In the cultivation of traditional Chinese medicinal materials, weeds can significantly impact both the yield and quality of the crops. Manual weeding is not only labor-intensive and time-consuming but also difficult to maintain consistently. Currently, there are limited herbicides that are widely used in the production of medicinal herbs, with most still in the experimental phase. Based on practical experience, the author recommends three key stages for herbicide application: pre-sowing, post-sowing before emergence, and post-emergence.
**Pre-sowing Herbicide Application**
This is the most critical period for weed control. Farmers should aim for a single application to ensure that weeds do not compete with the medicinal plants throughout their growth cycle. The recommended herbicides include 48% Trifluralin and 50% Acetochlor.
48% Trifluralin is effective against annual grassy weeds like crabgrass and goosegrass, as well as small-seeded broadleaf weeds. It remains active in the soil for 2–3 months. Apply 80–100 ml per acre mixed with 40–50 kg of water, spraying the soil surface 5–10 days before sowing. Immediately after application, the soil should be tilled to a depth of 5–7 cm.
50% Acetochlor inhibits weed germination and root development, effectively controlling various annual grasses and some small-seeded broadleaf weeds. It should be applied either before sowing or 3–5 days prior to transplanting. Use 70–75 ml per acre mixed with 40–60 kg of water, evenly sprayed on the soil surface. However, it should not be used on certain medicinal herbs.
**Post-sowing Pre-emergence Herbicide Application**
After sowing, if the crop has not yet emerged, 20% Glyphosate (Traceless Water) or 41% Roundup can be used. For crops like windproof (Saposhnikovia divaricata) or Bupleurum, apply 150–250 ml of 20% Traceless Water mixed with 25–30 kg of water, or 150–200 ml of 41% Roundup with 30–40 kg of water. Spray when weeds are visible, but avoid using these products once the seedlings have emerged, as they may damage young plants.
**Post-emergence Herbicide Application**
For weeds that have already emerged, 6% Kecaoxing EC and 8% Hibiscus are suitable options.
6% Kecaoxing is effective against annual and broadleaf weeds, and has a strong inhibitory effect on perennial weeds. Apply 70–80 ml per mu mixed with 30–40 kg of water, spraying when weeds are 5 cm tall.
8% Hibiscus provides long-lasting control over a wide range of grassy weeds, including goosegrass, crabgrass, and perennial weeds like Imperata. Use 25–30 ml per acre with 20–30 kg of water, applying it during the 3–6 leaf stage of the weeds. It is safe for broad-leaved medicinal herbs like Radix Astragali and Atractylodes macrocephala but harmful to grassy species such as alfalfa.
Proper timing and selection of herbicides are essential to maximize yield and quality while minimizing risks to medicinal plants. Always follow label instructions and consider environmental impact.
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