As we all know, nicosulfuron, sulfuron-methyl and mesotrione are commonly used herbicides after maize seedling.
Detailed introduction of several herbicides after maize seedling;
nicosulfuron
Chinese name: nicosulfuron
English common name: nicosulfuron
Nicknames: Yunongle, Yansufulong.
Physical and chemical properties: the original drug is a white solid, soluble in slightly acidic to neutral water, soluble in dichloromethane, chloroform, dimethylformamide and toluene.
Toxicity: low toxicity. The acute oral LD50 of the original drug to rats is greater than 5000 mg/kg. Slight irritation to eyes and skin.
Weeding mechanism: Nicosulfuron-methyl is a selective herbicide with systemic conduction, which is absorbed by stems, leaves and roots of plants and quickly transmitted, so that sensitive weed cells are blocked from dividing, growth stops, heart leaves turn yellow and die gradually. Usually annual weeds.
65438 died in 0-3 weeks, and high dose can also kill perennial weeds.
Preparation: 4% suspension.
Control targets: it can control and kill gramineous weeds such as barnyard grass, green bristlegrass, cattail, wild oat and crabgrass, broad-leaved weeds such as xanthium sibiricum, chickweed, amaranth, Solanum nigrum, purslane and Polygonum hydropiper, as well as sedge weeds, and also has effects on Chenopodium album, Tribulus terrestris, Kochia scoparia, ferret petals and reeds.
Application technology: used for chemical weeding in corn field. When 3-5 leaves and 2-4 leaves of weeds are basically in full bloom after maize seedling, 30-40 kilograms of water per mu should be sprayed with 4% suspending agent 60- 100 ml.
The mixture of nicosulfuron and atrazine, 2- methyl -4- sodium chloride and sulfuron-methyl can reduce the dosage, expand the weed control spectrum and improve the weed control effect.
Precautions:
① Pay attention to the drug resistance of different corn varieties when using drugs. Exploded corn, sweet corn and non-horse-toothed corn fields cannot be used.
(2) Corn that has been applied with organophosphorus pesticides can only be used after 7 days, and nicosulfuron can no longer be used in corn fields that have been used with long-acting herbicides.
(3) It rains 6 hours after application, which has no effect on the drug effect and does not need to be sprayed again.
④ Nicosulfuron is not suitable for corn fields where amaranth and cochineal insects are frequent.
This medicine is harmful to the eyes. Irritating to skin, nose and throat. When applying pesticides, wear masks and protective clothing to prevent contact and inhalation.
⑥ It should be stored in a dry and dark place to avoid contact with food and feed.
Comments: Nicosulfuron has passed the patent protection period and is mine at present.
The main advantages of this product are wide weed control spectrum, superior to mixed atrazine, and cheap and good quality. However, the disadvantage of this product is that if it is not used properly, it is easy to produce phytotoxicity. Take Central China as an example: the active ingredient is 3.5-3.8g/ mu, more than 5 g is easy to cause phytotoxicity, and less than 3.3 g is not effective in weeding.
After corn was damaged, it showed many symptoms, such as dead spots on leaves, weak growth due to losing green, twisted heart leaves, twisted heart leaves, severe dwarfing and so on.
Suggestion: Before the third leaf stage, when the corn beard is not open, it can be sprayed all over the ground, and the metabolic capacity of corn is also the strongest. Directional spraying should be carried out after the fifth leaf stage, and corncob leaves should not be sprayed. The liquid medicine is easy to form cumulative phytotoxicity in the horn mouth.
Sulfuron-methyl
Chinese name: sulfuron.
English common name: sulfuron-methyl.
Nicknames: Baocheng, Yumisusulfuron.
Physical and chemical properties: the original drug is colorless crystal, slightly soluble in water.
Toxicity: low toxicity. The oral LD50 of the original drug in rats is more than 7500mg/kg. Slight irritation to eyes.
Weeding mechanism: Sulfametsulfuron is a sulfonylurea systemic conduction selective herbicide, which is absorbed by plant stems and leaves. After the sensitive weeds were treated, cell division was inhibited, growth stopped, and gradually turned green and died. However, corn can quickly metabolize it into non-toxic substances with strong drug resistance.
Preparation: 25% dry suspension.
Control target: Sulfsulfuron-methyl can control most annual and perennial gramineous weeds and broad-leaved weeds in corn fields, such as Chenopodium album, Amaranthus retroflexus, Portulaca oleracea, Semen Celosiae, wild watermelon seedlings, amaranth, crocodile, crabgrass, barnyard grass,
Green bristlegrass, beef tendon, etc. It also has good control effect on sedge, but it has poor control effect on Solanum nigrum and Commelina communis.
Application technology: Sulfsulfuron-methyl can be used for chemical weeding in corn fields dominated by broad-leaved weeds. The method is to use 5-6g of 25% dry suspending agent per mu in summer corn fields in the south and 6-8g in spring corn fields in the north at the 2-4 leaf stage or 2-4 leaf stage after maize emergence.
Grams, 30-40 kilograms of water, adding surfactant and spraying.
Sulfametsulfuron is rarely used alone, but it is usually mixed with herbicides such as atrazine and thiophanate-methyl to expand the weed control spectrum and improve the control effect.
Precautions:
(1) The liquid medicine should be prepared and used now, and should not be kept for a long time to avoid degradation and failure.
(2) The drug has extremely high activity. After application, the spraying equipment should be carefully and thoroughly cleaned with washing powder, and wastewater should not be poured into other crop fields. When applying pesticide, it is suggested to spray it with a fan-shaped nozzle, and spray it evenly on the border surface at a certain spraying height and walking speed to avoid re-spraying or missed spraying, and do not spray it in windy days, so as to avoid uneven application, and the liquid will float to other crop fields, which is prone to phytotoxicity.
③ Be sure to pay attention to the difference of drug resistance of individual corn varieties, and popcorn, sweet corn and non-horse-toothed corn fields should not be used.
(4) This product is toxic and slightly irritating to eyes, skin, nose and throat. You should abide by the rules for the safe use of pesticides, wear work clothes when applying pesticides, and wash your hands and face with soap after applying pesticides.
⑤ 7 days before and after the application of sulfuron-methyl, try to avoid using organophosphorus pesticides, otherwise it may cause phytotoxicity.
⑥ Pay attention to the application period, and apply the pesticide before the fourth leaf of corn.
If it exceeds the 4-leaf stage, it will cause phytotoxicity, which is characterized by difficulty in jointing, short plant height, pale and yellow leaves, and curly, hard and red heart leaves, but it usually recovers after 10- 15 days.
⑦ It should be stored in a dry and dark place to avoid contact with food and feed.
Comments: The main advantages of sulfuron-methyl are high activity and low dosage. Especially for the malignant weed "sedge", it is more effective and prominent. However, the disadvantage of this product is that it is easy to lose drug damage, and the main reasons for drug damage are:
First, the user does not carry out "secondary dilution" as required; The second is to play the trumpet, causing cumulative drug damage. The compound application of the drug and atrazine has been applied in the United States.
There is a certain amount of state-owned consumption, although registered in China, but the current consumption is not large. In Henan province, dimethyl chloride is mainly mixed, and Cyperus rotundus has a good control effect.
Suggestion: Take North China as an example, the active ingredient is 1.2- 1.6g/ mu. Directional spray, don't trumpet.
mesotrione
Chinese name: mesotrione
English name: mesotrion
Physical and chemical properties: the original drug is a dark solid with melting point 165℃.
The solubility in water at 25℃ is 65438 0.5 mg/L.
Toxicity: low toxicity. The acute oral LD50 of industrial rats is more than 5000mg/kg, and the acute percutaneous LD50 is more than 2000mg/kg. It has moderate irritation to rabbit eyes, no teratogenic, carcinogenic and mutagenic effects, and low toxicity to birds and fish.
Weeding mechanism: mesotrione is a selective broad-spectrum herbicide. It can be absorbed by the roots and stems and leaves of weeds, and hinder the biosynthesis of tyrosine and tocopherol by affecting the synthesis of 4-hydroxyphenylpyruvate, thus affecting the class.
The biosynthesis of carotene makes weeds turn white and die. Within 3-5 days after application, the plant showed symptoms of yellowing and albinism, followed by dead spots, which spread all over the plant two weeks later. This product can be rapidly degraded, and its half-life in soil is 9 days.
Preparation: 10%, 48% aqueous solution.
Control objective: Control annual broad-leaved weeds and some gramineous weeds in corn fields, such as Chenopodium album, amaranth, abutilon, Xanthium sibiricum, Setaria viridis, crabgrass and Solanum nigrum. It also has a good control effect on Cyperaceae weeds such as Cyperus rotundus.
Application technology: Before the emergence of corn after sowing, use 48% water agent15-40ml per mu, and spray 40kg of water on the soil surface. Weeds basically bloom at the stage of 3-4 leaves of corn, and when most of them are 2-5 leaves, 48% water agent 15-30ml is used per mu, and 30 kg of water is sprayed evenly.
Note: When the application amount is too large, corn will appear short-term discoloration and whitening symptoms, and in most cases it can be recovered in a short time, which has no effect on corn yield.