How to care for Cymbidium sinense in winter? Pay attention to these five points for an easy overwintering

For the vast majority of flowers and plants, winter is a rather difficult period, and the same is true for Cymbidium sinense. It has no great resistance to cold weather, so you must pay extra attention when growing it in winter. How do you care for Cymbidium sinense in winter? Below, the editor will walk you through it.

1. How to care for Cymbidium sinense in winter

There are many things to pay attention to when it comes to how to care for Cymbidium sinense in winter. Not only do you need to pay attention to watering and light, you also need to take anti-freeze measures. The specifics are described in detail below, and interested friends can take a look.

1. Temperature control

When it comes to how to care for Cymbidium sinense in winter, temperature control is a very important point. Although Cymbidium sinense is generally kept indoors in winter, you still need to pay attention to temperature control. After all, winter temperatures are relatively low, and in winter it is best to keep the indoor temperature above 10°C, so as to ensure it will not be damaged by frost due to temperatures that are too low.

2. Fertilizer management

The fertilizing requirement for Cymbidium sinense starts in late spring and stops in late autumn, so Cymbidium sinense does not need fertilizing in winter. However, before entering winter we still need to apply enough fertilizer to help it get through the winter better, and by the following spring we can resume normal fertilizing.

3. Watering management

When it comes to how to care for Cymbidium sinense in winter, watering is also a very important point. Generally, we can keep the watering frequency to once a week, and the amount of water does not need to be too much. Keeping the soil as dry as possible is enough, because winter temperatures are too low, and a small amount of water is more helpful for Cymbidium sinense to overwinter.

4. Light management

After entering winter, we generally keep Cymbidium sinense indoors, so it cannot get enough light, which can easily affect its growth the following year. Therefore, when the temperature rises at noon each day, it is best to move it outdoors to receive a few hours of light and carry out photosynthesis, which is more helpful for its overwintering.

5. Anti-freeze management

If you want Cymbidium sinense to get through winter safely, you need to do a good job of anti-freeze treatment. Before winter begins, we need to add an appropriate amount of anti-freeze water to its potting soil, which can improve the cold resistance of Cymbidium sinense and give it the means to overwinter smoothly.

Summary: After reading the above, I believe everyone now has some understanding of how to care for Cymbidium sinense in winter. In fact, winter care for Cymbidium sinense also has some points in common with its usual care. You can cross-check them against each other, and refer often to the article on Cymbidium sinense cultivation methods.

Prevention and treatment of small black spots on the backs of orchid leaves

    In orchid growing, if you want to grow strong, disease-spot-free orchid seedlings, the first thing you must face is infectious diseases, which fall into four major categories: fungal, bacterial, viral and nematode. These have pathogenic bacteria that can spread through certain channels, infecting one another, expanding from few to many and from point to area, spreading and causing damage. The pathogens of infectious orchid diseases are mainly fungi, followed by bacteria and viruses; insect pests are rare. Usually only a few kinds of fungi harm orchids, such as Colletotrichum, Phytophthora, Fusarium, Rhizoctonia solani, Pestalotiopsis fungi, Phyllosticta fungi, Cercospora fungi and so on, surviving by parasitism or saprophytism. Disease occurs under suitable conditions.

 The pathogen that infects orchids first comes into contact with the infectable parts of the host plant and begins to reproduce and spread within the orchid (mainly in the above-ground tissues), then produces pathogenic effects, usually divided into three stages: invasion, incubation and onset. From the pathogen invading the host plant to the start of establishing a parasitic relationship is called the invasion stage; from the establishment of the parasitic relationship to the beginning of symptoms appearing is called the incubation stage; the period after symptoms appear is called the onset stage. Pathogen, host and suitable environmental conditions, none of the three can be missing, and this is called the disease triangle of plant diseases. Simply put, it lies dormant in winter, develops in spring and summer, and lies dormant again in winter. Fungi such as Fusarium and Pestalotiopsis overwinter in diseased leaves and soil in the form of mycelium and acervuli, using acervuli as the primary and secondary inoculum to complete the disease process the following year.

 The invasion of pathogens is related to environmental conditions, among which humidity and temperature have the greatest influence. Within a certain range, humidity determines whether spores can germinate and invade, while temperature affects the speed of germination and invasion. In winter the temperature is low, and humidity is relatively lower than in spring and summer. At the same time, orchids enter dormancy, and the invasion speed of pathogens is slow, but this does not mean they cannot cause harm to orchids. In addition, light also has a certain relationship with pathogen invasion. For pathogenic fungi that easily invade through stomata, light can determine the opening and closing of the stomata, thereby affecting invasion. We have found that orchid plants with good light have strong disease resistance, while orchid plants with poor light, because their stomata are often open, are prone to disease due to pathogen invasion. Therefore, sunning orchids in winter is advocated by orchid growers.

 When a pathogen invades orchid tissue, it initially forms a local or point infection, called local infection. Local infection is relatively easy to treat. When local infection spreads, it causes infection of the whole plant, called systemic infection. At this point treatment is somewhat troublesome. Therefore, early detection and early treatment should be achieved. During the orchid growing period, most of the irregular disease symptoms have already been brought under control by us, and the few orchid plants with conditions such as soft rot and stem rot have already been removed from the orchid house. After entering winter, the number and types of residual pathogens that can threaten orchids are already very few, so disease prevention in winter has a very ideal effect.

 Another favorable factor is that in late autumn and early winter, due to the temperature, pathogens are in an inhibited state. Orchids gradually shift from vigorous reproductive growth to a dormant form, and bacteria, fungi, viruses and nematodes gradually go dormant, their resistance greatly weakened. The effects of various pesticides can be fully exerted. As long as you pursue the pathogens relentlessly, the good results will be very obvious the following year, and this is the easiest time of the year for orchid disease management.

 What to clean in the winter garden cleanup

 In winter, because the orchid house is closed and the air cannot be exchanged, this stable and sealed environment is very favorable for pathogens to overwinter. Although winter temperatures are very low, the vitality of pathogens is very strong. Moreover, because of daytime solar radiation, the temperature in the closed orchid house will still rise above 15°C, and pathogens will still slowly reproduce. After the temperature drops at night, pathogens will again be in an inhibited state, and this repeats over and over, rising by day and falling by night. This year is again a rare warm winter. Entering mid-November, the minimum temperature is still hovering around ten-plus degrees, whereas in past years it was already very cold at this time. If this warm winter situation continues, the growth of pathogens will exceed their losses, and the accumulation will still be considerable. It should be noted that, thanks to the improvement of our orchid-growing facilities, even in the coldest days of the three nine-day periods, whether on balconies, in orchid rooms, in Jiangnan or in Saibei, the temperature of our orchid-growing sites will not drop below 5°C. This is especially true for orchid houses cultivating cold-sensitive orchids such as Cymbidium ensifolium, Cymbidium tortisepalum and Cymbidium sinense.

 Although it is said that in winter, because the activity of pathogens is weak, they will not cause too much harm to orchids, if pesticides are not applied at regular times and in regular amounts, pathogens will accumulate to a certain level and then proliferate rapidly in early spring. Therefore, after entering winter, spraying fungicides several times at regular intervals is very necessary.

 At the same time, although winter temperatures are low, because we close the orchid house, this causes humidity to be rather high. Gray mold can develop under conditions of low temperature and high humidity, causing water-soaked lesions on the sepals and petals, and in severe cases rotting the petals. It is said that in China it has only been seen affecting Phalaenopsis and Cymbidium hybridum, and the situation for Chinese orchids is unknown, but since gray mold is a common disease of flowers in winter, the author still advocates being cautious.

 In spring, new orchid plants are prone to black spot, brown rust, crown rot and so on. The occurrence of these symptoms is caused by the accumulation of pathogens in winter. Black spot overwinters as mycelium or acervuli in dead leaves or soil. At a temperature of 10°C the spore germination rate can still reach 50%, and the following year it spreads with spring rain in February and March. The control agent is 50% mancozeb 1000x solution. Brown rust causes great damage to orchids and is difficult to control; only by emphasizing prevention over treatment can the disease be effectively controlled. Control with copper sulfate, fungicide, boric acid, lice disease cleaner (containing triadimefon, also controlling scale insects) and others all have poor effects. Once brown rust occurs, it spreads quickly and is difficult to control, but as long as you avoid extensive management and appropriately control the number of orchid flowers and shorten the flowering period, it helps improve the plant's disease resistance and reduces opportunities for pathogen invasion. For orchid plants that have not developed disease, spray thiophanate and triadimefon for prevention. Try to avoid using agents containing “copper” or other heavy metal ions.

 Overwintering pathogens cause primary infection after the new generation of plants begins to grow in spring. In fact, once a pathogen infects successfully, it is very little affected by external factors. In other words, contact fungicides are powerless against it, so everyone's advocacy of prevention first is very reasonable. Understanding the above principles, we can carry out proactive prevention and treatment. In addition to regular and quantitative pesticide prevention during the growing period, removing pathogens during the dormant period can achieve twice the result with half the effort.

 How to clean the orchid garden

 1. Pruning First, prune diseased and dead leaves to eliminate places where fungi can parasitize. When cutting off dead and diseased leaves, be careful to move gently and act accurately and decisively, and carefully place the cut dead and diseased leaves into plastic bags in order to prevent spores from scattering after being disturbed by vibration. The cut diseased leaves should be centrally destroyed.

 2. Garden cleanup On a sunny day, orchid growers should clean up the garbage, dust, weeds and so on in the orchid house to eliminate pathogens and intermediate hosts. The dust outside the orchid pots should also be wiped clean.

 3. Disinfection After cleaning the garden, first disinfect the site. Before orchids are brought into the room and placed, the orchid-growing site should be disinfected in advance. You can evenly spray the ground with 50 ml of formalin or potassium permanganate plus 10 kg of water per square meter, or spray the ground and walls with 50% carbendazim wettable powder or 36% thiophanate-methyl suspension at 500x solution. Then close doors and windows tightly for sealing, and open the windows after about 10 days to let the gas volatilize.

 Second, disinfect the seedlings. When introducing plants in autumn, select strong seedlings and eliminate diseased and weak ones. Avoid letting the wolf into the house. Newly introduced varieties or wild-collected orchids should first undergo medicinal treatment. Many people soak them in a 1000-800x potassium permanganate solution for 15 minutes. Potassium permanganate is a strong oxidant and releases nascent oxygen upon contact with organic matter, causing the active genes of proteins in the bacterial cells to be oxidized and denatured, thereby achieving a sterilizing effect. It is a fairly good fungicide. Low concentrations of potassium permanganate have an astringent effect, while high concentrations have a disinfecting and antiseptic effect, but its disinfecting action is brief and superficial.

 4. Replace the growing medium For orchid plants that are managed normally but grow very poorly, there is a great possibility that the growing medium has been infected by pathogens, because a large portion of pathogens parasitize the soil. During the orchid's dormant period, we unpot it to check the root system and so on. If there are black roots or rotten roots, it indicates that the root system has already been infected by pathogens and root rot has occurred. We then need to replace the growing medium, disinfect and replant it, in order to improve the growing environment of the orchid roots. At the same time, drench the orchid pot with medicine once or twice. What needs to be explained here is that root drenching only targets pathogens in the growing medium. If pathogens have already invaded the orchid roots, even the best medicine is ineffective, because the root bark of orchid roots is thick and the medicinal liquid cannot get in. The only option is to use scissors to cut off the diseased roots, and you must not be soft-hearted, otherwise there will be endless trouble.

There are small black spots on the backs of orchid leaves. How should they be handled?

In orchid growing, if you want to grow strong, disease-spot-free orchid seedlings, the first thing you must face is infectious diseases, which fall into four major categories: fungal, bacterial, viral and nematode. These have pathogenic bacteria that can spread through certain channels, infecting one another, expanding from few to many and from point to area, spreading and causing damage. The pathogens of infectious orchid diseases are mainly fungi, followed by bacteria and viruses; insect pests are rare. Usually only a few kinds of fungi harm orchids, such as Colletotrichum, Phytophthora, Fusarium, Rhizoctonia solani, Pestalotiopsis fungi, Phyllosticta fungi, Cercospora fungi and so on, surviving by parasitism or saprophytism. Disease occurs under suitable conditions.

The pathogen that infects orchids first comes into contact with the infectable parts of the host plant and begins to reproduce and spread within the orchid (mainly in the above-ground tissues), then produces pathogenic effects, usually divided into three stages: invasion, incubation and onset. From the pathogen invading the host plant to the start of establishing a parasitic relationship is called the invasion stage; from the establishment of the parasitic relationship to the beginning of symptoms appearing is called the incubation stage; the period after symptoms appear is called the onset stage. Pathogen, host and suitable environmental conditions, none of the three can be missing, and this is called the disease triangle of plant diseases. Simply put, it lies dormant in winter, develops in spring and summer, and lies dormant again in winter. Fungi such as Fusarium and Pestalotiopsis overwinter in diseased leaves and soil in the form of mycelium and acervuli, using acervuli as the primary and secondary inoculum to complete the disease process the following year.

The invasion of pathogens is related to environmental conditions, among which humidity and temperature have the greatest influence. Within a certain range, humidity determines whether spores can germinate and invade, while temperature affects the speed of germination and invasion. In winter the temperature is low, and humidity is relatively lower than in spring and summer. At the same time, orchids enter dormancy, and the invasion speed of pathogens is slow, but this does not mean they cannot cause harm to orchids. In addition, light also has a certain relationship with pathogen invasion. For pathogenic fungi that easily invade through stomata, light can determine the opening and closing of the stomata, thereby affecting invasion. We have found that orchid plants with good light have strong disease resistance, while orchid plants with poor light, because their stomata are often open, are prone to disease due to pathogen invasion. Therefore, sunning orchids in winter is advocated by orchid growers.

When a pathogen invades orchid tissue, it initially forms a local or point infection, called local infection. Local infection is relatively easy to treat. When local infection spreads, it causes infection of the whole plant, called systemic infection. At this point treatment is somewhat troublesome. Therefore, early detection and early treatment should be achieved. During the orchid growing period, most of the irregular disease symptoms have already been brought under control by us, and the few orchid plants with conditions such as soft rot and stem rot have already been removed from the orchid house. After entering winter, the number and types of residual pathogens that can threaten orchids are already very few, so disease prevention in winter has a very ideal effect.

Another favorable factor is that in late autumn and early winter, due to the temperature, pathogens are in an inhibited state. Orchids gradually shift from vigorous reproductive growth to a dormant form, and bacteria, fungi, viruses and nematodes gradually go dormant, their resistance greatly weakened. The effects of various pesticides can be fully exerted. As long as you pursue the pathogens relentlessly, the good results will be very obvious the following year, and this is the easiest time of the year for orchid disease management.

What to clean in the winter garden cleanup

In winter, because the orchid house is closed and the air cannot be exchanged, this stable and sealed environment is very favorable for pathogens to overwinter. Although winter temperatures are very low, the vitality of pathogens is very strong. Moreover, because of daytime solar radiation, the temperature in the closed orchid house will still rise above 15°C, and pathogens will still slowly reproduce. After the temperature drops at night, pathogens will again be in an inhibited state, and this repeats over and over, rising by day and falling by night. This year is again a rare warm winter. Entering mid-November, the minimum temperature is still hovering around ten-plus degrees, whereas in past years it was already very cold at this time. If this warm winter situation continues, the growth of pathogens will exceed their losses, and the accumulation will still be considerable. It should be noted that, thanks to the improvement of our orchid-growing facilities, even in the coldest days of the three nine-day periods, whether on balconies, in orchid rooms, in Jiangnan or in Saibei, the temperature of our orchid-growing sites will not drop below 5°C. This is especially true for orchid houses cultivating cold-sensitive orchids such as Cymbidium ensifolium, Cymbidium tortisepalum and Cymbidium sinense.

Although it is said that in winter, because the activity of pathogens is weak, they will not cause too much harm to orchids, if pesticides are not applied at regular times and in regular amounts, pathogens will accumulate to a certain level and then proliferate rapidly in early spring. Therefore, after entering winter, spraying fungicides several times at regular intervals is very necessary.

At the same time, although winter temperatures are low, because we close the orchid house, this causes humidity to be rather high. Gray mold can develop under conditions of low temperature and high humidity, causing water-soaked lesions on the sepals and petals, and in severe cases rotting the petals. It is said that in China it has only been seen affecting Phalaenopsis and Cymbidium hybridum, and the situation for Chinese orchids is unknown, but since gray mold is a common disease of flowers in winter, the author still advocates being cautious.

In spring, new orchid plants are prone to black spot, brown rust, crown rot and so on. The occurrence of these symptoms is caused by the accumulation of pathogens in winter. Black spot overwinters as mycelium or acervuli in dead leaves or soil. At a temperature of 10°C the spore germination rate can still reach 50%, and the following year it spreads with spring rain in February and March. The control agent is 50% mancozeb 1000x solution. Brown rust causes great damage to orchids and is difficult to control; only by emphasizing prevention over treatment can the disease be effectively controlled. Control with copper sulfate, fungicide, boric acid, lice disease cleaner (containing triadimefon, also controlling scale insects) and others all have poor effects. Once brown rust occurs, it spreads quickly and is difficult to control, but as long as you avoid extensive management and appropriately control the number of orchid flowers and shorten the flowering period, it helps improve the plant's disease resistance and reduces opportunities for pathogen invasion. For orchid plants that have not developed disease, spray thiophanate and triadimefon for prevention. Try to avoid using agents containing “copper” or other heavy metal ions.

Overwintering pathogens cause primary infection after the new generation of plants begins to grow in spring. In fact, once a pathogen infects successfully, it is very little affected by external factors. In other words, contact fungicides are powerless against it, so everyone's advocacy of prevention first is very reasonable. Understanding the above principles, we can carry out proactive prevention and treatment. In addition to regular and quantitative pesticide prevention during the growing period, removing pathogens during the dormant period can achieve twice the result with half the effort.

How to clean the orchid garden

1. Pruning First, prune diseased and dead leaves to eliminate places where fungi can parasitize. When cutting off dead and diseased leaves, be careful to move gently and act accurately and decisively, and carefully place the cut dead and diseased leaves into plastic bags in order to prevent spores from scattering after being disturbed by vibration. The cut diseased leaves should be centrally destroyed.

2. Garden cleanup On a sunny day, orchid growers should clean up the garbage, dust, weeds and so on in the orchid house to eliminate pathogens and intermediate hosts. The dust outside the orchid pots should also be wiped clean.

3. Disinfection After cleaning the garden, first disinfect the site. Before orchids are brought into the room and placed, the orchid-growing site should be disinfected in advance. You can evenly spray the ground with 50 ml of formalin or potassium permanganate plus 10 kg of water per square meter, or spray the ground and walls with 50% carbendazim wettable powder or 36% thiophanate-methyl suspension at 500x solution. Then close doors and windows tightly for sealing, and open the windows after about 10 days to let the gas volatilize.

Second, disinfect the seedlings. When introducing plants in autumn, select strong seedlings and eliminate diseased and weak ones. Avoid letting the wolf into the house. Newly introduced varieties or wild-collected orchids should first undergo medicinal treatment. Many people soak them in a 1000-800x potassium permanganate solution for 15 minutes. Potassium permanganate is a strong oxidant and releases nascent oxygen upon contact with organic matter, causing the active genes of proteins in the bacterial cells to be oxidized and denatured, thereby achieving a sterilizing effect. It is a fairly good fungicide. Low concentrations of potassium permanganate have an astringent effect, while high concentrations have a disinfecting and antiseptic effect, but its disinfecting action is brief and superficial.

4. Replace the growing medium For orchid plants that are managed normally but grow very poorly, there is a great possibility that the growing medium has been infected by pathogens, because a large portion of pathogens parasitize the soil. During the orchid's dormant period, we unpot it to check the root system and so on. If there are black roots or rotten roots, it indicates that the root system has already been infected by pathogens and root rot has occurred. We then need to replace the growing medium, disinfect and replant it, in order to improve the growing environment of the orchid roots. At the same time, drench the orchid pot with medicine once or twice. What needs to be explained here is that root drenching only targets pathogens in the growing medium. If pathogens have already invaded the orchid roots, even the best medicine is ineffective, because the root bark of orchid roots is thick and the medicinal liquid cannot get in. The only option is to use scissors to cut off the diseased roots, and you must not be soft-hearted, otherwise there will be endless trouble.