Tea gardens are widely distributed, with different terrains and climates in different tea regions, resulting in a wide variety of weed species in tea gardens and difficulty in prevention and control. Weeds in tea gardens compete with tea trees for resources such as air, water, nutrients, and sunlight. At the same time, many weeds are also intermediate hosts of tea plant diseases and pests, seriously affecting tea quality and yield. Studies have shown that tea gardens without any weed control management reduce yields by 14.98% to 19.84% compared to normal weed control tea gardens.
Chemical weed control was one of the main methods for weed control in tea gardens in the past, with significant weed control effects and low costs. However, the long-term use of chemical herbicides in tea gardens has seriously affected the stability of the tea garden ecosystem and brought huge risks to tea quality and safety. With the strengthening of public health and environmental awareness, it is imperative to research and promote green grass control technology in tea gardens.
Development of weed control technology in tea gardens
1. Traditional manual weeding stage
In the early days of tea gardens, manual weeding was mainly relied on to remove weeds, which involved manual removal, cutting, and tillage. Manual weeding is simple and safe, but it requires a large amount of labor, requires high investment, and has low efficiency, which can no longer meet the requirements of modern tea garden weeding management.
2. Chemical weed control stage
After the 1960s, chemical weed control methods gradually emerged. At that time, commonly used chemical herbicides in tea gardens included simazine, atrazine, glyphosate, paraquat, and thatch blight. Chemical herbicides have the advantages of good weed control effect, long shelf life, and low cost. By the 1980s, chemical herbicides were widely used in tea gardens, and chemical herbicides became the main means of weed control in tea gardens at that time.
3. Formation of green prevention and control concept for weeds in tea gardens
In the 1980s and 1990s, the international community successively proposed the concept of sustainable development and advocated reducing the use of chemical pesticides globally. People gradually realized the harm of using chemical herbicides in tea gardens. To avoid environmental pollution and risks to tea quality and safety caused by the use of chemical herbicides, the concept of green weed control in tea gardens has begun to take shape by comprehensively using agricultural control, physical control, biological control, and chemical ecological control methods to replace chemical weed control.
Application status of green weed control technology in tea gardens
1. Mechanical weeding
Mechanical weeding is a technical measure that uses agricultural machinery and equipment for weeding, and is a non chemical weeding method. At present, the commonly used weed control machinery in tea gardens can be divided into tillage type weed control machinery and cutting type weed control machinery according to their principles.
2. Manual covering and weeding
Artificial weed control refers to the use of non living coverings such as straw, rice husks, black film, and weed control cloth in tea gardens to isolate the light, heat, space, and other resources required for weed growth, thereby inhibiting weed growth. Artificial coverage weed control is a simple, feasible, and efficient measure that is very suitable for weed prevention and control in young tea gardens.
3. Natural herbicides for weed control
Natural herbicides refer to herbicides developed from secondary metabolites produced by animals, plants, microorganisms, etc. that have inhibitory effects on weeds. Compared with chemical herbicides, natural herbicides are more easily degraded and less toxic in natural environments, making them an environmentally friendly herbicide. Natural weed control active substances have a wide range of sources, and currently there are many studies on natural active substances from plant and microbial sources.
(1) Plant derived herbicides for weed control
Plant derived herbicides refer to biologically active substances extracted from natural plants with herbicidal effects, or herbicides derived from them as lead substances. Plant derived herbicidal active substances have a wide range of sources. Currently, over 2000 natural substances with herbicidal activity have been found in more than 30 families of plants worldwide. These substances are classified by structure into terpenes, alkaloids, coumarins, etc. Plant derived herbicides have the advantages of low toxicity, low residue, safety, and high efficiency, and are highly concerned in the field of weed control. However, the application of plant derived herbicides in tea gardens has not been reported yet.
(2) Microbial derived herbicides for weed control
Microbial herbicides are a type of herbicide produced from microorganisms, their tissues, and metabolites. The microorganisms used for development are mainly plant pathogenic microorganisms, and currently there are many studies on herbicides derived from fungi, bacteria, and actinomycetes.
(3) Mineral based herbicide
Aidida is a mineral based herbicide currently reported in literature for tea gardens, with a main component of 57% paraffin oil. Aidida is a non selective, stem leaf contact herbicide that has good control effects on one-year and perennial broad-leaved and gramineous weeds, as well as lower plants such as lichens, mosses, and ferns. After spraying with Aidida, the effect time is fast, and most weeds dry up on the day of application. But currently, the cost of using Ai Di Da for weed control in tea gardens is relatively high, so it is still difficult to promote its use.
4. Biological control grass
Biological weed control refers to the use of natural enemies that are not conducive to weed growth, such as other grasses, crops, and herbivores, to control the occurrence and damage of weeds. Biological control has the advantages of not polluting the environment, not producing pesticide damage, and high economic benefits. At the same time, biological control is simpler than agricultural and physical control, and is an important research direction for weed control in the future.
(1) Intercropping control grass
After the tea garden grows grass, the grass occupies the blank habitat of the tea garden in advance with a certain amount of biomass, forming dominant species, which prevents weeds from obtaining sufficient growth conditions such as light, water, and space, thereby inhibiting their germination and growth. At present, many herbaceous plants have been introduced into tea gardens, and commonly used grass species include grasses such as rat grass, ryegrass, clover, and early maturing grass; Leguminosae includes white clover, flat peanut, purple clover, round leaved cassia seed, hairy sweet potato, etc; At the same time, the tea garden can also be intercropped with some crops with certain economic value, such as soybeans, mung beans, peanuts, buckwheat, taro and other crops, as well as Chinese medicinal materials such as Lysimachia christinae and helianthemum to suppress the occurrence of weeds.
(2) Insect control grass
Insect weed control is the use of host specific insects to feed on weeds and achieve the goal of weed prevention and control. After being released, insects gradually reach a balance with weeds and can generally exert long-term effects once released. The use of insects to control weeds is one of the earliest techniques applied in weed biological control, but it is mainly used for the prevention and control of invasive weeds, such as the use of ragweed moths to control the worldwide malignant weed ragweed. The application of such technology in tea gardens has not been reported yet.
(3) Plant eating animals control grass
Plant eating animals control weeds by using animals that feed on plants, such as chickens, ducks, geese, sheep, etc., to step on and feed on weeds in tea gardens. Animal weed control can not only effectively prevent and control weeds in tea gardens, but animal feces can also increase soil organic matter in tea gardens. At the same time, selling animals can also earn additional income, making it a safe, effective, and economically efficient way to control weeds in tea gardens.
The development of grass control technology
At present, the green grass control technology in most tea gardens is relatively backward. To promote green and efficient grass control, efforts need to be made in terms of ideological concepts, research and improvement of grass control technology, and technology promotion.
1. Change weed control to weed control
We need to abandon the traditional weed control concept of “not a single blade of grass grows” in tea gardens, and switch from weed control to weed control. We should use grass growth and retention, and implement “grass suppression”. Intensify research on the types, occurrence patterns, and hazard grading of weeds in the region, timely control malignant weeds, and reasonably retain weeds that are less harmful to tea gardens and do not become dominant species.
2. Promote the mechanization of weed control in tea gardens
The terrain of tea gardens in our country is complex, and most tea garden construction and tea tree planting are not standardized. The weed control machinery in farmland or orchards on the market is difficult to directly apply to tea gardens, and the quality of tea garden machinery on the market varies greatly. The weed control effect in the field still needs to be evaluated and verified. In order to smoothly implement mechanical weeding in tea gardens, it is necessary to standardize garden construction and planting, develop exclusive weeding machinery for tea gardens, simplify the structure of tea garden weeding machinery, reduce overall quality, and facilitate transportation to adapt to complex terrain tea gardens.
3. Accelerate the research and development of natural herbicides
Natural herbicides are environmentally friendly herbicides. In recent years, many studies have shown that natural herbicides have good weed control effects in tea gardens, and their weed control effects are not inferior to traditional chemical herbicides. However, at present, the research on natural herbicides in China is still in the stage of theoretical research and new technology development, and there is a great lack of commercialized products. In the future, we should track and study natural herbicide products with good commercialization potential, reduce production costs, scale production, and successfully commercialize the developed products, and then gradually promote their use in tea gardens.
4. Improve the research on intercropping and grass control technology
Inter cropping and grass control are commonly used methods in tea gardens nowadays, and the focus of research is on selecting suitable inter cropping grass species and matching application models for tea gardens. There are still shortcomings in the promotion and use of mouse grass grass, white clover, purple clover, etc. Grass species such as rat grass are relatively expensive and require nitrogen supplementation. Spring trampling and deep pruning in hand picked tea gardens can affect the growth of rat grass in the next cycle.
Each tea region should choose suitable tea garden intercropping plants and patterns based on the climate characteristics of the region, tea garden cultivation, pruning, and fertilization management modes. Further research is needed on the weed suppression mechanism of intercropping plants, whether it affects the growth of tea trees and tea quality, and to solve the problems of mechanized and efficient sowing and supporting management, so as to enable tea farmers to better accept the technology of “grass suppression”.
5. Establish a green grass control technology combination system
China’s tea gardens have a wide distribution area and significant terrain differences, resulting in a complex composition of weeds. Using a single weed control technique may have little effect and fail to meet the requirements of weed control in tea gardens. Therefore, future research on green weed control technology in tea gardens should establish corresponding technical combination models based on different terrain environments. In young tea gardens, a combination of covering and intercropping techniques can be applied, which involves covering the tea rows with anti grass cloth and planting rat grass, white clover, etc. between rows. Adult tea gardens can achieve long-term grass control effects by rotating different grass species in summer and autumn. At the same time, various grass control techniques should be organically matched with management techniques such as cultivation and fertilization, forming a complete set of green cultivation management models.