How to Comprehensively Prevent Orchid Diseases? A Detailed Guide to Practical Methods

Comprehensive Prevention of Orchid Diseases It's the peak season for diseases again. I'm posting an article I previously published in China Flowers in the hope that it will be useful to everyone—— Orchid diseases are caused by fungi, bacteria and viruses, and mostly occur on the leaves, followed by the flowers, pseudobulbs and roots. Their susceptibility and prevalence are noticeably higher than in other flowers. Once an orchid plant becomes diseased, it loses its elegant, serene charm and its ornamental value declines. The occurrence and development of orchid diseases are closely related to the cultivation environment and management level of the orchids. As long as you understand the causes of orchid disease, you can effectively prevent these diseases. Create a good environment for growing orchids The environment in which orchids grow is extremely favorable to the reproduction of pathogens, especially fungi. Humid, stuffy air, shady and dim spaces, and permeable soil rich in organic nutrients all provide excellent conditions for fungi to thrive, which is why fungal diseases of orchids are especially numerous. How can we overcome the unfavorable factors in the environment? First, the air must be clean. The less dust in the air, the less dust accumulates on the surface of orchid leaves, and the smaller the chance of pathogen transmission. The orchid-growing environment should avoid facing streets, factories and other heavily polluted places as much as possible. Second, shading must be moderate. Different orchid varieties have different light requirements. Too much shade makes orchid plants tender, green and weak; too little shade makes the leaves yellow and withered with scorched leaf tips, and either extreme may invite disease. Only with moderate shading are orchid leaves firm and glossy, with strong disease resistance. It is best to let orchids bathe in morning light as much as possible, because morning light is both beneficial to orchid growth and has a certain sterilizing effect. Furthermore, a certain humidity and air movement must be maintained. Too high air humidity favors the reproduction and growth of diseases, while too low humidity is unfavorable to orchid growth; in addition, air movement can prevent the air from becoming stuffy and keep the air fresh, so controlling air humidity and air movement well is also a key measure for disease prevention. Finally, the soil must be sterilized before use. Put the soil in a pot and steam it thoroughly, then let it cool naturally. This method can effectively kill the fungi and bacteria in the soil. Cultivate strong seedlings and strong plants Those with strong, robust bodies have strong disease resistance, and the same is true for orchid plants. If an orchid plant is thin, weak, damaged or incomplete, it is very easy for it to become diseased. Cultivating strong seedlings and strong plants is an important means of improving the disease resistance of orchids. When raising seedlings, in addition to providing an environment suitable for orchid growth, the most important thing is to provide comprehensive and abundant nutrients for orchid growth. The formulated nutrient soil must contain abundant organic matter, nitrogen, phosphorus, potassium and trace elements; rationally applying nitrogen, phosphorus, potassium and various trace element fertilizers is also a key measure for cultivating strong seedlings and strong plants. The claim that fertilization increases the occurrence of orchid diseases is not scientifically justified. When other nutrients are lacking, applying too much nitrogen fertilizer alone will make orchid plants tender, weak and prone to disease; but rational fertilization will only make orchid plants more disease-resistant, and can also prevent the occurrence of diseases such as physiological nutrient deficiency disorders in orchids. In addition, division should be done appropriately. Do not blindly divide plants for the sake of temporary commercial benefit. This practice violates the growth rules of orchids, damages the orchid plants, worsens the root system, produces weak new shoots and makes them susceptible to disease, and will only produce the opposite of the desired result. In addition, different orchid plants have different resistance to different pathogens (this situation does indeed exist), and beginners may do better to grow some varieties that fellow orchid growers generally consider not easily susceptible to disease. Eliminate sources of disease Sources of disease are divided into external sources and the orchid's own sources. First is eliminating external sources. When introducing plants, try not to bring in diseased orchids. For wild-collected orchids, the withered, rotten, diseased and damaged leaves and the diseased, shriveled old pseudobulbs should be cut off. Newly introduced orchids should be grown separately for a period of time to observe whether disease occurs. Generally, after treatment, diseases are brought back into routine management; but if it is a disease never seen locally before, it should be resolutely burned. Second is reducing the orchid's own sources of disease. Because orchid leaves stay evergreen all year round and do not wither for several years, and even when withered they do not leave the mother plant, once disease occurs the source of disease will persist for a long time, and new shoots are immediately surrounded by pathogens after they emerge. Therefore, diseased leaves and withered leaves should be cut off in time, and the cut leaves should be taken out of the orchid growing area and burned together. Chemical prevention Chemical prevention is the last line of defense in orchid disease prevention, and it is also an effective method. For fungal diseases, the chemicals that can be chosen include carbendazim, thiophanate, chlorothalonil, mancozeb, etc.; for bacterial diseases, streptomycin, chloramphenicol, etc. can be chosen. Be sure to apply the chemicals before disease occurs or in the early stages, as this can achieve twice the result with half the effort. In areas or seasons prone to disease, apply once every ten days; where disease occurs less, once a month or once a season is sufficient. Application methods: first, alternate the use of various chemicals. For example, alternating carbendazim, thiophanate and mancozeb gives good preventive results and also makes it less likely for pathogens to develop chemical resistance. Second, the dosage can be appropriately reduced, with the lowest concentration indicated on the chemical label being best. Third, choose chemicals according to the disease. Different pathogens have different sensitivities to chemicals. For example, for anthracnose, carbendazim, thiophanate, etc. are used for prevention; for bacterial soft rot, chloramphenicol, and for Fusarium stem rot, dexon, all have very good control effects (this is the result of my many years of testing, everyone may as well give it a try). These two diseases can be completely cured through these two chemicals. (Liu Jingqiu)