Fusarium mycorrhizal rot of Panax notoginseng (Panax notoginseng)

The scientific name of Panaxnotoginseng (Burk.) F.H.Chen is Panaxpseudo-ginsengWall.var.notoginseng (Burkill) Hoo&Tseng. Alias Tian Qi. Araliaceae perennial herbs, with rhizomes and flowers and leaves as medicine, with the functions of promoting blood circulation and removing blood stasis, reducing swelling and pain, stopping bleeding and reducing blood pressure. It is a specialty of Guangxi and Yunnan, and has been produced in many counties south of the Yangtze River and Guangdong in recent years.

Symptoms are also known as root rot, rotten chicken shit, smelly seven, and so on. The disease can occur in Panax notoginseng from one year to three or four years old, but it is mainly harmful to Panax notoginseng in one or two years. At the time of onset, the color of the aboveground leaves turned yellow and the growth potential was poor. When the temperature is high at noon in the early stage, the leaves droop slightly and can recover sooner or later. Dig up the diseased plant, and the root becomes yellowish brown or rotten. The main, lateral and fibrous roots can all occur, and most of them are in the main root. And it is the most common that the root stem begins to rot in the sheep's intestines. If only one side of the root is rotten, the leaves on the corresponding side sometimes turn yellow. In the later stage, the root of the disease all became black-brown or gray-white, thin mud-like, so it was called "chicken shit rotten", which may be related to the subsequent invasion of bacteria. The disease is serious in the high temperature and humidity season from May to August every year.

The pathogen Fusari μ msolani (Mart.) Sacc.f.sp.radicicola (Wr.) Snyd.&Hans. It is called the specialized type of Fusarium root disease, which belongs to the subphylum fungus. On PSA, the aerial hyphae were more developed, the flora were striped, dense and thick, grayish white, and the reverse side of the petri dish turned blue-green in the later stage. Microspores are produced early and more; solitary on small bottle peduncles, with various shapes, mostly curved oval. The megaspores are produced on the much-branched conidiophores, and the sporogenic cells are bottle-pedicled; the megaspores are unequilateral spindle-shaped, slightly curved, wide and short; (2) there are 4 compartments, most of which are separated by 3, and the basal podocytes are not obvious; generally, the second cell at the base is the widest; the apical cell is slightly beak-shaped. Three separated macrospores 26-40 × 5-6 (μ m). In addition to infecting the roots of Panax notoginseng, the bacteria can also infect potato tubers or stem bases, tulip bulbs, konjac tubers and so on.

The way of transmission and disease conditions are seeds, seedlings, diseased soil and diseased bodies to carry bacteria through the winter. the disease is easy to be induced by heavy soil viscosity, poor drainage and many underground pests in the field. Especially after transplanting of two-year-old Panax notoginseng, the watering is uneven or untimely, the root is dry and soft, the soil moisture is saturated, the root hair is easy to suffocate to death, and the bacteria invade easily. It occurred in the seedling stage in March, the temperature increased and dried in April and May, and the disease stagnated. It was high temperature and rainy from June to September and entered the peak period of the disease. The occurrence of the disease is also related to excessive water loss or heating in the process of transporting seedlings. The soil in the field is too sticky and the plant growth is poor, so the disease resistance of root tissue is not strong and the disease is serious when nitrogen fertilizer is applied in production.

Control methods (1) select disease-free and healthy seeds and seedlings. (2) choose the plot with good drainage and loose soil to plant Panax notoginseng. (3) in general, continuous cropping of Panax notoginseng should not exceed 3 years. (4) do a good job in the management of Panax notoginseng garden, remove the diseased plant or root in time, and disinfect the diseased point with lime or medicine. Prevent sudden dry and wet in winter and spring, timely watering in the dry season, timely drainage after rain, and promote the use of enzyme retting compost. (5) at the initial stage of the disease, the roots were irrigated with Bordeaux solution or 12% green copper EC at 1:2, which had a certain effect.