How to scientifically control weeds during the cultivation of Chinese medicinal herbs
As is well known, weed control in the cultivation of Chinese medicinal herbs generally uses chemical control methods, but when using chemical herbicides, attention must be paid to how to use them reasonably.
I. Points to note
1. Pay attention to the selectivity, specificity and timing of chemical herbicides; do not misuse or use them indiscriminately.
2. Strictly control the restricted dosage. The use of herbicides should be based on the specific soil quality and take into account the farmland microclimate, and should strictly follow the dosage range, application concentration and application amount specified in the product instructions.
3. Mix agents reasonably. When mixing two or more herbicides, strictly control the mixing ratio, application time and spraying technique, and consider whether there is any antagonism or other side effects between them. A small amount can first be taken for a miscibility test; if precipitation, flocculation, layering, floating or deterioration occurs, it indicates that their safety has changed and they must not be mixed. In addition, pay attention to the synergistic function of mixed agents. For example, the herbicidal effect of a mixture of benthiocarb and propanil is greater than the sum of the herbicidal effects of the individual agents, so the dosage of the mixture should be reduced when used (generally within half the dosage of each single agent) to avoid phytotoxicity and ensure the safety of the medicinal materials.
4. Pay attention to application isolation and wind direction; the droplets should not be too fine, so as to avoid drift causing phytotoxicity to nearby farmland, and also pay attention to the impact on subsequent crops.
5. Master the best time for applying herbicides and the key technical points of operation, properly store the agents to prevent misuse, and thoroughly clean the spray equipment to avoid misuse that causes phytotoxicity to other crops.
6. Pay attention to the influence of environmental conditions on herbicides. Factors such as temperature, moisture, light, soil type, organic matter content, soil tillage and land preparation level will all directly or indirectly affect the herbicidal effect of herbicides.
7. Use herbicides flexibly. For weed control by applying herbicide to the soil at the base of medicinal plants, it must be carried out under conditions without dew, so as to avoid the stems and leaves being harmed by contact with the liquid. For agents to which crop seedlings and embryos are sensitive, soil treatment should be applied before sowing after covering the seeds, and the sowing quality should be improved as much as possible, with the sowing rate appropriately increased. For some transplanted medicinal materials, because their seedlings are large while the weeds are small, concentrated application can be adopted in the seedling band (20—30 cm wide near the seedlings). For herbicides with poor selectivity or contact action, protective application should be implemented, that is, the liquid should be sprayed directly or splashed onto the soil surface, avoiding contact with the medicinal seedlings as much as possible, and application must not be delayed until the seedlings are vigorous and the green leaf area is large. If the crop rotation permits, before sowing or transplanting the medicinal materials, measures such as dryland irrigation, wetting of paddy fields and film mulching to induce germination can be taken to make weeds sprout in advance and then be killed with agents.
8. At present, there are no herbicides on the market specifically for medicinal materials; most are borrowed from herbicides for vegetables, fruit trees, etc. Therefore, herbicides must be purchased or weed control operations carried out under the guidance of experts or technicians with practical experience, so as to avoid economic losses and adverse consequences.
II. Applicable pesticides
Common weeds in medicinal herb fields mainly include barnyardgrass, foxtail grass, lovegrass, crabgrass, goosegrass, shortawn foxtail, thatch, redroot amaranth, purslane, small cockscomb, polygonum and lambsquarters, Russian thistle, pepperwort, shepherd's purse, alligator weed, goosefoot and field bindweed, etc. These weeds not only compete with medicinal plant plants for nutrients and water in the soil, but also worsen the environment and spread diseases and insect pests, seriously affecting the yield and quality of Chinese medicinal materials. In the process of weed control, different methods should be adopted for different weeds according to their different properties. Selecting chemical agents for weed control not only saves money and labor, but is also relatively thorough and can achieve better control effects.