When is the best time to apply spring herbicides, and how should you choose them?
The whole year's work depends on a good start in spring. Spring is the season for sowing and also a season when weeds run rampant. Doing a good job of spring weed control is of great significance for ensuring a bumper harvest all year round. Herbicide is a type of chemical agent that can effectively kill weeds, and using herbicides can do a great job of helping crops grow. So when is the best time to apply herbicides?
What is the best time to spray spring herbicides?
Through field surveys and monitoring, in wheat production, chemical weed control before winter is more effective than in spring. At present, pesticide should be sprayed earlier to kill pests. This is because weed growth in wheat fields has 2 peak emergence periods.
The amount of weeds emerging before winter accounts for more than 90% of the total weed population, with less than 10% the following year, and the weeds that emerge after the new year are shaded by wheat seedlings, grow weakly, and have a relatively small impact on wheat growth; when applying pesticide before winter, the wheat seedlings have not yet closed their rows, the exposed area of weeds receiving the pesticide is large, the weeds are small and have poor resistance, the dosage used is less and the cost is low, about 2/3 of the cost of conventional spring weed control; the safe interval period after pre-winter application is long, it is safe for the next crop, and it can prevent phytotoxicity to adjacent sensitive crops; biennial weeds emerge at the same time as wheat in autumn and compete for nutrients, and pre-winter weed control can prompt wheat to absorb more nutrients, helping wheat form strong seedlings and increasing yield.
The application time for pre-winter chemical weed control is after the 3-leaf stage of wheat, and the effect is best when the weeds have basically all emerged and their tissues are still tender, generally from mid-to-late November to early December, that is, about 40 days after wheat sowing. To ensure control efficacy, the pesticide should be applied in clear, fine weather with a temperature above 10°C and good soil moisture.
Based on production practice, you can choose to apply it after irrigation or rain in clear, fine, windless weather, ensuring that no rainfall occurs within 8-12 hours after application. If the temperature is below 6°C and the soil is dry, the efficacy is hard to bring into play, which will affect the weed control effect.
What herbicide is good to choose?
Wheat field herbicides are selective chemical agents. For the control of broadleaf weeds such as cleavers (Galium aparine), flixweed (Descurainia sophia), and shepherd's purse (Capsella bursa-pastoris), use 10 g of 10% tribenuron-methyl or 1 g of 75% Express per mu, mix with 40 kg of water and spray evenly, and the control efficacy can reach more than 95%. For the control of grass weeds such as wild oat, jointed goatgrass, and Phleum paniculatum, use 40-50 mL of 6.9% Puma or 20-25 mL of 3% Sigma per mu, add 50-100 mL of the product's adjuvant, mix, and dilute with 40 kg of water for even spraying, and the control efficacy can reach more than 85%.