#2020年金稻穗计划 #
<h1 class = "pgc-h-arrow-right" > the species of cotton pests in the first section</h1>
There are many species of plant-eating insects in the cotton field, more than 300 species have been recorded, but most of the species are at a low density level due to the influence of environmental factors and the mutual restriction of biological communities, which is not enough to cause economic damage to cotton. However, about 30 of them occur in a large number and can cause harm to varying degrees, and should be listed as the object of prevention and control.
The species or categories that are widely distributed and more serious in the country are: cotton aphids, cotton bollworms, red bollworms, cotton red spiders, cotton blind bugs, etc. Although some species are not widely distributed, they are more harmful in local areas, or although widely distributed, they are not seriously occurring all year round, such as cotton leafhoppers, cotton thrips, small ground tigers, cotton diamond diamonds, cotton tip elephants, cotton bridge worms, cotton leaf curls, etc. China's north and south cotton areas are different, the main cotton insect species and the degree of harm have their own characteristics, such as the cotton area of the Yellow River Basin, with cotton aphids, cotton bollworms are the most serious, followed by cotton red spiders, cotton thrips, cotton blind bugs, etc., and red bollworms due to weak resistance to low temperature, although distributed, but the degree of harm is far less than the southern cotton area, Xinjiang cotton area The insect has not yet been distributed, so it is classified as a protected area and listed as a quarantine object. The cotton area of the Yangtze River Basin is dominated by cotton red spiders, red bollworms and cotton blind bugs. The harm of cotton aphids and cotton bollworms has decreased slightly in recent years, but it often occurs seriously. Cotton blind bugs tend to be serious, followed by cotton leafhoppers, small ground tigers, bridge-building insects, leaf curls and so on. Liaohe cotton area, once a year ripe, cotton aphids, cotton bollworms are the mainstay, followed by cotton blind bugs, small land tigers and so on. Due to the special climatic and geographical conditions in Xinjiang's cotton area, some cotton insects are unique to the region, and cotton bollworms and cotton blind bugs are the main species, followed by cotton long-tube aphid, cotton black aphid, yellow-ground tiger and jujube aphid in southern Xinjiang. Cotton aphids have also occurred severely in the area in recent years. South China cotton area is a scattered cotton area, the planting area is small, cotton aphids, cotton bollworms, red bollworms, cotton red spiders, cotton diamonds, cotton leafhoppers have occurred, but the degree of harm has declined in recent years, especially cotton diamonds. In addition, the report of the harm of Asian corn borer in the cotton field has attracted attention, and corresponding control measures need to be considered. Recently, in some provinces and cities in North China, it has also been found that the American spotted fly endangers cotton leaves, and the relevant departments should strengthen surveillance.
<h1 class = "pgc-h-arrow-right" > the second section of china's cotton pest control</h1>
First, cotton blind bugs
There are 5 common species of cotton blind bugs, namely green blind bugs, medium black blind bugs, alfalfa blind bugs, three-point blind bugs and pasture blind bugs, all of which belong to the order Hemiptera, the family Hagmatodidae. Due to the large number of cotton blind bugs, more than one species often occurs in an area, and it has been propagated on the host in early spring before moving into the cotton field, and the time for different species to move into the cotton field is uneven in the morning and evening, from the beginning of the bud of cotton to the flowering and bell period. Adult cotton blind bugs and nymphs suck the sap of cotton plants, causing growth and development deformities, and budbells fall off, which has a great impact on yield and is an important pest at the budding stage.
1. Distribution and harm of green blind bugs are the most widely distributed, and a certain number of occurrences occur in the north and south cotton areas, which is the dominant species. The medium-black blind bugs occur in the northern cotton area, and the cotton area of the Yangtze River Basin has a large insect population density in Jiangsu, Zhejiang, Anhui and other provinces. Alfalfa blind bugs are also species that occur in the northern cotton region. Three-point blind bugs and pasture blind bugs are mainly distributed in the northern cotton region, the latter is more important in the northwest inland cotton area. In the 1970s, the occurrence of cotton blind bugs in a few areas along the lower Reaches of the Yangtze River has been aggravated, in recent years, the development of cotton fields, cropping systems, especially the expansion of green manure, broad beans and other areas, resulting in an increase in the number of insect sources inside and outside the cotton field, and often several kinds of mixing occur, generations overlap, has become an important control object of the budding period, the cotton plant damage rate in these areas can reach 30% to 60%.
In addition to harming cotton, it can also harm beans, green manure, cruciferous vegetables, hemp, sunflowers of the Asteraceae family and some trees.
The seed leaves of the cotton plant are damaged to cause a dead top, the top buds are damaged after the true leaves appear, the buds are overgrown, resulting in headless cotton or multi-head cotton, the leaf damage causes leaf breaking madness, the bud bell is damaged and causes a large number of shedding, and the top and side hearts are killed so that the branches and leaves grow wildly into broom cotton.
2. The occurrence law and main habits of cotton blind bug species are different, and the algebra occurs in 1 year, and the algebra occurs in the south of the same species more than in the north. For example, green blind bugs occur in 3 to 5 generations in 1 year in the northern cotton region, and 5 to 7 generations in the southern cotton region.
Cotton blind bugs overwinter with eggs in the leaves, veins, petioles, stalks, branches, and bark of host plants. Only pasture blind bugs overwinter as adults in bark cracks, under dead branches and overgrow. In the spring, it first lives and multiplies on overwintering plants, and the cotton plants move into the cotton field when they are about to bud, and the harm is the most intense in the peak of the bud, and it gradually declines after the bell. Cotton blind bugs like warm and humid, rainy years are more harmful, the most suitable temperature is 23 to 30 degrees, the relative humidity is 80%, 11 benefits or 35 benefits 92
The above affects growth and development. Therefore, temperature is the main influencing factor in early spring and precipitation in summer. Cotton plants grow tall, dense and tender green, and have more buds are seriously affected. The amount of nitrogen contained in the plant is directly proportional to the degree of harm, and the medium-sized leaves, young buds and young bells are more seriously affected because the nitrogen content is higher than that of the old leaves, large buds and big bells. Large-water, high-fertility cotton fields are heavier than arid and low-fertile fields.
3. Prevention and control methods
(1) Strengthen the control of wintering insect source areas and early spring hosts Cotton blind bugs have been breeding hazards on wintering and early spring hosts for a period of time before moving into cotton fields, which is the source of insects that occur in cotton fields and is an important link in prevention and control measures. Before the incubation of wintering eggs, combined with fertilizer to eradicate weeds on the edge of the field, strengthen the management of cotton fields, and apply fertilizer reasonably. If necessary, it should also be administered according to the insect situation and control indicators to suppress the source base of the insect.
(2) Seedlings and buds are applied at the seedling stage with 40% mutapulophosphorus emulsion or liquid drops to prevent and control some of the cotton blind bugs that moved into the cotton field early. In addition to long-term mutamolone, 1000 times liquid sprays such as oxidized Leguo, octyl thiophos, and 1605 also have good prevention effect. In addition, 30% Saidan emulsion, 10% imidacloprid wettable powder, 20% amidoxic emulsion, 5% anti-Taibao emulsion and other 2000 times liquid spraying, the combination effect of cotton aphids and leaf mites is better.
According to the research and demonstration practice of green blind bugs and medium black blind bugs, the seedling stage is 4-7 100 plants, 8-11 larvae are 100 plants, and 10-20 larvae are 100 plants at the bell stage. This prevention and control index can be used for reference and application in various places.
Second, cotton red spider
Cotton red spider, also known as cotton leaf mite, is widely distributed in China's cotton area, and there are many kinds.
The main hazards are cinnabar leaf mites, but truncated leaf mites and dipered leaf mites often mix with them. Cinnabar leaf mites, also known as red leaf mites, belong to the order Tick mites, leaf mites.
1. Distribution and harm of cotton red spider is the world's pest mite, China's cotton-producing areas are distributed, is the main pest mite at the seedling stage, in some cotton areas, the harm during the budding period is also quite serious.
Cotton red spider to adult mites, young mites, if the mites suck leaf juice hazards, the affected leaves appear yellow and white or red spots, light caused by red leaves, heavy leaves dry and hard, blown by the wind all off the stalks, like fire. When the seedling stage occurs early, serious hazards can cause the destruction of seeds. The mite eating miscellaneous, a wide range of host plants, China is known to have more than 100 species of 32 families, in addition to cotton, there are still corn, sorghum and other food crops; beans, hemp, melons and other oilseeds and vegetable crops, in apples, peaches, pears and mulberry, locust, Tsubaki and other fruit forests can occur, wild weed hosts are wider. Intermittent outbreaks are not severe all year round. In recent years, due to the expansion of the area of intercropping and planting of cotton and grain and oil crops, favorable living conditions have been created for cotton red spiders, and many cotton areas have a tendency to aggravate the harm. The cotton area of the Yangtze River Basin has been listed as an important target for prevention and control, and some cotton fields in the northern cotton area also need to be prevented and controlled all year round. The dry and high temperature climate in the cotton area of Xinjiang is conducive to the reproduction of red spiders, the mite plant rate can reach more than 50%, and the yield loss of cotton fields that are not timely is often up to 50%.
2. Occurrence rules and main habits of cotton red spider occur for more than 10 generations in 1 year, and more than 20 generations occur in the southern cotton area in 1 year. Each cotton area can have more than 2 peaks during the growth and development of cotton. Two to three peaks occurred in the cotton area of the Yellow River Basin from mid-to-late June to mid-August; in the cotton area of the Yangtze River Basin from late April to early September, there were three to five peaks; and two peaks in the inland cotton areas of the northeast and northwest. During the peak period, eggs, young mites and adult mites often appear simultaneously, which causes certain difficulties in prevention and control.
In addition to the soil cracks under the dead branches and leaves of the cotton field, the cotton red spider overwinters in addition to the overwintering of the mites, the weeds outside the field, under the soil, under the bark can overwinter. Adult mites are dormant or active, and in some areas a small number of eggs and mites can overwinter. In the following year, when the temperature rises by 5 to 7, the overwintering insect state begins to move. When the cotton seedlings are not unearthed, they first breed on the weeds outside the cotton field or on the host in early spring, and then move into the cotton field, so the source of mites outside the cotton field is closely related to the harm that occurs in the cotton field. The optimal temperature for the propagation of cinnabar leaf mites is 25 to 30 degrees, and the relative humidity is 35% to 55%, so the high temperature and low humidity are harmful, especially drought is more conducive to large occurrence.
More than 30 benefits and relative humidity greater than 70% are not conducive to its reproduction. Its diffusion is affected by conditions such as wind direction, wind speed, temperature, rainfall and terrain, generally hot and rainy days occur quickly, and wind can spread by wind; more rainfall and heavy rainfall intensity are unfavorable to its spread. The vertical distribution on cotton plants is generally the largest in the middle of the leaf. In the cotton field, most of the spread is spread inward by the edge of the field, and more spots begin to occur, so the prevention and control requirements are timely.
Cotton field cultivation management technology and cotton plant growth status are also closely related to the occurrence of cotton red spiders. When the osmolality of cotton leaf cells is 669.76 kPa, it is most beneficial to its sap aspiration, and when the osmolality is increased to 1379 kPa, it can inhibit its development. Therefore, the rational application of nitrogen and phosphate fertilizer can increase the osmotic pressure of cotton leaf cells and reduce the harm. When the cotton plant due to insufficient water and fertilizer, weak growth, although the osmotic pressure has not changed, but the plant body soluble sugar content is high, is still conducive to its reproduction, and this kind of cotton field is easy to cause high temperature and low humidity of the small ecological environment, and suitable for the reproduction of cotton red spider, the cotton plant itself water loss is also fast, so the degree of damage will still be serious.
(1) Suppress the source of winter and spring mites, control the spread of mite sources in the center Before the cotton seedlings are unearthed, strengthen the investigation of the source of mites inside and outside the cotton field, and timely eradicate weeds and dead branches and leaves in the field and at the edge of the ground; pay attention to the winter ploughing and irrigation measures of the cotton field; and strive to reduce the number of overwintering and early spring mite sources. After the cotton seedlings are unearthed, the focus is on monitoring the food-loving hosts in the field such as corn and beans, and timely remove the old leaves of the lower part of the corn and take them out of the field, and the beans and other crops should be sprayed in time if mites occur.
(2) Rational layout of crops, strengthen the choice of cultivation and management of cotton and set of crops, and expand the area of wheat according to the possibility of planting as few mung beans, broad beans and corn as possible;
(3) Early and timely chemical control In the early stage of cotton fertility, when the red spider appears as a dot, the mites are grasped through field investigation, and when the yellow and white plants appear in the cotton leaves, the rate of yellow and white plants can be used.
When leaf mites spread from dots to the whole field, especially wheat camp cotton fields and arid cotton fields, it should be monitored and strive to apply drugs in a timely manner before several peaks to reduce the number of occurrences. In the case of drought and little rain or high temperature and low humidity, strengthen the field mite investigation and timely apply whole field pesticides to avoid disasters. The seed treatment and drug point and coating control of cotton aphids also have a certain effect on cotton leaf mites. Areas that practice spot-by-point and whole-field spraying, as well as areas that develop resistance, generally strive to use fewer broad-spectrum agents and more selective pesticides. According to different situations, one of the following agents is selected to spray: 20% trichloroicidicol 1000 to 1500 times liquid, 20% trichloroicide alfalfa sulfone 800 times liquid, 73% g mite emulsion 3000 times liquid, 5% jameon gram emulsion 1500 times liquid, 20% tachymolone emulsion 3000 times liquid, 20% sulfur suspension 300 times liquid, 50% bromomerate emulsion 1000 times liquid and 10% imidacloprid wettable powder 1000 times liquid, etc., have good preventive effect. The above pesticides can also be used in rotation with broad-spectrum pesticides such as mutamol and oxidized fruit to delay drug resistance. Some cotton areas are diluted with 80% dichlorvos emulsion and 20% trichlorocarbonic sulfone, and sprayed with 4:1 mixed into 1000 times liquid, and the anti-mite prevention effect is also very good.
3. Cotton field Asian corn borer
The Asian corn borer is a genus of Lepidoptera, moth family. Larvae can feed on the tender buds or petioles on the top of the cotton, and can also moth the cotton stems to cause the cotton plant to break. Moth-eating young buds cause twisted flowers, and moth-eating buds and bells can make them fall off or cause germs and rott bells.
1. Distribution and harm of the cotton field Asian corn borer is a worldwide distribution of pests, china in addition to the Qinghai-Tibet Plateau, in the country's corn planting areas have distribution. In particular, the spring maize area in the north and the spring and summer maize area in the Huanghuai Plain are seriously harmful. Over the years, with the expansion of the area of wheat and cotton intercropping and the reduction of the area of spring corn, corn borer has gradually turned to harm cotton and has an increasingly serious trend, becoming an important target for prevention and control. Wheat and cotton cropping area is large, or spring and summer corn and cotton staggered planting is more serious, such as timely control often lead to cotton yield reduction.
2. Occurrence pattern and main habit of overwintering in the stalks of affected cotton and corn with old mature larvae. The number of generations in 1 year gradually increases from north to south, and 3 to 4 generations occur in the cotton area of the Yellow River Basin and 3 to 4 generations in the cotton area of the Yangtze River Basin. Overwintering adults mostly lay eggs on wheat, spring maize and cotton seedlings, and feed on them after hatching into larvae. The cotton area of the Yellow River Basin entered the peak of larval harm in early to mid-June, and the first generation of the cotton area in Jiangsu was concentrated in the cotton field hazard, and the second and third generations were transferred to the corn field. The summer corn cotton area focuses on the first generation. The temperature is 25 to 30, and the average relative humidity of more than 60% is conducive to its occurrence, and the dry climate, too low temperature or too much rain is not conducive to it. Wheat-cotton intercropping fields occur in much more often than flat cotton fields. Adults tend to black light, and the corn heart leaf stage is also more attractive to adult spawning.
(1) Suppress the source of winter and spring insects, reduce the damage to the cotton field wheat and cotton intercropping, wheat is transported out of the field in time after harvesting, and the larvae are strictly prevented from being transferred to the cotton plant; the cotton mixed planting area is as far as possible to avoid staggering, and some areas can plant some corn sparsely in the cotton field to induce the insects to spawn and extinguish the eggs.
(2) The second generation of corn borer in the cotton field has more than 3 eggs and the third generation of about 4 eggs in the cotton field, and the drug is applied immediately when the egg hatching peak is mastered. It can be selected with 2.5% cypermethrin emulsion 2000 times liquid or 50% parathion emulsion 2000 times liquid, 50% octylthion emulsion 1500 times liquid, 20% diocyanide emulsion 2000 times liquid, 20% amidoxic emulsion 2000 times liquid and 90% crystalline dimethodium 1500 times liquid spray control. Some cotton areas release red-eyed wasps or spray B.t. emulsions and white zombies during the peak of spawning in the 2nd to 3rd generation.
Fourth, cotton thrips
There are three species of cotton thrips, namely smoked thrips (cotton thrips), flower thrips, and yellow thrips, belonging to the order Taemona, Thripsidae. The control of smoky thrips is the most important, and the adults and nymphs of thrips file cotton seed leaves, true leaves and growth points.
1. Distribution and hazards Of tobacco thrips are distributed in all major cotton areas, and the harm in northern cotton areas is more serious. In addition to cotton, there are more than 20 species of host plants such as tobacco, vegetables, melons, beets, and potatoes. After the cotton is damaged, silver-gray spots are produced, and the leaves are deformed; when the growth point is seriously damaged, it can break or form headless cotton, or cause the cotton seedlings to die, and the buds and flowers are damaged and fall off. In the southern cotton area, the occurrence of flower thrips is more serious, and the host plants are still beans, green manure and rice. Yellow thrips are mostly distributed in some cotton areas of Yunnan. Thrips do not occur all year round, and some cotton areas have risen in recent years.
2. Occurrence rules and main habits of smoked thrips occur in 6 to 8 generations in the cotton area of the Yellow River Basin in one year, and 3 to 4 generations in the cotton area of the Liao River Basin. Adult insects overwinter mainly on the inner sheath of green onions and garlic leaves, under soil blocks, under soil cracks and at the fallen leaves of dead branches.
The following spring began activity, breeding on the wintering host for a period of time and then migrating to early spring crops and weeds, and the cotton seedlings were unearthed and moved into the cotton fields. Smoky thrips occur more often in dry years, with temperatures below 25 and relative humidity below 60%. Flower thrips are suitable for medium temperature and high humidity. The cotton fields are surrounded by weeds, or early spring hosts near thrips occur early and heavy.
3. The control method applies medicine to the early spring host crop before the adult insects move into the cotton field, avoid intercropping with the early spring host of the thrips in the cotton field, and generally wheat cotton is planted, which can reduce the harm of the thrips. In the cotton field, the drug can be used to control cotton aphids at the same time as treating thrips. In addition to the above-mentioned cotton field host plants, climatic conditions are also very important, and the insect investigation is strengthened, especially after the seedling is fixed, the sampling survey should be carried out regularly. Generally, there are 10 insects in the first 100 plants of 3 true leaves, 20 to 30 insects in 100 plants after 4 true leaves, or when the rate of insect plants reaches more than 5%, the control is carried out. The agents applied are 50% octylthion emulsion or 35% vulturethion emulsion 1500 times liquid, 35% saidan emulsion 2000 times liquid or 10% imidacloprid wettable powder 2000 times liquid, 44% polyemonium clear emulsion 30 ml to water 60 kg spray can also be.
Fifth, cotton field American spotted fly
The Cotton Field American Spotted Diving Fly belongs to the order Diptera, submerged fly family, also known as vegetable spotted diving fly, snake-shaped spotted diving fly, kale spotted diving fly and so on. There are many host plants, including more than 100 kinds of plants such as cotton, hemp, tobacco and a variety of vegetables. On cotton, larvae are used to feed on the leaf flesh, causing multiple white tunnels to affect leaf photosynthesis. The larvae often make the leaves white and even decay.
1. Distribution and harm of cotton field American spotted fly is distributed in Brazil, Canada, the United States, Mexico, Chile and other more than 30 countries and regions, in recent years spread to China, in 1994 in Hainan Province for the first time found, has spread to from south to north 12 provinces, municipalities, autonomous regions. In the yellow river basin cotton areas such as Henan, Shandong, Hebei and other provinces to harm cotton is also the first time, and then successively found in Shanxi. Due to the rapid occurrence of harm, overlapping generations, many types of host plants, and the rapid emergence and development of drug resistance, sufficient attention should be paid to it. Many countries have listed it as quarantine subjects.
2. Occurrence patterns and main habits of American spotted diving flies are multi-food pests, with many types of host plants, and different degrees of feeding on different crops. It is the most addictive to beans and tomatoes, lighter to vegetables such as eggplant and cabbage, and less harmful to cotton than vegetables and fruits.
The worm lays eggs on the front of the leaves of the host plant, and after hatching, the larvae dive into the leaves to feed on the leaf flesh, taking the form of a snake-shaped diving channel, pupating at the end and showing a granular protrusion. Pupae can stick to the leaves and fall into the soil. The length of each insect period is greatly affected by temperature and humidity. High temperature and high humidity are conducive to its occurrence, short life cycle, and generational overlap. 25 ~ 32 is suitable for its growth and development, the relative humidity is 70% to 80% is appropriate, under this condition about 20 days can complete a generation. More than 34 benefits and less than 20 benefits are not conducive to their growth. Therefore, the hazards on the plant are generally distributed vertically from bottom to top. Adults have weak flight power, transmission between hosts mainly relies on wind, and long-distance spread transmission is mainly the spread of host plants with eggs or larvae with means of transport or packaging materials. Adults and young larvae are sensitive to agents, but the insects have rapid resistance to pesticides and have a high level of resistance, so the selection of drug types, the mastery of the appropriate period of control and the mode of administration should be taken seriously.
(1) Strictly implement quarantine to prevent the spread of the insect The main hosts of the insect are mostly fruits and vegetables, and it occurs seriously in the southern region. Therefore, the fruits and vegetables transported to the north should be strengthened quarantine, and once the vegetables to be transported north are found, they should be sold in situ to prevent the expansion of the insect. In addition, it is necessary to strengthen the investigation of the epidemic area, and it is strictly forbidden to import vegetables and flowers from the epidemic area.
(2) The layout of variety planting is reasonable, strengthen field management to intercropping or rotating the crop varieties and non-food-loving varieties that are pest-loving, and achieve appropriate planting, deal with old leaf remnants, pick affected leaves, and concentrate on burning or fertilizer or deep burial.
(3) The field is mainly based on timely medication, combined with booby-trapping and the use of effective natural enemies according to the field insect situation investigation, and the pesticide spraying of adult insects at the peak of feathering and the peak of juvenile larvae is mastered. Due to the large number of insect pests from the seedling stage to the budding stage, the types and frequencies of medication are also more, and under normal circumstances, the insect can often be treated at the same time. However, it is easy to cause serious harm to cotton fields with more insects, and can be sprayed with 2.5% kung fu permethrin 3000 times liquid, 10% cypermethrin 3000 times liquid, 40% Lego 1000 times liquid, 48% Lesben emulsion 1000 times liquid, 1.8% Aifodin emulsion 3000 to 4000 times liquid, 25% insecticidal double water agent 500 times liquid, 5% katamine emulsion 2000 times liquid, 5% anti-tetheroparamole emulsion 2000 times liquid and 1% synergistic 7051 biopescin 2000 times liquid. In general, the medication should be mainly for prevention and control, and the treatment of young larvae should be treated at the same time as the treatment of adult insects, and attention should be paid to rotation or mixing to prevent drug resistance. In addition, in some areas, fly-killing paper or yellow sticky cards are used in the field to booby trap.
6. Cotton bollworm
Cotton bollworm is an important pest during the budding period. It belongs to Lepidoptera, Noctiaceae. Larval borers feed on flowers, buds and bells, and several generations can occur in the cotton field, the harm period is long, and the impact on cotton yield and quality is very large, and it has been listed as the main control object in the north and south cotton areas of China.
1. The distribution and harm of the cotton area in the Yellow River Basin occurs all year round, and the harm is the most serious; the cotton area of Xinjiang and the cotton area of the Liaohe River also occur every year, and the number is larger; although the cotton area of the Yangtze River Basin is lighter, it has also been quite serious in recent years. Especially since the 1990s, in the cotton areas of northern China, the cotton areas have been rampant for many years, the loss of cotton damage is extremely serious, the general cotton field production has been reduced by 40% to 50%, and some cotton fields that are not timely or have poor control quality have been reduced even heavier, and even have to change to other crops.
Cotton bollworm is a heterogeneous food and is a multi-food pest. In addition to cotton, corn, wheat, broad beans, peas, green manure crops, hemp and tomatoes, peppers, sunflowers, etc. are its host plants.
The larvae feed on the young leaves and top buds of cotton, but the main food damage buds, flowers and bells causes shedding, the development of cotton plants is delayed, there are many flowers after frost, and it can induce pathogenic bacteria to cause rotten bells. Cotton bollworm can occur in multiple generations in the cotton field, and sometimes coincides with the peak of the occurrence of aphids, so the insect infestation at the cotton bud stage is more significant than the insect pest at the seedling stage.
2. Occurrence patterns and main habits of cotton bollworms occur algebraically in 1 year more in the south than in the north.
Three generations occur in the cotton areas of the Liaohe River and most of Xinjiang; 4 to 5 generations occur annually in the cotton areas of the Yellow River Basin and some cotton areas in the Yangtze River Basin at latitude 32 to 40 yi north latitude; 5 generations occur in the cotton areas of the Yangtze River Basin at latitude 25 to 32 yi north latitude; 6 generations occur in the south China cotton area south of 25 degrees north latitude; and 7 generations occur in some cotton areas in Yunnan, and there are no pupae in winter. The generation of harm is the second generation in the Cotton Area of Liaohe and the Cotton Region of Xinjiang, the second and third generations of the Cotton Area of the Yellow River Basin, the third and fourth generations of the Cotton Area of the Yangtze River Basin, and the third, fourth and fifth generations of the Cotton Region of South China. The first generation of each cotton area occurs outside the cotton field, and the cotton begins to enter the cotton field after the bud. Cotton bollworms pupate overwinter at 2 to 6 cm below the soil. In the cotton area of the Yellow River Basin, in the year of the occurrence of cotton bollworm, due to the large amount of occurrence and the prolongation of the occurrence period, the hazard generation has increased in some cotton areas. Adults have phototropism in nocturnal activity, tendentious toward poplar branches, and have strong flight ability. Moths can be detected by black light lamps, and poplar branches are planted in cotton fields in the early morning to trap and kill. After the emergence of overwintering adults, they lay eggs on wheat, tomatoes, peas and other crops, hatching as larval hazards, cotton begins to bud during wheat harvest, and the first generation of adult insects transfers to cotton fields. The second generation of eggs is mostly laid on the front of the young leaves at the top of the cotton plant, the third generation of eggs are mostly laid on the leaves and buds, and the fourth generation of eggs are basically all laid on the leaves and buds. The larvae are 5 to 6 years old, and the age is more or less related to the type of food and environmental conditions. The hatching larvae are not very active on the same day, and the next day they are transferred to the growth point to harm, after peeling, they begin to eat young buds and flowers when they are 2 years old, and the buds open up after the buds are affected, turn yellow-green, and fall off after 2 days, and the bells that are eaten by moths also cause shedding. A larvae can harm more than 10 buds, flowers and bells in a lifetime. After the age of 4, the amount of food increased sharply, and the harm increased. During the second and third generations in the cotton area of the Yellow River Basin, the reproductive growth stages of cotton buds, flowering and bolling coincided, which had a great impact on yield. Although the number of insect mouths is large during the fourth generation, the amount of natural enemies is large, the cotton plant has entered the ring, and there is no need to control it in general years.
The harm of cotton bollworm is affected by the comprehensive factors of cotton field ecosystems. The appropriate temperature for adult eggs to lay is 25 to 28 degrees, and the relative humidity is above 70%. Overwintering adults occur early when temperatures are high. The temperature in China's cotton areas is more suitable during the occurrence of cotton bollworms, so humidity and rainfall are often the key, rainfall is large, especially heavy rain, heavy rain can wash away eggs and hatching larvae, which can significantly reduce egg volume, egg hatching rate and field egg plant rate. During the occurrence period of each generation, such as the average monthly precipitation of about 100 mm, the relative humidity of more than 70% is seriously occurring; if there is continuous rainfall in the early stage of pupae, and the rainfall is large, it has an inhibitory effect on the development and feathering of the pupae; once the rainy and high temperature weather passes, the amount of eggs in the cotton field can suddenly increase, and it is conducive to egg hatching and larval harm.
At present, the area of multi-ripe planting has expanded, and wheat, corn, sorghum, etc. have provided sufficient feeding materials for cotton bollworms. Cotton plant planting density is also increasing, water and fertilizer conditions have also improved, these are beneficial to the occurrence of cotton bollworms, coupled with the strong flight ability of cotton bollworms, it is more harmful to transfer between different hosts. Therefore, the layout of crops and the improvement of cultivation techniques should strive to reduce the beneficial impact on cotton bollworms. Cotton has a strong ability to compensate, taking the yellow river basin cotton area as an example, the second generation of cotton bollworm during the occurrence of harm, is the strongest compensation capacity of cotton plants, so the control indicators have a lot of room for relaxation, and should not be immediately applied at the sight of the bud bell falling off, because the natural physiological shedding rate of cotton at this time is generally up to 60%; the third generation of cotton bollworm hazard period, is the cotton plant compensation ability tends to decline stage, the control indicators should be slightly stricter, because it is difficult to compensate after the bud bell falls off at this time.
The degree of resistance to cotton bollworm varies greatly between different varieties of cotton, generally speaking, there are honey glands, polychaetic, narrow curly bracts, chicken foot leaves and secondary biomass varieties containing gosypols, condensation tannins, sesquiterpenes and cotton bollworm, which are resistant to cotton bollworms, so the choice of cotton varieties is also an important factor affecting the degree of cotton damage. The natural enemies in the cotton field are rich in resources, and a variety of predatory spiders, ladybirds, insectivorous bugs, grasshoppers and parasitic natural enemy insects have an important control role in cotton bollworms and should be protected and utilized.
3. Control method Cotton bollworm has become the most important pest in the main cotton-producing areas of China, and often rampant. Over the years, various regions have accumulated a complete set of prevention and control experience. Different ecological cotton areas have their own applicable measures, which are difficult to apply uniformly. To sum up, there are mainly the following prevention and control methods: (1) winter cultivation and winter irrigation, timely cultivation and stubble suppression of the insect source base after cotton harvest in time to remove cotton firewood and vigorously promote cotton field ploughing, conditional places combined with winter irrigation, is an effective measure to kill the overwintering pupa under the soil, suppressing the harm of the first generation of cotton bollworms in the wheat field.
In some areas, the stubble is also cultivated in time after wheat harvest, which can reduce the insect source base of the wheat field into the cotton field hazard, and is conducive to promoting the early occurrence of cotton seedlings.
(2) Reasonable adjustment of crop layout, selection of suitable varieties of cotton and wheat, corn, sorghum, rape and other crops of intercropping or flower arrangement planting, strip planting, etc., can not only improve the index of multiple seeds, is conducive to breeding and enriching the natural enemy resources of cotton fields, and can improve the ecological environment of cotton fields to reduce the degree of harm caused by cotton bollworms. For example, wheat cotton planting and paying attention to the selection of suitable early maturing varieties can worsen the feeding conditions of the first and fourth generations of cotton bollworms; the planting of corn, sorghum and rapeseed induced crops in the cotton fields mentioned above can not only reduce aphid infestation, but also disperse the egg concentration of cotton bollworms in cotton fields and reduce the degree of larval harm.
Cotton planting methods are diverse, and different ecological cotton areas should be determined in combination with the actual local situation, but they all strive to have a reasonable layout and pay attention to the selection of supporting varieties, promote early cultivation techniques, and avoid direct broadcasting of summer cotton after wheat or late planting of wheat fields with spring cotton varieties.
(3) Scientific and rational use of drugs, correct grasp of control technology Chemical control is still an important control method, for the cotton bollworm, which can cause rampant harm to the pest more need scientific and rational use of drugs, correctly grasp the control technology, in order to avoid adverse side effects at the same time of prevention and control. Specifically, it is necessary to strengthen the investigation of the insect situation, and when deciding on the prevention and control of drugs, according to the control indicators, adopt effective technologies, such as selecting pesticide varieties and dosages, and strive to reduce the number of prevention and control.
Through field investigation, the fertility status of cotton plants and the occurrence density of each generation of cotton bollworm eggs and larvae are grasped, and the drugs are used at the most appropriate time for control. Through research and practice in Henan, the Institute of Plant Protection of the Chinese Academy of Agricultural Sciences believes that it is crucial to grasp the first application time of each generation of cotton bollworms.
For a long time, cotton field medicine, including the prevention and control of cotton bollworm, there are many varieties, because it can not be scientifically and rationally selected, cotton bollworm has become resistant to many pesticides, and some pesticides also have a killing effect on a variety of effective natural enemies. Therefore, when using the original conventional varieties or developing and applying new varieties, it is necessary to choose carefully, and the use of pesticides in rotation or mixing should also be taken seriously. For the varieties and types of cotton field drugs and the problems that should be paid attention to, they are introduced as follows.
Pyrethroid pesticides on cotton aphids due to resistance to the production of basically no longer use, the control of cotton bollworm should also be used as little as possible or limited, generally the second generation of cotton bollworm has a low control effect and do not use or increase its concentration. For example, 2.5% cypermethrin, 20% permethrin is 1000 to 1500 times liquid, and the third generation of cotton bollworm is limited to one time. 10% cypermethrin 1000~1500 is slightly more effective, and the situation of 2.5% kung fu permethrin is similar, and the area used in cotton areas is gradually increasing.
2.5% Uranus emulsion 3000 times liquid, have a good effect on cotton bollworm and cotton leaf mites.
Organophosphorus pesticides have been used for a long time in the control of cotton pests and occupy an important position. Due to its many varieties, the control objects are different because of their specific degree of toxicity, and the cotton bollworm should be selected when controlling it. Good prevention effect is octylthion, water amine thion, methyl 1605, long-term dauphin and dichlorvos, etc., when applying should pay attention to safety protection, to avoid poisoning accidents. Among them, although the long-term mutapulator is low toxicity, it is broad-spectrum, and the effect on cotton bollworm is general, and it is difficult to control the harm in the year when the number is large. Although the anti-effect of octyl thionate on cotton bollworm is good, the medicinal effect is short, and it is easy to cause medicinal harm to cotton when the application concentration is high. Although dichlorvos also has good control of cotton bollworm, it is also a continuous short-term effect. Some cotton areas use organophosphorus preparations 100 to 200 times the dim sum, and the habit of rubbing the heart to control the second generation of cotton bollworms. Some cotton areas mix organophosphorus with permethrin pesticides, which is believed to play a synergistic role, and its cost is lower than that of single-use permethrin pesticides, and the use of higher toxic pesticides and less toxic pesticides can also reduce and prevent drug poisoning.
Similarly, the mixing of pesticides with high residues of active ingredients with pesticides with low residues is beneficial to reducing the amount of pesticide residues in agricultural products. In general, phosphorus medicine is mixed, and if appropriate, it can complement each other's strengths. At present, there are many mixed preparations in the pesticide market, and more caution should be taken when purchasing and using them to prevent counterfeit and inferior varieties.
The compound pesticides that are better at the control of cotton bollworms have 20% of the broad killer, 20% of the antidovir, 21% of the emulsions such as synergistic cyanoma 1000 to 1500 times liquid, as well as the anti-bell, cotton boll treasure, anti-bell, etc., some in addition to the good prevention effect, can also target the resistant cotton bollworm. Insect peeling inhibitor insecticides such as anti-Taibao, jammed, etc. are mostly imported, the price is high, and the application time should be mastered during the peak period of eggs. This type of medicine has a slow effect, but the effect is long, the toxicity to the young larvae is stronger, and it is very safe against natural enemies.
At present, the application of biopesticides such as B.t. emulsion (containing 8 billion to 10 billion with crystal spore per gram) is also promoted in cotton areas, and the amount of 3000 to 3750 ml per hectare is diluted by 200 times the water at the peak of the egg. Cotton bollworm and polyxel virus preparations can also be sprayed in a small number of areas with a routine spray of 600 g per hectare. In addition to a certain degree of anti-efficacy, these pesticides are also safe against natural enemies and also have the advantage of delaying the emergence of drug resistance.
When using the above pesticides for control, the method of application is also very important. For example, the second generation of cotton bollworm eggs are mostly produced at the top of the cotton plant and on the tender head, so the liquid is concentrated on the top and fully sprayed, or the drip and heart smear methods are adopted to avoid the damage of the top heart and young buds. Cotton bollworm spray should be sprayed with all cotton plants in the year of large occurrence due to the large amount of eggs, and the walking speed should be slower when spraying. Prevention and control of the third and fourth generation of cotton bollworms, because the eggs are mostly produced on the edges, and the cotton plants are tall, the liquid medicine should be sprayed on the tip of the group, and attention should be paid to spraying on all sides to protect the young buds. In addition to the manual sprayer with a spray blade aperture of 0.7 to 1 mm, it is best to use a motorized sprayer for low-volume spraying or a handheld sprayer for ultra-low-volume spraying in areas with conditions.
(4) The use of trophobia to trap adult bollworms has phototropism, and various types of lamps can be set up in cotton fields for trapping and killing. In the past, many black light lamps were used, and in recent years, many cotton areas have promoted the application of high-pressure mercury lamps, because of their power and light source intensity, and the spectral wavelength is also suitable for the tendency of cotton bollworms, so the booby trap effect is better than that of black light lamps. Generally, 1 300-volt high-pressure mercury lamp (which covers an area of more than 10 times that of black light) is installed every 0.067 hectares to control 6.67 hectares of cotton fields. Large containers of water are used under the lamp, and the water surface is sprinkled with diesel or washing powder. In the cotton field near the lamp or other crops, the cotton boll worm eggs are relatively high should pay attention to prevention and control. The lamp is more effective in large area continuous film use. Planting some crops in and around the cotton field that coincide with the adult stage of cotton bollworms, such as corn, sorghum, carrots, celery and other crops, can also have a luring effect on adult insects, which can be hunted or killed, and can also reduce the amount of eggs on the cotton plant. The lure of semi-dead poplar branches inserted into bundles at the head of the cotton field is also an auxiliary measure. In addition, the use of sexual attractants to monitor and report the dynamics of adult insect occurrence has a lot of experience everywhere, but it is still under continuous study as a large-scale application of control means.
(5) Selection of insect-resistant varieties In recent years, China has strengthened the breeding of insect-resistant varieties, not only accumulated a lot of resources and breeding experience, but also laid a good foundation for the future cultivation of high-quality and insect-resistant varieties, and cultivated a number of insect-resistant varieties, which are being trial-planted demonstration and promotion, such as China Cotton Institute 30, Jinmian 26, etc. Some cotton areas choose varieties that are inconsistent with the spawning and feeding periods of pests during the growing period of planting cotton, avoiding the harm period, thereby reducing the harm. For example, the selection of early maturing insect-avoiding short-season cotton, appropriate late sowing or selection of early-maturing varieties of wheat, which can worsen the feeding conditions of the first and fourth generations of cotton bollworms, and play a good role in reducing insect pests in wheat-cotton two-ripening areas. In addition, the breeding and application of genetically engineered cotton has also developed greatly.
7. Cotton red bollworm
Cotton red bollworm is mostly found in India, and then spread to various places with cotton seeds, and is distributed in most cotton-producing countries around the world, and has now expanded into a world pest and a phytosanitary object. It belongs to lepidoptera, Wheat Moth family. Larvae harm buds, flowers, bells and seeds, and can be spread with cottonseed or seed cotton transport, which is an important pest at the budding stage, and the most serious occurrence occurs in the cotton area of southern China.
1. Distribution and harm in China's cotton areas, except for Xinjiang and Gansu, which have not yet been found, are distributed in other cotton areas. The insect loves heat and is not tolerant of low temperatures, so the harm in the southern cotton area is heavier than that in the northern cotton area. In addition to cotton, its host plants also harm okra, artichoke, yellow sunflower, hibiscus and so on. The larvae feed on cotton buds, flowers, bells and seeds, causing the bud bells to fall off, resulting in stiff petals, yellow flowers and rotten bells. When the larvae are harmed, they also spit silk and tangle, and the seed damage affects the germination rate and oil output. In recent years, the harm in the southern cotton area has aggravated the trend, and the northern cotton area has mainly used natural low temperatures in the past, which can basically control the harm, but at present, the scattered storage of flowers, the storage places are mostly indoors, and the temperature in winter is higher, so the harm has a tendency to rise, which is worthy of attention.
2. Occurrence law and main habits of the algebra that occurs in 1 year, 18 Yi ~ 26 Yi occurs in more than 5 generations in the cotton area of South China; 26 Yi ~ 34 Yi in the north latitude such as Zhejiang, Jiangsu, Sichuan, Hunan, Hubei and other provinces, 3 to 4 generations occur; 34 Yi ~ 40 Yi in north latitude such as Henan, Shandong and Hebei, Shaanxi, Gansu most of the region occurs 2 to 3 generations, north of 40 Yi north such as Liaoning, only 2 generations occur.
Larvae overwinter in seed cotton and disperse to various sites as seed cotton is received and stored.
Propagation expands due to transport and can overwinter in cocoons in indoor crevices. The overwintering larvae begin to pupate when the temperature rises above 18 in the following year, and 24 to 25 yi feather. The first generation of eggs are mostly produced on the young head and young leaves, young shoots, buds and young stems of cotton, the second generation is mostly produced on the lower green bells of the cotton branches, and the third generation is more abundant in the middle and upper parts of the cotton plants. On the bell with sepals most. The first generation of larvae moths eat flower buds, the second generation of larvae moths eat green bells, causing nodule-like protrusions between the bell shell and the inner wall, the old green bells are mothed, the inner wall of the shell forms insect channels, and some invade cottonseed through the bell chamber wall and eat fiber. Non-overwintering mature larvae mostly pupate in bud bells, and some larvae pupate under the fallen leaves or underground.
High temperature and humidity are conducive to the reproduction of red bellworms, and the suitable temperature for growth and development is 20 to 35 degrees, and the relative humidity is above 80%. The moderate temperature of spawning is 25 to 28, and the adult worms that develop after feeding on buds have a high amount of eggs. Adult lifespan is proportional to temperature, and overwintering larvae die at -16 positive times, or at -5 positive temperatures for 1 month. Cotton field cotton plants are larger, and the field temperature increases, which is conducive to adult egg laying, and the egg survival rate is also high, which will cause serious harm. However, excessive rainfall is not conducive to its reproduction, and it occurs lightly. The size of the overwintering base of red bollworms is closely related to the number of subsequent generations, so strengthening wintering control and lowering the overwintering base has a great effect on controlling the occurrence of the second and third generations. The moth stage is highly consistent with the bud stage, which is conducive to the early breeding hazard of red bellworms, and the damage is aggravated by the early appearance of the bell stage in the later stage.
The damage to the cotton fields adjacent to the source sites of the overwintering insects is more severe, and the early harm is more obvious.
(1) Strengthen the control of overwintering, and suppress the concentration of overwintering sites of red bollworms, and the size of the overwintering base has a great impact on the number of the second generation and subsequent generations. In areas where wintering control is better, the first generation is not cured because cotton has the ability to compensate, such as low insect population density, and the focus is on the second and third generations, especially for the second generation of control. The specific measures for overwintering prevention and control, the northern cotton area is to use natural low temperature to kill insects, that is, the seed flowers are stacked outdoors or in the cold house; there are also curtain racks and flowers in the tanning field to make the red bollworm larvae gather under it, release the chickens to peck, dig a ditch around the tanning field to spread pesticides to block the poisoning; cover the flowers with sacks, so that the larvae crawl on it, and sweep it away before drying the flowers the next day; the upper four walls of the cotton barn are sewn or set up paper tapes on the wall, and the paper tape is completely removed after the flower collection is completed. In the adult feathering stage, 80% dichlorvos emulsion is used to smoke and kill with 800 to 900 times liquid or sprayed with 800 to 900 times liquid. It is also possible to unleash an effective predator, the Black Green Wasp (Golden Wasp), or place a 3-watt black light trap in the cotton barn. Remove the dead bell and concentrate on treatment or burn the straw or fertilizer. In the southern cotton area, in addition to wintering control, it is also necessary to combine field control.
(2) Field agent control focuses on the prevention and control of the second and third generations, to grasp the insect situation in time, mainly in each generation of moths and egg laying peak periods of spraying, the eggs and larvae are killed before the moths into the buds and bells. In addition to monitoring and reporting according to the field survey, the trap of the red bollworm enticing device can also be used in the cotton field, and the different types of cotton fields can be selected, with an area of 0.067 hectares, and the trap can add a small amount of washing powder to the basin to calculate the number of moths lured. In some cotton areas, when the cumulative number of moths in 3 pots and 5 days reaches more than 100, prevention and control measures are taken. During the second and third generations of red bollworms, most of the cotton plants were already tall. From the peak to the peak of the moth, the poisonous soil is sprinkled between the rows (every 0.067 hectares, 80% of the dichlorvos 50 grams of water and 1.5 to 2.5 liters of spray are fully mixed on 25 kg of fine soil and sprinkled). In recent years, some cotton areas, such as Hubei, Jiangsu and other places, have tried sexual attractants (microcapsules or fiber clips) hanging in the field for matering of female and male moths, and have also achieved good control effects. In the egg-growing period of drug control, the second generation of red bellworms should focus on spraying the drug on the lower green bell and taking into account the upper and middle buds, and the third generation of prevention and control mainly focuses on spraying the drug on the middle and upper green bells, and strive to spray evenly. The prevention and control indicators are formulated according to the local conditions, and it is generally believed that the second generation should be based on the amount of 100 eggs on the day 60 to 80, and the third generation should be based on the amount of 160 to 200 eggs per 100 plants. Some people believe that the egg size index should vary according to the type of cotton field, such as the growth and growth of cotton plants, the temperature and humidity conditions caused by the closure of cotton fields, and whether they are close to the source site of wintering insects, which will affect the occurrence and the relationship between pests and the growth period of cotton plants, thus determining the degree of leniency of control indicators. Field control drug varieties can refer to cotton bollworm and strive to treat both, mainly organophosphorus pesticides, but also some permethrin pesticides and mixed preparations. Such as 50% sulfanodolin emulsion, 2.5% Uranus emulsion, 44% Sukai emulsion 1000 times liquid, 40% oxidized Leguo emulsion, 50% octylthion emulsion 1500 times liquid, 2.5% cypermethrin 3000 times liquid and cypermethrin, permethrin, chrysanthemum emulsion 1500 ~ 2000 times liquid.
(3) Timely and early sowing, reasonable fertilization to cultivate strong seedlings, promote early onset, in order to reduce the harm of red bollworms in the later stage.
(4) Strengthen quarantine when the cottonseed is transferred, and the insect cottonseed cannot enter the area where there is no distribution of the insect, that is, the protected area.
8. Cotton aphids
Cotton aphids are small in size and belong to the order Homoptera, Aphid family. To adult aphids and aphids suck in harm.
There are two types: winged aphid and wingless aphid. During life, they migrate to the overwintering host plant (the first host) for both sexes to reproduce, and the male and females mate to lay eggs and overwinter, and camp parthenogenesis during the endangerment of the cotton field (the second host).
1. Distribution and harm of cotton aphid is a worldwide distribution of pests, China's cotton-producing areas are distributed, the northern cotton area is the most serious, followed by the Yangtze River Basin cotton area. Cotton aphids are not only harmful at the seedling stage, but also continue to be harmful at the bud stage, which is the so-called "aphid metallurgy." It takes cotton and melon as the main host, plus more than 100 other host plants. Overwintering, they migrated to a variety of grasses and woody plants, such as purple flower dicho, summer solstice grass, hibiscus, peppercorns, pomegranates, etc. Adult aphids and young aphids gather on the leaf surface or young stems to suck up sap, causing leaf curls and stagnating the growth of cotton plants. Cotton seedlings that were damaged before 3 true leaves were not easy to return to normal growth. The budding period can cause the budding to fall off, which seriously affects the yield. Cotton aphids can expel a large amount of water and honeydew during the process of sucking sap, causing parasitism.
2. Occurrence rules and main habits of cotton aphid occur for more than 20 generations a year, the breeding speed is fast, and the number rises sharply in the short term. After the cotton seedlings are unearthed, the cotton aphids on the overwintering host produce winged aphids, migrate into the cotton field, and the solitary females breed and begin to occur in spots, if not prevented in time, with the increase of insect population density, the unfavorable feeding conditions produce winged aphids, and the second migration and spread in the cotton field. At that time, the cotton began to bud, and the aphid plant rate could be as high as 100%. Before and after flowering, cotton aphids continued to develop, forming a third migration and spread, and the northern cotton area continued to be seriously endangered after falling into ambush. After mid-to-late October, as the temperature drops, the cotton plants age, and then migrate for the fourth time, returning to the overwintering host plants, the fetus has winged females and males, and the tail lays eggs for wintering.
The breeding temperature of cotton aphids is generally 16 to 22 benefits, and the relative humidity is about 60%. During the occurrence of rainfall, the amount of aphids often decreases, the daily rainfall is more than 20 to 30 mm, and the monthly rainfall is about 100 mm, which has a significant inhibitory effect on cotton aphids. Moderate rain and heavy rain have a mechanical scouring effect on cotton aphids. The temperature is above 27 degrees Celsius, and the relative humidity of more than 85% has an inhibitory effect on its reproduction, and the adaptability of the aphid is stronger than that of the aphid.
The growth, nutritional status and development stage of cotton plants have a close influence on the growth and harm of cotton aphids. The several migration and spread of cotton aphids in the cotton field is the transformation period of the development stage of the cotton plant, and the cotton aphids at the seedling stage migrate from the overwintering host to the cotton seedling hazard; when the cotton begins to bud, the cotton aphids undergo the second migration and spread; the cotton plant flowers migrate again during the flowering period, and the cotton plant spits out in late autumn and migrates back to the wintering host. Therefore, the aphid monitor can predict the decline of the number of cotton plants according to the growth stage of cotton plants and the rising trend of winged aphids as the basis for taking control measures. The recovery ability is weak when it is affected by aphid in front of the 3 true leaves, and after the 3 true leaves, with the steady growth of the cotton seedlings, it has a certain recovery ability after being affected by aphids. Therefore, the control indicators of cotton aphid should be formulated, and the 3-leaf stage should be strict, and the 3-leaf stage can be relaxed. Cotton aphids in nitrogen-deficient cotton plants have low reproduction, too much nitrogen fertilizer is applied, and the number of cotton aphids increases, and nitrogen fertilizer should be applied reasonably according to different planting densities in cotton field management.
Different cotton planting methods form different cotton field ecological environments, which have an important impact on the occurrence of cotton aphids and the natural natural enemies of cotton aphids. Large flat-crop cotton fields, single crops, cotton aphid natural enemies species and numbers are small, cotton aphid occurrence is large, migration and spread space is also large, the harm is more serious. Wheat cotton adjacent crop, cotton aphids into the peak period, is the wheat plant mature about to harvest stage, wheat plant natural enemies such as ladybugs, grass worms, aphid cocoon bees, etc. from the wheat field into the cotton field, thereby strengthening the control of cotton aphids. In addition, the wheat plant is higher than the cotton seedling, which plays a barrier to the migration and diffusion of cotton aphids. It is precisely for this reason that the wheat cotton planting, cotton aphid hazard is significantly reduced, such as better management at the seedling stage, during the occurrence of cotton aphids in general years, it can not be prevented and controlled, or the prevention and control of key cotton fields can be carried out. In some cotton areas, there are cotton fields for rapeseed, corn or sorghum, which can not only increase economic income, but also facilitate the transfer of natural enemies in the wheat field, and the harm of cotton aphids is significantly reduced.
(1) Planting enticing crops in cotton fields, protecting and breeding natural enemies cotton size ridge planting, small ridge 50 cm, large ridge 86 cm. Plant 1 row of lure crops every 4 to 5 rows of cotton. The enticing crops are planted in large ridges and can be grown in rapeseed or corn, or mixed rapeseed and sorghum. Rape strip sowing, the amount of seeds per hectare is about 1500 grams, pay attention to the selection of short plants, early and long flowering period varieties, spring and winter varieties can be mixed sowing, sorghum can not be sown in the large ridge but sown between cotton rows, hole sowing, hole spacing 2 ~ 2.5 meters, each hole double plant. These organic crops are sown at the same time as cotton. Rapeseed is mastered at ploughing into the soil at the time of fast wheat harvest. Planting enticing crops in the cotton field, the main role is to attract a large number of natural enemies in the wheat field to transfer into the cotton field, first multiply on the enticing crops, and once the cotton aphids enter the peak, the natural enemies on these enticing crops will be transferred to the cotton plants, which can effectively inhibit the cotton aphids. Practice has shown that the effect of planting rapeseed and sorghum in the cotton field at the same time is the best, and the breeding of natural enemies on sorghum is not only beneficial to the control of cotton aphids, but also has a good control effect on the second and third generations of cotton bollworms.
(2) Seed treatment can be mixed with 3% furandan granules, the ratio of medicine to cottonseed is 1 cinnamon, and it can be sown after mixing well for 12 to 24 hours. Due to the resistance of cotton aphids to furantine and the more expensive price of the drug, the cost of control has increased. Many cotton areas use 75% 3911 emulsion to impregnate seeds. 1 kg of dried cottonseed per 100 kg. The specific method is: first put 55 to 60 liters of warm water into the soaking tank and mix well with the poured agent, and finally pour the cotton seeds in and stir them well, and then shovel all the seeds out of the pile when the liquid is all drained. Seeds can generally be sown 24 hours after dipping. If possible, 10% imidacloprid active ingredient 50 to 60 grams of cotton seeds can be mixed with 100 kg, which not only has better prevention effect but also can reduce the number of aphids in the future. Due to the late sowing period of wheat tau cotton fields, the use of imidacloprid seeds can basically control the harm.
(3) Strictly according to the control indicators of field application of cotton aphid control indicators are generally based on the aphid plant rate, the amount of 100 plants and the rate of curly leaf curls to decide whether to use drugs, but the most important impact on cotton plants is the curly leaf rate. The rate of 3 true leaf rolled leaves before the leaf was 10%, the rate of the three true leaf rear leaf roll plants was 20%, and the rate of the leaf curl plant when the aphid occurred was 5%-10%. In addition, it is also necessary to look at the situation of the benefit-to-harm ratio to determine whether it is necessary to apply drug control. At the seedling stage, such as ladybird (insect) aphid ratio of 1:120, the parasitization rate of natural enemies in the aphid stage is 30%, or the effective natural enemy and aphid ratio is 1:50 to 1:80, even if the leaf curl plant rate reaches the control index, it is not controlled by spraying.
Since cotton aphids have become resistant to agents in recent years, the application of pesticide spraying needs to pay attention to the choice. Parathrin insecticides should not be used to prevent aphids, 20% butyric Budweiser emulsion 6000 times liquid is not only highly effective, but also has a long shelf life, 20% amidoxine and 35% cedan (endosulfan) emulsion 1500 times liquid is also a highly effective agent for the prevention and control of cotton aphids. In some areas, in order to prolong the residual period of the agent, a sustained release agent such as polyvinyl alcohol is also added for preparation. In addition, spot spray can also be used to provoke treatment in the mode of administration; topical target administration, that is, with an assorptive agent to drip the heart or coat the stem. Specifically, 40% daumin emulsion and 40% oxidized Lego emulsion can be sprayed with a sprayer at a height of 3 to 5 cm at the top of the cotton seedling for about 1 second. If the stem is coated, the liquid is applied to the junction of red and green of the cotton stem at the adult stage, and the care is not necessary to re-coat, let alone ring coating. Drip heart and coated stem can not only reduce the control area, save medication, but also avoid killing predators.