When is the right time to apply wheat herbicide: before the New Year, in winter, or post-emergence?

AbstractWheat weeding generally targets 2 periods, before the New Year and just after the New Year, that is, the wheat seedling stage and the wheat green-up stage, 2 time windows. In most regions, the wheat seedling stage is around late November, and the wheat green-up stage is between late February and early March. These 2 time windows are the best periods for spraying wheat with herbicide.

I. When is the right time to apply wheat herbicide

1. There are usually 2 periods, before the New Year and just after the New Year, that is, the wheat seedling stage and the wheat green-up stage, 2 time windows. In most regions, the wheat seedling stage is around late November, and the wheat green-up stage is between late February and early March. These 2 time windows are the best periods for spraying wheat with herbicide.

2. For weeds in wheat fields, post-emergence herbicides for controlling grass weeds, herbicides for controlling broadleaf weeds, and compatible broad-spectrum herbicides can be used. Commonly used ones include tribenuron-methyl, cyanazine, MCPA, bromoxynil, and other mixtures, to broaden the weed control spectrum. Among them, tribenuron-methyl is a systemic, highly selective, translocated sulfonylurea high-efficiency herbicide, with safe and reliable quality.

3. Spraying can be done at the 3-4 leaf stage of wheat and the 2-3 leaf stage of weeds, using 75% tribenuron-methyl dry flowable 0.9-1.8g per mu, plus cyanazine 16-27g/mu, diluted with 30kg of water, mixed and compounded, and sprayed evenly. Alternatively, cyanazine can also be mixed and compounded with 2, MCPP, 4-CPP, isoproturon, atrazine, etc., which can broaden the types of weeds killed and improve the control effect.

II. Timing and precautions for applying herbicide to wheat

1. Do not use herbicide before the 4-leaf stage of wheat or after jointing

Wheat before the 4-leaf stage is very delicate, and its detoxification ability and immunity are low, so it is prone to herbicide damage. Generally, after the jointing stage, wheat enters the booting stage and is relatively fragile. At this time, using herbicide is likely to cause herbicide damage, especially MCPA, which may cause the wheat ears to fail to emerge or become deformed, seriously affecting wheat yield.

2. Do not use wheat herbicide when the temperature is below 6°C

In low-temperature weather, the control effect of herbicide is not ideal. It needs to be applied when the daily average temperature is above 6°C. The weeding effect is relatively good from around 10 a.m. to 3 p.m., because weeds absorb light and grow vigorously, their stomata gradually open, and they easily absorb water and herbicide solution. The opposite is true at low temperatures, so a better weeding effect can be achieved.

3. Do not use wheat herbicide when the soil is dry

When the soil is relatively dry, seize the opportunity when the wheat field is watered and apply the pesticide promptly, which helps ensure the herbicide efficacy. The efficacy of most herbicides requires a certain level of soil moisture. When soil moisture is 40%-60%, it is favorable for the herbicide to take effect.