Herbicide-resistant weeds hard to control? Straw turned from waste into treasure comes to the rescue

Straw turned from waste into treasure cleverly controls herbicide-resistant weeds

--Jiangsu explores technology for managing herbicide-resistant weeds in paddy fields

Intern Wei Xiaomin, Reporter Zhang Ye

"Traditional methods require spraying twice, but this new technology can achieve zero application of chemical herbicides during the rice growing period, and simultaneously solve the problems of soil fertilization and straw disposal."

Recently, in Nanzha Town, Huai'an City, Jiangsu, a lush and gracefully swaying patch of rice was growing vigorously. Fu Yousheng, associate researcher in the Plant Protection Office of the Huaiyin Institute of Agricultural Sciences in the Xu-Huai Region of Jiangsu, pointed to the demonstration field behind him and carefully explained to experts from various places the advantages of the green prevention and control management technology for herbicide-resistant weeds in dry direct-seeded paddy fields, namely "full-amount wheat straw return coverage + no-till."

Meanwhile, the paddy fields outside this demonstration area were at the "second kill" stage of the traditional "first seal, second kill, third supplement" method. No matter how hot the weather, farmers had to spray herbicides under the scorching sun.

Weeds are the "nightmare" of paddy fields. They not only compete with rice for fertilizer, sunlight, and space, inhibiting the normal growth of rice seedlings, but also serve as intermediate hosts and transmission vectors for rice diseases and pests, worsening rice diseases and pests.

Fu Yousheng presented a figure: at present, the area of crops in China seriously harmed by weeds year-round is as high as 1.23 billion mu, including 4.824 million hectares of rice in the Yangtze River Basin. He said that traditional chemical weed control technology has the advantages of being fast, efficient, and labor-saving, and is currently a key measure for controlling weeds in paddy fields.

After rice is sown and before emergence, the soil is first sprayed for sealed treatment; at the 2-3 leaf stage of weeds, corresponding stem and leaf treatment agents must be selected for a second treatment; afterward, a third application is used on weeds that still slip through. This is the so-called "first seal, second kill, third supplement." Fu Yousheng said: "These traditional methods not only pollute the environment, but also increase the cost of rice cultivation."

"With the expansion of chemical weed control area and the rapid development of chemical weed control, weed resistance to herbicides has gradually increased, and resistance is showing an explosive trend," introduced Li Yongfeng, researcher at the Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences. "The spread and expansion of herbicide-resistant weed populations not only directly affects crop yield and quality, but also indirectly spreads important crop diseases and pests, threatening the safe production of rice and polluting the ecological environment."

Relevant experts told reporters that over the past 20 years, pesticide companies around the world have not successfully commercialized and developed a new herbicide variety, and there is a lack of new herbicide varieties that can effectively control resistant weeds. Therefore, only by establishing a monitoring and integrated management technology system for weed resistance can the harm of resistant weeds in paddy fields be reduced. Since 2013, supported by the public welfare (agricultural) industry scientific research special project "Research and Demonstration of Weed Resistance Monitoring and Management Technology," the Institute of Plant Protection of the Jiangsu Academy of Agricultural Sciences, the Plant Protection Office of the Huaiyin Institute of Agricultural Sciences in the Xu-Huai Region of Jiangsu, and family farms began exploring management technology for herbicide-resistant weeds in paddy fields in Nanzha Town, Huai'an City.

"We proposed a complete green management plan. First, appropriately increase the seeding rate and manually broadcast seeds 1-2 days before wheat harvest; then use a crawler-type combine harvester to harvest wheat to ensure uniform straw coverage, and spray herbicide on the first day after harvest to kill the stubble; on the third day after stubble killing, irrigate so that the field surface is completely soaked, then let it dry naturally," said Li Yongfeng.

How does this technology manage only weeds without harming rice? The reason is that during the stubble-killing process, residual weeds in the wheat field and some early-growing barnyardgrass have already been killed. In addition, the no-till technology prevents weed seeds in the lower layer from being turned up into the shallow soil. In this way, the distribution of weed seeds in the shallow surface layer where rice grows is reduced, and weed seeds distributed in the lower layer are also in a "suppressed" and "dormant" state. Even weeds with stronger herbicide resistance find it difficult to grow well due to limitations of light, space, and so on. After absorbing water, rice germinates in three to four days, completely suppressing the weeds and ultimately winning out.

"Normally, a yield of more than 700 kilograms per mu is no problem," Fu Yousheng told Science and Technology Daily. "Reducing the use and abuse of pesticides and enabling ordinary people to remove weeds at the lowest cost is our ultimate goal."