How to prevent orchid pests and diseases? These methods must be mastered

1. Substrate too wet or too dry Balconyorchid growingis very different from growing on the ground. Orchid pots on the ground are directly connected to the earth, can maintain moisture, and because the air humidity is high,orchid growingis easy to do well. Butbalconyorchid growingrelies entirely on manual adjustment; with strong light, low humidity, and improper management, it is easy to cause excessive wetness or dryness, or because the soil becomes compacted and not breathable, it is easy to breed pathogens. Here, I quote a passage from the late Qing dynasty work Linghai Lanyan by Ou Jinze as an appropriate analysis: "Orchids live within the interaction of qi, relying on yin and yang to grow, and when yin and yang are unbalanced, the orchid becomes diseased! Whenever disease comes from yang, the leaf tips are often scorched; in mild cases it does not extend downward, in severe cases the entire tail section is scorched. When disease comes from yin, black spots appear on the leaves; in mild cases they do not penetrate to the back, in severe cases both the head and feet are black. If the leaves are scorched but the roots are not yet damaged, it can still sprout in spring. If the head is black, the roots must be rotten, and unless cultivated for several years, it cannot recover. If orchids are not planted by experienced hands, they often fail to follow the proper method. If the pot is deep and the roots shallow, and the pot wide and the shoots few, then the earth qi does not circulate, which is a yin disease. If the pot is shallow and the roots long, and the pot narrow and the shoots many, then the soil nutrients are not moistened, which is a yang disease. If the mud is too coarse and too loose, then water qi is not retained, which is a yang disease. If the mud is too fine and too compact, then water accumulates easily and becomes stagnant, which is a yin disease. If the mud is not prepared according to method, peel off the surface mud layer by layer, add new mud, and do not disturb the orchid roots; this is the safest. If the pot is not suitable, even if it is not the right season, it should still be repotted and replanted. If the shading is too sparse, then yang disease; if too dense, then yin disease; if watering is too much, then yin disease; if too little, then yang disease. These diseases are caused by people. When the wind is high and things are dry, and the severe heat steams them, then yang disease; when rain falls for a long time, and severe frost kills, then yin disease. These diseases are caused by heaven. Zhang Zhongjing said: 'When yang is seen, treat it with yin methods; when yin is seen, treat it with yang methods.' People and things follow the same principle. Yang disease first injures the upper part, then reaches the lower part; yin disease first injures the lower part, then reaches the upper part. As for uneven dryness and moisture, and excessive fertilizing, then yin and yang are both diseased. In severe cases there is no way to save them; in mild cases the new shoots are crooked and swollen, overlapping and regrowing, which is called jia leaves; when seen, they must be cut off, and perhaps they can regrow. If one cannot bear to cut off what one loves, it is no different from nurturing a sore for the orchid." This passage explains the causes and harms of excessive wetness or dryness very clearly, and is worth orchid growers paying much attention to. 2. Pollution and infection Pollution sources come from toxic substances and dust in the air, wall dust, and the dirty water, thick fertilizer, and various waste materials used by orchid growers being piled into orchid pots, causing thick dust accumulation on orchid leaves, orchid pots covered with filth, flowers ruined and leaves decayed, and spots all over. Orchid growers should pay attention to beautifying the environment, being particular about hygiene, frequently washing leaves to remove dust, and keeping orchid pots clean. If there is a lot of dust on orchid leaves or disease spots appear, use medicinal cotton or toilet paper to gently wipe both sides of the orchid leaves, or dip it in alcohol to disinfect, keeping the orchid leaves breathing freely and growing robustly. The sources of infection by pathogens (fungi and bacteria) or viruses come from: (1) When new orchids are purchased, they carrypests and diseasesor bring in viruses, without strict disinfection, sterilization, and pest elimination. Some viruses such as the Vanda mosaic virus still have no cure to this day, and it is even more impossible to remove them by disinfection, so the only way is to strengthen one's ability to identify them, not buy and not plant them, and eliminate them root and branch. (2) During pruning or when dividing plants and changing pots, pathogens and viruses from the tools used or the substrate are introduced into the orchid plant. Therefore, before pruning, the tools must be disinfected, the substrate must be disinfected and sterilized, and the orchid plant must be disinfected before planting, then left for the floating water to dry before planting; after planting, place it in a cool place, and only water it after two or three days. (3) After potting soil has been used for a long time, pathogens naturally breed because it is too wet, not breathable, and acidic or alkaline.