Too much weeds in the field not only affects the growth of corn seedlings, but also competes with corn seedlings for nutrients, which makes the seedlings weak and affects production. Most people use herbicides to eliminate weeds in the field, but the improper use of herbicides not only does not have the effect of weeding, but also affects the growth of corn seedlings. How to use herbicides to achieve grass killing without hurting seedlings?
Herbicide use should be early
It is best to take the medicine before the weeds are unearthed after sowing. Weeds emerged and have exceeded 3 leaf stages, and the efficacy will be reduced.
If you are using a corn seedling-type herbicide-type drug, the best period of use is the 3-5 leaf stage of the corn and the weed 1-3 leaf stage. Properly control the weeding time.
Ensure the moisture content of the soil before use
The temperature and humidity of the soil are the key factors to ensure the efficacy of the drug. Applying after raining in front of the seedlings ensures that the agent quickly reaches the position where weeds are absorbed.
The soil is relatively moist, and the actual sprayed liquid easily forms a film on the surface of the soil. Once the weeds are germinated, they will come into contact with the liquid and absorb, eventually dying.
When the soil is dry, the moisture of the liquid is easily volatilized, and it is impossible to ensure that the active ingredient of the liquid is diffused into a film, which seriously affects the effect of weeding.
Moderate dose
It is reasonable to choose to use the herbicide and to ensure the proper amount, not to use too much or too little. Too much negative impact on corn seedlings, too little to achieve herbicidal effect, use in strict accordance with the instructions on the instructions.
Pre-emergence soil treatment type medicinal agent: 150-250 g per acre
Maize post-emergence herbicide type: 80-150 g per mu.
Fighting medicine pays attention to technical level
Choose the right herbicide----use the dosage according to the instructions-----the medicine shakes evenly-----spray evenly-----select the windless and sunny afternoon spray----close as close as possible Spray on the ground to avoid spraying onto the corn leaves.
If the dosage is too large, or if the medication is not used during the medication, or if it is high temperature, high humidity or arid environment, it will cause phytotoxicity.
In fact, many phytotoxics can be restored by themselves or sprayed by some growth-promoting regulators or liquid fertilizers to promote recovery, but there are also many people who do not remove the phytotoxicity of the herbicides and cannot save them in time. Xiaobian sorts out the symptoms of phytotoxicity of common herbicides in several corn fields for your reference. At the same time, the cause of the phytotoxicity of the herbicide is relieved, and it can be prevented in advance to reduce the incidence of phytotoxicity.
Nicosulfuron
Nicosulfuron is most susceptible to phytotoxicity when used in large quantities or heavily sprayed core leaves plus high temperature and dry weather.
After the damage, the corn leaf turns yellow and then spreads to the whole leaf and other leaves; the growth of the corn is inhibited, the plant is dwarfed, and some of the clusters and secondary stems may be produced, which can be recovered in one week, and severely inhibit growth. Hard to recover.
Pictured: Typical phytotoxicity symptoms of nicosulfuron in the growing season â–²
Atrazine
When the amount of atrazine used is too large or it is exposed to high temperatures, it is easy to cause phytotoxicity.
The top of the leaf is chlorotic, yellowing or light green appears, and the growth is slow. Generally, the phytotoxicity is not serious, and it can be recovered in 7-10 days.
Pictured: The symptoms of phytotoxicity caused by improper administration of atrazine in the growing season of corn â–²
Mesotrione
Because of its high safety, mesotrione has a slightly better control effect on the grass in the ground, and is favored by some farmers. Because of its high safety, the whole field spray also causes everyone to reduce the safety awareness of herbicides, but the large dose The use of high temperatures will still cause phytotoxicity.
Mainly manifested as whitening of corn leaves (pre-fading but not dry, different from paraquat phytotoxicity) affecting photosynthesis, and at the same time have a significant inhibitory effect on corn growth, and the greater the dosage, the more serious the phytotoxicity.
Pictured: Phytotoxicity of spraying mesotrione in corn field â–²
Dimethyltetrachloro
The herbicide has good control effect on corn sedge and large broadleaf weeds, and is often used in combination with nicosulfuron. There is a certain sales volume in the market, and the herbicide is a hormone herbicide. They mainly induce crop deformity, and the roots, stems, leaves, flowers and ears have obvious deformation phenomena.
When the corn is sprayed or used in an excessively hot day, the leaves of the corn are curled, the leaves are thick green, the heart leaves are whip-like or onion-like, the stems are flat and fragile, and are easily broken. The roots are short and thick deformed to support the roots, and the main roots are short. Fertility is inhibited; it is easy to fall in the rainy and high-humidity weather, and mainly affects the developing aerial roots in the later stage, and the root system shrinks, which affects the absorption of normal nutrients of corn and has certain influence on the ear of corn.
Pictured: The symptoms of using metformin in corn fields â–²
In summary, the phytotoxicity of the herbicide is mainly caused by the amount of the drug and the weather, so it is reasonable to use the drug according to the situation of weeds in the field.
1. Do not increase the dosage;
2. Secondly avoid high temperature application, it is best to use the medicine when the temperature of the sun is relatively cool in the afternoon;
3. When there is not much time, try to spray the core leaves as much as possible;
4. If the weather is too dry, it is best to water the water, create a microclimate in the field, and then spray the medicine;
5. You can choose a highly safe herbicide, such as the current popular safe nicotinin, or add a safener spray;
6. If the phytotoxicity has occurred, it should be rescued in time. If the amount of herbicide is too large to cause phytotoxicity, it should be sprayed with clean water in time to remove the residual liquid of corn leaf surface, reduce the concentration of herbicide in corn and reduce the phytotoxicity;
7. When the phytotoxicity is light, for corn with yellow and dry leaves, but the heart is normal, some foliar fertilizer or conditioner can be sprayed to relieve the phytotoxicity, such as brassinolide, and later strengthen the management of corn fertilizer and water. Remediate water and fertilizer, not causing large losses;
8. Found that the corncob leaf twisted together, cut open by hand or hard object.
Spraying precautions:
1, avoiding the noon high temperature glare medication
Spraying herbicides at a high temperature before and after noon, when the light is strong, the first is that the medicament is volatile and wasteful! Second, the weed pores are closed at this time, the absorption liquid is limited, and the spray is not easy to hit the target, and the control effect is not ideal.
2, choose rainy cloudy medication
If it is sunny, it should be sprayed after 8-10 am after sunrise or no dew after sunset at 5 pm. When the wind is large, the spraying should be stopped. Otherwise, the spraying will be uneven, and it will easily cause phytotoxicity.
3, should pay attention to body protection
In the taboo, the liquid in the barrel is too full. Some farmers like to spray the liquid in the sprayer tank very full. This is not only unfavorable for spraying, but more importantly, if the lid of the sprayer is not tightly closed, the drug sprays on the body when the applicator walks in the field, and the person is easily poisoned during the hot season. The correct way is that the upper surface of the liquid in the barrel should be below the mark line when dispensing, and the closed loop of the lid must be intact to ensure that the lid is tightly closed.
4, taboo free to increase the concentration of liquid
Some farmers need to increase the efficiency of the work, or increase the control effect, often increase the amount of herbicides, reduce the dilution ratio of herbicides, and increase the concentration of herbicides at will, even in the hot summer season. Due to the rapid evaporation of water at high temperatures in the hot sun, if the concentration of pesticides sprayed is too high, it is easy to cause medicinal damage to plant leaves.
5, taboo and organophosphorus pesticides mixed
Such as dichlorvos, omethoate, chlorpyrifos, phoxim, malathion and so on. It is highly susceptible to phytotoxicity when mixed with herbicides in hot weather.
More pesticide knowledge , please pay attention to China Pesticide Network
(Source: Sannong Encyclopedia)
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