Symptoms and Control methods of Salvia miltiorrhiza Blight

Salvia miltiorrhiza scientific name Salvia miltiorrhiza Bunge alias red ginseng. It belongs to perennial herbs of Labiatae. Taking root as medicine has the effects of removing blood stasis, promoting blood circulation and regulating menstruation, nourishing the heart and eliminating annoyance. Produced in Zhejiang, Anhui, Sichuan, Liaoning, Inner Mongolia, Hebei, Henan, Shandong, Jiangsu, Jiangxi, Hubei, Guizhou, Yunnan and other provinces (regions).

In the early stage of symptom onset, the lower leaves of the aboveground plants turned yellow, while the top leaves lost water and drooped in the high temperature at noon, and could still recover sooner or later, and the whole leaves sagged and did not recover in the later stage, and began to rot from the base. Dig out the underground part, it can be seen that the main root epidermis of the plant is watery and slightly yellowish; peeling off the epidermis, it can be seen that the pith is completely rotten, the color of the decaying pith remains the same, slightly smelly, showing wet rot. The spread rate of this type of disease is fast, and generally infected plants can cause death within 2 weeks. When the soil is moist, it can occur soon after planting seedlings, spread quickly, and the roots can intermittently produce white mildew, that is, the mycelium or fruiting body of the pathogen.

The pathogen Phytophthora cactor μ m (Leb. Et Cohn) Schroet. It is called Phytophthora, which belongs to the subphylum flagellate fungi. On V8 juice medium, the aerial mycelium was sparse, light, branched less, and the young mycelium was colorless, septate, thin, 2-4 μ m wide. The aged hyphae are thicker and slightly yellowish, and a sparse septum may appear in the later stage, with a width of 5-6 μ m, and the branches are right-angled; sporangium peduncles are no different from hyphae, symmetrical branches, sporangium terminal or interspore, a large number of sporangia, and no delamination. The sporangium is pear-shaped or subglobose, with a size of 20-34 × 18 color 28 (μ m), the ratio of length to width 1-1.2, and the sporangium papillae is obvious or inconspicuous, single or double, especially the intersporangium with double papillae, 0.5-6 μ m high and 3.5-6 μ m wide. The mature sporangium is easy to fall off, the base is nearly round, not stipitate or stipitate, and the stalk is 0.5-3 μ m long. sporangia are easy to germinate in water and release zoospores. Zoospores reniform, subglobose at rest. The oospores are numerous, globose, yellowish, with a non-smooth surface, 18mur26 (21) μ m in diameter, clavate in male, mostly homofilamentous, lateral, smaller, 6mur7 (μ m); oospores globose, yellowish, nearly full, 14-20 μ m in diameter and 1.5-4 μ m in wall thickness. The optimum temperature for growth was 23 ℃ and 28 min, and no thick-walled spores were formed. On CMA and PSA, the mycelium flourished and could form sporangia, egg organ and male organ, but the variation was great.

The pathogen overwintered with mycelia and oospores left in the soil with diseased tissue. In the following year, the hyphae or oospores met water to produce sporangia and zoospores, which were transmitted to the sprouting bud tube of Salvia miltiorrhiza through irrigation water and Rain Water. Attachments and invading filaments penetrated through the epidermis into the host, and disease spots appeared in 3 days under high temperature and humidity conditions, which produced a large number of sporangia and spread by wind, rain or irrigation water. Repeated infection was carried out many times. The pathogen produces sporangia in two ways: one is to extract short mycelial sporangium peduncles from stomata and form sporangia at the tip. Second, the hyphae were extracted from the stomata, the hyphae branched, the hyphae grew on the branches, and the sporangium was formed at the top. The sporangia released zoospores germinated or germinated directly into the bud tube after resting on the leaf surface for 2 hours, and began to invade from the stomatal guard cell space, and the hyphae spread between and within the leaf cells, and also protruded from the stomata, then invaded from the stomata or spread on the leaf surface, and the disease appeared after a few days of incubation. The severity of the disease is related to the arrival of the rainy season sooner or later, the temperature and the rainfall. When the disease occurs early and the temperature is high, the disease is serious. In general, the disease begins to occur in the rainy season, and when there is heavy rain, it spreads rapidly or causes epidemic. In production, continuous cropping or flat-bed cultivation is prone to disease, long-term flood irrigation, many watering times, large amount of water and serious disease.

Prevention and cure method

1. Rotation has been carried out for more than 3 years.

2. The use of high border cultivation can reduce contact with bacteria, if plastic film mulching can be used, the effect is better.

3. Strengthen water and fertilizer management, apply compost made by enzyme bacteria retting, increase phosphorus and potassium fertilizer, properly control nitrogen fertilizer, and adopt formula fertilization technology conditionally. The diseased plants were removed immediately and disinfected with quicklime.

4. After the occurrence of the central diseased plant, spray 72% urea manganese zinc (KKangling) wettable powder 800x solution or 72% DuPont Kelu or 72g frost cyanide wettable powder 800x liquid, 56% mountain water dispersible microgranule 800x liquid, 18% metalaxamide ·manganese zinc wettable powder 600x liquid, 70% ethyl phosphine manganese zinc wettable powder 500x solution, 50L per 667m2, about once every 10 days, depending on the disease prevention and treatment for 3 times.