【Biological Characteristics】
It prefers warm climate, is drought-tolerant, and grows well in acidic soil. It can grow in infertile soil as long as it is loose and well-drained.
【Cultivation Techniques】
Seeds and division propagation. Sow the seeds in April, mix them with sludge ash in a ratio of 1:50-100, and sow them on raised beds. Use 10.5-15kg of seeds per 1hm2, water the soil to keep it moist, remove the straw after germination, and cover with a shade net that allows 30%-40% of light to pass through. Remove the shade net in late September and plant the seedlings with a row spacing of 30cm×30cm in the second spring rainy season.
【Disease and Pest Control】
During the cultivation of medicinal plants, they are often affected by harmful organisms or adverse environmental conditions, leading to a series of changes and damages in physiological functions and tissue structures, resulting in abnormal disease symptoms such as withering, rotting, spots, powdery mildew, and leaf deformation, collectively referred to as diseases.
The causes of diseases in medicinal plants include biological factors and non-biological factors. Infectious diseases caused by invading organisms such as fungi, bacteria, and viruses are contagious and are called infectious or parasitic diseases. Non-infectious diseases caused by non-biological factors such as drought, waterlogging, extreme cold, and nutrient imbalance that affect or damage physiological functions are not contagious and are called non-infectious or physiological diseases. Among infectious diseases, the pathogens that cause diseases are called pathogenic organisms, among which fungi and bacteria are commonly referred to as pathogens. Infected plants are called host plants. The occurrence of infectious diseases depends not only on the action of pathogenic organisms, but also on the physiological status of the host and the external environmental conditions. It is the result of the interaction of the three factors of pathogenic organisms, host plants, and environmental conditions.
【Classification of Diseases】
Fungal Diseases
Fungal diseases are the most common types of diseases caused by fungal infections. Fungal diseases are generally more likely to occur in hot and humid conditions. The fungal spores overwinter in diseased remains, seeds, and soil. The spores are spread by wind and rain. Under suitable temperature and humidity conditions, the spores germinate and grow into hyphae, invading the host plants. They can cause symptoms such as lodging, seedling death, spots, blackening of fruits, and wilting. The diseased parts often have obvious mold, black spots, or powdery appearance.
Bacterial Diseases
Bacterial diseases are caused by bacterial infections. Most bacteria have one or several flagella and can enter the plants through natural openings (such as stomata, lenticels, and water pores) and wounds. They are spread by flowing water, rainwater, and insects. They overwinter in diseased remains, seeds, and soil, and are prone to occur in high temperature and high humidity conditions. The symptoms of bacterial diseases include wilting, rotting, and perforation. In the later stages of the disease, bacteria mucilage may overflow from the diseased parts, which is a characteristic of bacterial diseases.
Viral Diseases
Viral diseases are mainly transmitted by vector insects carrying the viruses, and some viral diseases can be transmitted by nematodes. Viruses overwinter in living tissues such as weeds, tubers, seeds, and insects. The main symptoms of viral diseases include flower and leaf deformation, yellowing, leaf rolling, dwarfing, necrosis, and spots.
Nematode Diseases
Plant-parasitic nematodes are tiny in size and mostly invisible to the naked eye. They can cause nutritional deficiencies and weaken the growth of plants, and even lead to death. Root-knot nematodes cause abnormal swelling in the affected parts of host plants. Cyst nematodes cause excessive branching of the roots, abnormal growth of the underground parts, and stunted growth and yellowing of the aboveground parts, such as Rhizoctonia solani. Nematodes overwinter in the soil or seedlings, mainly spread through seedlings, soil, and fertilizers.
Pest Infestations
There are many types of animals that can harm medicinal plants, mainly insects, as well as mites, snails, and rodents. Although many insects are pests, there are also beneficial insects, which should be protected, bred, and utilized. Therefore, understanding and studying insects, and mastering the occurrence and decline patterns of pests, are of great significance for pest control and the production of high-quality medicinal plants. Insects have different feeding habits and feeding methods, and their mouthparts are also different, mainly including chewing mouthparts and piercing-sucking mouthparts. Insects with chewing mouthparts, such as beetles, locusts, and caterpillar larvae, feed on solid food and cause mechanical damage to roots, stems, leaves, flowers, fruits, and seeds, such as notches, holes, breakage, boring into stems, and cutting off roots. Insects with piercing-sucking mouthparts, such as aphids, scale insects, leafhoppers, and mites, use their needle-like mouthparts to penetrate plant tissues and suck the sap, causing symptoms such as withering, wrinkling of leaves, leaf rolling, necrotic spots, shedding of growing points, and gall formation (caused by saliva stimulation). In addition, there are insects with siphoning mouthparts (such as butterflies), insects with sponging mouthparts (such as flies), and insects with chewing-sucking mouthparts (such as bees). Understanding the mouthparts of pests can not only help identify the types of pests based on their harmful conditions but also provide a basis for pesticide control.
【Control Methods】
1. Agricultural Control Methods:
Agricultural control methods involve a series of measures, such as adjusting cultivation techniques, to reduce or control diseases and pests. They are mostly preventive and include the following:
(1) Reasonable crop rotation and intercropping: Reasonable crop rotation and intercropping are important for disease and pest control and full utilization of soil fertility in the cultivation system of medicinal plants. The selection of rotation crops is also crucial. Generally, plants belonging to the same family or plants that are serious hosts of certain diseases or pests should not be selected as subsequent crops. The selection principles for intercropping crops should be basically the same as for rotation crops.
(2) Deep cultivation: Deep cultivation is an important cultivation measure that can promote the development of plant roots, enhance their resistance to diseases, and destroy the nests of hibernating pests and the overwintering sites of pathogens in the soil, directly eliminating pathogenic organisms and pests.
(3) Weed control, pruning, and field cleaning: Weeds, diseased remains, and fallen branches in the field are often hiding and overwintering places for diseases and pests, and are the sources of diseases and pests in the following year. Therefore, weed control and field cleaning, combined with pruning to burn or bury diseased remains and fallen branches in the field, can greatly reduce the severity of diseases and pests in the following year.
(4) Adjustment of sowing period: Some diseases and pests are closely related to the growth and development stages of medicinal plants. If the growth and development stages that are prone to massive infestations can be avoided, it is possible to prevent diseases and pests and achieve the purpose of control.
(5) Reasonable fertilization: Reasonable fertilization can promote the growth and development of medicinal plants, enhance their resistance and recovery abilities after being affected by diseases and pests. Proper addition of phosphorus and potassium fertilizers can reduce flower and leaf diseases. However, organic fertilizers or compost must be fully decomposed, otherwise, the residual pathogens and underground pests such as wireworms may not be killed, leading to increased underground pests and certain diseases.
(6) Selection and utilization of disease-resistant and pest-resistant varieties: Different types or varieties of medicinal plants often have significant differences in their resistance to diseases and pests. Therefore, it is meaningful to further select and breed ideal disease-resistant and pest-resistant high-quality varieties by utilizing these disease-resistant and pest-resistant characteristics.
2. Biological Control Methods:
Biological control is the use of various beneficial organisms to control diseases and pests. It mainly includes the following:
(1) Using parasitic or predatory insects to control pests: Parasitic insects include endoparasites and ectoparasites. Through artificial breeding, parasitic insects can be released into the field to control pest populations. Predatory insects mainly include mantises, ladybugs, and ground beetles. These insects mainly prey on pests and play an important role in suppressing pest populations. Breeding and releasing these beneficial insects in large numbers can control pests.
(2) Microbial Control: Microbial control utilizes fungi, bacteria, and viruses that parasitize pests to cause diseases or inhibit their damage to plants.
(3) Animal Control: Animal control utilizes beneficial birds, frogs, chickens, ducks, etc., to eliminate pests.
(4) Application of Sterile Insects: By irradiation or chemical treatment, pests can be rendered infertile and unable to reproduce offspring, thereby achieving the purpose of eliminating pests.
3. Physical and Mechanical Control Methods:
Physical and mechanical control methods involve the use of various physical factors and equipment to control diseases and pests. For example, using the phototaxis of pests for light trapping; selecting diseased seeds that are lighter than healthy seeds based on weight to eliminate seeds infested with pests; and using warm water for seed soaking, etc. In recent years, progress has been made in control using radiation technology.
4. Chemical Control Methods:
Chemical control methods involve the use of chemical pesticides to control diseases and pests. The main advantages are fast action, good effect, convenient use, and the ability to eliminate or control a large number of diseases and pests in a short period. Chemical pesticides include insecticides, fungicides, and nematicides. Insecticides can be further classified into stomach poisons, contact poisons, systemic insecticides, and fumigants based on their modes of action. Fungicides can be classified as protectants and curatives. There are many methods of pesticide application, such as spraying, dusting, seed coating, soaking, fumigation, and soil treatment.
The body of an insect consists of an epidermis, cuticle cells, and a basal membrane. The epidermis is divided into an inner layer, an outer epidermis, and an upper epidermis from the inside out. The upper epidermis is the outermost and thinnest layer, which contains waxes or similar substances that play a vital role in preventing water evaporation from the body and the entry of pesticides. Generally, the resistance of the insect cuticle to pesticides increases as the insect instar advances. Therefore, solvents that can dissolve fats and waxes are often added to insecticides, such as emulsions, which generally have higher toxicity than wettable powders. Pesticides enter the insect body mainly through the mouthparts, epidermis, and stomata. Therefore, it is of great significance to select appropriate pesticides based on the structure of the insect cuticle to improve control efficacy. In addition, it is necessary to understand the occurrence patterns of diseases and pests, seize favorable control opportunities, and apply pesticides in a timely manner. Attention should also be paid to the rational mixing of pesticides, alternate use, safe use, and avoidance of pesticide damage and human and animal poisoning.
In recent years, due to the large amount of chemical pesticides used and the improper use and abuse of pesticides, people have paid more and more attention to biological control.
