Academician of the Chinese Academy of Engineering Kang Zhensheng
In 2021, the mainland will save 250 billion catties of grain through pest control, accounting for 18.3% of the country's total grain output.
"Pests and diseases are eternal problems, and it is impossible to deal with them once and for all, and the types and levels of pests and diseases are constantly changing. As a response, we can only strengthen the selection and breeding of disease-resistant varieties, strengthen the detection and early warning of crop diseases and insects, strengthen the screening of green and low-toxic pesticides, and strengthen the application and promotion of public welfare prevention and control measures. ”
Wen | "Lookout" News weekly reporter Hu Yongshun Yao Youming
Scientific and effective prevention and control of crop diseases and insect pests is an important measure to ensure national food security and green and high-quality agricultural development. The China Association for Science and Technology recently released the 2022 major problem problems, how to scientifically and effectively prevent and control wheat stem base rot ranked among the 10 industrial technical issues.
Wheat gibberellosis, stripe rust, stem base rot, etc. are known as "wheat cancers", and generations of scientists and many agricultural workers on the mainland have waged unremitting struggles to protect food security. Kang Zhensheng, academician of the Chinese Academy of Engineering and director of the State Key Laboratory of Crop Stress Biology in arid areas, has long been engaged in the research on the occurrence of major wheat diseases and prevention and control technologies, and is one of the representatives.
Recently, combined with how to scientifically and effectively prevent and control wheat stem base rot, why the current situation of stripe rust prevention and control is still grim, how to effectively prevent and control several major wheat diseases, etc., the "Lookout" news weekly reporter interviewed Academician Kang Zhensheng.
Kang Zhensheng, who has been dealing with wheat diseases all his life, believes that the key to "insects are not a disaster, and the disease is not epidemic" is "prevention first, comprehensive prevention and control". "Pests and diseases are eternal problems, and it is impossible to deal with them once and for all, and the types and levels of pests and diseases are constantly changing. As a response, we can only strengthen the selection and breeding of disease-resistant varieties, strengthen the detection and early warning of crop diseases and insects, strengthen the screening of green and low-toxic pesticides, and strengthen the application and promotion of public welfare prevention and control measures. Kang Zhensheng said.
Compete with wheat germs for food
Lookout: How did you come into contact with and get into the profession of plant pathology? What is the importance of the profession in ensuring national food security?
Kang Zhensheng: I was one of the first students after the resumption of the college entrance examination. Before coming to Yangling's Northwest Agricultural College (one of the predecessors of Northwest A&F University), I went to the countryside in Shiquan County, Shaanxi Province. In the production team, I have run a dough machine room and raised pigs. At that time, he filled in the volunteer times as a major in agricultural mechanization at Northwest Agricultural College, and was later admitted to the plant protection major. I didn't quite understand what the profession was for, and a brigade accountant told me I was studying crop pests and diseases.
After entering the school, our thirst for knowledge is very strong. In his sophomore year, Mr. Li Junyan, who teaches plant pathology, held a symposium after class, starting from a piece of begonia leaf that was sick, saying that field crops may also be infected by this pathogenic bacteria, causing losses caused by diseases. Since then, I have been more interested in plant pathology, and I have done a graduation internship with Mr. Li on cotton disease control.
Ensuring food security on the continent is an eternal theme. For decades, in the pursuit of high quality and high yield of agricultural products, we have changed the farmland environment and reduced the resistance of crops to diseases and insect pests. Under the modern agricultural ecological environment, our agricultural genetic system has become fragile, and diseases and insect pests are prone to epidemics and hazards. Plant protection, pest control and disease control play a very important role in ensuring food security. In 2021, the mainland will save 250 billion catties of grain through pest control, accounting for 18.3% of the country's total grain output; In 2021, the mainland will avoid a reduction in wheat production of 73 billion catties, accounting for 26.3% of total output, through pest control and pest control.
"Lookout": What benefits have been achieved in the comprehensive prevention and control technology system of wheat gibberellosis created by your team and applied and promoted in the main wheat-producing areas of the mainland?
Kang Zhensheng: Wheat gibberellosis is a worldwide panicle disease that can be caused by a variety of fungal infestations. In mainland China, this disease is mainly prevalent in the middle and lower reaches of the Yangtze River winter wheat area, south China winter wheat area, Huanghuai Basin winter wheat area and northeast Sanjiang Plain spring wheat area, is the main disease and key control object of wheat. Wheat gibberellosis can not only cause a serious reduction in wheat yield, but also infected wheat grains containing a variety of fungal toxins, which can cause human and animal poisoning and serious diseases. Therefore, a lot of financial and manpower has been invested at home and abroad for the study of the disease prevention and control strategy and the host disease resistance mechanism.
In 1997, I did several years of research in Germany, and for the first time in the world, I clarified the time, location and route of infection of gibberellosis bacteria, and corrected some errors and incomplete understandings of the infection process in the world. In the past, it was thought that the full blooming period was the main time for gibberella to infect wheat, and it was also the best time to control wheat gibberellosis, but later, we corrected this time to the first flowering period.
Our team screened out a batch of triazole fungicides to solve the single problem of drug use in the prevention and treatment of gibberellosis in China. At the same time, a comprehensive prevention and control technology system for gibberellosis was built, and the key technology of disease prevention and control of "zoning treatment, active attack, and seeing flowers and spraying medicine" was established, which increased the prevention and control effect from about 30% of the original to 77% today, and saved an average annual loss of 5.6 billion catties of wheat.
"Lookout": Wheat stripe rust often causes wheat yields to decrease by 10% to 30%. How did you fight the world of wheat stripe rust mutation for so long?
Kang Zhensheng: Wheat stripe rust is a low-temperature fungal disease transmitted by the air. For decades, generations of scientists on the mainland have worked tirelessly and diligently to lay the scientific research foundation for wheat stripe rust. My teacher, Academician Li Zhenqi, Researcher Liu Hanwen of the Shaanxi Academy of Agricultural Sciences, and other scientists of the older generation rode a donkey as early as the 1950s to investigate and simulate experiments in various parts of the northwest in the summer and autumn. They found that every year, the source of the pathogenesis of wheat stripe rust in the eastern part of the mainland is blown from the west, and the areas bordering Gansu, Qinghai, Ningxia, Shaanxi, Sichuan and other provinces and regions are the "more summer volatile areas" where stripe rust bacteria hide in yuexia. Stripe rust bacteria are cold and not heat-resistant, and spread over long distances through atmospheric circulation. With high altitudes and low temperatures in the northwest, rusty fungus can successfully cross the summer and spread all the way to the east. At that time, it was also found that the resistance to stripe rust almost disappeared after the Lovrin wheat, which was originally introduced as a disease-resistant variety, was widely planted in the "Yuexia Variable Zone" for several years. Older scientists believe that pathogenic variation of stripe rust bacteria is the main reason for the loss of disease resistance of wheat varieties.
From 1982 to 1983, our research team traveled to almost all townships in southern Gansu and collected nearly 7,000 wheat specimens. After investigation and experimental analysis, a new strain of Lovrin wheat infected with stripe rust was found and published for the first time in China. In the past, the traditional theory was that stripe rust bacteria were asexual reproduction, but our team found that the reason why pathogenic bacteria mutate is because of sexual reproduction in nature, and wheat stripe rust bacteria are "bearing children" on wild barberry widely distributed in the northwest mountains, so that the "next generation" mutates, producing pathogenic new strains, resulting in the loss of disease resistance of the original disease-resistant wheat varieties. The answer to this question, the selection of disease-resistant varieties, the prediction and forecasting of disease resistance, the rational layout of disease-resistant varieties, and how to form a biological barrier according to this are of great significance.
We summarize the prevention and control techniques to prevent the sexual reproduction of stripe rust bacteria as "covering, shoveling, spraying", that is, covering the wheat stack, eradicating barberry and spraying fungicides to reduce the rate of mutation of pathogenic bacteria. We advocate the establishment of a set of comprehensive prevention and control methods, including prevention first, comprehensive prevention and control, focusing on the control of summer areas, continuous control of winter areas and other principles, but also include wheat planting structure adjustment, rational use of disease-resistant varieties, sexual reproductive control, field agronomic measures, timely application of pesticides and other specific methods. Now, the prevention and control of wheat stripe rust in the mainland has been at the forefront of the world, and every year through the comprehensive treatment technology system of wheat stripe rust, we can avoid the loss of 4 billion to 5 billion catties of grain production.
In a wheat field in Leidian Village, Leidian Town, Deqing County, Huzhou City, Zhejiang Province, members of the Party Member Agricultural Machinery Service Team operate a plant protection drone to control wheat pests and diseases (april 2, 2022) Photo by Wang Zheng/This journal
Establish the concept of "prevention first, comprehensive prevention and control"
"Lookout": Why is the current situation of stripe rust prevention and control still grim? What are your suggestions for implementing the prevention and control of wheat stripe rust?
Kang Zhensheng: Our enemy, the pathogen, is very smart and has its own way of survival. Why is stripe rust up again? In recent years, a new strain of bacteria has emerged, namely No. 34 in the strip, which is a dominant small species with strong pathogenicity. In fact, the mutation of germs has always been a problem we face, once the bacteria mutate, then the original disease-resistant varieties we used to produce will lose their disease resistance.
In 2017 and 2020, due to the new strain becoming the dominant small species, coupled with the warm winter, the pathogenic bacteria base was large, resulting in a high incidence of stripe rust and a pandemic. However, in this process, agricultural scientific and technological personnel accurately monitored and reported, and government departments actively mobilized the masses and provided funds for prevention and control, and finally controlled the disease at a level of harm, that is, "there is no disease or disaster". In the future, we must also do a good job of preventing its sexual reproduction. New small species rely on sexual reproduction, we have developed the corresponding prevention and control measures, which need to be further promoted and applied, through the control of sexual reproduction to reduce the rate of bacterial mutation, extend the service life of wheat stripe rust-resistant varieties, which is the fundamental way to solve the problem.
Stripe rust bacteria lurk in the mountains of the northwest in the summer, so controlling the source of summer fungus in the west is crucial to ensuring wheat production. On the one hand, it is necessary to mobilize the masses to take prevention and control measures, and further call on relevant departments to attach great importance to this problem and increase investment, so as to do the basic work in the coming year; On the other hand, wheat stripe rust is an airborne disease, and the trajectory of the pathogen requires us to carry out cross-regional full-cycle prevention and control. On the basis of understanding the pathogenic characteristics of pathogenic bacteria, strengthen the breeding of disease-resistant varieties, and take disease resistance as an important indicator of variety breeding. At the same time, we should also pay attention to the rational layout of disease-resistant varieties, lay out disease-resistant varieties with different genes in different regions, form a biological barrier in a large region, and prevent the epidemic of wheat stripe rust. This is a systematic project, involving the government, farmers, plant protection experts, etc., can not "headache and pain, foot pain to heal the foot", but according to its occurrence law, design a green prevention and control comprehensive control system.
"Lookout": How to improve the problem of heavy treatment and light prevention in plant protection?
Kang Zhensheng: Heavy treatment and light prevention will become dependent on chemical pesticide-based prevention and control measures. Under the new situation, we must establish the concept of "prevention first, comprehensive prevention and control" and deeply practice the concept of green agricultural development.
Doing a good job in plant protection involves the inclination of scientific and technological input policies, the support of grass-roots agricultural technicians and the improvement of conditions, and it is a systematic project. There are diseases and insects are not afraid, as long as the insects are not a disaster, the disease is not epidemic.
From the perspective of research and development, it is necessary to understand the occurrence of diseases and insect pests in the new situation and make predictions. Clarify the time and dosage of pesticide use. Comprehensively consider the corresponding measures of various diseases and insect pests from sowing to harvesting, including variety disease resistance, ecological regulation, and cultivation systems, and create an ecological system that is conducive to crop health and not conducive to the occurrence of diseases and insect pests, and essentially lowers the base of diseases and insect pests. We should also increase the prediction and prevention and control of pests and diseases, and improve the overall disease resistance of crops through the full cooperation of experts in many fields such as plant protection, breeding, and organic agriculture.
The study of wheat stem-based rot requires multidisciplinary joint research
"Lookout": Why has wheat stem-based rot occurred in the main wheat-producing areas of the mainland in recent years? How to carry out scientific and effective prevention and control?
Kang Zhensheng: Stem base rot is a worldwide wheat soil-borne disease, first discovered in 1950 in Queensland, Australia, and is currently found in dozens of countries such as the Americas, Europe, and Asia. In mainland China, wheat stem base rot is a new disease, which was first reported in 2012 in Qinyang, Jiaozuo, Henan. At present, the disease has spread in Henan, Shandong, Hebei, Anhui, Jiangsu, Shanxi, Shaanxi and other provinces in the main wheat producing areas of Huanghuaihai, and the incidence area has expanded year by year, and has spread to the wheat area in the northwest, north China and the Yangtze River Basin. In particular, some wheat fields in northern Henan, middle East Henan, southwestern Lu, northwestern Lu, central and southern Hebei, central Shaanxi, and southern Jinnan caused huge losses. According to the survey, the loss of general sick land can reach about 20%, and the loss of serious plots can reach more than 60%. In addition to the decline in yield, pathogenic bacteria can also infect the panicle to cause panicle rot (gibberellosis) and produce mycotoxins such as vomitoxin and zearalenone.
The occurrence of this disease is closely related to the level of variety resistance, farming system, soil environment, number of pathogens in the field, and climatic conditions. The current production-promoted wheat varieties have low levels of resistance, and most of them are susceptible or highly susceptible to stem-based rot. The Huanghuai wheat area of the mainland is mainly a wheat-corn two-cropping system per year, and the return of straw to the field makes it easy for germs to accumulate, coupled with the deterioration of the soil ecological environment caused by the application of a large number of chemical fertilizers, and the spread of diseases caused by mechanical cross-regional operations, which makes the disease prone to occurrence and epidemic. Climate change has led to warm winters and drought and little rain during the wheat filling period, which has also aggravated the occurrence and degree of damage of wheat stem base rot.
Recently, pathologists from all over the country have had many focused discussions on what should be done to face these situations. I suggest: First, find out the family background as soon as possible, and grasp the distribution of diseases in various places, the degree of harm and the types of pathogens; The second is to strengthen the research and development and application of relevant technologies to improve the level of disease monitoring and early warning; The third is to carry out systematic basic research to clarify the pathogenic mechanism and the molecular mechanism of pathogen and host interaction; The fourth is to attach great importance to the mining and utilization of disease resistance resources to improve the disease resistance of varieties; Fifth, strengthen green and efficient prevention and control technology and product research and development to enhance disease prevention and control capabilities; The sixth is to set up major scientific and technological projects as soon as possible to carry out multidisciplinary joint research.
It is recommended to set up major scientific and technological projects for wheat stem-based rot monitoring and early warning and green prevention and control technology, organize the superior strength of relevant research units across the country, strengthen the joint research of plant pathology, wheat breeding, wheat cultivation, soil ecology, biotechnology, information technology, biological and chemical pesticides, etc., and build a rapid monitoring and early warning system for wheat stem-based rot in the mainland and an efficient green prevention and control technology system for organically integrated diseases as soon as possible, so as to provide technical support for ensuring the safe production of wheat and national food security. ■