Weeds Queen 02 "grasps two key opportunities for weeding. Jiang Yongzheng: turning enemies into friends with weeds and reducing the use of herbicides is not a dream."

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Jiang Yongzheng, head of the pesticide application team of the Agricultural Drug Toxicology Laboratory, delved into weeds for 40 years and stepped down in July this year, but her relationship with weeds is not over yet. Jiang Yongzheng's research career has seen the process of weeds from unpardonable to accepted. Farmers used to do "weeding", but now they have to learn how to "symbiosis with weeds," and good weed management is the king.

"Weed Queen" Jiang Yongzheng has studied weeds for a long time and taught farmers the strategy of integrated weed management (Photography / Lin Yijun) Weed management must be fought for a long time and two key opportunities for weeding must be mastered.

There is a huge weed seed bank underground, how on earth should farmers deal with it? Jiang Yongzheng says that most farmers want to weed when they see the grass, and frequently patrol the fields and mow the grass, but fertilizing and watering after weeding will once again stimulate the seed bank in the soil to sprout, so not long after weeding, the weeds are dense again. So for convenience, some farmers will choose to use herbicides.

"Farmers often call and say,'I have so-and-so grass in my field, how to get rid of it at this time?' But in fact, there is no effective way to control weeds, and weeds are all long-term war of resistance. " Jiang Yongzheng says that most people do not understand why there is so much grass, so they hope to have a solution at once, but there are a large number of weeds, and they must be patient and keep company with them.

Jiang Yongzheng calls weeding weed management, because when dealing with weeds, one must first understand its characteristics. "there are two key times for weed management: the first month after the crop is planted and before the weeds bloom." She explained that when crops first sprout, the growth rate is not as fast as weeds, and weeds need to be cut to reduce competition. When the crops grow tall, they will block part of the sun, and the growth rate of weeds is naturally not as fast as that of crops. For example, weeds under fruit trees generally do not grow high because of their shade.

Jiang Yongzheng said that at this time, these weeds close to the ground can conserve water on the surface, and then just make sure that the weeds are not too high. The next weeding time is before the weeds blossom and bear seeds. "No one knows how many weed seeds are underground. I will tell the farmers: 'let these seeds grow as much as possible.'" Because one plant grows, there will be one less seed in the ground. "then weeding before the weeds blossom and bear seeds will reduce the seeds in the future, and the management of the field will be more and more smooth.

Low weeds such as Oxalis officinalis are suitable for grass cultivation in orchards and can keep water and heat in the soil. (photo / Lin Xiejun) keep the grass properly, the crops grow better, and attract natural enemies to help.

Jiang Yongzheng believes that weeds are not harmful to agriculture, and with a full understanding of their characteristics, weeds can be good companions for field crops. "making use of the characteristics of weeds, do not let weeds affect crops in terms of quantity or growth, but can be added points."

In recent decades, with the rise of organic and natural farming methods, grass cultivation symbiotic with crops has been gradually accepted by farmers, and many orchards, such as dragon fruit and Wendan, will be recommended under fruit trees. Jiang Yongzheng said that the negative harm of weeds is mainly because they compete with crops for nutrients, or become habitats for diseases, insect pests, rats, and other pests, or damage the original vegetation caused by the spread of large areas such as small flowers, but if they know enough about weeds, staying in the field can make the soil healthier.

"if there is no grass at all, the soil is tantamount to no protection. Once the topsoil is easily lost by strong winds and heavy rain, and it is too clean, once other weed seeds with a better growth advantage fly in, because the lack of competition is more likely to accelerate their foothold and become a weed that is difficult to control."

Jiang Yongzheng said that the eradication of weeds is a lack of economic considerations, only want to control the emergence of weeds without taking into account environmental protection. It is a sustainable and labor-saving way to keep grass properly and do comprehensive management of weeds.

"Farmers should first ask themselves why they don't want weeds." Jiang Yongzheng explained that without affecting the growth of crops, weeds can reduce soil erosion caused by wind and rain, increase soil permeability, form an impervious layer in the soil, and maintain soil ecology. for Taiwan, where the rainy season is concentrated in summer, weeds can reduce the loss of topsoil, help reduce surface water evaporation, and even shorten the time for Rain Water to soak the soil.

"if weeds are well controlled, they can actually help crops grow." Grasses can intercept nutrients lost in the soil, dense roots can also absorb available nitrogen in the soil, even the nutrients contained in weeds after death and decay can be released, returning to the soil surface can also provide crops with more nutrients, and weeds can be properly preserved. It can also provide a living environment for natural enemies, allowing a variety of natural enemies to control pests.