Orchid leaves turning yellow and withered: is it a disease? With a few simple steps, even people who have never grown orchids can tell the difference

Orchids are the easiest to keep alive, and also the hardest to keep thriving. That is because they need special care not only during the flowering period, but also when they are not in bloom, or the leaves will easily develop scorched yellow patches, black spots and the like, greatly reducing their ornamental value. Especially during the plum rain season, orchid leaves often turn yellow and withered, which makes orchid growers very anxious. Today I will teach you two methods.

There are two situations in which orchid leaves turn yellow and withered. One is physiological. Wild-collected orchids (shanxia lan) are mostly potted around March. When their root system has not yet grown new roots and cannot absorb nutrients from the soil, the plant's growth depends mainly on the stored nutrients supplied by the mother seedling. So during the plum rain season, the mother seedling (especially the oldest growth) will gradually turn yellow and withered.

The characteristics of physiologically yellowed leaves are: the yellowing starts from the leaf tip and slowly moves downward, and the speed is not fast; in addition, the yellowed leaves develop gradually from the oldest growth and the outermost leaves inward. This situation is what we commonly call "retiring old growth" (tui lao cao).

The second situation is pathological. The hot, humid weather of the plum rain season is most suitable for the growth of fungi, bacteria and viruses. If the environment is poorly ventilated and the mother seedling itself carries pathogens, it can easily trigger pathological yellowing of leaves. This situation needs to be dealt with promptly, otherwise it will spread within a short time.

The characteristics of pathologically yellowed leaves are easy to distinguish: the yellowing extends from the bottom upward, from the leaf stalk all the way up, and often the leaf stalk has already rotted while the upper half of the leaf tip is still glossy green; another pattern is from the inside outward, with rot starting from the heart leaf of the orchid growth, and sometimes the heart leaf has completely rotted while the outermost leaves are still green. So this kind of yellowed leaf is very deceptive, and once discovered it must be dealt with promptly.

For the first, physiological type of yellowed leaf, tip out the pot of Cymbidium goeringii (chunlan) shown in the picture below, and you can see that its orchid roots are growing very robustly and the buds are also very good. This shows that it has gradually adapted to the environment after transplanting. We can ignore the yellowed leaves on this orchid; just cut them off and it will be fine, then proceed with normal care.

The orchid with the pathological condition shown in the picture below has also been tipped out of its pot, and its roots have completely lost vitality. The chance of reviving such an orchid is not great. For rescue methods, you can refer to an earlier article (treating soft rot).

Actually, no matter which kind of rot it is, root rot, soft rot, stem rot, black rot and so on, they all share one common feature: viruses like high temperature and high humidity. I do not have professional knowledge, but I think the best way to treat viruses is: do not give them what they like, and create what they do not like. So when encountered with this situation, first control water (at most more than a month without rain or watering), absolutely forbid fertilizer, strengthen ventilation and dry-sprinkle fungicide powder.

Friends, do you have any other clever tips? You are welcome to share them in the comments section.