A few days ago, after the Jiangsu “watermelon cracked melon†was reported by the media, the parties faced many reasons for the cracking of watermelon and the use of “ expansion agent â€. To this end, the reporter interviewed Zhang Chaoxian, a researcher at the Institute of Plant Protection, Chinese Academy of Agricultural Sciences, on relevant issues.
Reporter: What is the "expansion agent"? What is the role? Which vegetables and fruits are mainly used in China?
Zhang Chaoxian: In the 1920s and 1930s, humans discovered that trace amounts of natural plant hormones such as ethephon and gibberellin existed in plants, which have the effect of controlling growth and development. In the 1940s, research on synthetic analogues began, and 2,4-D, bud-dan, etc. were gradually developed and gradually promoted. At present, plant growth regulators have been widely used in agroforestry production in the world. China has been producing and applying plant growth regulators since the 1950s. The application of plant growth regulators can not only greatly increase the yield of crops, improve the quality of agricultural products, but also improve the stress resistance of crops, making agricultural production labor-saving, cost-effective and efficient.
The "expansion agent" that everyone calls is one of the plant growth regulators. It has the function of accelerating cell division, promoting cell enlargement, differentiation and protein synthesis, increasing fruit setting rate and promoting fruit enlargement. Commonly used are chlorpyrifos and gibberellic acid . In China, chlorpyrifos is mainly used in horticultural crops such as watermelon, and gibberellic acid is mainly used in crops such as citrus. From the perspective of years of use, the technology is mature and the production effect is good.
Reporter: Can it be used in production? Is the Ministry of Agriculture permitted to use or have relevant regulations?
Zhang Chaoxian: In our country, we have clearly incorporated “expanding agents†into the scope of pesticide management for strict control. According to the Regulations on the Administration of Pesticides, only pesticide products that have obtained pesticide registration and have been produced for production can be produced, operated and used. China's pesticide registration requirements are very strict. The pesticide products applied for registration can only be registered if they have been scientifically evaluated to prove better control effects and have control over the health and environmental impacts of humans and animals. The used pesticides will be restricted or unregistered if they are found to be at greater risk to agricultural and forestry production, human and animal safety or the ecological environment.
Chlorpyrifos and gibberellic acid are registered pesticide varieties in China. When the pesticide registration is approved in China, the period of use, the amount of the drug and the method of application are specified on the label of the pesticide, and the scope of use and the interval between safety are marked. At the same time, China has also formulated the "Guidelines for the Rational Use of Pesticides" and pesticide residue standards to guide and regulate the use of pesticides. A large number of field experiments have proved that the "expanding agent" has no obvious adverse effect on the quality of watermelon under reasonable use. In practical applications, the melon farmers should apply the medicine according to the dosage, the period of administration and the application method prescribed by the label. If the period of use is improper, or the dosage is increased or the treatment is not uniform, the local concentration will be too high, and the abnormal fruit, cracked fruit and the like may occur. Harmful symptoms.
Reporter: It has been reported that the "expansion agent" was developed by Japan, but later the melon and fruit deformed, no longer used, why is China still using it?
Zhang Chaoxian: Chlorpyrifos was first developed in the United States, and Japan began production and use in 1985. According to the investigation, chlorpyrifos is still registered and used in Japan. The registration range is grape, kiwi, watermelon, melon, eggplant, tobacco and other crops (not as some experts have said, Japan has stopped registering and using it). In the late 1980s, China introduced this “expansion agent†from Japan. In 1992, it obtained pesticide registration in China and began to apply it in some provinces. At present, chlorpyrifos is not only widely used in China, but also widely used in the United States, the European Union, Australia, Japan, South Korea and other countries and regions. Long-term use practices have proved that it does not cause harm to human health.
As a plant growth regulator, gibberellic acid was first developed and produced in the United Kingdom in 1961. In 1985, domestic pesticide production enterprises obtained pesticide registration in China. Currently, gibberellic acid is widely used worldwide and has not been found to be harmful to humans.
Reporter: What is the status of the company that produces "expanding agents"? is it legal?
Zhang Chaoxian: At present, there are 60 "expanding agent" products registered in China, containing two kinds of active ingredients (clopidogrel and gibberellic acid), involving 45 pesticide production enterprises, all of which are national pesticide designated enterprises. With the corresponding production conditions and capabilities, the products approved for production registration are legal.
Reporter: What is the reason for the emergence of "watermelon cracked melon" in some places in Jiangsu, is the use of "expansion agent" improper, or the weather? Has there ever been a "watermelon cracker"? What other provinces have similar problems?
Zhang Chaoxian: According to analysis, the phenomenon of “watermelon split melon†in some places in Jiangsu is caused by a combination of various factors. First, it is related to the variety planted. The name of the watermelon variety that appeared "split melon" is called "Japan Almighty Champion". It was just introduced and promoted locally last year. It is characterized by thin skin and easy cracking. Secondly, it is the result of the combination of weather factors and watermelon growth characteristics. After a long period of drought, watermelons absorb large amounts of water in a short period of time and are prone to cracking. Since the spring of this year, the drought in Jiangsu has been heavier. In the days before and after the occurrence of “cracked melonsâ€, it coincided with heavy rains in the local area. In low-lying areas and where there is a lot of water, there are more cases of “melting melons†in the transition of watermelons. Third, it is related to the improper use of the "expansion agent". The "expanding agent" should generally be sprayed on the melon tire on the day of flowering of the watermelon female flower or 1-3 days before flowering, and should be applied according to the recommended dosage at the time of registration. Judging from the situation of watermelon “split melon†appearing in some places in Jiangsu, melon farmers are “expanding agents†that are applied when watermelon is nearing maturity and are about to go on the market. As far as the current situation is concerned, the phenomenon of “split melon†of watermelon in some parts of Jiangsu is still a few cases. It has rarely appeared in China before, and it has not happened in other provinces. This type of problem is a production technology issue, not a quality safety issue, which is mainly solved by strengthening technical guidance.
Reporter: What kind of impact does the “expanding agent†have on crops and is it harmful to the human body?
Zhang Chaoxian: The use of “expansion agents†has certain technical requirements, and the impact on different crops and different varieties is different. Under normal use conditions, it can promote fruit enlargement, early maturity and increase yield. However, if it is used excessively or improperly, it may cause phytotoxicity such as fruit malformation, fruit cracking, and fruit loss.
In order to protect human health, the United Nations Food and Agriculture Organization (FAO) and the World Health Organization (WHO) have established pesticide safety assessment norms and guidelines, and developed countries and other developed countries have established a strict risk assessment system. In accordance with international standards, China has established a relatively complete pesticide safety evaluation system based on the experience of developed countries. Many developed countries such as the United States and Japan have listed it as a list of substances that do not require toxicity management exemption, and their residues do not need to establish safety limit standards. There is no scientific evidence to show that it will cause harm to human health.
Reporter: Is “expanding agent†a pesticide or a fertilizer? Is it illegal to add like "Clenbuterol"?
Zhang Chaoxian: "Expansion agent" is one of the plant growth regulators. According to the "Pesticide Management Regulations" promulgated by the State Council in 1997, the definition of pesticides is "pigmentation agent". The "expanding agent" such as clopidogrel and gibberellic acid is essentially different from "clenbuterol". Chlorpyrifos and gibberellic acid belong to the pesticides approved for use in registration, while "clenbuterol" is prohibited by the state. Illegal additives produced, sold and used.
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