Pest and Disease Control Methods for Growing Orchids on Balconies

Orchids belong to the family Orchidaceae, are monocotyledonous plants, and are perennial herbs. They are 20 to 40 cm tall, with long tubular roots. The leaves grow in clusters from the stem, are linear-lanceolate, slightly leathery, and form a bundle of 2 to 3 leaves.

　　

(1) Substrate too wet or too dry. Growing orchids on a balcony is very different from growing them on the ground. Orchid pots on the ground are directly connected to the earth, can remain moist, and because the air humidity is high, orchids are easier to grow well. But when growing orchids on a balcony, everything depends on manual adjustment; the light is strong, the humidity is low, and poor management can easily lead to excessive wetness or dryness, or because the soil becomes compacted and lacks air, it easily breeds pathogens. Here, I quote a passage from the late Qing dynasty writer Ou Jinze's Linghai Lanyan as a fitting analysis: "Orchids live within the intermingling of qi and rely on yin and yang to grow. When yin and yang are unbalanced, the orchids become diseased! Whenever disease comes from yang, the leaf tips are often scorched; in mild cases it does not spread downward, and 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 the back of the leaf, and in severe cases both the head and base turn black. If the leaves are scorched but the roots are not yet damaged, they can still sprout again in spring. If the head turns black, the roots must be rotten, and unless they are cultivated for several years, they cannot recover. If orchids are not planted by experienced hands, they often fail to follow proper methods. If the pot is deep and the roots are shallow, and the pot is wide with few shoots (that is, seedlings), then the soil qi does not circulate, which is a yin disease. If the pot is shallow and the roots are long, and the pot is narrow with many shoots, 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 and easily becomes clogged, which is a yin disease. If the mud is not prepared properly, peel off the surface mud layer by layer and add fresh mud without disturbing the orchid roots; this is the safest. If the pot is unsuitable, then even if it is not the right season, the pot should still be changed and the orchid replanted. If shading is too sparse, it is a yang disease; if too dense, it is a yin disease. If watering is too much, it is a yin disease; if too little, it is a yang disease. These diseases are caused by people. When the wind is high and things are dry, or when there is scorching summer heat, it is a yang disease; when there is long rain and drenching, or harsh frost and killing cold, it is a yin disease. These diseases are caused by heaven. Zhang Zhongjing said: 'When it appears as yang, treat it with yin methods; when it appears as yin, treat it with yang methods.' People and things follow the same principle. Yang diseases first damage the upper part and then reach the lower part; yin diseases first damage the lower part and then reach the upper part. As for uneven dryness and moisture, and excessive fertilizing, then both yin and yang become diseased. In severe cases there is no way to save them; in mild cases the new shoots become curled and swollen, growing again in overlapping layers, which is called gall leaves. When seen, they must be cut off, and perhaps they can grow again. If one cannot bear to cut off what one loves, it is no different from nurturing an abscess for the orchid." This passage explains very clearly the causes and harms of excessive wetness or dryness, and is worth orchid growers paying close attention to.

　　

(2) Pollution and infection. Sources of pollution come from toxic substances and dust in the air, wall dust, and the use of dirty water, concentrated fertilizer, and various kinds of garbage and waste piled into orchid pots by orchid growers, causing heavy dust accumulation on orchid leaves, orchid pots covered with dirty matter, flowers ruined and leaves decayed, and marks all over the plant. 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 the 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 newly purchased orchids have pests or diseases or carry viruses, and are not strictly disinfected, sterilized, and treated for pests. Some viruses, such as the Cymbidium 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 or 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 plants. Therefore, before pruning, the tools must be disinfected, the substrate must be disinfected and sterilized, and before planting, the orchid plants must be disinfected, then left until the floating water dries before planting. After planting, place them in a cool, shaded place, and water only after two or three days.