Symptoms and Control Methods of Bacterial Soft Rot

　　Soft rotSymptoms: This is a disease caused by bacteria, and the pathogen issoft rotErwinia, which generally begins to cause disease on newly sprouted seedlings of the current year. If not controlled in time, the entire pot can be infected and damaged. After the seedlings are infected, water-soaked dark brown necrotic patches initially appear at the leaf base. After a few days, the entire leaf base turns black and wet-rotted. After about a week, the rot worsens, and the whole seedling is easily pulled up. The characteristic of this disease is leaf base rot with a foul odor. The leaf tip generally shows no symptoms. On large seedlings, the leaf surface may show dehydration-like or water-soaked patches.OrchidOnce infected, there is generally no cure, and the disease can only be controlled to prevent it from spreading. Occurrence characteristics: The disease overwinters in diseased residual tissues and contaminated substrate. When conditions are suitable, it enters with water droplets throughorchidwounds and natural openings. The disease is most severe from May to June each year, and it easily becomes epidemic under high temperature and high humidity conditions.CultivationIf the substrate is too fine and has poor permeability, if nitrogen fertilizer is applied excessively, or if there are continuous high temperatures and rainy days, this disease is easily induced. Control methods: Mainly prevention. Usually, care should be taken not to keep it too wet, maintain ventilation, and do not water directly over the top during the new seedling growth period. After watering or spraying, ventilate promptly to keep the leaf base dry. If infection is found, remove it promptly, clean up the diseased tissue, soak the orchid roots and pseudobulbs in a disinfectant for 1-2 hours, take them out to dry, apply ointment to the wounds, and then plant them in a moist but slightly dry substrate. When planting, expose the pseudobulbs by 1-2 cm, place them in a ventilated and cool place, and spray the leaves or drench the roots with a fungicide every 7-10 days for 2-3 times. Observe the disease situation promptly. If there is a trend of spread, remove and disinfect again until the disease is completely controlled. Control agents: 95% Dexon 1000x solution 50% Amobam 1000x solution 75% agricultural streptomycin 500-800x solution 20% Yekuning 1000x solution Author: Xu Maojin