Experts predict that this year's major diseases and pests of food crops pose a risk to more than 70% of the production areas.
How to "grab grain from the worms" to ensure a bumper harvest
Guangming Daily reporter Yang Shu
May is the critical period for wheat jointing and ear extraction. However, as the temperature rises, wheat stripe rust has also entered an epidemic period, and farmers are always vigilant and most concerned.
At the end of January this year, the Ministry of Agriculture and Rural Affairs issued a document pointing out that in 2021, major diseases and pests of wheat, rice, corn and other grain crops will recur, and it is expected that the area of occurrence in the country will be 2.1 billion mu, an increase of 14% year-on-year, posing a risk to more than 70% of the production areas. In terms of specific diseases and insect pests, major diseases and insect pests such as wheat stripe rust, red mildew and corn borer have shown a recurring trend, which directly threatens the safety of grain production.
Why are agricultural pests and diseases re-emerging this year? What impact will it have on food security? Under the premise of ensuring food security and the quality and safety of agricultural products, what are the new and practical measures for the prevention and control of agricultural diseases and insect pests?
Crop losses from agricultural pests and diseases can range from 10 to 20 percent per year
There are many kinds, great influences, and frequent outbreaks, crop diseases and insect pests are one of the most important agricultural production disasters in China. Lu Yanhui, deputy director of the Institute of Plant Protection of the Chinese Academy of Agricultural Sciences, introduced that as a big agricultural country, more than 50 kinds of agricultural diseases and insect pests occur in China every year, with an area of about 7 billion mu, resulting in crop yield losses of up to 10% to 20%. Taking wheat stripe rust and gibberellosis prevalent in China in recent years as an example, stripe rust is caused by fungi and spread by air currents, and once the temperature and humidity are suitable, it is easy to spread on a large scale. It can cause wheat yields to be reduced by 20% to 30%, more than 50% in severe cases, and even harvests are cut off. The same gibberellosis caused by fungi will not only make wheat rot, the average yield reduction of 20% to 30%, but also produce toxins on the wheat grains, causing poisoning after human and animal food.
"However, the agricultural diseases caused by these fungi have existed in nature for a long time, and with the co-evolution of crops, new physiological subspecies have been constantly mutated, making it impossible for us to fundamentally kill these bacteria, so we can only strive to strengthen prevention and control and reduce its harmful impact as much as possible." Liu Taiguo, a researcher at the Institute of Plant Protection of the Chinese Academy of Agricultural Sciences, said.
This is true of diseases, and it is also true of insect pests. In 2019, the grassland moth native to the Americas first migrated from Myanmar to invade China, this alien invasive insect is known as a "marching insect", which can fly more than 100 kilometers a night, its fertility is strong, and the larvae like to bite the young heart leaves of corn, which can lead to a 20% to 40% reduction in corn yields, and even ruin the harvest. In 2018, it exploded in Africa, causing economic losses of $1 billion to $3 billion. However, due to the suitable environment, in just two years, this pest has been "settled" in parts of southwest China and south China, and it has also appeared in northern regions such as Beijing and Liaoning, posing a serious threat to china's main corn-producing areas and becoming the first of the top ten crop pests in China.
"As a creature of nature, we cannot completely kill a pest, but reduce its harm by regulating its number to a certain level." Wang Zhenying, a researcher at the Institute of Plant Protection of the Chinese Academy of Agricultural Sciences, said that due to the continuous migration of grassland moths from abroad, coupled with the local insect sources that have been "settled", the situation of prevention and control of grassland moths in China this year is very grim. In addition, changes in various factors such as climate change, farming systems, and crop variety changes will also affect the incidence of agricultural pests and diseases.
"Last winter was relatively cold, and the humidity was also large, which made the source base of stripe rust bacteria overwintering bacteria larger, combined with the overall more suitable climate situation this year, so it is believed that this year's wheat stripe rust and gibberellosis and other diseases may still be a recurring trend." Liu Taiguo said that with the recent rise in temperature and the increase in rainfall, it is also conducive to the rapid epidemic of red mildew disease in Sichuan, Shaanxi, Hubei, southern Henan and other wheat areas, and there is a trend of northward expansion and westward migration.
Prevention and control technology "multi-pronged" to ensure green, safe and productive
Since the beginning of this year, the central government has arranged 800 million yuan of funds for the prevention and control of major diseases and insect pests of grain crops, which will be used to support 26 provinces (autonomous regions and municipalities) such as Henan, Shandong, Hebei, Jiangsu, Anhui and Hubei to do a good job in the prevention and control of major diseases and pests of grain and other crops.
How to prevent and control it? How to ensure green safety? Wang Zhenying and Liu Taiguo introduced that spraying and applying chemical pesticides is still the most effective way to control agricultural pests and diseases in the short term. Under the concept of green development, China's pesticide application has achieved negative growth for 3 consecutive years, in food crops, the scientific application of high-efficiency and low-toxicity pesticides is the basic principle, and large-scale spraying of pesticides by agricultural drones is the norm. At the same time, the application of pesticides for the prevention and control of pests and diseases generally has a certain time interval with the mature period of grain harvest, during which the pesticides have been basically degraded, which can ensure the quality and safety of agricultural products.
The promotion and application of biopesticides has undoubtedly added "green" to prevention and control. For example, the biopesticide bt engineering bacteria g033a made of Bacillus thuringiensis (referred to as bt) in China has shown that its field control effect on the grassland moth can reach more than 85%, and it also has a good prevention effect on armyworms and corn borers, while maintaining high toxicity to similar pests, it is safe and friendly to the environment, showing good application prospects.
High-altitude monitoring lights, high-altitude insecticidal lamps, sex pheromone traps, remote monitoring radars... Wang Zhenying told reporters that in recent years, all kinds of "insect catching artifacts and monitoring equipment" have been used in large quantities in various parts of China, and physical prevention and control of agricultural diseases and insect pests has become the norm.
In addition, the ancient wisdom of "biological symbiosis" has also been applied to the battle of "insects seizing food". Although the grassland moth is powerful, it also has natural enemies to control its number and harm. Researchers have found that natural enemy insects such as red-eyed bees, nocturnal moths, and cocoon bees can parasitize in the grass moth to lay eggs and reproduce, and insects such as cockroaches and beneficial bugs can actively search for the grassland moth and attack and prey, and field experiments have shown that they are effective in the prevention and control of grassland moths. A large number of artificially expanded these natural enemy insects are released into the field, which has also become a new force to achieve green prevention and control, continuous prevention and control and effective prevention and control of agricultural pests and diseases.
Under active prevention and control, China's grain production target this year will have little impact
China's grain output has exceeded 1.3 trillion catties for 6 consecutive years, in the face of this year's heavy incidence of agricultural diseases and pests, the public can't help but worry, is there a guarantee for food security in 2021? Experts have confidence in this.
"Although it is predicted that the occurrence of insect pests such as grassland moth this year will be heavier than last year, based on China's perfect crop disease and pest detection and control system, diverse prevention and control methods and technologies, and previous successful experience, the harm of grassland moth can be effectively controlled and will not cause large impact losses on the production of corn and other crops." Wang Zhenying said.
Liu Taiguo also analyzed and pointed out that China has gradually built a modern plant protection disaster prevention and mitigation system, formed a set of mature response plans, and in accordance with the idea of "early planning, early monitoring, early preparation, and early prevention", it can achieve "a national chess game" to prevent and control diseases and insect pests. Therefore, "under active prevention and control, this year's agricultural pests and diseases should have little impact on the target of 1.3 trillion kilograms of grain output, and there is no need to worry too much." ”
At the same time, Liu Taiguo said that just as human injections can form "immune" antibodies against diseases, planting disease-resistant varieties is undoubtedly a way to fundamentally prevent and control agricultural pests and diseases. "Agricultural diseases occur every year, light or severe, and changes in various factors may induce disasters, but at present, less than half of the wheat with medium disease resistance in China's wheat-producing areas is still less than half." Therefore, in the breeding of food crops, more excellent varieties with resistance to a variety of diseases should be selected, and in the early stage of the breeding process, comprehensive disease resistance identification should be carried out, the breeding process should be accelerated, and varieties with good resistance should be promoted, while taking into account the yield and quality requirements, which depends on the further improvement of breeding technology. ”
"The general public should also remain vigilant about invasive alien species, and once a new suspicious invasive species is discovered, actively contact relevant departments such as local plant protection to make a contribution to the protection of biosecurity and food security." Wang Zhenying said.
(Guangming Daily, Beijing, May 11)
Guangming Daily ( 2021-05-12 09 edition)
Source: Guangming Network - Guangming Daily