How can tea garden plants effectively control tea pests?
Using plants to control tea garden pests and diseases not only saves money, but also ensures that there is no pesticide residue in the tea, allowing the production of high-grade, high-quality tea, giving drinkers peace of mind, and causing no environmental pollution at all - truly achieving multiple benefits at once.
Chinaberry leaves
Collect 2 kg of chinaberry leaves, chop them, add 10 kg of water, boil for 1 hour, then filter. After cooling, add a 2% washing powder solution diluted 200 times and spray. This can control tea bagworm, smaller green leafhopper, tea caterpillar, leaf roller, slug moth and many other pests.
Chinese wingnut leaves
Collect 5 kg of Chinese wingnut leaves, chop them, add a little water, mash them, then squeeze out the leaf juice. Then add 2 kg of water per kg of original juice and spray. This can control tea geometrid, leaf roller, tea caterpillar, tea bagworm, slug moth and others.
Camphor leaves
Collect 2 kg of camphor leaves, chop them, add 10 kg of water and 0.2 kg of table salt, boil for 1 hour, then filter and spray. This can control tea anthracnose, sooty mould, violet root rot, powdery mildew, white star disease, garden red star disease, tea cloud leaf blight and others.
Pine needles
Collect 5 kg of pine needles, chop and mash them, add 25 kg of water, boil for 1 hour, then filter, and add a 2% soap solution diluted 400 times and spray. Spray once a week for 3 consecutive times. This can control tea violet root rot, tea cloud leaf blight, ring spot, tea blister blight, algal leaf spot and others. It can also simultaneously control tea caterpillar, tea geometrid, red spider, aphids, slug moth, scale insects and others.
Paulownia leaves
Collect 5 kg of fresh paulownia leaves, chop them, add a little water, mash them, then squeeze out the original leaf juice. Then add a 200-times dilution of the soaking liquid from yellow tobacco leaves and their stems, stumps, roots and processing waste (leaf stalks, veins) and spray. This can control tea mites, smaller green leaf mites, tea caterpillar, tea geometrid, leaf roller, slug moths, tea aphids, scale insects, black scale lice, red spider and others.
Tobacco
Take 5 kg of yellow tobacco leaves and their roots, stems, stumps and processing waste, chop them, add 10 kg of water, soak for 2 days, then boil for 1 hour, filter out the original liquid, add 15 kg of water and spray. This can control tea mites, scale insects, tea caterpillar, tea geometrid and others. Pouring it around the stumps can control root-knot nematode disease, and can also kill the larvae of scarab beetles (white grubs), cutworms, wireworms, mole crickets and others.
Integrated control techniques for pests and diseases in organic tea
Integrated control of pests and diseases in organic tea is, in practice, coordinated control. That is, based on the basic situation of tea production in each specific tea garden, and by comprehensively considering the occurrence characteristics and damage levels of various pests and diseases, the control period is determined according to local conditions, and reasonable measures such as agricultural, biological, physical, plant-based and mineral pesticides, as well as plant quarantine and other pest and disease control measures are selected, so as to achieve the goal of effectively controlling the damage of pests and diseases, being harmless to humans and animals, and causing no pollution to tea and the environment.
I. Integrated pest and disease control techniques for newly built organic tea gardens
1. Carefully carry out garden planning and build a good three-dimensional ecological environment for the tea garden. Do a good job in tea garden production planning; shade trees and green manure crops should be planted along roadsides, at corners, between rows, along ridges and on terrace walls. Build water sources and open up water storage ponds. For three consecutive years, combine tea garden management with digging deep trenches and burying green manure and organic fertilizer for soil improvement.
2. Strict plant quarantine. When introducing improved variety seedlings, fully understand the occurrence of pests and diseases that are absent locally and already present elsewhere, and proceed according to the local needs and the quarantine requirements of the source area. For cuttings and seedlings to be brought into the garden, strict quarantine must be carried out before they are transported into the tea garden, in order to prevent new pests and diseases from settling, spreading and dispersing locally.
3. Select tea tree varieties resistant to pests and diseases. According to the needs of producing commercial tea, select corresponding pest- and disease-resistant varieties. Organic tea gardens mainly producing green tea may choose Fuding Dahao, Longjing 43, Fuyun 20, Jiulong Dabai and others, and may also choose varieties suitable for both oolong tea and green tea such as Dangui, Meizhan and Baiya Qilan; tea gardens mainly producing oolong tea may choose Jiulongpao, Huangguanyin, Dangui, Mingke No. 1, Rougui, Shuixian and others.
II. Integrated pest and disease control techniques for tea in production gardens
1. In green tea areas originally dominated by Fuyun 6, low-yield tea garden improvement can be combined with appropriate replanting and replacement with Fuyun 20, Fuding Dahao, Longjing 43 and others, and varieties suitable for both oolong tea and green tea such as Huangdan, Meizhan and Dangui may also be appropriately introduced. For tea areas with oolong tea processing conditions and sales channels, Dangui, Jiulongpao, Huangguanyin, Mingke No. 1 and others may be appropriately substituted.
2. Agricultural control. This means using various agricultural cultivation and management technical measures to control the occurrence and damage of tea tree pests and diseases. In particular, do a good job in winter garden cleaning, spring and summer tillage and weeding, and autumn deep plowing, which is beneficial to good soil moisture and can also remove weeds, pests and diseases; carry out reasonable tea tree pruning and picking; scientifically apply organic fertilizer, increase the application of oil-tea camellia seed cake fertilizer or other crop seed cake fertilizer; and carry out reasonable drainage and irrigation. Develop tea garden green manure to increase the activity of natural enemy insects in the tea garden, thereby achieving the purpose of controlling pests.
3. Manual capture and poultry predation. For gregarious pests, manual capture can be adopted to directly eliminate them. For example, tea caterpillar and tea silkworm larvae are strongly gregarious, and the infested branches can be broken open and dipped into nicotine water or 1% soap solution; raising native chickens in the tea garden can prey on the larvae, pupae and adults of many pests; for the protective cases of bagworms and the leaf rolls of leaf rollers, they can be directly removed.
4. Biological and physical control. These two control methods are harmless to humans and livestock, and do not pollute tea or the environment. Biological control means actively creating a good living environment suitable for natural enemy insects, birds, frogs and others, which can effectively control the economic damage caused by tea pests to tea trees. In tea production, many pests and diseases cannot cause damage to tea trees precisely because of the natural control role of these natural enemies. In production practice, for example, releasing parasitic wasps to control leaf rollers, bagworms, tea caterpillar and others; using pathogenic microorganisms to control insects, among which Beauveria bassiana is more commonly used in production, spraying a spore liquid of 0.1-0.2 billion/mL in the tea garden, with a control effect of 70%-80% on pests such as tea caterpillar, geometrid, leaf rollers and weevils. Beauveria bassiana 871 powder 2 kg/mu as poisonous soil controls Myllocerinus aurolineatus; using bacteria to control insects, among which Bacillus thuringiensis is widely used in production, and "Bt" bacteria has a good control effect on leaf-eating pests of Lepidoptera such as tea silkworm, geometrid, tea slug moth and tea caterpillar; using viruses to control insects, among which the nuclear polyhedrosis viruses of tea caterpillar, geometrid and tea slug moth are more commonly used in production, that is, spraying a small amount of virus liquid locally in tea gardens with high pest density, and when the larvae die in large numbers, collecting the dead larvae, drying them, putting them into insect storage boxes and placing them in a refrigerator, and when field larvae are about to cause damage, taking out the dead larvae, mashing them, soaking them in a small amount of water, then filtering with gauze and diluting the filtrate into virus liquid, and when the larvae are at the 1st-2nd instar, spraying 40-50 dead larvae extract per mu, with a control effect of over 90%.
Physical control is mainly trapping and killing methods. Those more commonly used in production are mainly light trapping, sugar-vinegar trapping, bait trapping and others, while sex pheromone trapping is used less.
5. Green pesticide control. The application of green pesticides itself is non-toxic and harmless, and does not cause environmental pollution, but green pesticides must be applied at the appropriate time during the young larval stage of pests, reflecting earliness and speed. Commonly used in production is rotenone (also known as derris extract), which has contact and stomach toxicity to pests. Applying 7.5% rotenone emulsifiable concentrate 500-times dilution of Lubao to control tea smaller green leafhopper, if sprayed twice within 24 hours, can achieve a effect of 70%-80%. Rotenone cannot be mixed with alkaline pesticides and is highly toxic to fish, so when using it, care should be taken to prevent harm to fish ponds; matrine is extracted from the roots of Sophora flavescens and has contact and stomach toxicity to pests. Using 0.3% matrine aqueous solution 1000-times dilution to control tea smaller green leafhopper, it is best to spray on cloudy days at 4 p.m. or in the evening, and spraying twice within 24 hours gives the best control effect. Matrine has a relatively slow effect, so it should be applied 3-5 days in advance; azadirachtin is extracted from the neem tree and is a new type of biological insecticide with high efficiency and low toxicity. Spraying Aihe brand 0.3% azadirachtin emulsifiable concentrate 600-times dilution has a relatively ideal control effect on pests such as tea smaller green leafhopper, and the application time should be during the young larval stage, chosen on cloudy days at 4 p.m. or in the evening. Azadirachtin has a relatively slow effect and should be applied 2-3 days in advance, and cannot be mixed with alkaline pesticides. The standards after use of the above green pesticides are all lower than the "Organic Tea" standard.
6. Mineral pesticide control. Mineral pesticides mainly include copper sulfate, Bordeaux mixture, lime sulfur mixture, petroleum oil emulsion, wettable sulfur and others, among which the most commonly used are Bordeaux mixture and lime sulfur mixture. 0.6%-0.7% half-strength lime Bordeaux mixture has a relatively good control effect on tea tree diseases and moss, and should be sprayed before spring tea buds break when they are half a grain of rice in size and after autumn tea picking; lime sulfur mixture has multiple effects of killing insects, mites and fungi, and also has a relatively good control effect on scale insects, but this pesticide easily causes phytotoxicity and its use standards should be strictly followed. It is generally used for tea garden cleaning before winter, and is not used during tea production periods, nor during high temperature and drought.
Main diseases of tea roots and their control
1. Tea seedling southern blight
(1) Distribution and symptoms: Tea seedling southern blight is a common root disease in nurseries. It has a wide distribution range and causes serious damage. Besides tea, it can also harm more than 200 kinds of plants such as cucurbits, Solanaceae, hemp, tobacco and peanut. It occurs at the root collar; the diseased part initially shows brown spots, with white cottony material on the surface. After expansion, it encircles the root collar, forming a white silky fungal membrane, and can spread to the soil surface. In the later stage, rapeseed-like sclerotia form on the diseased part, changing from white to yellow-brown to dark brown. Due to the pathogenic action of the pathogen, the cortex of the diseased plant rots, water and nutrient transport is blocked, leaves wither and fall off, and finally the whole plant dies.
(2) Pathogen: It is a fungus of the genus Thanatephorus in the Basidiomycota. The mycelium is initially colorless, later slightly brown, dense, and forms sclerotia. The sclerotia are round, with a smooth, hard surface, and dark brown. Under hot and humid conditions, it produces reproductive bodies, namely basidia and basidiospores, but these are not common, and their role in transmitting the disease is also not great.
(3) Occurrence pattern: It mainly overwinters in the soil as sclerotia or attached to diseased tissues, and can survive for 5-6 years under dry conditions. At the turn of spring and summer of the following year, when temperature and humidity are suitable, it germinates and produces mycelium, which spreads along soil gaps or is transmitted by rainwater, irrigation water, farm tools and others, infecting the root collar of seedlings and causing damage. High temperature and high humidity favor disease occurrence, with the most severe occurrence from June to August. The disease is also more severe in sticky and heavy soil, where acidity is too high, in low-lying terrain, where tea seedlings grow poorly, and where the previous crop was a susceptible host.
(4) Control methods: Choose uncultivated land or land of non-susceptible crops as the nursery. Pay attention to tea garden drainage, improve the soil, promote strong seedling growth, and enhance disease resistance. In susceptible nurseries, diseased seedlings should be removed promptly and the soil disinfected. Chemical agents include 50% carbendazim 500-times dilution, 0.5% copper sulfate solution, or 70% thiophanate-methyl 500-times dilution. Tea seedlings can also be soaked and disinfected with 20% lime water before transplanting.
2. Tea root crown gall disease (compared with tea seedling damping-off)
(1) Distribution and symptoms: It mainly harms tea seedlings, occurs seriously in some tea areas, and causes tea seedlings to die. It is common in cutting nurseries, and both main and lateral roots can be affected. The pathogen invades from the cut of cuttings or root wounds, initially producing light brown spherical protrusions, which gradually expand into tumor shapes, small ones like millet grains and large ones like peas; multiple tumors often heal together into irregular large tumors. The tumors are brown, lignified and hard, with a rough surface. After tea seedlings are affected, fibrous roots decrease, and the aboveground part grows poorly or dies.
(2) Pathogen: The tea root crown gall pathogen is Agrobacterium, a bacterium. The bacterial body is short rod-shaped, with 1-3 polar flagella. It forms gray-white round colonies on ordinary culture medium. The optimum temperature for development is 25-29°C, and the lethal temperature is 51°C (10 minutes). It develops best at pH 7.3.
(3) Occurrence pattern: The crown gall pathogen overwinters in soil or diseased tissues. When the environment is suitable the following year, it spreads and causes damage via water flow, underground insects and farm tools. The pathogen invades from seedling wounds or cuts, grows and develops within the tissues, stimulates cells to divide rapidly, and produces tumors.
(4) Control methods: Strictly inspect seedlings, control underground pests, and reduce root wounds. When necessary, seedlings can be soaked in 20% lime water for 10 minutes for disinfection before transplanting.
3. Tea seedling root-knot nematode disease
(1) Distribution and symptoms: It is mainly distributed in warm tea-producing areas. This disease is caused by a very small nematode. When the nematode invades tea roots, it causes tumors to form on the roots, shaped like soybeans, rapeseeds and others, and varying in size. Affected root systems have no fibrous roots and are deformed; sometimes the root ends are thicker than the front part. The aboveground part of the diseased plant grows poorly, the plant is short, growth is weak, leaves turn yellow, and in dry seasons the leaves easily fall off in large numbers and the plant dies.
(2) Occurrence pattern: Root-knot nematodes are aerobic organisms that prefer high temperature and dryness, and occur in multiple generations per year. When the soil temperature reaches 25-30°C and soil moisture is about 50%, in sandy soil with high terrain and loose soil structure, one generation can be completed in 20-30 days. Nematodes occur more in the surface soil than in the lower soil, and stop activity below 10°C.
(3) Control methods:
① Choose uncultivated land as the nursery. Land that has been planted with crops such as peanut, cucurbits, beans and sweet potato is not suitable as a nursery. In midsummer, the soil should be deeply plowed, exposed to the sun for 10 days, and then plowed once more, which can kill nematodes in the soil.
② For seedlings that have already developed the disease, increase the application of phosphate fertilizer and potassium fertilizer; improve their disease resistance, and at the same time disinfect with lime or apply 1:20 tea seed cake water into the soil, which also has a relatively good control effect.
4. Tea violet root rot
(1) Distribution and symptoms: It is distributed in various tea-producing areas, but occurs relatively commonly in North China and East China. This disease mainly occurs at the seedling stage and adult plant stage, harming the roots or root collar. First the fibrous roots rot and become brown or dark brown, then it spreads to the lateral roots, which after rotting become purple-brown. The surface of the diseased spots is covered with purple-brown filamentous material, and on the surface of the diseased roots there are hemispherical granular sclerotia. The base of the small stem plus cm is often surrounded by purplish-red mycelium, soft in texture; it easily peels off, and the root cortex also easily peels off. In severe cases, the aboveground part wilts, new shoot sprouting decreases, and the diseased plant dies.
(2) Occurrence pattern: Generally, the disease is more severe at the turn of spring and summer or the turn of summer and autumn when it is hot and rainy. Tea gardens with high groundwater levels, poor drainage and excessively dry soil are prone to the disease. This pathogen can survive in the soil for many years, and spreads and expands with farming operations, rainwater, underground pests and root contact. It can also spread over long distances when transporting infected seedlings and soil. Continuous cropping and previous susceptible crops also make the disease more likely.
(3) Control methods:
Select sterile healthy seedlings. Once diseased seedlings are found, dig them out and burn them promptly, wash tools after use, and then soak the remaining healthy seedlings in 20% lime emulsion for 1 hour, or soak the roots in 50% carbendazim 1000-times dilution for half an hour before planting. Tea gardens with poor drainage and high water levels should pay attention to drainage, and drainage ditches should be dug well before waterlogging. For land that was previously planted with sweet potato, potato and fruit trees and where this disease has occurred, disinfect with 70% quintozene, using 2.5 kg per mu mixed with fine soil for soil disinfection, or irrigate the soil with formalin 30-times dilution. In the early stage of disease occurrence, irrigate the root collar with potassium permanganate or carbendazim 1000-times dilution.