What are the methods for preventing and treating orchid viruses?

YesOrchidsThere are many treatises on the study of viruses, each with its own merits. We believe thatgrowing orchidsrequires great attention to environmental hygiene. We have discussed thatorchidslove sunlight, need ventilation and air permeability, and that soillesscultivationand granular mediacultivationshould be used as much as possible, and that organic fertilizers should be used sparingly and are not recommended. With these conditions, the probability of orchid diseases will naturally decrease, but during the growth process of living organisms, many factors can cause disease, and we should have some basic knowledge to try to avoid theorchidswe grow suffering losses. The common and frequently occurring diseases of Cymbidium orchids in the Jiangsu-Zhejiang region include orchid leaf black spot disease, southern blight, stem rot, anthracnose, root rot, and Byarlas disease (caused by a virus), among several others. The direct cause of occurrence is the invasion of harmful fungi, bacteria, and viruses intoorchid plants, causing undue losses to orchid seedlings. The indirect cause is mostly poor microenvironmental sanitation conditions. Poor ventilation and air permeability, long-term waterlogging in the pot, excessive use of chemicals, and the potting medium being in a chronically acidic state for a long time are also causes of disease. If imported hormone-type fertilizers are frequently used, causing an imbalance of nitrogen, phosphorus, and potassium fertilizers, viral diseases may also occur. Because the viral system develops within cells, if cells synthesize too rapidly and there is a deficiency of phosphorus and potassium factors, immunity declines, the viral protein body gains the upper hand, disrupting the normal growth of orchid leaves, so that the virus takes advantage of the weakened state to enter. Our understanding of orchid diseases should be clear in our minds, with emphasis on prevention, especially prevention during spring and winter should be done well. Before orchids are brought out of the house (shed) in spring and before they are brought into the house (shed) in winter, the orchid shelves, doors and windows, floor, and walls should be sprayed and cleaned with lime-sulfur mixture or methyl thiophanate or concentrated limewater. When repotting or changing pots, after washing the orchid pots, they can be soaked and washed with 1% copper sulfate or potassium permanganate; if the orchid roots are not seriously damaged, they should not be washed. Orchid leaves should be sprayed and washed with "Daconil" or "Carbendazim," then planted into a sterile medium. After being placed on the shelves, during windless seasons, every one to two weeks, thiophanate, lime-sulfur mixture, carbendazim, cephalosporin, etc. (choosing one according to the situation) should be used alternately to spray the leaves. During the plum rain season, fororchid plantsin the middle and lower reaches of the Yangtze River, pesticide application for pest control can be combined with watering and fertilizing to increase the number of prevention and treatment applications. When humidity is frequently at a high ratio, it is best to choose lime-sulfur mixture to lower the pH value. Black spot disease is mostly caused by anthracnose fungi harming the leaves. Black spot disease is a frequently occurring disease ofCymbidium goeringii, Cymbidium faberi, as well as autumn orchids and New Year orchids. When it first appears, it forms small scars, round spots, and patch-like shapes. If not treated in time, it can spread to the entire pot and even damage others. If it occurs at a high position, it can be cut off; if it occurs in the middle of the leaf, thiophanate or lime-sulfur mixture can be applied. To prevent spore germination, the entire plant and the pot surface should be sprayed with carbendazim or zineb at least twice a day. Stem rot is caused by southern blight fungi harming the orchid stem. In diseased orchids, first there are white visible filamentous bodies on the surface of the medium, and soonorchid plantsshow yellow-brown water-soaked areas on the upper part of the pseudobulb and leaf base. Gently lifting with the hand will pull it up, so it is also called "pulling-head disease." If this disease is found, the pot should be immediately turned out, the orchid pot soaked and washed with 1% sulfur, the obviously infected pseudobulbs cut off, and the whole orchid plant should also be soaked and washed for more than five minutes, then air-dried, with "Daktarin" applied to the affected areas, and thecultivationmedium replaced before repotting. Root rot mostly occurs in potted orchids with poor air permeability. Black-brown rotting lesions can be seen on the roots, or the orchid roots are hollowed out leaving only the epidermis and root veins. The pathogen harming orchids is mostly an acidophilic damping-off fungus, caused by waterlogging in the pot, long-term acidity, and blocked circulation in the orchid body. Root rot is not easy to detect in time; its manifestation is that the orchid plant has no luster for a relatively long period, does not produce shoots, remains weak for a long time, and shrinks back. Once discovered, the pot should be immediately turned out, rotten roots cleaned up, and the rotting parts scraped off with a fingernail, leaving the central column vein for support and water transport. Then wash clean, disinfect with potassium permanganate, and repot. Tip burn disease is a frequently occurring disease of Cymbidium orchids in the middle and lower reaches of the Yangtze River region, causing especially great damage to variegated-leaf orchids. First the plant partially shrinks, then all of it is damaged, especially old plants, which shrink back relatively quickly, so it is also called "shrink-head disease." It is mostly caused by low humidity in the orchid growing area and water draining too quickly from the pot. The treatment method is to cut off the shrunken and necrotic parts, then apply additional thiophanate, Daconil, etc., and take care that the pot and environment do not become too dry. In summary, orchid pots should be checked frequently, with early detection and early treatment, to avoid losses. Chemicals should be used with caution. Thiophanate, carbendazim, etc. can be commonly used for spraying and drenching potted plants. Huakang No. 2 produced by Sichuan Chengdu Huayi Company has obvious effects. Use lime-sulfur mixture and Bordeaux mixture as cautiously as possible, but they are effective for disinfecting the environment and tools. During the plum rain season or summer high temperatures, orchids are prone to disease, and sterilizing pesticides should be sprayed and drenched frequently. However, human antibiotics should not be applied to orchids, because it is not yet clear whether various antibiotics will damage the plant immune mechanism. (Guan Wenchang, Zhu Hexing)