Pest and Disease Control Methods for Medicinal Flowers and Key Sowing Points for Different Seasons
To control pests and diseases in medicinal flowers, you must first understand the causes of disease and the types of pests and diseases, grasp the patterns of their occurrence and development, and implement the policy of "prevention first, integrated control." Second, you must consider the situation comprehensively, pursuing benefits while avoiding harm, improving both the yield and quality of medicinal flowers while reducing environmental pollution. In particular, you must prevent toxic residues from harming the body. Once these principles are understood, the following control methods can be applied:
1. Plant quarantine is a method of controlling pests and diseases in medicinal flowers based on a series of quarantine laws and regulations established by the state, in order to prevent the introduction of new dangerous pests and diseases from other countries or other epidemic areas and to limit the spread of local pests and diseases to the outside.
Therefore, quarantine procedures must be strictly followed when introducing medicinal flowers and transporting seedlings.
2. Agricultural control is the method of comprehensively applying cultivation and management techniques to control and eliminate pests and diseases, known as agricultural control methods. The following methods are commonly used:
(1) Breeding pest- and disease-resistant varieties. Different varieties of medicinal flowers vary greatly in their resistance to pests and diseases, so breeding high-quality, high-yield medicinal flower varieties resistant to diseases is an economical and effective measure for pest and disease control. For example, spiny safflower is more resistant to anthracnose than spineless safflower. Within the same variety, individual plants resistant to pests and diseases should also be selected for seed preservation. In addition, disease-free or less-diseased species should be selected to reduce sources of infection.
(2) Rational crop rotation. Different medicinal flowers have different pests and diseases, and each pest and disease has a certain host range.
Therefore, frequently rotating different medicinal flowers or crops in a region or on a piece of land causes pests and diseases that are unsuited to the new environment and food source to gradually decrease and naturally die out; it can also achieve good results against soil-borne pests and diseases as well as monophagous and oligophagous pests. At the same time, crop rotation can also improve the soil, promote the growth and development of medicinal flowers, and enhance their resistance to
pests and diseases. For example, for medicinal flowers with severe root rot, rotating them with gramineous plants in a paddy-upland rotation for more than 4 years can reduce the occurrence of root rot and southern blight.
(3) Adjusting the sowing period. Some pests and diseases are often closely related to a certain phenological stage of the medicinal flower's growth and development. If this growth and development stage can be made to avoid the dangerous period of massive infection and damage by pests and diseases, the harm can be avoided or reduced. For example, sowing safflower early at the appropriate time can avoid the harm of anthracnose and the safflower fruit fly; sowing Job's tears late at the appropriate time can reduce the occurrence of smut; sowing daylily in summer can avoid the harm of seedling-stage pests in spring. Therefore, adjusting the sowing period is an effective means of avoiding disease and preventing pests.
(4) Deep plowing and careful cultivation can promote the development of the medicinal flower root system, enhance its ability to absorb nutrients, and make it grow vigorously, while also directly killing pests and diseases.
(5) Cleaning the field. Diseased and pest-damaged plant residues in the field, as well as dead branches, fallen leaves, and weeds in the field, are often places where pests and diseases hide and overwinter, becoming sources of pests and diseases for the following year. Therefore, collecting and burning diseased plant residues and fallen leaves and cleaning the field can reduce the occurrence of pests and diseases.
(6) Strengthening field management includes technical measures such as rational fertilization, timely drainage and irrigation, and hoeing and weeding. Through careful field management, the effect of pest and disease control can be achieved.
3. Biological control. The method of using certain beneficial organisms from nature to eliminate or suppress certain pests and diseases is called biological control.
Biological control currently mainly uses insects to control insects, bacteria to control insects, bacteria to control diseases, and birds to control insects. For example, predatory beneficial insects such as ground beetles, aphid-eating ladybugs, aphid-eating hoverflies, and aphid-eating flies are used to control aphids; parasitic wasps such as braconid wasps and Trichogramma are used to control cabbage caterpillars; parasitic bacteria and fungi such as Beauveria bassiana, Bacillus thuringiensis, and Serratia are used to control cabbage caterpillars, fruit borers, white grubs, scarab beetles, cutworms, and many other pests; antibiotics such as kasugamycin, "5406," and neomycin are used to control Rhizopus rot and anthracnose. Biological control is an important aspect of integrated control, with advantages such as being harmless to humans, livestock, and plants, safe to use, free of toxic residues, non-polluting to the environment, long-lasting in effect, and preventive in nature, and it has broad prospects for development.
4. Physical and mechanical control. The method of using temperature, light, and mechanical equipment based on the living habits of pests and diseases and their occurrence patterns to eliminate pests and diseases is called physical and mechanical control. For example, pests with weak mobility, concentrated damage, or death-feigning behavior can be manually captured and killed; for phototactic Lepidoptera and certain underground pests, moth-attracting lamps or black-light lamps can be used to trap and kill them; high-temperature and low-temperature methods can be used to control warehouse pests. Since diseased seeds weigh less than healthy seeds, winnowing and water selection can be used to eliminate diseased seeds. In recent years, new physical technologies such as ultrasound and radiation have also been used to directly kill pathogens and pests.
5. Chemical control. The method of applying chemical pesticides to control pests and diseases is called chemical control. It has the characteristics of fast action, good effect, convenient use, the ability to eliminate or control large outbreaks of pests and diseases in a short period, and relatively little restriction by region and season, and it is currently a commonly used method for pest and disease control. However, it also has major disadvantages, such as the development of pesticide resistance in pathogenic organisms after long-term use, while also harming some beneficial organisms, which is unfavorable to biological control. In addition, it has disadvantages such as pesticide residues, environmental pollution, and effects on the quality of medicinal flowers.
Among the chemical pesticides commonly used at present, according to their toxic effects on pests and diseases, they can be divided into two major categories: insecticides and fungicides. In addition, there are herbicides and others. Insecticides, according to their properties and the different ways they enter the pest's body and act, can be further divided into stomach poisons (such as lead arsenate and trichlorfon), contact poisons (such as pyrethrum), systemic agents (such as dimethoate, "1059," and "1605"), and fumigants (such as dichlorvos and chloropicrin). Most fungicides currently used are protective agents (such as Bordeaux mixture and zineb). Protective agents need to be applied before the medicinal flowers develop disease, and then reapplied each time the effective period expires. Fungicides also include therapeutic agents (such as lime sulfur mixture and thiram) and systemic agents (such as nabam, dexon, and antibiotics).
When using the above agents, methods such as spraying, dusting, fumigation, seed dressing, seed soaking, smearing, soil treatment, and preparing poisoned grain, poisoned bait, and poisoned soil can be used to control pests and diseases.
When using chemical agents, attention should be paid to: understanding the properties of the pesticide, applying the right pesticide for the problem, seizing the opportunity, spraying at the right time, mastering the technique, ensuring efficacy, paying attention to safety, and avoiding phytotoxicity and poisoning of humans and livestock. In recent years, with the development of atomic physics, ionizing radiation has begun to be used to directly kill pests. In addition, lasers can also be used to control pests.