Symptoms and control methods of orchid round spot disease

Spot disease is a common leaf disease of orchids, distributed in Fujian, Jiangsu, Zhejiang, Shanghai, Nanjing and other places. Symptoms: the disease mainly harms leaves. In the early stage, there are small brown spots on the leaves, which rapidly expand into a round color, wide, light brown in the middle, yellow protuberances on both sides, occurring in the upper, middle and base of the leaves, and more in the middle and base of the leaves. Different from orchid anthracnose, the disease spot is large, often across the leaf surface, blocking the upper and lower water and nutrient transport, so that the leaves above the disease spot wither and die. The harm is more serious than anthrax. The pathogen and the regularity of the disease: Cylindrosporiumsp. The pathogen overwinters with mycelium or conidia. Conidia can endure a low temperature of 0 degrees Celsius for 20 days without weakening the germination ability. When the environmental conditions are suitable, the splashing of water droplets will spread by means of wind and rain and watering. When the soil is hardened, the basin distance is too dense, the ventilation and light transmittance is poor, and the leaves are injured, it is easy to lead to this disease. Among orchids, cold orchid, spring orchid, Jianlan and cymbidium are susceptible, and cold orchid is the most infected. Prevention and control methods: 1, timely removal of disease, withered leaves, reduce the source of infection. Cut off the disease spots in the upper and middle parts in time and keep the green parts as much as possible. 2. Spraying 1% Bordeaux solution twice a month can prevent and cure the disease. Spray 75% chlorothalonil 500 times when you get sick.