Why are the leaves of autotrophic panax notoginseng black?

Anthracnose of Panax notoginseng: The symptom is that Panax notoginseng can occur in seedling stage and adult stage. After the onset of seedling stage, reddish-brown spindle lesions appeared at the base and the center was depressed. Because the stems are very thin, the diseased parts often collapse and die. Commonly known as "dry foot disease". After the onset of adult stage, symptoms can appear in leaves, stems and fruits of Panax notoginseng. The diseased spots on the leaves are yellowish brown, nearly round, and the center is easy to be perforated. The diseased spot on the stem is spindle-shaped and yellow-brown. After the lesion is enlarged, the diseased part is dry and twisted, resulting in the death of the upper stem and leaf. Commonly known as "neck-twisting" fruit, the lesion is pale yellow to reddish brown, and there are many black granules without umbilicus on it. ?

Prevention and control: Clean up the Panax notoginseng garden in winter, burn diseased branches and leaves in time, strengthen cultivation management, apply decomposed manure and increase phosphorus and potassium fertilizer to improve plant disease resistance. Seed disinfection: soak in 38% ~ 40% formalin solution with 0/50 times of 10 minute to remove soft skin, and then use 0.5% ~ 1.5% thiophanate-methyl or 0/:400 times of thiophanate-methyl and 45% zineb. In rainy season, plastic film can be used to cover the top of the shade shed to prevent the rain from directly wetting the plant surface and reduce the relative humidity in the field.

Location: Wenshan, Yanshan, Maguan, Xichou, Guangnan, Malipo, Funing and Qiubei in Yunnan, and Tian Yang, Jingxi, Tiandong and Debao in Guangxi. Wenshan in Yunnan has a long history, large output and good quality. Known as "Wensanqi" and "Tianqi", it is a famous authentic medicinal material.