Chemical weeding in vegetable fields started late in China, and there are few specialized herbicides for controlling weeds in vegetable fields. The vast majority of herbicides currently used in vegetable fields are used in wheat, corn, soybean, cotton, rice and other major crop fields, and are borrowed for vegetable fields after testing. Therefore, when applying herbicides under different conditions, it is necessary to conduct trials and demonstrations before popularizing and applying them.
Due to the large variety of vegetable types, complex cultivation methods, frequent rotation and stubble, and intercropping and intercropping, the chemical weeding in vegetable fields is more complicated. Research work on chemical weeding in vegetable fields used to focus on the selective identification of weeding based on the family, genus, and species to which the vegetables belong, and achieved great results. In order to help the vegetable farmers to master and flexibly apply the weeding technology, the following is to introduce the chemical weeding technology in the vegetable field from four new perspectives.
1. Introduction from the perspective of planting time
1. Weeding before planting
Almost all vegetables can be used for weeding before planting-the "universal" variety-contact-type, sterilizing herbicide "paraquat (g no trace)", because it has a broad spectrum of herbicidal Light), effective results (weed leaves start to change color 2-3 hours after application, and die within 1-3 days), non-volatile, no residue (on contact with soil, they will be absorbed and passivated) and other unique advantages, It can also be used in greenhouse vegetables.
(1) Weeding before live broadcasting. In addition to the selection of general varieties, the size of vegetable seeds must be paid attention to when selecting other herbicides, and "medicine selection should be based on species", please refer to the relevant content of 2.1.
(2) Weeding before transplanting. The transplanted vegetables are transplanted to the field after the seedling stage, so they have a strong tolerance to herbicides. For soil treatment before transplanting, the following herbicides can be selected as appropriate, and applied before transplanting after site preparation, such as: 48% fluralin EC, 50% prochloraz WP, 50% acetochlor EC, 24% ethoxyfluoride Grass ether (Guoer) EC, 33% pendimethalin (Shi Tian Bu) EC, 72% metolachlor (Dur) EC, 50% dilachlor (Dahuili) WP, 60% buta Amine EC, 12.5% ​​clomazone (oxachlor) EC, etc. However, melons and vegetables, especially cucumbers, are sensitive to most herbicides; celery is sensitive to diquat, so special care should be taken.
2. Weeding before sowing
When selecting herbicides, attention must be paid to the size of vegetable seeds, which should be "selected for different species", refer to the relevant content of 2.1. Some vegetables have a longer seedling emergence period, and paraquat can be applied 3 days before the vegetables are unearthed. However, this method has high technical requirements and is not recommended.
3. Weeding during growth
(1) Full spraying. Most vegetables are broad-leaved vegetables. â‘ If you control gramineous weeds during vegetable growth, there are many types of herbicides to choose from, such as: quizalofop (precise gram), pymetrozine (premium), and oxazole Hecaoling (Wei Pa), high-efficiency flumethoprim (high-efficiency chlordiazepoxide), dimethoprim (naproxen), dimethonone (Zaluotong), pyranone (quick capture) and so on. â‘¡If the broad-leaved weeds are controlled during the growth of vegetables, there are few varieties of herbicides to choose from. According to reports, fomesafen (Huwei) can be used in leguminous vegetable fields, and clofluxacin (making it prosperous) can be used in garlic fields to control broad-leaved weeds.
(2) Spraying between lines. Because there are few herbicides for controlling broad-leaved weeds during vegetable growth, and broad-leaved grass damage is often quite serious, in order to effectively control the grass damage, people have found a new way, and found that broad-spectrum herbicides can be used to solve grass and The method of broad-grass-spraying paraquat (Kemoon) in a directional spray between vegetable rows. In order to prevent the medicine liquid from escaping, a special or self-made "crop spray protection cover" can be added to the nozzle, or a refractive nozzle can also be used. The medicine does not have systemic conductivity, even if a small amount of liquid is contaminated on the vegetables, it will only produce local necrotic spots, which will not affect the normal growth of the entire vegetable. This method can also be used in greenhouse vegetables.
2. Introduction from the perspective of planting methods
1. Live vegetable weeding
(1) Vegetables seeded with small seeds. Such vegetables are more sensitive to herbicides, and many herbicides may affect the emergence of vegetables, and even die gradually after emergence. The available soil treatment agents before and after sowing are: 33% pendimethalin (Shi Tian Bu) EC, 50% dichlorchlor (Dahuili) WP, 50% acetochlor EC, etc. Therefore, manufacturers such as 72% Dole EC particularly reminded that vegetables with small seeds, such as amaranth, parsley, and celery, are sensitive to Dole and should not be used.
(2) Vegetables seeded by large seeds or propagated by vegetative organs. The resistance of such vegetables to herbicides is enhanced, and the positional and time difference selectivity of herbicides can be used, and the requirements for physiological and biochemical selectivity are not high, so it can be used as a soil treatment agent before and after sowing. Available: 48% fluroxen EC, 50% prochloraz WP, 50% acetochlor EC, 24% ethoxyflufen (Guer) EC, 33% pendimethalin (Shi Tian Bu) EC, 72 % Metolachlor (Dur) EC, 50% napropamide (Dahuili) WP, 60% butachlor EC, 12.5% ​​clomazone (oxachlor) EC, etc.
2. Weeding transplanted vegetables
The transplanted vegetables are weeded before transplanting, which not only has a high safety factor, but also has many varieties to choose from, refer to the relevant content of 1.1.2.
3. Introduction from the perspective of planting facilities
1. Bare ground cultivation
At present, many vegetable chemical weeding techniques are based on the results of studies conducted under bare-field cultivation conditions, which are relatively mature and complete.
2. Protected cultivation
Under the cultivation conditions of protected fields, not only the occurrence time and growth rate of weeds are significantly different from those in the open field, but also the exertion of herbicide efficacy and the formation of phytotoxicity are also different. For example, high temperature and high humidity in the protected field, early weeds occur, and high herbicide efficacy; at the same dose, open field application does not cause phytotoxicity, while application in the protective field is prone to phytotoxicity. In view of the specific temperature, humidity and microclimate cultivated in the protected area, the recommended dosage of various herbicides applied on the open ground should be halved or reduced by 1/3 or even more to avoid phytotoxicity. For example, the amount of 50% diquat (Dahuili) WP in open field vegetable fields is 100 grams per mu, while in plastic film vegetables it is 80 grams and in greenhouse vegetables 50-60 grams.
A large amount of work must be carried out on chemical weeding of vegetables grown in protected areas, especially in greenhouses, in order to explore suitable herbicides, safe dosage and safe application period.
(1) Plastic film cultivation. Because the temperature and humidity in the plastic film can fully guarantee the herbicide to exert its medicinal effect, a lower dosage can receive a good herbicidal effect. The film-covered vegetables generally reduce the dosage by 1 / 5-1 / 3 compared to the open field vegetables. If the herbicide is applied only in the mulch, the amount of medication should be calculated based on the actual spray area in the mulch. The herbicides that can be used before the transplanting of plastic film transplanted vegetables are: 48% fluralin EC, 50% prochloraz WP, 50% acetochlor EC, 24% oxyfluorfen (Guer) EC, 33% pendimethalin (Shi Tian Bu) EC, 72% metolachlor (Dur) EC, 50% napropamide (Dahuili) WP, 60% butachlor EC, 12.5% ​​oxadiazon (Evil Grass) EC etc. Use the herbicide after sowing and before mulching on the direct seeding vegetable with plastic film. Pay attention to the size of vegetable seed, please refer to the relevant content in 2.1.2.
(2) Bow shed cultivation. After application of vegetables in the small bow shed (small arch shed), if the temperature in the film is too high, the plastic film at both ends of the bow shed should be opened to ventilate and cool down to avoid phytotoxicity.
(3) Greenhouse cultivation. Due to the high temperature and humidity in the greenhouse, the shed is airtight and airtight. Most herbicides in the greenhouse will often cause phytotoxicity. Greenhouse vegetables are generally not allowed to use herbicides. If medicines are necessary, it is advisable to apply soil treatment agents at low doses before or after sowing, or to apply the "universal" variety paraquat (Kemoon).
4. Introduction from the perspective of planting environment
1. Xerophytic vegetables. Many current chemical weeding techniques for vegetables are based on the results of studies conducted under dry land cultivation conditions.
2. Aquatic vegetables. Herbicides available for this type of vegetables are: 50% prochloraz WP, 60% butachlor EC, 12.5% ​​oxadiazon (oxachlor) EC, 24% ethoxyflufen (guar) EC, 10% bensulfuron-methyl (when farming) WP, etc.
Source: China Rural Household Network
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