Talking about Diseases and Drug use

We know that plants and animals are made up of cells, and there are nuclei in the cells. We often hear about the difference between germs and fungi, but we don't know their auspiciousness. In fact, among microorganisms, only fungi have real nuclei and complete organelles, so they are also called eukaryotic microorganisms; bacteria have only primitive nuclear structure, no nuclear membrane and nucleolus, and few organelles, which belong to prokaryotic microorganisms; on the other hand, viruses have no cellular structure and belong to protoorganisms. All three types mentioned above can cause disease in orchids.

1. Fungal diseases

Fungal diseases are caused by fungi. The main difference between it and bacteria is the nucleus, fungi have nuclei, bacteria do not have nuclei. Fungi, like bacteria, play an important role in the material cycle of human beings, animals and plants, and fungi are beneficial and harmful. What we study here is its harm, such as White Cuckoo, Brown spot, Black spot and mildew, which are disadvantageous to the growth of orchids. Fungi are a class of lower organisms without chlorophyll, with individuals of different sizes, most of which can only be seen under a microscope.

Fungal mycelium is composed of hyphae, no differentiation of roots, stems and leaves, no chlorophyll, can not make their own nutrients, and live in a parasitic or saprophytic way. The fungal hyphae are tubular, and most of them have a septum. This kind of hyphae is multicellular, and there are small holes in the center of the septum, so that the cytoplasm and nucleus can pass through. The hyphae of some fungi have no septum and are multinucleated cells. Fungi reproduce by asexual reproduction and sexual reproduction. There are many kinds of straight bacteria, which can be divided into flagellum, zygote, ascomycetes, ascomycetes and semi-knowns, which are widely distributed in nature and are closely related to human beings.

Humans have been using fungi for thousands of years. The fermentation products of fungi can be made into food and condiments with different colors, aromas and tastes, such as fermented bean curd, soy sauce and so on. The production of enzyme preparation, desizing of fabric, dewaxing of petroleum, production of antibiotics and steroid drugs are all related to fungi. Many kinds of fungi are famous medicinal materials and have been widely used. Auxin secreted by fungi can promote plant growth. This is a beneficial aspect of fungi.

Fungi can decompose all kinds of organic matter, increase soil fertility, and play an important role in the material cycle in nature. Fungi often cause mildew of food and industrial products such as textiles, leather products, paper, wood, optical instruments and so on. Fungi also cause plant diseases. As pathogenic microorganisms, fungi can also invade human beings and animals.

The development of fungi can be divided into two stages: nutrition and reproduction. The hyphae are vegetative, and asexual and sexual spores are vegetative. They mainly spread through the seedlings of wind, rain, insects or flowers, and invade the body through natural pores such as stomata, water pores, lenticels and various wounds in the epidermis of flowers and plants, and can also directly invade the harmless epidermis. The diseased site showed symptoms such as white powder, rust powder, coal dirt, spots, rot, wilt, deformity and so on.

Among the flower diseases, fungal diseases are the most common, widely distributed and harmful.

Orchid diseases caused by fungi account for at least 2% of the total diseases. The fungi that infect orchids are parasitic. They absorb nutrients from the host and destroy the tissue, causing the host to produce many symptoms, such as rot, rust, quenching, wilt, ulcer, anthrax, scab, spots, and so on. Some fungi are parasitic on the surface of orchid plants and insert into epidermal cells with special hyphae; others grow between cells or surround living cells; but most fungi indiscriminately pass through tissues (including cells) to kill them. There are more than 100 species of fungi belonging to more than 30 genera that harm orchids. The common ones are Collectotrichum, Sclerotium, Botrytis, Phytophthora, Fusarum, Uerdo and Coleosporium, which cause anthracnose, Sclerotinia, Fusarium wilt and so on.

2. Bacterial diseases

Bacterial diseases are caused by bacteria. Bacteria: our common soft rot bacteria, which can rot the roots, stems and leaves. Such bacteria are called "pathogens". It is mainly based on prevention.

There are bacteria living on the surface and inside the object. It is a very tiny creature that is invisible to the naked eye. 1 billion bacteria are piled up to the size of a millet. The cell of bacteria is composed of cell wall, cell membrane and cytoplasm. it has no nucleus and forms an oval dormant body called "spore". It is very stubborn and has strong vitality in a harsh environment. The vitality and fecundity of bacteria are very strong because they reproduce by means of simple division. The speed of a generation of 20 cents and 30 minutes is astonishing. If you see orchids with diseases today, if you are negligent, they will get out of control tomorrow, and it is caused by bacteria. Bacteria generally do not contain chlorophyll and can only absorb ready-made organic matter to maintain life, which is called "heterotropy" in botany. Heterotropy can be divided into two situations: saprophytic and parasitic. "saprophytic" is characterized by the survival of animal and plant remains, such as Bacillus subtilis, which can cause plant remains to rot. As soon as the respiratory function of bluegrass declines and stops, bacteria invade immediately. Parasitism is the absorption of organic matter from living animals and plants to survive. Beneficial blue bacteria are symbiotic with Langen. Most bacteria are beneficial, but they are also harmful. On orchids are "soft rot bacteria" and "anthrax". It can be used alternately with low toxic topiramate, Shizhongqing, carbendazim and potassium permanganate for prevention and control.

Bacteria are a class of single-celled lower organisms whose morphology can only be observed under a microscope. Reproduction is the most basic function of bacterial life. Bacterial reproduction goes something like this: genetic data in a single DNA loop in a bacterial cell is copied, and then the cell wall slowly expands to form new cells, and finally the bacteria divide into two identical cells. Under favorable conditions, this process occurs every 20 minutes, so their reproduction rate is quite fast. In view of the reproductive characteristics of bacteria, antibiotics are used to prevent the growth of new cell walls during their division, so as to achieve the purpose of treatment.

3. Virus diseases

Viral diseases are caused by viruses. In recent years, virus disease has risen to a position second only to fungal diseases. virus is a kind of parasite that can harm many kinds of precious flowers. the virus is mainly transmitted through pruning insects, grafting, mechanical damage and other pathways. Even in pruning, cutting flowers, weeding, hands and gardening tools contaminated with virus juice, can play a role in transmission. It is mostly due to poor sanitary conditions of the small environment. Poor ventilation and permeability, long-term retention of water in the basin, excessive use of drugs, plant materials in the basin, so that nitrogen, phosphorus and potassium fertilizer imbalance, virus disease may also occur. Because the virus system occurs in the cell, if the synthetic cell is too fast, and the lack of phosphorus and potassium factors, the immunity decreases, the virus protein body has the upper hand, destroying the normal growth of orchid leaves, so that the virus takes advantage of the deficiency.

Plant virus is one of the pathogens that affect the yield and quality of crops, which often brings great disasters to agricultural production. Many human famines caused by plant viruses have been recorded in history. For example, in the middle of the 19th century, as a result of the first "green revolution", only a single high-yield food crop potato was widely cultivated in Europe. From 1843 to 1847, a large area of potato virus disease occurred in Europe due to abnormal climate. Nearly 5/6 of potatoes were destroyed, and in some places there was no harvest. At that time, 1 million of Ireland's 8 million people died of direct starvation or indirect disease, and 1.64 million fled to North America to make a living. In areas such as the Americas and Japan, crops such as tobacco and strawberries have been affected by plant viruses that have led to devastating attacks.

Many plants carry plant viruses. Due to the limitation of human vision, smaller organisms are less likely to be found, so viruses are discovered much later than other organisms.

Most of the plant viruses belong to single-stranded RNA viruses and a few are DNA viruses. Its basic forms are rod-shaped, filamentous and equiaxed symmetrical near-spherical icosahedron. Although plant virus is a strict intracellular parasite, but the specificity is not strong, often a virus can be parasitized on different species, genera and even different families of plants. For example, tobacco mosaic virus can infect more than 10 families and more than 200 kinds of herbaceous and woody plants.

More than 600 kinds of plant viruses are known, and most seed plants are prone to virus diseases. After being infected by virus, plants generally show three kinds of symptoms: ① causes mosaic or chlorosis due to the destruction of chlorophyll or chloroplast in host cells. ② hinders the development of plants and causes dwarfing, arbuscular branches or deformities. ③ kills plant cells and makes plants appear withered spots or necrosis.

Because plant viruses generally have no special adsorption structure, and no virus-specific receptor sites have been found on the surface of plant cells, the infection pathway of plant viruses is mainly through wounds. For example, ① invades cells by damaging plants with insect piercing mouthparts. ② invades by contacting plant wounds with diseased sap. ③ invaded by the wound of artificial grafting.

At present, the basic strategy for the prevention and control of plant virus diseases is that prevention is more important than treatment and comprehensive control. The main results are as follows: 1. Breeding disease-resistant varieties which can not be invaded by virus or cannot be replicated even if the virus invades, and disease-resistant varieties with strong adaptability to virus infection.

In addition, poison-transmitting insects should be eliminated and chemical pesticides, biological pesticides or physical traps should be used to control insects.

Because of its suitable location and ecological balance, wild orchids have diseases, but they are controlled to a minimum by nature. coupled with the fact that orchids thrive in the wild, we can see that some orchids have incomplete leaves but exuberant growth. If it's domesticated, it must be dying. Therefore, we have to use drug assistance.

The correct use of drugs can avoid diseases and get twice the result with half the effort.

Matters needing attention in pesticide application

Temperature, the active components of biological pesticides are composed of protein crystals and living spores, and must be controlled above 20 ℃. Once the spores are sprayed below the above-mentioned temperature, the propagation speed of spores in the pest will be very slow, and protein crystals are difficult to play their role, and the control effect is often not shown after spraying. According to the experiment, the insecticidal effect of spraying biological pesticide at the temperature of 25 ℃ and 30 ℃ is 1 times higher than that of spraying biological pesticide at 10 ℃.

In the environment, the greater the humidity, the more significant the effect of spraying biological pesticides, especially the powdered biological pesticide preparations. It is best to spray bacterial powder when there is dew sooner or later, so that the agent can adhere to the stems and leaves and make the spores multiply quickly.

Ultraviolet rays in sunlight have a deadly effect on spores. Scientific experiments have shown that the death rate of spores can reach 50% in only 30 minutes under the direct exposure of intense sunlight. After 1 hour of irradiation, the death rate of spores is 80% higher, and ultraviolet radiation can deform parasporal crystals and reduce the efficiency. Therefore, choose to apply biological pesticides after 16:00 or on cloudy days, the efficacy will be better.

Rain Water's torrential rain will wash away the biological pesticides sprayed, making the spores lose their lethality. However, if there is light rain for five or six hours after spraying, the efficacy will not be reduced, but will be improved. Because light rain is very beneficial to the reproduction of spores, it can kill more pests.

Look at the wind: the application of bacterial pesticides in windy days is wasteful, especially the powder, it loses more. At the same time, windy days are not conducive to spore germination. Therefore, bacterial pesticides should be applied on windless or breezy days.

Matters needing attention in pesticide application

Do not use live water to prepare pesticides because there are many impurities in living water, and its dispensing is easy to block the nozzle of the sprayer, and at the same time, it will destroy the suspension of the liquid and produce precipitation.

Do not use well water to prepare pesticides because well water contains more mineral substances, especially calcium and magnesium. When these minerals are mixed with the drug solution, it is easy to produce chemical combination and form precipitation to reduce the efficacy.

Do not arbitrarily increase the amount of water, too much water will reduce the concentration of pesticides, spray on crops leaving only a very small amount of pesticides, not enough to kill pests, and there will be a complete failure, loss of killing ability. Excessive addition of water will also cause the loss of pesticides and lead to environmental pollution.

Do not spray pesticides in wind, rainy days or hot sun when spraying pesticides will make pesticide powder or liquid disperse; while spraying pesticides in rainy days, pesticides are easy to be washed by Rain Water and reduce efficacy; spraying pesticides in the hot sun, plant metabolism is exuberant, leaf stomata open, prone to drug damage, at the same time easy to make drugs volatilization, reduce the control effect. Therefore, it is appropriate to know the best time of application: 8-11:00, 3-6 p.m.

Do not increase the amount of pesticides at will because pesticides have to go through strict field efficacy tests before they are approved for production and sale, and then determine the actual use data, such as dosage, time, times and so on. Therefore, according to the dosage specified in the instructions, the control effect can be achieved, and increasing the dosage will not only increase the input, but also cause drug damage to crops, increase pesticide residues in agricultural products, and aggravate environmental pollution.

Avoid unreasonable mixed use of pesticides some mixed use of pesticides can increase the control effect, reduce the dosage, or achieve the effect of both insect, grass or disease, insect treatment, and the mixed use of more labor-saving.

Avoid random use of expired pesticides must be used within the shelf life, otherwise it will cause losses.

The correct use of fungicides and the correct use of fungicides are of great importance. Rational use can get twice the result with half the effort. Improper use is ineffective, there are orchid friends vent their anger on the orchid medicine, lost confidence in the orchid, really wronged fungicides.

Note:

First, the use of fungicides should first look at the object of prevention and control. The so-called prescribing the right medicine to the case. If you don't prescribe the right medicine, even the best medicine can only be wasted.

Second, the use of fungicides depends on its content. In the use of agents, different contents of the same fungicide use different concentrations, 50% carbendazim wettable powder dilution or 500 Mel 1000 times. It can control flower black spot, brown spot, lawn frog eye disease, powdery mildew and other diseases, and has a good effect, while 25% of carbendazim needs to be diluted to 250 min 500 times. Therefore, in order to reduce unnecessary loss and waste, the content of fungicides should be checked before using them.

Third, seize the opportunity to use fungicides. As we all know, the occurrence of plant diseases and insect pests is very seasonal, and plant protection should give priority to prevention and treatment, especially diseases, so we must seize the opportunity to control plant diseases and insect pests to the lowest point. in order to get twice the result with half the effort.

Fourth, the use of fungicides should alternate with each other. Long-term single use of fungicides is easy to cause drug resistance of bacteria and can not achieve the desired control effect.

Fifth, the use of fungicides should master the taboo object. Almost every fungicide has its own taboo object. Before using it, we must make it clear that topiramate cannot be mixed with copper preparation, and chlorothalonil cannot be mixed with strong alkaline agents such as stone sulfur mixture.

In addition, attention should be paid to the sensitivity of some fungicides to plants.

Note 2

1. When spraying with liquid agent, it is often necessary to mix or dilute the agent into an appropriate concentration with water. Too high concentration will cause drug damage and waste, while too low concentration will be ineffective. Some non-wettable or difficult to wetting powder, you should first add a little, the powder into a paste, and then add water to prepare, you can also add some wetting agents.

2. Spraying too early will cause waste or reduce the control effect, and if it is too late, a large number of pathogens have invaded the host, and even if the therapeutic agent is sprayed, there will not be much harvest. Spraying should be protected in time according to the law of the disease and the situation at that time or according to the short-term prediction.

3. The spraying times are mainly determined according to the residual period of the agent and meteorological conditions. Generally, it is sprayed once every 10 murals for 15 days, and a total of 2 Mel is sprayed for 3 times. The supplementary spraying after rain should consider the cost and save the use of medicine.

4. if the amount of spraying is appropriate, all parts of the plant cannot be carefully protected if there is too little, and if there is too much, it will be wasted or even cause drug damage. Spraying requires fine fog and uniform spraying, and all parts that should be protected by the plant, including the front and back of the leaves, should be sprayed.

(5) there are many reasons for the drug damage to plants caused by spraying, the agents with strong water solubility are easy to cause drug damage, and different crops have different sensitivity to drugs, for example, Bordeaux solution generally does not cause drug damage, but crops sensitive to copper can also cause drug damage. In addition, it is also related to meteorological conditions, generally, the effects of temperature and sunshine are more obvious, high temperature, strong sunshine or heavy fog, high humidity are easy to cause drug damage.

6. Pesticides which are easy to decompose and fail in the case of alkaline substances should not be mixed with alkaline substances.

A small number of pesticides have a synergistic effect after mixing. For example, the mixed use of dimethoate neutral and acidic bactericides such as dimethoate zinc, wettable sulfur and colloidal sulfur is not only unaffected, but slightly improved.

7. Long-term use of a single agent (mainly internal inhalation fungicides) will lead to drug resistance of pathogens and invalidate the agents used. In order to avoid this problem, different types of agents can be used alternately, or a mixture of internal fungicides and traditional fungicides can be used.

I sincerely hope that Lanyou's orchids will thrive.