Control of powdery mildew of hundred-day grass

Powdery mildew occurs in all parts of China, and it is one of the main diseases. The leaves of the severely damaged plants withered and withered as soon as they bloomed. Seriously affect the ornamental of the plant.

Symptoms: the disease mainly harms the leaves, mainly on the adult leaves. At the initial stage of the disease, sporadic white powder appeared on the surface of the susceptible leaves. With the development of the disease, the leaves were covered with gray powder, and small black spots were scattered in the white powder in autumn, which was the closed shell of the pathogen. In the later stage of the disease, the diseased leaves were withered and yellow, wrinkled and died.

Pathogen: the pathogen is monocystic powdery mildew fungus (SphaerothecafuligineaSchlecht), belonging to ascomycete subphylum, Sclerotinia, powdery mildew order.

The law of disease: the pathogen overwintered on the remnant of the diseased plant with mycelium and closed capsule. When the temperature is suitable in the coming year, conidia and ascospores are produced, and the spores are transmitted by wind and rain and begin to infect. The disease can occur from May to October. The peak period of the disease is from August to September, especially when the temperature is high and the humidity is high.

Prevention and treatment: ① to reduce the source of infection: timely removal of diseased plants and destruction. ② chooses the area with good ventilation and drainage to plant. Don't plant too closely. ③ medicament prevention and cure: at the initial stage of the disease, spray 15% trimethoprim wettable powder 1000 times, or 70% methyl topiramate wettable powder 1000 times. At the same time, we should also pay attention to powdery mildew on other plants nearby to prevent cross-infection.