Remember these 3 key points for orchid disease prevention

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Orchid diseases mostly begin with soggy, stuffy, unclean substrate or overly dry substrate. When the substrate is soggy and stuffy and unclean, air is pushed out, pathogens multiply in large numbers, orchid roots are damaged, and various diseases arise from this, harming the orchid plant. When the substrate is too dry, the fleshy roots, after physiological dehydration, shrivel and lose their transport capacity, so water and nutrients cannot be supplied in time, and orchid leaves become rough with scorched tips. Orchids struggling on the brink of life and death will open their stomata wide to absorb moisture from the air in order to stay alive, and various pathogens seize the opportunity to invade, with disease following soon after. In addition, fertilizer or pesticide concentrations that are too high, exceeding the concentration of orchid plant cells, cause reverse osmosis and make the orchid lose water, which likewise triggers disease.

To prevent orchid diseases, in addition to measures such as keeping the environment clean and moist, ventilated, watering and fertilizing lightly and evenly, applying chemicals at the right time and in the right amount, keeping the substrate clean and permeable, and providing suitable light, you should even more so, based on the actual conditions of each place, grasp the main contradiction and carry out targeted prevention and control. In the Jiangsu and Zhejiang area, the plum rain season has warm, hot weather and high air humidity; it is the golden season for orchid growth during the year, and also the peak period for various diseases. According to the author's observations over many years, various diseases are most likely to occur when the temperature is around 22 degrees. To avoid disease, two points must be noted in this season: first, control watering; second, apply chemicals in time.

In autumn, the climate turns from hot to cool, and this is another growing season for orchids. Autumn air is relatively dry, and orchids lose water easily, so take care to water in time. At the same time, after enduring the hot summer, orchids have consumed a great deal and their resistance is relatively weakened, so in early autumn phosphorus and potassium fertilizer should be supplemented in time to strengthen disease resistance.

Autumn is also a peak period for various diseases, so chemicals must be applied in time. During the period from one week before the Start of Autumn to Cold Dew, orchids must be treated with chemicals once every ten days, to ensure that the orchids can grow healthily throughout the whole autumn and until the spring of the following year.

In winter, orchids need to be kept warm and brought indoors. Some people set up sealed plastic sheds on an indoor balcony or under eaves that shelter from wind and face the sun, and place the potted orchids inside to receive sunlight. Sometimes the temperature inside the shed rises above twenty degrees, letting the orchids be steamed in stuffy conditions, and disease spots occur from time to time. Once discovered, applying liquid medicine to the leaf surface is of no avail. With sealed plastic sheds, including glass sheds, you must always be careful; once the temperature inside the shed exceeds ten degrees, open the windows and open the film in time to let the orchids ventilate. On days with high temperature and strong sunlight, appropriate shading is also necessary; never let them be exposed to the sun and steamed. The late orchid-growing master Mr. Wang Shuping of Yuyao emphasized this point in his article "Fifty Years of Orchid Growing Experience," saying, "Orchid growers often overlook this point, so it must be especially pointed out."

In summary, on the basis that other management measures can also be kept up in time, controlling watering and applying chemicals in time during the plum rain season; watering in time, supplementing phosphorus and potassium, and applying chemicals at the right time in autumn; and not exposing orchids to the sun or letting them be steamed in winter are the keys to disease prevention and treatment in different seasons. Grasp these three key seasons when disease is likely to occur, and the disease prevention effect will be very different. As for the high-temperature season, because the temperature is too high, disease is not obvious, and doing a good job of ventilation and shading is enough.

In addition, the layout and treatment of the substrate also require much attention. In the orchid pot, the substrate should be coarse at the bottom and fine at the top, with clear layers, so that water is received evenly. It is best not to mix substrates of different coarseness together when planting orchids, so as to avoid uneven water distribution when watering due to obstruction by large particles of substrate, causing orchid roots that receive excessive water to rot and orchid roots that receive insufficient water to shrivel. Before planting orchids, the substrate must be disinfected; it can be sun-dried, steam-sterilized, or stir-fried in a pan. The purpose is to kill pathogens and eliminate the disease sources inherent in the substrate.

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