What are the methods for weed control in sorghum fields?
How do you control weeds in sorghum fields? Please explain the methods. Weeds are a major disaster in sorghum production, competing with sorghum for water, nutrients, light and space, causing a decline in sorghum yield and quality. Weed damage is especially severe in low-lying land and saline-alkali land, and it is year-round, that is, weeds cause damage at any time...
How do you control weeds in sorghum fields? Please explain the methods
Weeds are a major disaster in sorghum production, competing with sorghum for water, nutrients, light and space, causing a decline in sorghum yield and quality. Weed damage is especially severe in low-lying land and saline-alkali land, and it is year-round, that is, weeds cause damage at any time. The harm weeds do to sorghum is mainly at the seedling stage; weed occurrence at this stage is extremely unfavorable for cultivating strong seedlings, and some plots are often destroyed and resown because of weed damage, or suffer reduced yield.
There are hundreds of species of weeds harmful to sorghum, and they differ in appearance, ecology, reproductive habits, damage characteristics and sensitivity to herbicides. Therefore, weed control must be handled flexibly according to the weed species and local cultivation practices. The main control methods are:
1. Deep ploughing Deep ploughing is one of the effective methods of weed control. Most weed seeds germinate well within 1 cm of the soil surface; the deeper the ploughing, the more unfavorable it is for weed seed germination. For example, shortawn foxtail (Alopecurus aequalis) germinates well within 1-3 cm, but cannot germinate below 5 cm. Weeds have a considerable reproductive coefficient: a single flixweed (Descurainia sophia) plant can produce 500,000 seeds, and purslane (Portulaca oleracea) can produce 200,000 seeds. After deep ploughing, large numbers of seeds can be turned into deep soil so that they cannot germinate, which can reduce weed damage.
2. Rotary tillage Rotary tillage before sowing can effectively eliminate a large batch of weeds that have germinated on the soil surface, thereby lowering the base population of weeds occurring in the field. Rotary tillage can also eliminate perennial creeping-rooted weeds such as bermudagrass (Cynodon dactylon); the apical dominance of dormant creeping-rooted weeds in the rotary tillage layer can be destroyed, delaying the time when weeds harm sorghum, which is favorable for cultivating strong seedlings.
3. Inter-row cultivation Inter-row cultivation can directly eliminate weeds; in fields with lighter weed damage, inter-row cultivation is an effective measure for eliminating weeds. However, with manual and semi-mechanized operations, the labor for inter-row cultivation and weeding often accounts for more than half of the total labor for field management, and the efficiency is low, the labor intensity is high and it is very tiring. In places with heavier weed damage and a tight labor supply, it is often easy for a weed infestation to occur because of the lack of labor.
4. Chemical weeding Chemical weeding is a good method that people have worked out in the practice of struggling against weed damage: economical, effective, safe and low-cost. Production practice has proved that the use of chemical weeding has the advantages of timely weed reduction, good effect, light labor intensity, high work efficiency and low cost. Applying chemical weeding can achieve relatively high economic and social benefits. With the development of our country's agricultural modernization, chemical weeding technology will be accepted by more and more of our country's farmers, and chemical weeding methods will develop and be applied more and more rapidly, thereby changing the backward technology of field management of thousands of years and bringing greater benefits to farmers and society.
Chemical weeding is mainly carried out in two periods: from sowing to before emergence, and after emergence at the 5-8 leaf stage. The specific methods of use and the agents are described separately below:
(1) Chemical weeding after sowing and before seedling emergence Chemical weeding method Chemical weeding from after sowing to emergence is a method of weed control using the time-difference selection method; it involves spraying herbicide after the sorghum seeds are sown but before the seedlings emerge, and weeds that germinate early die quickly upon contact with the chemical. That is, it uses the difference in germination time between the seeds and the weeds to carry out chemical weeding. Sorghum is very sensitive to chemical agents, so when using them one must strictly control the variety of agent, the time, the concentration and the method; otherwise, crop injury is easily caused. The chemical weeding methods commonly used in sorghum fields after sowing and before emergence are:
First, use 200-300 g of 25% chlorotoluron wettable powder per mu, mix with 50 L of water, and spray evenly on the soil surface.
Second, use 150 g of 25% chlorotoluron wettable powder per mu, plus 150 mL of 50% thiobencarb (also known as benthiocarb, thiobencarb, and Saturn) emulsifiable concentrate, or plus 50 mL of 60% butachlor (also known as Machete, butachlor, and Delchlor) emulsifiable concentrate, mix with 45-50 L of water, and spray on the soil surface.
Third, use 75-120 g of 80% bifenox (also known as modown and methyl bifenox) wettable powder per mu, mix with 35-40 L of water, and spray on the soil surface. If drought occurs, shallow harrow 2-3 cm to mix the liquid with the soil and increase the chance of contact with weeds and grass.
Fourth, use 100-150 mL of 72% metolachlor (also known as Dual) emulsifiable concentrate per mu, mix with about 35 L of water, and spray on the soil surface; or use 75 mL of metolachlor plus 100 mL of 40% atrazine (also known as atrazine) suspension concentrate, mix with water and spray on the soil surface.
Fifth, use 150-200 g of 50% linuron wettable powder per mu, mix with 40 L of water, and spray evenly on the soil surface.
Sixth, use 200-300 g of 50% prometryn wettable powder per mu, mix with 40 L of water, and spray evenly on the soil surface.
Seventh, use 25-40 mL of 48% dicamba (also known as Banvel) aqueous solution per mu, mix with 35 L of water; or 20-30 mL of dicamba plus 150-300 mL of 40% atrazine suspension concentrate, or plus 200-300 mL of 48% alachlor (also known as Lasso and alachlor) emulsifiable concentrate, mix with 35 L of water, and spray on the soil surface.
Eighth, use 50-80 mL of 72% 2,4-D.J ester emulsifiable concentrate per mu, mix with 35 L of water, and spray evenly on the soil surface.
Ninth, use 200-300 mL of 40% simazine suspension concentrate per mu, mix with 40 L of water, and spray evenly on the soil surface. Note that this agent has a long residual effect; the following crop should not be wheat, rapeseed, soybean or similar crops. When the following crop is corn or sugarcane, the dosage can be increased to 500 mL.
(2) Chemical weeding method at the seedling stage Chemical weeding at the seedling stage uses the different biochemical processes of herbicide metabolism in crop and weed plants to achieve the purpose of killing weeds and protecting seedlings. After sorghum emerges, at the 5-8 leaf stage, its tolerance to chemicals is relatively strong and the use of herbicides is relatively safe, while before the 5 leaf stage and after the 8 leaf stage it is very sensitive to herbicides, so chemical weeding at the seedling stage is generally carried out at the 5-8 leaf stage; otherwise, crop injury is easily produced. Chemical weeding of sorghum is mostly carried out before emergence, and generally herbicides should not be sprayed at the seedling stage. If weed damage is indeed severe at the seedling stage, the spraying time, concentration and variety must be strictly controlled. The commonly used chemical weeding methods at the seedling stage are:
First, at the 4-5 leaf stage after sorghum emergence, use 40-65 mL of 72% 2,4-D.J ester emulsifiable concentrate per mu, mix with about 35 L of water, and spray evenly on weed stems and leaves; this mainly controls broadleaf weeds and sedge family weeds, and is ineffective against grass family weeds.
Second, at the 4-5 leaf stage after sorghum emergence, use 200-250 mL of 40% atrazine suspension concentrate per mu, mix with 35 L of water, and spray evenly on weed stems and leaves. It can control monocotyledonous and dicotyledonous weeds as well as deep-rooted weeds.
Third, at the 4-5 leaf stage after sorghum emergence, use 100 mL of 20% MCPA aqueous solution and 12.5 mL of 48% dicamba aqueous solution mixed per mu, mix with 35 L of water, and spray evenly on weed stems and leaves. The above herbicides can also be used alone, in which case the application concentration should be doubled.
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