Incidence regularity and control of lily leaf blight

Lily is native to the eastern and central regions of China. More hardy, like strong light, not resistant to shade. Lack of light can affect growth and flowering. It is suitable for sandy loam with good drainage and rich organic matter. Poor disease resistance, susceptible to disease in a high-temperature and humid environment. The lily plant is upright and upright, the flower is big and colorful, and there are many varieties, which are suitable to form a piece or cluster dotted with the edge of the grass or form a flower border, which is quiet and harmonious. Lilies are also treasures of potted and cut flowers.

Lily leaf blight, also known as lily gray mold, affects plant photosynthesis, hinders growth and reduces ornamental value. When the disease is serious, it leads to the death of the whole plant.

Symptoms: the affected parts are mainly leaves, stems, buds and flowers. At the initial stage of the disease, chlorotic spots appear on the susceptible leaves, and then the spots expand into round or oval, light yellow to reddish brown. Some lesions are grayish in the center and purple at the edge. When dry, the disease spot is dry and light gray. In the later stage of the disease, the leaves withered and died. The stem is susceptible and the diseased part becomes brown and broken. Buds and flowers suffer, turn brown and rot. The young plants were damaged and the growing point died. When wet, the disease part produces gray mildew, which is the conidiophores and conidia of pathogens.

Pathogen: the pathogen is Botrytiselliptica (Berk.) Cooke, which belongs to the subphylum Trichospora, Trichospora, Trichospora and Botrytis. Sclerotia occasionally form on bulbs, but are common on flowers that land in summer.

The law of disease: the pathogen overwintered on the diseased plant and residual body with mycelium and sclerotia. In the following spring, the hyphae and sclerotia germinated after overwintering to produce conidia, which were transmitted to the plants through wind and rain, causing the first infection. Under suitable conditions, multiple infections can occur in a growing season, and finally the bacteria enter the overwintering place. In a cool, rainy, dewy and foggy humid environment, the bacteria produce a large number of conidia. When the air humidity is saturated and the temperature is 16 ℃, the conidia germinate fastest. When the temperature is 10-18 ℃ and foggy and humid, the pathogen is easy to complete infection, and new conidia can be formed within a few days.

Prevention and treatment: ① reduces the source of infection: wiping buds, thinning flowers and removing diseased leaves and old leaves should be buried or burned immediately. At the end of the growing season, the diseased plant and all diseased bodies should be buried or burned. ② to strengthen cultivation management, greenhouse should be ventilated and humid, sunny enough. ③ medicament prevention and cure: during the onset of the disease, spray 1-100 Bordeaux solution or 50% Dysen zinc wettable powder 800-1000 times, once every 10-15 days, 2-3 times.