Causes and Control Methods of Orchid Soft Rot

Causes and Control of Orchid Soft Rot Cause One: The application of hormones, especially bud-promoting hormones, leads to a multiplication of seedlings. At first, the parent plants have accumulated nutrients to supply them, so symptoms of malnutrition do not appear. But with many seedlings consuming heavily, the stored nutrients are depleted ahead of time. The nutrients referred to here are not carbohydrates or ordinary proteins, but mainly trace elements. The new seedlings cannot yet absorb trace elements through new roots to balance the deficiency. Low levels of trace elements lead to reduced resistance. Some seedlings may not have been treated with hormones themselves, but many re-exported seedlings have been, so hidden dangers already exist, or such seedlings inherently have lower immunity.

Two: Uneven dryness and moisture, and abrupt changes from cold to heat. The air is dry while the pot is waterlogged; in summer and autumn the pot temperature is too high. At this time the pores of roots and leaves are all open, just as a person sweats and pants. Watering at this moment is like a person drenched in sweat taking a cold shower; the water carries pathogens and other substances straight in, easily triggering disease. The roots are stimulated, the pores suddenly close, and the metabolic waste accumulated inside becomes trapped, inducing pathological changes. For orchid pots on a balcony that receive light on one side but lack proper shading, one side is hot and the other cool; the orchid plant as a whole cannot adapt, and disease is also likely.

Three: Excessive fertilizer, especially excessive nitrogen fertilizer. And so on.

On prevention:

One: Soft rot bacteria spread through wounds, so it is important to avoid mechanical damage to orchid plants. During pruning and division, pay attention to sterilizing tools to prevent cross-infection;

Two: According to references, soft rot is a bacterial disease. For prevention, using only fungicides such as thiophanate-methyl is not very effective. It is advisable to use antibacterial drugs such as chlorothalonil. It is said that Bordeaux mixture is one of the most effective agents for controlling this disease and various other orchid diseases.

Three: According to references, soft rot is a symptom, and several kinds of bacteria cause this symptom. If it is caused by tiller rot bacteria, attention should be paid to adjusting the pH inside the pot to inhibit it; this bacterium is basophilic. If caused by rot bacteria, attention should be paid to adjusting the pH inside the pot to inhibit it; this bacterium is basophilic. The potting soil should preferably be slightly acidic.

Four: Avoid sudden temperature changes and avoid uneven heating on two sides of the potting soil.

Five: Control the temperature inside the pot and maintain appropriate air temperature. Both should be moist rather than wet.

Six: After disease onset, treat different seedlings differently. For weak seedlings, conservative treatment can be considered, that is, mainly controlling humidity inside the pot to inhibit the disease, without repotting. Wait until the weather cools, then take the opportunity to repot and operate. Because this disease generally occurs when temperatures are high, surgery at this time is not necessarily good for weak seedlings. For strong seedlings, repotting can be considered, but be sure to clean out the brown diseased parts completely; do not take chances. Some say applying miconazole nitrate to the affected area is effective; you can try it.

Seven: Do not seek treatment blindly in a panic; using drugs indiscriminately will instead cause harm.

Eight: Orchid plants after division must be disinfected. If they are disinfected, dried, and then planted, they can be given settling water. If the roots are still very fresh and not dried when planted, do not rush to give settling water. Newly planted orchids should be placed in a cool, ventilated place for 7--10 days. Do not rush to expose them to sunlight, especially the side with the division wound.

Nine: There is experience suggesting that when dividing, do not separate the pots, or twist at the wide part of the orchid's rhizome to stimulate sprouting. Note that not all orchids are suitable for this. The first condition is that your orchid garden has no tiller rot bacteria, and the second is that you must not water immediately, otherwise pathogens will invade through the opening and cause harm instead.

Soft rot infects old seedlings slowly. When ventilation is good, temperature and humidity are low, and the plant is strong, it is not easily noticed, as if it lies dormant without showing. At this time you must not be careless; you should spray regularly for prevention. Otherwise, once high temperature and high humidity occur and new seedlings grow vigorously, it may break out. Then it will be too late.

http://www.dfac.cc/showtopic-17-300555-0-0-1.htm Excerpted from "Collection of Famous Varieties of Yilan Network"