Ginseng Blight and its Control

Rain Water is big this year, and the high temperature and humidity are very suitable for the reproduction of ginseng blight. The optimum temperature for the occurrence of ginseng blight is the soil temperature of 10: 30 ℃, the soil temperature of 20: 26 ℃ is the most suitable for the disease, and the disease will stop when the temperature is below 5 ℃ and above 30 ℃. The main pathogen of ginseng blight is caused by infection of Phytophthora cactorum (Leb.et Coh.) Schroet, a subphylum of flagella. Ginseng blight pathogen overwintered by hyphae and spores attached to the remains of diseased plants, soil and roots of diseased ginseng. The suitable period for the onset of the disease usually begins in June, and the peak period is the rainy season of high temperature and humidity from July to August. After occurrence, the harmful symptom to the aboveground plant was that there were brown water-immersed irregular disease spots on the base of the young stem or petiole at the initial stage of the affected plant, which rapidly expanded the whole compound leaf, resulting in the drooping leaves of the whole plant. The harmful symptoms to the underground ginseng root are yellowish brown water immersion, gradually expanding soft rot, the root bark is easy to peel off and give off a fishy smell, and the external white hyphae of the rotten root in the later stage, often with soil particles. The prevention and cure method is to pay attention to the ventilation of the shed and the drainage of the bed. Keep the bed well ventilated and drained, strengthen field management, and remove diseased plants to prevent the spread of bacteria. Quicklime or potassium permanganate 0.5% can be used at the acupoint. 1% solution for disinfection. Before the beginning of the rainy season, one spray of Bordeaux solution was sprayed, and then once every 7 to 10 days. You can choose 50% mancozeb 600 times, and spray 3 times 5 times depending on the condition. Or using these solutions to treat soil has a better effect.