The copyright belongs to the original author, in case of infringement, please contact us
Cotton is an important cash crop and strategic material, and it is the second largest crop after grain in China and occupies an important position in the national economy. Xinjiang is the largest high-quality cotton production base in China and has unique conditions. However, there are also many constraints in the cultivation process, such as pests and diseases.
According to reports, the cumulative area of diseases and pests in Xinjiang in 2020 was 1.4599 million hectares. If cotton diseases and insect pests are not effectively controlled, not only will the area where they occur will continue to expand and spread, resulting in a significant decline in the yield and quality of local cotton fields, or even extinction, but also become an obstacle to a bumper cotton harvest in the coming year.
In this cotton defense war, scientists played a very crucial role.
In 2020, Xinjiang's cotton planting area was 25.019 thousand hectares (37.529 million mu), down 1.5% from last year, but thanks to good management, the yield per unit area increased by 93.8 kg/ha (6.3 kg/mu) compared with last year.
(Source: CCTV)
The glamorous rays that covet Xinjiang cotton
"Know thyself and know the other, never lose a battle". If you want to win this battle, you must first know which bugs and "plague gods" are at work. There are many pests that covet cotton in Xinjiang. Let's first pull out the four kinds of insects, cotton aphids, cotton leaf mites, and whitefly, and see what carving tricks they all use.
1. Cotton aphids
Cotton aphids occurring in Xinjiang are mainly cotton black aphids, cotton long tube aphids and cotton aphids, which are smaller pests, and wingless female aphids are less than 2 mm long, which is one of the important pests in the cotton seedling stage. Cotton aphid mainly sucks the growth point and young leaves of cotton with a sucking mouthpiece, and there will be pale yellow green spots or leaf curls in the affected part, affecting the photosynthesis of leaves, and when the leaves are deformed, shrunken, dried up or fallen leaves. In addition, cotton aphids are also able to produce honeydew and produce coal pollution disease (click here to review useful information about coal pollution disease). As vector insects, they can also help transmit some plant viruses.
From left to right: wingless cotton aphid; cotton leaf infestation
(Image source: Tianshan Plant Protection)
Cotton aphids are highly adaptable, and aphids are able to survive in different lifestyles depending on the region and host. Cotton aphids generally reproduce in less than 10 days at the right temperature, and if the conditions are right, the offspring of an aphid can reach more than one million (including offspring produced by the offspring). In recent years, the resistance of cotton aphids has increased, which deserves our vigilance.
2. Cotton blind bugs
The cotton blind bug is also a pest of cotton that uses a sucking mouthpiece as a pest of cotton. The cotton blind bugs that are more harmful in Xinjiang are mainly pasture blind bugs, alfalfa blind bugs and green blind bugs. Cotton blind bugs only have 3 worm states: eggs, nymphs (larvae) and adults, and both adults and nymphs can be harmful to cotton, and they mainly suck the top buds, edges, buds and young bells with a needle, and suck the sap of the cotton plant.
For the top buds, young leaves, and young buds, the infringement of cotton blind bugs is mainly carried out in the form of "smearing" - the cotton top buds will wither and turn black into headless seedlings or head-breaking madness after being harmed; the young leaves will form leaf breakers; the young buds will turn from yellow to black and fall off after a few days. If the bud of cotton is invaded, it will form an opening bud and fall off soon; the wound of the young bell will be water-stained spots, and the weight will be rigid and fall off; the top or side heart will be injured, and the broom cotton will be formed.
From left to right: green blind bugs; cotton leaves are damaged
3. Cotton leaf mites
Also known as cotton red spider, is a type of pest that is more harmful in the cotton areas of China, in the cotton area of Xinjiang, its dominant species are truncated leaf mites and Turkestan leaf mites, leaf mites are small, generally about 1mm, the naked eye is not carefully observed is also difficult to see.
Cotton red spider mainly sucks nutrient juice on the back of the cotton leaf, for the initial appearance of more yellow and white spots on the front of the leaf, after a few days the petiole becomes red, heavy leaf light stalks, such as fire, resulting in a large area of yield reduction or harvest failure. Even if it does not lead to a light rod, it will seriously affect the photosynthesis of cotton, so that the cotton plant cannot grow normally, the plant is short, resulting in a decrease in yield. The ambitions of the cotton leaf mite are not only in cotton, but also in other food crops and cash crops.
From left to right: cotton leaf mites; cotton leaf pests
4. Whitefly
Whitefly is also a type of pest of sucking mouthpieces, farmers call "small white insects", the size is also small, about 1mm or so, with fast transmission speed, strong reproductive ability, heavy harm, strong resistance, difficult to control the characteristics.
When harming cotton, whitefly sucks plants with adults and nymphs, causing the leaves to fade green, yellow, wilt, and even the whole plant to die, and can also spread macular virus disease, resulting in crop yield reduction; it is particularly noteworthy that its adult and nymphs will secrete a large amount of honeydew, pollute plants, easily lead to the occurrence of coal pollution disease, and will pollute cotton wool, so that the fiber sugar content increases, affecting the textile process.
Whitefly is a highly harmful invasive pest. This pest from the United States can be said to have traveled all over the world. According to reports, whitefly was first discovered in Arizona, USA, in 1962, and since then, it has spread to many countries and regions in South America, Europe, Africa, Asia, and Oceania. Among them, Sudan, Turkey, Egypt, Israel and other countries, as well as the former Soviet Union and Central Asian countries after the 1980s, suffered the most. In 1998, China's scientific and technological workers first found whitefly on a poinsettia sold in the Nanchang Road Bonsai Flower Wholesale Market in Urumqi City; in 1999, the insect was also found in the cotton test field of the Turpan Long-staple Cotton Research Institute. In recent years, the occurrence of whitefly in Turpan, Hami, Kezhou and Kashgar has been relatively heavy.
From left to right: smoking whitefly nymphs; adult whitefly
In addition to these kinds of insects that take the lead in making noise, the pests that harm Xinjiang cotton are also cotton bollworms, cotton thrips, double-spotted firefly beetles and other pests. Some "plague gods" are not willing to be lonely, they spread quickly, will bring "disaster" to cotton, such as cotton blight and verticillium wilt.
Both cotton blight and verticillium wilt are fungal diseases. Blight and verticillium wilt mainly overwinter in disease residues, soil and manure, and the cultivated land of diseased cotton fields, rake harrow, medium cultivation, watering, agricultural operations, etc. are the main ways of close transmission. The pathogenesis mainly harms the vascular bundles and other parts of cotton, and once it occurs, it is difficult to eradicate, and it is called "cotton cancer". At present, the incidence area of Verticillium wilt in Xinjiang exceeds 50% of the sown area, of which the area of severely ill fields exceeds 1 million mu.
It can be said that the pests and "plague gods" who covet Xinjiang cotton know how to reproduce rapidly and spread harmful substances, coupled with their increasing resistance to drugs, which has really brought certain difficulties to the prevention and control work.
Scientists on! Stop the bugs' plot
Cotton is so precious that nature does not allow bugs and plague gods to act arbitrarily. In response to cotton pests and diseases, a variety of control measures have been adopted, including phytosanitary, physical, chemical, biological, agricultural and so on.
The first three methods are easier to understand, such as phytosanitary is to prevent the introduction or transmission of some quarantine diseases and insect pests; physical control is to use light to trap some light-oriented pests; chemical control is to apply the corresponding pesticides according to the types of diseases and insects in the field.
However, we must not only effectively control pests and diseases, but also overcome the adverse effects of chemical pesticides and avoid the destruction of biological resources and the environment. In Xinjiang, scientists have followed the principle of sustainable development and the plant protection concept of "prevention first, comprehensive treatment", made these attempts, and achieved good results.
1. Biological control - biological pesticides, precision strikes
Nature has many natural predators of cotton pests. We need to take advantage of these predators. For example, during the occurrence of seedling aphids, when the ratio of natural enemy units in cotton fields (1 seven-star ladybird, 2 spiders, 2 aphid lions, 4 aphid flies, and 120 aphid cocoon bees is 1 natural enemy unit) and the aphid population is higher than 1:150, no pesticide is applied to control and natural predators are used to control aphids. In addition, we can breed and release natural enemies such as ladybirds, red-eyed bees, and aphid cocoon bees to achieve the purpose of directly suppressing pest populations.
In addition, at the beginning of the hatching of cotton bollworm eggs, spraying insect viruses, Bt and other biopesticides not only has a good control effect, but also can effectively protect natural enemies; in order to prevent seedling disease, blight, verticillium wilt, seeds can be treated with Bacillus subtilis, amino oligosaccharides, allicin, and drip irrigation or foliar spray at the seedling and bud stages.
Qin Qilian Research Group of the Institute of Zoology, Chinese Academy of Sciences, successfully developed a burlasma polyhedral virus insecticide. This viral insecticide has a viral content of up to 500 billion virions per gram of original drug, more than 20 times more than similar products, and is currently the highest known viral insecticide in the world. With this biopesticide, only 2 to 3 grams per acre of cotton field can control pests.
Since 2005, researchers have begun to conduct a multi-site comparative test of the efficacy of the new ultra-high insect virus insecticide Datian in some cotton fields of the Corps, and the control effect of cotton bollworm is better than that of conventional chemical pesticides. Especially when chemical pesticides almost completely kill the natural enemies of cotton bollworms in the field, this viral insecticide has almost no impact on the natural enemies of cotton bollworms, and can degrade itself in nature after use, without causing pesticide residues, and its overall control effect is 80%, reducing the release of nearly 100 tons of chemical pesticides into the environment, and the ecological benefits are significant.
2. Agricultural control - not only to kill insects, but also to increase production
This is an advanced version of biological control. Plants play an important role in the conservation and proliferation of natural enemies in ecosystems and in the natural control of pests. Agricultural control can use plants to regulate biological relations in farmland ecosystems, and it differs from traditional biological control in that it indirectly uses natural predators rather than direct artificial reproduction to release natural enemies. Agricultural control through crop layout, intercropping and intercropping, cotton field cropping can reduce the occurrence of diseases and insect pests, but also promote each other to increase production.
Experts from the Institute of Zoology of the Chinese Academy of Sciences and the Xinjiang Institute of Ecology and Geography of the Chinese Academy of Sciences found that the reason why Xinjiang cotton aphid has become the main pest is that the planting area of winter wheat has decreased significantly, resulting in a decrease in the source of natural enemies of cotton aphid in cotton fields, and sufficient food and insufficient natural enemies have caused the occurrence of cotton aphids in Xinjiang.
High-yielding Xinjiang cotton (Source: The Great Change - a large-scale exhibition celebrating the 40th anniversary of reform and opening up)
After years of exploration and in-depth research, they found that alfalfa, bitter beans, etc. have the largest amount of food insects, and can be used as a natural enemy breeding reservoir, thus creating a simple way to induce natural enemies on the edge of the cotton field to bring natural enemies into the cotton field to control cotton aphids: planting alfalfa belts under the shade of the edge of the cotton field, when the cotton alfalfa enters the cotton field and begins to harm the cotton, cut off the alfalfa belt, and place the cut-down alfalfa in the cotton field, thus achieving the purpose of making full use of natural enemies to control cotton aphids with human assistance. Moreover, alfalfa is a high-quality pasture grass, suitable for the development of animal husbandry in agricultural areas, and alfalfa as a leguminous plant is also conducive to improving soil fertility.
3. Promotion of new varieties - genetically modified cotton, RNAi cotton
If we get a breed that is resistant to pests and diseases, it will fundamentally solve the problem of pests and diseases.
In 2007, Xinlu Cotton No. 1, the first transgenic insect-resistant cotton variety in Xinjiang, co-bred by the Institute of Economic Crops of the Xinjiang Academy of Agricultural Sciences and the Institute of Biotechnology of the Chinese Academy of Agricultural Sciences, passed the national examination and approval, and the transgenic insect-resistant cotton variety Santa No. 6, which was co-bred in 2011, passed the national examination and approval. According to the survey, in 2012, xinjiang's transgenic insect-resistant cotton planting area has exceeded half. Since the large-scale planting of transgenic insect-resistant cotton, Xinjiang cotton bollworm has not suffered serious harm and is in a controllable state, which fully demonstrates the technical effect of transgenic insect-resistant cotton. Relevant research and analysis show that farmers can obtain direct income from transgenic insect-resistant cotton technology. Studies of GM cotton planted from 1999 to 2001 showed that GM cotton per hectare could raise incomes by more than 1,800 yuan.
In addition to genetically modified cotton, RNAi cotton is also playing a big role. In order to cure the so-called "cotton cancer", Guo Huishan's research group of the Institute of Microbiology of the Chinese Academy of Sciences has made a series of important progress on the infestation biology of cotton verticillium wilt, the theory and application of plant-fungal cross-RNAi and the establishment of a broad-spectrum and rapid cotton genetic transformation system on the basis of 20 years of accumulated experience in plant antiviral RNAi research, and after more than ten years of efforts, a series of important progresses have been made in the infestation biology of cotton verticillium wilt, the theory and application of plant-fungal cross-RNAi and disease resistance, and the establishment of a broad-spectrum and rapid cotton genetic transformation system. Successful germplasm innovations against Verticillium wilt in early maturing upland cotton.
The guo huishan research group of the Institute of Microbiology of the Chinese Academy of Sciences established a field workstation for cotton verticillium wilt and blight in Xinjiang
(University of Chinese Academy of Sciences website)
The results of multi-year, multi-point continuous resistance identification showed that the resistance of RNAi cotton was increased by 55.7% compared with that of the recipient variety. In 2017, the research team used the created antigen combined with hybrid breeding to successfully cultivate a new strain of early maturing upturnel cotton with completely independent intellectual property rights (Zhongke Cotton No. 1), and the disease resistance identification and productivity test results of the northwest inland cotton area of the country showed that the resistance of the new strain was increased by 22.25% compared with the pilot control variety in the region, and the yield in the severely diseased field was increased by 41.7% compared with the control variety (local main planting variety).
New technology helps defend cotton
The situation of cotton diseases and insect pests is complex, closely related to regional and human operations, and the climatic conditions may be different every year, so the prevention and control of cotton diseases and insect pests should be adapted to local conditions, establish scientific prediction and forecasting technology, and carry out scientific prevention and control to achieve the purpose of green prevention and control and bumper harvest.
With the development of science and technology in China, some new technologies may be more widely used in the prevention and control of cotton diseases and insect pests: such as the application of new cotton high-quality germplasm resources, including more insect-resistant and disease-resistant and high-yield transgenic cotton; the application of 3S technology (3S is the collective name of GIS, RS and GPS, that is, geographic information system, remote sensing and global positioning system) in pest prediction and forecasting; the application of digital identification and monitoring and early warning technology of diseases and insects in pest monitoring and forecasting The application of big data and 5G technology in the monitoring, forecasting and control of some important pests; the wider promotion of plant drones.
These technologies can make the scheming bugs and plague gods nowhere to hide, and I believe that we will eventually be able to win the cotton defense war.
Source: Science Compound