Best Time for Winter Wheat Weed Control, Herbicide Selection and Efficient Spraying Methods

At present, in winter wheat growing regions, wheat sowing is underway. In a few days, weeds in the wheat fields will gradually emerge. Winter wheat weed control requires proper methods and approaches; a reasonable timing will certainly suppress weeds. When is the time to spray herbicides on winter wheat? What should be noted when spraying herbicides on winter wheat?

There are 2 optimal timings for winter wheat weed control

Do not spray when the temperature is below 6°C

The best period for controlling wheat seedlings is during the wheat seedling stage (mid-to-late November) and the green-up stage (late February to early March), which are the optimal periods for controlling weeds in wheat fields.

Controlling weeds during the wheat seedling stage (mid-to-late November) is a good choice. At this time, the weeds are relatively young, their resistance to chemicals is relatively low, control is relatively easy, and the dosage does not need to be too large to eliminate the weeds.

The green-up stage (late February to early March) is also an optimal period for weed control. However, at this time, the weeds are older and have relatively strong herbicide resistance, so the dosage must be increased during control, which will invisibly increase the cost of application.

At the same time, another disadvantage is that it can easily cause herbicide damage to wheat, subsequent crops, and adjacent crops. Although weeds in wheat fields can also be controlled during this period, extra care must be taken when applying chemicals.

Finally, a reminder: when controlling weeds in wheat, pay attention to weather temperature and humidity. When applying chemicals, the average temperature should be above 6°C, and it is best to do so between 10 a.m. and around 3 p.m. If the soil is relatively dry, increase the amount of water used. If there is standing water, it will affect the effectiveness of the wheat herbicide.

Therefore, when applying wheat herbicides, seize the timing, consider multiple factors, and apply chemicals promptly to lay the foundation for high wheat yields.

Patterns of weed occurrence in wheat fields

There are 2 peak periods of weed occurrence in wheat fields. The first is 30-40 days after wheat sowing, and the second is before wheat jointing the following year. Generally speaking, most grass-family weeds emerge before winter and basically grow at the same time as wheat seedlings, such as Bromus japonicus and Aegilops tauschii. The weed seedling stage is extremely similar to wheat seedlings and difficult to distinguish. Most broadleaf weeds occur in spring, and their seedling stage is easy to distinguish from wheat seedlings.

Key periods for weed control in wheat fields

According to the patterns of weed occurrence in wheat fields, there are two key periods for control.

The first is pre-winter control, mainly for grass-family weeds, roughly before early November, when wheat has grown 4-5 leaves and weeds have generally grown to 2 leaves and 1 heart. At this time, the control effect is best.

The second is spring control, mainly for broadleaf weeds, from late February to early March. The control period should be earlier rather than later; if too late, weed control becomes difficult, and wheat may suffer herbicide damage.

Suitable herbicides and formulations

The herbicides selected for chemical weed control in wheat fields should be determined according to the main weed species and the herbicidal spectrum of the herbicide. When the weed species in the wheat field fall within the herbicidal spectrum of the same herbicide, a single herbicide can be used for control. When several weeds occur together, such as a mixed occurrence of dicotyledonous and monocotyledonous weeds, several herbicides need to be mixed and applied in a certain proportion to broaden the herbicidal spectrum and improve the weed control effect. Below, based on the weed community types in Beijing wheat fields, several herbicide formulations are provided for selection.

For wheat fields dominated by broadleaf weeds such as flixweed (Descurainia sophia), shepherd's purse (Capsella bursa-pastoris), Lithospermum arvense, Chorispora tenella, Humulus scandens, and lamb's quarters (Chenopodium album), you can choose 10% tribenuron-methyl wettable powder at 10 grams per mu, or 75% tribenuron-methyl water-dispersible granules at 1 gram per mu.

For wheat fields dominated by Bromus japonicus, you can choose 70% flucarbazone-sodium (Biaohu) water-dispersible granules at 3-4 grams per mu.

For wheat fields dominated by false bindweed (Calystegia hederacea), you can choose 20% fluroxypyr (Starane) emulsifiable concentrate at 50-70 milliliters per mu.

For wheat fields dominated by shortawn foxtail (Alopecurus aequalis) and Beckmannia syzigachne, you can choose 10.8% fenoxaprop-P-ethyl (Puma) emulsifiable concentrate at 30-40 milliliters per mu, or 15% clodinafop-propargyl (Topik) wettable powder at 30-40 grams per mu.

For wheat fields with a mixed growth of Bromus japonicus and broadleaf weeds, mix 70% flucarbazone-sodium water-dispersible granules 3-4 grams + 10% tribenuron-methyl wettable powder 10 grams per mu.

For the above formulations, dilute with 30-40 kilograms of water per mu, and spray evenly using a hand-pressed sprayer or a spray vehicle.

Technical requirements for application

Accurate application. Herbicides should be sprayed at the recommended dosage. Arbitrarily increasing or decreasing the dosage is prohibited to ensure control efficacy and eliminate the occurrence of herbicide damage.

Mix and use immediately. When several herbicides are mixed for use, the secondary dilution method should be adopted, that is, first dissolve the herbicide with a small amount of water to form a mother solution, then dilute the mother solution to the prescribed spray volume for use. The mixed solution cannot be left standing for a long time and must be applied all at once.

Choose suitable climatic conditions for application to reduce drift and evaporation. In addition, most herbicides are positive temperature coefficient agents, so do not apply when the temperature is below 10°C.

Maintain application equipment properly. Before application, promptly maintain and service the spray equipment to prevent running, spurting, dripping, and leaking during application, and achieve uniform application.

Pay attention to safety. Application personnel should take safety precautions. Smoking and eating are prohibited during the operation to prevent poisoning accidents.