Precautions for Using Chemical Herbicides on the Chinese Medicinal Herb Patchouli
Precautions for Using Chemical Herbicides on the Chinese Medicinal Herb Patchouli:
1. Selection of chemical herbicides
Attention must be paid to the selectivity, specificity and timing of chemical herbicides. Herbicides must not be misused or used indiscriminately, so as to prevent the killing of medicinal seedlings.
2. Strictly control the restricted dosage
The use of herbicides should take into account the specific soil texture and the field microclimate, and strictly follow the dosage range, application concentration and application amount specified in the product instructions. For example, on generally poor sandy soil, herbicide application has very strong permeability, and medicinal materials are prone to herbicide damage, so the application amount should be small, or even avoided entirely; in rainy seasons when soil moisture is good, low-dose application should be used; when weeds emerge uniformly and density is low, the dose should be smaller; for plastic film mulching, because temperature and humidity conditions are favorable, the application amount should also be reduced.
3. Reasonable mixing of agents
When two or more herbicides are mixed for use, the mixing ratio, application time and spraying technique must be strictly controlled, and whether there is antagonism or other side effects between them must be considered. 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, attention should also be paid to the synergistic function of the mixed agent. For example, the herbicidal effect of the mixture of benthiocarb and propanil is greater than the sum of the herbicidal effects of the two single agents. When using it, the amount of the mixed agent should be reduced (generally within 1/2 of the amount of each single agent), so as to avoid herbicide damage and ensure the safety of the medicinal materials.
4. Correct use
Master the best time and technical essentials for applying herbicides, properly store the agents to prevent misuse, and thoroughly clean the spraying equipment to avoid misuse that may cause herbicide damage to other crops.
5. Pay attention to the influence of environmental conditions on herbicides
Factors such as temperature, moisture, light, soil type, organic matter content, and the level of soil tillage and land preparation will all directly or indirectly affect the herbicidal effect of herbicides.
6. Flexible application
When applying herbicide to the soil at the base of medicinal plants by the soil method, it should be done under conditions without dew, so as to prevent the stems and leaves from being damaged by contact with the liquid. For agents to which crop seedlings and embryos are sensitive, soil treatment should be applied after sowing and covering the seeds before sowing, 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 carried out on the ground 20-30 cm near the medicinal plants; for herbicides with poor selectivity or contact-killing 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 plants as much as possible, and it should not be applied when the plants are vigorous and the green leaf area is large. If conditions permit, measures such as dryland irrigation, paddy field moistening, and film mulching to induce germination should be taken as far as possible before sowing or transplanting the medicinal materials, so that weeds germinate in advance and are then killed with agents, so as to avoid affecting the growth and quality of the medicinal materials by applying agents after transplanting.
7. Other
At present, there are still no herbicides specifically for medicinal materials on the market; most are borrowed from those used for crops such as vegetables and fruit trees. Therefore, herbicides must be purchased and weeding operations carried out under the guidance of experts or technicians with practical experience, so as to avoid economic losses and adverse consequences.