How to prevent orchid rot? Master the fertilizing method for edible fungi
Most pests on orchids feed on the surface layer of the plant, but orchid rot is the opposite: it penetrates the surface layer of tissue and then spreads, destroying the plant's internal tissues. Therefore, once infection has already begun, spraying chemicals on the surface is usually not as effective as it is for eliminating pests. If possible, the parts of the plant infected with fungal and bacterial rot should be completely removed and destroyed, and then chemicals should be sprayed, or the plant should be soaked in a suitable chemical solution, mainly to prevent the remaining tissues from further infection.
The key to dealing with orchid rot and its diseases is to prevent penetration and the start of infection. These pathogens are present everywhere in the growing environment, but while they are outside the plant body, they are easily controlled by the actions taken by the orchid grower. Orchid growers can use various methods to reduce the possible infection caused by this kind of rot. Because this pathogen must penetrate the surface layer, it needs moist conditions to succeed. We should therefore work to reduce the length of time the plant is actually wet. In fact, when watering, it is unavoidable that water remains on the leaves, but if watering is done as early in the day as possible, or if the best conditions for evaporation can be provided, the time water remains on the plant's surface will be greatly shortened. Good air circulation is naturally even more favorable for creating these conditions. However, every effort should be made to avoid splashing water from one plant to another during watering, because this is the main pathway for the spread of pathogens. After watering, the plants should be gently shaken to remove water remaining on the stem tips, leaf centers and new growths; otherwise, even under dry conditions, water will still remain on the plants for a period of time. When it is a dark winter day and the climate cannot promote rapid evaporation of water, watering must be reduced.
To prevent rot infection of the root system and rhizome beneath the surface layer, they should be kept from remaining wet for long periods. The decomposition of potting media, or overwatering, creates the best conditions for infection by black rot. Therefore, repotting is one of the good preventive measures. In addition, good cultivation practices, such as frequently using sterilized tools to cut leaves and branches and keeping the cut surfaces on the plant clean, also help prevent pathogen infection. I personally have found that using an inexpensive lighter available on the market to burn knives or scissors is a convenient and fast sterilization method. Other good sterilization methods include soaking scissors or cutting blades in boiling water, or in 2% formalin, or in a Clorox solution, and not using them a second time after one use (if you want to use them again, they must be sterilized first). If the same unclean knife or scissors is used to cut orchids, it will spread pathogens to all the plants. Cut wounds on plants are the places most likely to invite infection. Therefore, experienced orchid growers often use materials to seal the wounds, blocking the pathway of pathogen infection, or apply some disinfectant powder to the wound (such as sulfur powder or Daconil powder). Some people also use a very hot blade to cauterize the cut surface. General sanitation, such as removing dead leaves and branches, or orchid plants with infectious diseases, also helps reduce the possibility of pathogen spread and can achieve the goal of preventing infection.
In orchid cultivation, even if various preventive methods are used, bacterial or fungal rot is still encountered from time to time. Therefore, orchid growers should pay special attention in winter to the cold, dark and humid conditions of the growing area, because at this time and under these conditions, as stated above, rot occurs most frequently (of course, it can also occur in warm weather). The victims of this disease may all be small seedlings and mericlones, meeting this calamity in their juvenile stage. Although we cannot say that healthy plants that have already grown to flowering size rarely die, generally the smaller and weaker the seedlings, the more likely they are to suffer a fatal attack. Those growing in community pots are especially targets of pathogen infection. In the center of these community pots, a core of potting medium appears; it is the last place to dry out and the first place to decompose. Usually the top is the oldest, and the pseudobulbs produced there are also the weakest. Black rot or root rot takes advantage of such favorable conditions and runs rampant, so quite a few seedlings lose their vigor or even their lives when they begin to grow.
Finally, a rot prevention program should generally include regular spraying of chemicals. To deal with fungal wilt and the spread of bacterial rot on seedlings, readers are advised to use "Daconil powder," diluted at 1 gram per 600 parts water, spraying the plants once a month as preventive maintenance against pathogens. In this way, a protective layer is formed on the plant's surface, and pathogens will be eliminated before they begin to infect.