Symptoms and Control Countermeasures of Orchid Root Rot

Orchid root rot mainly harms seedlings in seedling pots and can also infect older mature plants. The fleshy roots and rhizomes of the injured seedlings appeared water-stained brown spots at the initial stage, and then gradually rotted and blackened. If not controlled, the rot could develop to the stem and lower leaves, and finally form a brown rot area around the plant, resulting in wilting and death of the seedlings. When the adult plant is damaged, it usually causes rhizosphere damage, and the rot is mostly limited to the root, but sometimes the rot can also be extended to the rhizome and pseudobulb. The leaves and pseudobulbs of susceptible plants are yellowing, shrunken, delicate and twisted, growth decline, and may eventually die. Orchid root rot is caused by Rhizoctonia sclerotiorum of the genus Rhizoctonia. The pathogen does not form spores and spreads through mycelium infection. The suitable temperature for growth and development is 20 Mel 24 degrees Celsius, and the suitable pH is 5.5. Orchid root rot pathogen has a strong saprophytic habit, usually can rot on the plant remains of the soil, survive for a long time, and spread by Rain Water and irrigation water. When the basin soil is mixed with undermature organic fertilizer or bark that absorbs enough water, the orchid is most vulnerable to high humidity and stagnant water in the basin. Control method 1, remove all the decaying parts of the root and rhizome of the diseased plant, soak it with 50% carbendazim 500 Mel 600 times solution, then coat the incision with charcoal powder, change the basin and soil, or make the bottom disinfection, and then colonize it. 2. The diseased plant was irrigated with copper-ammonium mixture once every 10 days for 3 consecutive times, which could control the development of the disease. The formula of copper-ammonium mixture is as follows: 2 parts of copper sulfate and 11 parts of ammonium carbonate, which are fully mixed and placed in an airtight container for 24 hours. When in use, take 1 part of the powder and dissolve it in 400 parts of water.