How to prevent and control southern blight in orchids? Detailed guide to prevention and control methods

OrchidsSouthern blight generally damages the base of orchid leaves near the soil. In the early stages of damage, the affected area turns brown, becomes water-soaked, gradually rots and softens, and breaks easily. In severe cases, the pseudobulbs are also infected, and white silky mycelium is produced. The sclerotia on the diseased parts resemble rapeseeds, initially white, then yellow, and finally brown.
　　
Southern blight in orchids should be controlled mainly by manual methods, with chemical control as a supplement. The specific methods are as follows: First, promptly remove diseased leaves, pull out diseased plants and destroy them in a centralized manner. Second, strengthen ventilation between plants; plants should not be planted too densely. Third, strengthen fertilizer and water management. During the rainy season, avoid rain washing directly onto orchid seedlings; rain-shelteredcultivationis an important measure to prevent the occurrence of southern blight. Watering should follow the principle of "do not water if not dry, water thoroughly when watering," keeping the potting soil moist but not wet. Fourth, the growing medium should use fully decomposed humus soil to prevent the breeding of pathogens. Before use, the soil should be sterilized at high temperature, or disinfected with 0.2% quintozene. Fifth, when plants are affected by the disease, spray 25% metalaxyl or 75% chlorothalonil at 600 to 800 times dilution, once every 7 to 10 days, for 2 to 3 consecutive sprays.