Soybean corn strip intercropping is one of the effective technical measures for expanding soybean cultivation, which is an innovative development of traditional intercropping technology. It puts forward higher requirements for herbicide variety selection, application time, and application method. In order to standardize the use of herbicides and improve the effectiveness of weed control in soybean and corn strip composite planting fields, this guidance is specially formulated.
1、 Prevention and control strategies
Adhere to the plant protection policy of comprehensive prevention and control, fully utilize the effects of agricultural physical measures such as tillage, rotary tillage, and plastic film mulching to reduce the occurrence of weeds in the field and alleviate the pressure of chemical weeding. Using chemical herbicides, adhere to the application strategy of "soil sealing treatment before sowing and supplemented by stem and leaf orientation or isolated spray treatment after seedling", and carry out the "soil sealing+" control technology mode (soil sealing+rotary tillage stubble removal+water moisture generation+stem and leaf supplement control) according to local conditions, strive for weed control effect to reach more than 90%, so as to achieve no yield reduction of corn and increase the yield of a season of beans.
Tailor measures to local conditions. Develop weed control technology plans based on sowing period, planting mode, weed types, etc., highlight key areas, grasp key links, scientifically select suitable herbicide varieties and dosage, and carry out precise classification guidance.
Treat early and treat young. Priority should be given to using post sowing and pre seedling soil sealing treatment for weed control, in order to reduce the pressure of post seedling weed control. The focus of post seedling weeding is to focus on the control of broad-leaved weeds, especially in the critical stages of weed control such as seedling and seedling stages, to ensure the effectiveness of weeding.
Safe and efficient. The variety of herbicides used for weed control should ensure high efficiency and low risk, ensuring the safe growth of the current crop of soybeans, corn, and surrounding crops, while not affecting the next crop.
2、 Technical measures
（1） Striped intercropping of soybean and corn
In the southwest region, the intercropping model of corn sowing before soybean is often adopted, and the use of herbicides should be combined with sealing and killing. After sowing and before seedling, the soil shall be sealed with metolachlor (or acetochlor)+azosulfuron (or thiefensulfuron methyl) and other agents. If there are weeds in the field before sowing, glufosinate spray can be used; If the soil sealing effect is not ideal and needs to be treated by stem and leaf spray, nicosulfuron methyl+chlorofluoropyranoxyacetic acid (or dichloropyridic acid, methimaxone) can be selected in the post 3-5 leaf stage of maize seedlings, and the stem and leaf spray can be directed in the maize planting belt.
Three days before the sowing of soybeans, Glufosinate was used to carry out directional spray in the empty field to kill the weeds that had been found in the soybean belt. After sowing, soil sealing treatment should be carried out using herbicides such as glyphosate (or dimethoprim, acetochlor) and imidacloprid before planting. If the soil sealing effect is not ideal and needs to be treated by stem and leaf spray, select quinoxal (or high efficiency flumetafop.
（2） Strip intercropping of soybean and corn
Soybean and corn are sown simultaneously in the Yellow River, Huaihai River, the middle and lower reaches of the Yangtze River, and the northwest region. After harvesting the previous crop, rotary tillage or straw bundling should be carried out in a timely manner to remove it from the field. Within 2 days after sowing, under suitable soil moisture conditions, pesticides such as glyphosate (or glyphosate, acetochlor, or dimethoprim)+imidacloprid (or thiophene) should be used for treatment.
In the middle and lower reaches of the Yellow River, Huaihai River, and Yangtze River, when the current crop of wheat is subjected to soil sealing treatment, it is best to carry out physical rotary tillage to eliminate the crop, water to create soil moisture, and then sow and apply pesticides before planting; The field for live broadcasting of wheat stubble needs to increase the water usage per mu. If conditions permit, it should be watered in a timely manner after application of pesticides to leach the pesticides attached to wheat straw onto the soil surface and improve the sealing effect.
In the northwest region, actively promoting black plastic film mulching weed control technology to reduce the occurrence of weeds in the field. In arid and sandy areas, it is best to mix soil after spraying soil sealing herbicides to improve weed control effectiveness.
When the soil sealing effect is not ideal and needs to be treated by stem and leaf spray, we can use Nicosulfuron methyl (or oxazolone)+Metazolone (or clofepoxyacetic acid) in corn field, and Quinquifop-p-ethyl (or high efficiency flupirazole)+Metazolone (or Ethoxyflufen) in big soybean field according to the local grass conditions in the 3-5 leaf stage of maize seedlings, 2-3 leaf stage of soybeans, and 2-5 leaf stage of weeds. According to the local grass conditions, we can use spray to weed the stems and leaves of corn fields (or fenazolone)+Metazolone (or Clofepoxyacetic acid), and use Quinquifop-ethyl (or high efficiency flupirazole)+Metazolone (or Ethoxyflufen) to separate the stems and leaves of corn and. Difficult to control weeds can be manually removed in a timely manner.
3、 Precautions
（1） Priority should be given to seven herbicides registered on both corn and soybeans, including glyphosate, glyphosate, dimethoprim, imidacloprid, thiafenuron, and glyphosate. According to the results of experiments conducted in various regions in 2023, herbicides such as glyphosate, imidacloprid, and imidacloprid have shown good weed control effects in soil enclosure treatment. Different regions can choose to use them based on product registration.
（2） When selecting herbicides for stem and leaf treatment, attention should be paid to selecting herbicide varieties that are highly safe for adjacent and subsequent crops. Drifting of herbicides such as glyphosate, high-efficiency fluoropyrazine, glyphosate, and enoxazone can easily lead to corn damage, while drifting of herbicides such as chlorofluoropyranoxyacetic acid and dichloropyridyl acid can easily cause soybean damage. If herbicide damage occurs, timely spraying of brassinolide, gibberellic acid, potassium dihydrogen phosphate, etc. can alleviate the damage to a certain extent. At the same time, it is necessary to strengthen water and fertilizer management, promote root and seedling growth, enhance stress resistance, and promote rapid recovery and growth of crops.
（3） The amount of herbicide used for stem and leaf treatment should be calculated based on the actual planting area of each crop, and should not be re sprayed or increased arbitrarily. When spray stems and leaves, an isolation device must be set between the corn belt and the soybean belt to prevent the drift of liquid medicine from causing pesticide damage. The application equipment can be backpack type electric spray (a protective cover is required at the nozzle), or a self-propelled spray bar spray with a curtain that can separate the soybean and corn for application. The height of the nozzle from the ground shall be subject to the fact that the spray drops do not exceed the soybean belt or corn belt; When selecting herbicides that are not registered on both soybeans and corn at the same time, it is strictly prohibited for droplets to exceed the soybean or corn belt.
（4） When spraying herbicides, pay attention to weather changes such as wind speed, wind direction, and sunny or rainy weather. The application time should be before 10am and after 4pm. It should be used on sunny and windless days, and it is prohibited to use it on rainy and windy days to prevent reduced efficacy and pesticide damage caused by droplet drift.