How to Cleverly Use Herbicides in the Cultivation of Chinese Medicinal Herbs
Weeds in medicinal herb fields not only compete for light and nutrients, causing poor growth and development of the herbs, but also reduce both yield and quality. Manual weeding means working under the scorching summer sun and intense heat, often resulting in sunburned skin or even heatstroke, which not only increases labor intensity but also raises production costs. In recent years, experimental research on herbicides has achieved good results with chemical weeding, establishing the concept of scientific farming and building confidence among herb growers for increasing production and income.
[Pre-sowing weed control] For land with a high incidence of annual seed-propagated weeds. At the same time as plowing, and no later than 7-10 days before sowing, before the weeds sprout and emerge, apply 100-150 ml of trifluralin emulsifiable concentrate per mu, diluted in 40-50 kg of water, and spray the soil surface of the medicinal herb field. Immediately after spraying, perform shallow tilling to mix the soil to a depth of 5-10 cm, or follow with watering, but the effect is not as good as shallow tilling and mixing. Sowing can only be done 7-10 days after applying the herbicide. The field weed control effect reaches over 90%. However, this herbicide has a poorer effect on weeds such as black nightshade and cocklebur, while it works well on grasses, Chenopodiaceae, Polygonaceae, and Amaranthaceae.
[Post-sowing, pre-emergence weed control] After sowing medicinal herbs, a certain amount of time is needed for seedlings to emerge. During this period, various weeds will sprout and grow. When the field weeds first sprout and turn green, and the medicinal herb seedlings have not yet emerged, chemical weeding can be used to eliminate these newly sprouted green weeds. Apply 150-260 ml of Gramoxone per mu, which farmers call "green-kill," diluted in 25-30 kg of water, and spray the field to kill all emerged weeds. Because Gramoxone herbicide is deactivated and decomposed upon contact with soil, it has no effect on the unemerged medicinal herbs. However, it must be noted that once the medicinal herb seedlings emerge, use is prohibited to prevent killing the seedlings. Alternatively, 150-200 ml of Roundup aqueous solution can be used, diluted in 30-40 kg of water, for field spraying and control; weeds will wither and die within 5-7 days.
[Wiping to control perennial weeds] For perennial fibrous-rooted weeds such as white grass, bermudagrass, reed, Cyperus rotundus, bitter lettuce, sowthistle, and thistle, glyphosate aqueous solution can be used at 100-200 g per mu. When the weeds are 10-15 cm tall, wipe the growing points and young leaves of the weeds for a noticeable herbicidal effect.
[Weed control during the growing season] After the medicinal herb seedlings emerge, during the seedling growth stage, for annual grass weeds growing in the field, when they reach the 3-5 leaf stage, apply 65-100 ml of sethoxydim per mu diluted in 20-30 kg of water, or use haloxyfop or quizalofop. Three days after spraying, the growing points and young leaves of the weeds turn yellow and stop growing; after 7-10 days, the growing points and young leaves wither, rot, and gradually die. If it is a leguminous medicinal herb, acetochlor can be used; for pinnate-leaved species, broadleaf herbicides can also be used.
[Strict use of herbicides] Attention must be paid to the specificity and timing of chemical weeding. Do not misuse, abuse, or mix herbicides indiscriminately, to prevent killing seedlings. Strictly follow the dosage to avoid herbicidal damage. When mixing two or more herbicides, strictly control the mixing ratio, application timing, and spraying technique. Pay attention to application isolation and wind direction to prevent drift damage to adjacent fields caused by wind. Also pay attention to the effect of herbicides on subsequent crops, and master the timing and technical essentials of herbicide use. When herbicides need to be mixed with other pesticides, do so under the guidance of technical personnel. Pay attention to the influence of environmental conditions on herbicides. Temperature, moisture, light, soil type, leaf shape and size, family and genus classification, and the level of soil tillage and land preparation will all indirectly affect the effectiveness of herbicides.