellowish brown, and a diameter of 1-10 mm. The later color is darker and the surface is smooth. It usually occurs more in the middle and lower parts of the plant, and less in the young leaves in the upper part. After the plant is killed, it affects photosynthesis, and in serious cases, it can peel off or wither the cortex of the branches.

(2) Prevention and control methods: reasonable fertilization, drainage, proper pruning, cleaning of rural weeds, strengthening maintenance and management can reduce the occurrence of the disease to a certain extent. Spraying 75% chlorothalonil wettable powder 800-1000 times before the onset of early spring has a good preventive effect on the disease. In places where the disease is serious, it can be sprayed once in late autumn, which has a certain effect on reducing the incidence of the following year.

5. Root knot nematode disease of sweet-scented osmanthus

The disease is caused by southern root-knot nematode. The disease usually occurs in cutting seedlings of sweet-scented osmanthus, especially in 1-2-year-old seedlings, and sometimes the incidence is as high as 90%.

(1) symptoms: root-knot nematodes mainly damage the roots and initially form many root nodules of different sizes. The fibrous root of the diseased plant decreased and the root tip was enlarged. The nodules were yellowish white at first, then gradually turned brown and rotted. The growth of the aboveground part is weak and it is easy to die under drought conditions. Slightly damaged plants generally show no symptoms, but with the extension of plant cultivation years, the number of nematodes continues to increase, which is similar to the symptoms of fertilizer deficiency and drought, such as growth decline, yellowing, dwarfism and so on. therefore, the quilt is often mistakenly thought to be caused by lack of water and less fertilizer.

(2) Prevention and control methods: do a good job in plant quarantine, do not introduce seedlings from the affected areas. For the suspicious seedbed soil, use 10% gram line Dan granule to control, every 666.6 square meters with 400 grams of active ingredient, when applying, first remove the soil 3-5 cm deep under the crown, apply the medicine evenly, and then cover the soil. During the growing period, 10% limanku granules of 3-5 kg are applied every 666.6 square meters, which should be applied around the rhizosphere and can be applied in ditches, holes or sprinkles. Strengthen cultivation management and increase the application of organic fertilizers (because actinomycetes in organic fertilizers have some inhibitory effects on the growth of nematodes). Crop rotation should be carried out for more than three years in the affected area. The first use of disease-resistant rootstock varieties can often get a good preventive effect.

6. Purple feather disease of sweet-scented osmanthus

The disease is caused by Bordetella purpurea. The distribution of the disease is very common, and there are many kinds of killed plants. In recent years, it has caused devastating disasters in nurseries in some areas of Guizhou, and it is also quite common in sweet-scented osmanthus producing areas such as Suzhou, Hangzhou and Guilin.

(1) symptoms: the disease usually occurs in April, and the damage is serious from May to August. The leaves of diseased trees are light green and the new shoots are thin and weak. The underground young roots suffer first, and gradually spread to the thick lateral roots and main roots. At the beginning of the disease, the root skin loses its luster, then turns yellowish brown, and finally becomes dark brown. In severe cases, the cortex decays, leaving only cork and xylem separated from each other, and the surface of the root is wrapped with purple rhizomatous fungal cord. In the rainy season, the mycelium can spread to the neck of the root or the base of the stem, and sometimes even to the surface of the soil, forming a purplish red mycelium.

(2) Prevention and control methods: select sandy loam with good drainage to raise seedlings, and use pressing seedlings or cuttings can reduce the incidence of disease. The quarantine work should be paid attention to when the seedlings are transferred. The infected sweet-scented osmanthus trees should pick the soil to dry their roots in spring, remove all the soil under the crown and expose the root necks. After 10-15 days, each tree should apply 5-7.5kg of fully fermented "5406" bacterial fertilizer, or irrigate 2.5% ferrous sulfate solution. Then cover the soil, and the original diseased soil should be dug out. The soil in the serious disease area can be disinfected with furanbendazole or 50% carbendazim (5-10 grams per square meter), or spread on the root of the diseased plant with 50% carbendazol 250-300 times or Baume 5-degree stone-sulfur mixture. Pay attention to drainage, loosening the soil and increasing the application of organic fertilizer, which can reduce the harm of the disease to a certain extent. There are many kinds of diseases that lead to root rot of sweet-scented osmanthus, and their symptoms and incidence environment are often similar to purple plume, so the prevention and control methods can also refer to the methods of purple plume.

7. Iron deficiency of sweet-scented osmanthus

(1) symptoms: iron is a trace element. When sweet-scented osmanthus is deficient in iron, it first affects the formation of chlorophyll, especially the chlorosis between the veins of young leaves. During mild iron deficiency, the area near the leaf vein remains green, while the part far away from the leaf vein begins to yellowing. In serious cases, young and old leaves become yellow and white males, and some old leaves can also appear yellowish-brown necrotic spots, and are often attacked by some weak parasitic bacteria, resulting in early defoliation. Osmanthus fragrans, which suffer from iron deficiency, generally cannot blossom.

(2) Control methods: the prevention and treatment of the disease is mainly the use of chemicals to improve the properties of the soil. During the shoot growth period, 0.2% Mel 0.5% ferrous sulfate solution is sprayed on the leaves once a month, which is very effective. 2-3 days after spraying, the yellow leaves can turn green, but sometimes the effect can not last. Some parks put 0.1% ferrous sulfate solution in a salt bottle and put it upside down on the tree trunk. Slow drip irrigation is made by injecting needles inserted into the bark (the same method as doctors use droplet salt water). The effect is better, but the procedure is more troublesome. If the complex urea iron or ferrous sulfate is mixed with acidic organic fertilizer, the method is simple and easy to be effective in the soil with low alkalinity. The latest technology is to apply the highly stable crab iron Fe-EDTA (ethylenediamine tetraacetic acid iron) in the soil, with 20-40 grams per plant, which is quick and long-lasting. In addition, 0.1% concentration of crab iron solution can also be used for foliar spray, leaf color recovery faster, but not excessive, so as to avoid drug damage. Improve the soil, in the spring drought, pay attention to irrigation alkali. In low-lying areas, salt water should be removed in time to reduce soil salt content. Increasing the application of organic fertilizer, intercropping green manure under trees, increasing humus in soil, improving soil structure and physical and chemical properties have a certain effect on preventing and reducing the occurrence of this disease.

At present, the more ideal corrective measure of iron deficiency is to select a suitable variety of rootstock, or to carry out trunk or root grafting to change the variety of rootstock.

(2) insect pests and their control

1. Tetranychus citri

(1) Morphology: female adult mites are widely oval, dorsal protuberant, dark red or purplish red, tumor on the back, upper white setae, 4 pairs of feet, claw-shaped, well-developed inter-claw process. The male adult mite body is slightly smaller than the female adult mite, the ventral end is slightly pointed, into a diamond, the body is bright red or brown, the foot is longer, 4 pairs.

(2) Control methods: the control of adult trees should be strengthened in early spring and late autumn, and the prevention and control work in winter should be strengthened in nursery and young trees in addition to spring and autumn. The comprehensive control method must be adopted for citrus panonychus, that is, the principle of chemical control should be taken in the early stage, natural enemies should be protected and utilized in the later stage, conservation and management should be strengthened throughout the year and tree potential should be enhanced. In winter, 20% acarate wettable powder can be sprayed 600-800 times, which is effective. The mixture of stone and sulfur is safe to prey on mites with 1-2 Baume in winter and 0.3-0.5 in spring. In the first ten days of April, 20% dimethoate, or 40% omethoate, or 75% phoxim, or 280% dichlorvos, or 20% diformamidine emulsion can be sprayed once a week for 2-3 times, with an effect on both adult mites and young leeches. In recent years, the promotion of 73% carotene EC 4000, the efficacy can be maintained for about 24 days, the effect is good. When the suitable pesticide is not available for a while, spray type 20 clothing powder on the right (300-500 times liquid in summer), and sometimes the control effect is good. Pyrethroid pesticides should not be used in the control of this mite, because the killing effect of these pesticides on citrus Tetranychus panonychus is not ideal, and the drugs should be used alternately, which can not only improve the acaricidal effect, but also avoid drug resistance. The effect of applying omethoate in the root zone of young plants is also good, which can not only kill mites, but also protect natural enemies.

two。 Osmanthus fragrans

The main results are as follows: (1) Morphology: most of the front and rear wings are black, the front wing has 3 lines of yellow spots along the outer edge, and there are 3 yellow spots in the middle chamber. The hind wing has the same markings as the forewing. The head, chest and antennae are black, feet and abdomen are yellowish gray, with several black stripes.

(2) Control methods: in the larval stage and pupation stage, the sweet-scented osmanthus plants are often inspected and removed in time once the larvae and kidneys are found. In the larval stage, it can be sprayed with 1000 times of dichlorvos EC or 80-1000 times of trichlorfon.

3. Bemisia Tabaci

(1) shape: yellow, covered with white wax powder. The wings are translucent and covered with white wax powder. The compound eye is reddish brown, divided into upper and lower parts, with a small eye connected.

(2) Prevention and control methods: proper pruning, improving ventilation and light penetration, can reduce the damage. During the peak period of adult occurrence or when the larvae are hatched in large numbers, 40% omethoate EC, 50% malathion EC, 50% insecticidal EC, 25% imidophos EC 1000 times, 90% trichlorfon 1000 times, 80% dichlorvos 1500 times, 25% quinathion EC 1000 times, 20% diformamidine EC 1500 times, 25% parathion powder 2000-3000 times. Recently, it has been reported that spraying 2-3 times during the peak incubation period of eggs, 2.5% of the enemy kills EC with water 5000 times, and the control effect is the best.

White whitefly adults have a strong tendency to yellow, so yellow wood or plastic boards can be planted next to sweet-scented osmanthus trees, and sticky oil can be applied to the yellow plates to vibrate the branches of sweet-scented osmanthus, so as to make the adults fly and stick to the yellow plates to trap and kill them. it has a certain effect on controlling its damage. In addition, the use of small vacuum cleaners (such as special car vacuum cleaners), the adult period of continuous suction for several times, can completely control its harm.

Knowledge of identification and control of main diseases and insect pests in planting sweet-scented osmanthus trees

This paper tries to make a general introduction to the occurrence characteristics, identification methods and control measures of common and serious diseases and insect pests in the cultivation of sweet-scented osmanthus.

1. Identification and control of main diseases of sweet-scented osmanthus, the main diseases of sweet-scented osmanthus include Sujin peach coral anthracnose, Fusang anthracnose, orchid anthracnose, sweet-scented osmanthus anthracnose (Hefei, Chuzhou, Huangshan), Jinbian Ruixiang coal pollution, gardenia coal fouling, camellia algal spot (Hefei), sweet-scented osmanthus leaf blight, sweet-scented osmanthus pseudocercospora brown spot (Hefei, Chuzhou, Wuhu, Huangshan), sweet-scented osmanthus red spot (Hefei, Wuhu, Huangshan) Chuzhou, Huangshan), sweet-scented osmanthus shell needle leaf spot, sweet-scented osmanthus shell two-spore leaf spot (Huangshan city), sweet-scented osmanthus shell leaf spot disease (Huangshan city), sweet-scented osmanthus disc single hairy spore brown spot disease, sweet-scented osmanthus stem spot disease (Huangshan city), sweet-scented osmanthus big stem spot mildew brown spot, sweet-scented osmanthus Alternaria leaf spot disease (Huangshan city), sunburn disease, root knot nematode disease, cancer disease and so on. Among them, brown spot and leaf blight are the most serious and common.

1. Leaf spot

The disease spot occurs on both sides of the leaf. at the beginning of the disease, only some scattered brown spots appear on the leaf surface, and in the later stage, the center of the disease spot is gray-white to light brown, the shape is similar to round or irregular, and in severe cases, several disease spots are combined together; the edge of the disease spot is reddish brown to dark brown, with a light brown halo, and there are a large number of small gray-black mildew spots scattered on the front of the leaf. these are the conidia and conidia of the pathogen. Leaf back disease is brown; as the disease spot gradually expands and merges into large patches, it often leads to a large number of leaf death and shedding, seriously affecting the normal growth and flowering of the plant.

The pathogen overwintered on diseased plants and fallen leaves with mycelia. When the temperature increased from April to June of the following year, new conidia were produced and spread by airflow and Rain Water to cause infection, followed by new conidia and re-infection. The disease can occur from April to October, and the disease in the old leaves is more serious than that in the young leaves. Jin Gui varieties are the most prone to disease, followed by Yin Gui varieties, Dan Gui varieties are not easy to occur; plants with weak plant growth or transplanting in the same year are prone to disease; under the conditions of soil consolidation, sticky weight and insufficient fertility, the disease is easy to occur; in the high-temperature and humid season from July to August, the disease can spread rapidly.

Control methods: strengthen water and fertilizer management, often loosen the soil, avoid soil stagnant water, promote plant growth and improve plant disease resistance; thoroughly remove diseased leaves in winter and burn them centrally to reduce the pathogen of overwintering, which can significantly inhibit the occurrence of the disease in the coming year; before sprouting and leaf hardening of sweet-scented osmanthus plants in spring, spraying a lime-doubling Bordeaux solution of 100 times lime every semimonthly can prevent the occurrence of the disease. At the initial stage of the disease, 50% polysulfide suspension was sprayed, or 50% carbendazim plus 75% chlorothalonil wettable powder, or 50% Dysen zinc wettable powder was sprayed with 5000 times of propiconazole EC, with an interval of 48 days. When the seedlings in the worst-hit areas come out of the nursery, 0.1% potassium permanganate solution can be sprayed for sterilization.

2. Leaf blight

It is said that leaf spot is an important disease of sweet-scented osmanthus.

It mainly harms the leaves, the disease class mostly starts from the leaf tip or leaf edge, the primary yellowish green or light brown spots, and then gradually expand, showing reddish brown to grayish brown, the shape is nearly round or irregular; the back color of the disease spot is lighter, the edge is dark brown; the disease spot is sometimes curly and brittle, and several disease spots can fuse with each other up to the leaf 1x2, color 1, or irregular large patches. In the later stage, there are many small black spots scattered on the disease spot, that is, the conidium of the pathogen. The disease can occur throughout the year, causing a large area of leaves to dry up, resulting in early shedding; the damage of leaves in the middle and lower part of the crown is more serious than that at the top, and the disease of old leaves is more serious than that of new leaves.

The pathogen overwintered on diseased leaves with mycelium and conidia, and infected by conidia when the temperature and humidity were suitable in spring, and spread by wind and rain, especially from July to November; when the temperature was 20 ℃, Rain Water was more or more humid, poor ventilation, insufficient fertilizer, weak tree or suffered frost injury and mechanical injury; when the climate was hot and dry, but not watered in time, the disease was aggravated.

Control methods: in late autumn and early winter, thoroughly remove diseased leaves and burn them or bury them deeply to reduce overwintering pathogens, which can effectively inhibit the occurrence of the disease in the coming year; seedlings transplanted or introduced should be removed and burned centrally, and 50% carbendazim wettable powder or 0.1% potassium permanganate solution can be sprayed on the seedlings before leaving the nursery to carry out sterilization if necessary. Strengthen management, apply more phosphorus and potash fertilizer, often loosen the soil and weed, prevent soil consolidation or stagnant water, and timely watering and spraying in case of high temperature and drought, so as to increase the disease resistance of sweet-scented osmanthus plants. In the seriously affected areas, starting from late June, 70% mancozeb wettable powder 500x solution, or 75% chlorothalonil wettable powder liquid 800x, or 1 2vl 100 lime multiple Bordeaux solution were sprayed every semimonthly for 4 consecutive times, and the control effect was good; it could also be sprayed with 5000 times propiconazole EC with an interval of 48 days.

3. Coal pollution disease

The main performance is that the leaves and dry branches are covered with a layer of gray-black powder with different colors, and sometimes even form a black film. The reason is that when aphids, scale insects, whitefly and other insects pierce and harm sweet-scented osmanthus, the excretion causes the parasitism of many kinds of fungi, which leads to black and gray coal fouling disease.

It usually occurs in hot and humid seasons and in muggy, humid, concealed and poorly ventilated environments. The gray-black coal dirt layer not only affects the ornamental of sweet-scented osmanthus plants, but also affects the photosynthesis of leaves, leads to poor plant growth, and causes susceptible leaves to yellowing and wilting and fall off ahead of time.

Control methods: strengthen the shaping and pruning of sweet-scented osmanthus plants to ensure that the inner chamber of the plant is ventilated and transparent, and promote the plant to grow well; when aphids, scale insects, whiteflies and other insects are found to harm sweet-scented osmanthus, they should be effectively controlled and killed in time; potted plants, often spray water to wash the leaves In the early stage of the disease, spraying branches and leaves with 50% methyl sulfur suspension 500 times liquid, or 50% carbendazim wettable agent 800 liquid, or 75% chlorothalonil wettable powder 500 liquid, has a better control effect.

4. Chlorosis

Iron deficiency chlorosis. If it is mild iron deficiency, it is characterized by chlorosis and yellowing between the veins of young leaves, and the tissue of leaf veins is still green; if it is severe iron deficiency, the new and old leaves are all yellowed, the young leaves slowly stop growing, and some old leaves appear yellow-brown spots. The plant can not grow and bloom normally, which seriously affects the ornamental effect and flower harvest.

The reason is:

First, because of the alkalinity of the soil, the planting plants

Second, due to the improper proportion of formula in the preparation of potted soil, the pH value of potted plants is out of balance.

Third, the sweet-scented osmanthus planted in urban and rural areas after demolition, due to the incomplete cleaning of the building residue.

Fourth, management errors, such as high pH value of irrigation water, resulting in the existence of iron in the soil in the form of insoluble iron hydroxide, which can not be absorbed by the root system of sweet-scented osmanthus.

Control methods: mild iron deficiency, 0.5% ferrous sulfate solution can be irrigated on the root, 0.2% ferrous sulfate solution can be sprayed on the leaf surface; when iron deficiency is serious, 20rel 40 grams of chelated iron [F-EDTA] can be applied to the soil around the rhizosphere of each sweet-scented osmanthus (including potted sweet-scented osmanthus), and 0.1% chelated iron solution can be used for foliar spraying. During the spring shoot growing season, 0.2% ferrous sulfate solution is used to spray leaves every semimonthly; when preparing pot culture soil, 0.5% ferrous sulfate solution can be used to adjust its pH below 6.5.

5. Dry rot

It mainly occurred on the newly transplanted sweet-scented osmanthus plants with larger size.

In landscaping or transplanting of sweet-scented osmanthus, due to bruising during digging, scratching during long-distance transportation, strangulation during hanging, accidental injury, etc., the trunk or large branch bark of sweet-scented osmanthus plant was seriously damaged, or a large piece of dry skin was removed, which could not be properly protected in time. Rain Water and sewage infected the wound, causing a large number of invasion and parasitism of fungi (such as wood rot fungi) and bacteria (such as soil wild bacilli, etc.). Resulting in decay in the wound, xylem exposure or the formation of cancer, resulting in poor plant growth, a large number of leaves falling off, big branches withered, serious will cause the death of the whole sweet-scented osmanthus.

Prevention and treatment: for small wounds on the trunk or branches, wound healing agent should be applied in time; for smaller wounds that have undergone local or a small amount of decay, the wound can be cleaned locally until fresh xylem and phloem are exposed, and then apply wound healing agent on the fresh wound, which can promote the wound healing as soon as possible. For the old wounds on the trunk where the phloem has been destroyed and the xylem exposed for many years, the decayed exposed xylem can be cleaned up, and the fresh wound can be protected by regularly applying stone-sulfur mixture or quickly applying it to the fresh wound after being adjusted with two-component "dolomite glue" every year. For the thick sweet-scented osmanthus plants that have formed holes in the trunk, you can first thoroughly remove the rotten parts, be careful not to destroy the isolation layer between the decayed xylem and the undecayed xylem, and fill the cavity with polyurethane foaming agent.

2. Identification and control of main insect pests in sweet-scented osmanthus the main species of sweet-scented osmanthus pests are diamondback moth, mites, scale insects, whitefly, frost moth, bag moth, wax cicada, short-forehead negative locust and so on. Among them, mites, scale insects and whitefly are the most serious and common.

1. Cinnabar spider mite

The main mites harmful to sweet-scented osmanthus are Tetranychus citrus and Tetranychus cinnabarinus, which have occurred seriously in all parts of the province in recent years. The adult mite of cinnabar spider mite is 0.5 Mel 0.6 mm long, the female mite is oval, scarlet to rust red, or dark brown to dark brown; the male mite is slightly rhomboid, yellowish, slightly smaller, with a body length of 0.3 mi 0.4 mm.

Egg, round, reddish to pink. The young mites are nearly round and translucent when they are hatched, and the body is dark green after feeding. Nymph mites are oval in shape and dark in color. In the south, adult mites, nymph mites and eggs overwinter on host plants and weeds. When the average temperature is above 7 ℃ in the next spring, adult mites, young mites and nymph mites tend to feed on the back of the leaves, and the eggs are mostly laid on both sides of the veins of the dorsal leaves or under the dense fine silk netting. Each female mite can lay 50,500 eggs in a lifetime. High temperature and drought season is most conducive to its occurrence, resulting in the whole plant or a piece of sweet-scented osmanthus forest leaves gray, seriously affecting the growth, flowering and display of sweet-scented osmanthus.

The optimum temperature for the occurrence of the insect is 25 ℃-30 ℃, and the best air relative humidity is 35% Mel 55%. Strong winds and torrential rains can wash away the worm and reduce the population density.

Control methods: protect natural enemies, such as small black ladybug, small flower bug, thrips, Chinese lacewings, large lacewings, etc.; remove weeds under trees and burn them in winter, and kill overwintering adult mites, nymph mites and eggs with stone sulfur mixture of 0.3mur0.5 Bomeo; spray with 1500 times solution of 25% Bleba (mainly triazoltin) at the initial stage of occurrence. Or it can be sprayed with 2000 times of 1% acarine EC (the main component is avermectin); in addition, pesticides such as thiazox, fenpropathrin and mites can be sprayed and killed.

2. Blow cotton scale

Scale insects harmful to sweet-scented osmanthus, there are red round scale, rattan round shield scale, red wax scale, brown soft wax scale, cotton blowing scale, furfural shield scale, Kao's white shield scale, snake eye scale, sagittal shield scale, Japanese white scale, orange cotton scale, oval shield scale, black spot shield scale, side several oyster shield scale, coconut shield scale and so on. Among them, the harm of cotton blowing scale, bran shield scale, Japanese white scale and orange scale is quite common.

The adult worm is 5mi 7mm long, the female is oval, orange-red, the ventral surface is flat, the back is raised, and it secretes a white oocyst at the rear of the abdomen before spawning, on which there are 16 longitudinal stripes; the male has a thin abdomen, about 3 mm long, black chest, orange-red abdomen, long and narrow forewings, black, and the hind wings degenerate into hooks. Egg, oval, 0.7 mm long, orange-red, concentrated in the oocyst of the female.

Nymph, oval, orange, covered with yellowish wax powder. Pupa, 3.5 mm long, orange-red, with yellowish brown fine hairs scattered on the body, covered with white waxy powder. Cocoon, long oval, white, composed of loose wax silk, externally coated with white wax powder.

Most of the female adults are fixed in one place, secreting white waxy oocysts at the end of the abdomen and laying eggs while secreting wax. The spawning period is more than 30 days, and each female can lay hundreds to 2000 eggs. There are few males and more parthenogenesis; the larvae disperse after hatching, and then transfer from the tender shoots and leaves to the branches to cause social harm, absorb tree sap and excrete honeydew, causing coal fouling disease. Due to the cross-harm of diseases, it often leads to yellowing leaves and wilting branches of sweet-scented osmanthus.

Prevention and control methods: usually use less pesticides to protect natural enemies; find a small number of worms and wipe them to death in time; spray 0.350 Baosulphur mixture in winter to kill overwintering pests; at the peak of egg incubation, spray with 2000 times of 15% propofol wettable powder, or 1500 times of 40% dimethoate EC, or 3000 times of 40% quick killing EC.

3. Tea bag moth

Pocket moths, also known as "hanging ghosts". The pocket moth pests that harm sweet-scented osmanthus include tea bag moth, big bag moth, small bag moth and so on.

What they have in common is that the worms are hidden in the bag, and the larvae and female adults eat the leaves and twigs, and when they are serious, the leaves of the whole plant can be eaten up. The high temperature and drought lasts for a long time, and the harm is more serious.

Tea bag moth, adult dioecious, female wingless, 12-16 mm long, maggot-shaped, obese, small head, a pair of spines; male, 11-15 mm in length, 22-30 mm in wingspan, dark brown in body and wings, with a transparent rectangular spot near the tip of the forewing and near the center of the outer edge; egg, oval, creamy white, about 0.8 mm long Larvae, mature larvae 10-26 mm in length, brown longitudinal bands on the subdorsal line of each thoracic segment and upper line of the middle and posterior thoracic throats, jade white between bands; pupa, female hammer-shaped, dark brown, head small, chest curved, body length 14-18 mm, male brown, body length 11-13 mm, abdominal bending is hooked, gluteal spine each pair Protective capsule, olive-shaped, dark brown, silky, capsule length up to 25-30 mm, outside the capsule affixed with branch skin fragments and truncated branchlets, parallel longitudinal cleft neatly.

The worm produces 2-3 generations a year and overwinters as mature larvae; the adults often Eclosion in the afternoon and mate the next night; the females remain in the sac after Eclosion, and the males fly close to the female sacs after Eclosion to mate; the eggs are laid in the sacs, and each female lays about 500 eggs; after hatching, the larvae crawl from the excretory hole of the protective cyst to the branches and leaves, spit and droop, spread to the surrounding hosts with the wind to feed, and make protective capsules with leaves and twigs connected with silk. When the larvae crawl and feed, the head and chest are exposed outside the capsule, and the protective capsule is hung on the abdomen; the feeding time is mostly in the early morning, evening or cloudy day, and it is rarely eaten at noon in sunny days; at the initial stage, the mesophyll is eaten, and the remaining epidermis is transparent spotted. With the increase of the age, the leaves can be eaten into holes and engraved, and the leaves of the whole plant can be eaten up and chewed on bark, flowers and fruits.

Prevention and control methods: remove the protective capsule manually, destroy the larvae, protect the natural enemies, trap and kill the adults with black light and frequency vibrating lamp, spray 1000 times of 2 billion / g cotton instar nuclear polyhedrosis virus suspension during the peak spawning period, and spray 1000 times of trichlorfon crystal, 1000 times of 40% dimethoate EC, 1000 times of 1.2% nicotine and 1000-2000 times of thiazuron 3 during the peak period of spawning.

3. Frost moth

The adult body is 45-50 mm long, the body wing is dark gray, mixed with frosty white powder; the wingspan is 90-130 mm, the chest dorsal plate has brown-like semicircular stripes, there are two brown wavy horizontal lines in the middle of the forewing, there are two black longitudinal lines below the middle chamber, and there is a black curve at the top of the wing; the hind wings are brown, and the outer edges of the front and rear wings are connected by small black and white squares.

Ovoid, globose, green at first birth, then yellow. Larvae, green, 75-96 mm long, light green on the head, green on the chest, 8-9 rows of particles arranged horizontally on the back, yellowish green on the abdomen, 7 white diagonal bands on the side of the body, brown brown on the tail, purple-brown granules on the tail, 12-13 mm long, brown on the valves, yellow-brown on the chest feet, green on the abdominal feet.

Pupa, reddish brown, 50-60 mm long. The insect occurs for three generations a year in the Yangtze River Basin, and overwinters as pupae in the soil. The overwintering moth period is from the first ten days of April to the last ten days of July, the first generation from mid to late July to the first ten days of September, and the second generation from mid to late September to early October. The adults live in the dark places of trees, branches and leaves, weeds, crops and houses during the day, fly out at dusk, mate and lay eggs at night, and have strong flying ability and strong phototaxis; the adults mostly lay eggs on the back of the leaves, and the newly hatched larvae feed on the surface of the leaves, nibble slightly on the leaves into gaps and holes, and even eat all the leaves, and the mature larvae are pupated.

Control methods: turn the soil in winter to kill overwintering pupae; kill adults with black light; frost moth larvae appear on a small amount of sweet-scented osmanthus single plant, which can be artificially killed; before the 3rd instar larvae, spray with 1000 times of trichlorfon crystals, 1000 times of 40% dimethoate EC and 10 billion / g of cyanobacterium spore powder.

4. Spodoptera litura

Spodoptera litura, that is, "spicy seed". The diamondback moths that harm sweet-scented osmanthus include Spodoptera litura, Spodoptera litura and so on. Their larvae can sometimes eat up the leaves of plants such as sweet-scented osmanthus, wither the damaged branches, hinder the growth of sweet-scented osmanthus, and reduce the ornamental and economic value of flowers and trees. Spodoptera litura adult, 16-18 mm long, emerald green, with a quadrilateral dark brown spot on the wing base and light brown hind wings.

Egg, elliptic, 0.9-1 mm, yellowish green. The larva, about 24 mm in length when mature, has an emerald green body, a reddish brown head, three blue-purple and dark green strips in the center of the back, blue patches and thorns on the back, a pair of orange-red branches on the back of the first ventral segment, and black cashmere globular hairs at the end of the abdomen. Pupa, ovoid, 14-17 mm long, yellowish brown; cocoon, dark brown, flattened, covered with white filaments, elliptic, 14-17 mm long. The insect produces 2-3 generations a year in the Yangtze River basin, overwintering with mature larvae on branches, pupating from April to May, mid-May to early June, and Eclosion and spawning of the first and second generation adults from early August to mid-September.

The adults have strong phototaxis and can mate in the night of Eclosion and begin to lay eggs the next day. A single female can lay 600-900 eggs. The number of eggs to more than 100, mostly 30-40, concentrated in the back of the tender leaves, arranged in the shape of fish scales. The newly hatched larvae only feed on the mesophyll and lower epidermis, leaving the upper epidermis, biting through the epidermis after the 3rd instar, and feeding on the whole leaf after the 5th instar.

The larvae were 7 instar, fond of clustering, and gradually dispersed after the 5th instar. The mature larvae form cocoons at the cracks in the bark and at the base of the trunk, and some of the first generation cocoons on the back of the leaves. Control methods: timely check the white to translucent damaged leaves of sweet-scented osmanthus plants, and timely wear gloves to kill leaves with a large number of larvae to prevent them from being stung by their poisonous hairs; manually scrape off the overwintering cocoons from branches, which can reduce the number of overwintering cocoons and prevent serious occurrence in the coming year; kill feathered adults with black light to reduce the number of larvae of the next generation; biological pesticides such as Bacillus thuringiensis and cyanobacteria are used to control larvae.

During the larval development stage, the larvae were sprayed with 1000 times of trichlorfon crystal, 0.3% of azadirachtin EC, 1.2% of nicotine and 8000 times of diflubenzuron.

5. Whitefly

The main whitefly pests harmful to sweet-scented osmanthus are whitefly, orange green whitefly, cinnamon pollen whitefly (Hefei, Chuzhou, Wuhu city) and so on.

They mainly use the mouthparts of adults and larvae to pierce the mesophyll on the back of the leaves to absorb juice, making the leaves of sweet-scented osmanthus curly, chlorotic, yellow, and even withered; a large amount of honeydew excreted by them will seriously pollute the branches and leaves of sweet-scented osmanthus, and can cause coal fouling disease, resulting in poor growth of sweet-scented osmanthus, thus affecting the normal flowering and display of sweet-scented osmanthus.

Control methods: protect natural enemies, such as whitefly heteropod wasp, long-bellied whitefly wasp, whitefly black wasp, yellow jumping wasp, lacewing, ladybug, wasp, predator mite, etc.; whitefly can use yellow armyworm board to trap and kill adults Whitefly has strong drug resistance, so when selecting pesticides for control, we should pay attention to the principle of alternating use and mixed use. for example, 10% paracetamol EC 1000 times, 10% imidacloprid wettable powder 2000 times, 40% omethoate 1500 times, 25% permethrin 2000 times, 20% pyrethrin 2000 times, etc.

Control methods of leaf spot of sweet-scented osmanthus what are the control measures and causes of leaf spot of sweet-scented osmanthus?

Speaking of sweet-scented osmanthus, I believe everyone will not be strange, although the petals of sweet-scented osmanthus are small, but the fragrance is charming, deeply loved by many flower friends. Sweet-scented osmanthus leaf spot is a common disease in the process of cultivating sweet-scented osmanthus. So, do you know how to control sweet-scented osmanthus leaf spot? Let's study with the editor.

Sweet-scented osmanthus leaf spot is the general name of all kinds of spot diseases on sweet-scented osmanthus leaves, such as brown spot, blight spot, anthracnose and so on, which cause early defoliation, weaken plant growth, affect ornamental value, reduce sweet-scented osmanthus yield and cause economic losses.

Symptoms of brown spot of sweet-scented osmanthus

At the initial stage of the damaged leaves, the chlorotic macula appeared, which gradually expanded into a near-round spot, or an irregular spot was formed due to the limitation of leaf veins. The lesion is yellowish brown to grayish brown with a yellow halo on the periphery, with a diameter of 2~10mm. There are black mildew in the later stage of the disease, that is, conidia and conidiophores of pathogens. The pathogen of sweet-scented osmanthus brown spot belongs to semi-known subphylum, Trichospora, Cercospora and Cercospora. Conidia brown, suborbicular; conidia pedicel attached to it in bundles, light olive, unbranched, rarely transverse; conidia oblong, nearly colorless to light olive, straight or slightly curved, 15-58 × 2.8-3.7 μ m in size. The disease occurred from April to October, and the disease of the old leaf was more serious than that of the young leaf. The pathogen overwintered on the diseased leaves with mycelium as the source of infection at the beginning of the next year. Under suitable conditions of temperature and humidity, conidia were produced in the diseased part, which were transmitted to healthy leaves with air flow and water droplets, causing infection.

Symptoms of sweet-scented osmanthus blight

Most of the pathogens invaded from the leaf tip and leaf margin, and at first they were small light brown spots, and then gradually expanded into large round or irregular spots. In severe cases, several disease spots connected with each other to form large withered spots, which made the whole leaf dry up to 1 inch, 1 inch, 1 inch, 2. The disease spot is grayish brown to reddish brown, the edge is bright reddish brown, sometimes curly and brittle. In the later stage, many small black dots are produced in the disease department, that is, the conidium of the pathogen. The pathogen of sweet-scented osmanthus blight belongs to semi-known subphylum, Coelospora, Chlorospora, Leaf spot mold. The conidium is nearly spherical, with orifices, 100 ~ 150 μ m in diameter; the conidia are oblong to nearly fusiform, colorless, unicellular, 6.0 ~ 9.5 × 1.8 ~ 2.5 μ m in size. The development temperature of the pathogen was 10-33 ℃, and the optimum temperature was 27 ℃. Most of the diseases occurred from July to November, the pathogen overwintered on the diseased leaves with conidia, and the conidia were transmitted by wind and rain. The disease is serious in the environment of high temperature and humidity, poor ventilation and weak plant growth.

Symptoms of sweet-scented osmanthus anthracnose

Small chlorotic spots appeared at the initial stage of the damaged leaves, which gradually expanded to form round, semicircular or oblong disease spots. The disease spot is light brown to grayish white, with reddish-brown rings on the edge. In the later stage, many small black dots were produced in the disease department, that is, the conidia disk of the pathogen, and pink myxospore clusters appeared in the disease part when it was wet. The pathogen of sweet-scented osmanthus anthracnose belongs to the subphylum Cystis, Colletotrichum, Colletotrichum gloeosporioides. Conidium disk brown or black, 100 ~ 300 μ m in diameter, with several bristles on the disk; conidium cylindrical, size 12 ~ 21 × 4 ~ 51 μ m; conidium cylindrical, born under the leaf epidermis, break through the epidermis after maturity, size 11 ~ 18 × 4 ~ 6 μ m. The disease occurred seriously from April to June. The pathogen overwintered on the diseased leaves as conidia and spread by wind and rain.

The above is all I know about sweet-scented osmanthus today. I hope it will be helpful for flower friends to read this article. If you want to know more about sweet-scented osmanthus, please continue to pay attention to the succulent flower bed, we will provide you with more related knowledge!