Five Pest and Disease Control Methods for the Chinese Medicinal Herb Salvia miltiorrhiza

1. Root Rot

(1) Damage and symptoms:Salvia miltiorrhizaRoot rot occurs in hot, rainy seasons and damages the roots of the plants. In the early stage, only a few roots or part of the underground rhizome are affected first, gradually spreading to the entire root system. After the roots are damaged, wet rot develops, and the outer skin turns black. In the early stage of the above-ground damage, some branches and leaves wither and die, and in severe cases the whole plant dies. The damage occurs to varying degrees in all Salvia miltiorrhiza production areas, causing certain losses.

(2) Control measures

① Practice crop rotation: Because the soil carries the pathogen, continuous cropping of Salvia miltiorrhiza leads to early onset of the disease, severe conditions and rapid spread. It is best to rotate with gramineous crops for 3 to 5 years to reduce the pathogen population and lower the incidence of the disease.

② Use healthy seed material: Select disease-resistant varieties; select robust, disease-free seed roots; do not save seed from diseased fields, so as to reduce the disease.

③ Strengthen field management: Fertilize reasonably, apply more organic fertilizer, and increase the application of phosphorus and potassium fertilizers; drain accumulated water promptly during the rainy season, and take care to loosen the soil to improve the disease resistance of the plants.

④ Chemical control: Mix 1 kg of 70% dexon wettable powder or 50% carbendazim wettable powder per mu with 3 kg of fine soil and scatter it into the planting holes when planting, which has a certain control effect; disinfect cuttings and rhizome heads by soaking them in an 800-fold dilution of 50% Tuzet wettable powder or a 1000-fold dilution of 70% thiophanate-methyl wettable powder for 3 to 5 minutes, then dry them and plant; apply fungicides during the growing season by drenching the root zone of diseased plants in the early stage of the disease to control its spread. Commonly used pesticides include a 500- to 800-fold dilution of 50% Shujunling wettable powder or 50% dexon wettable powder, or a 1000-fold dilution of 96% copper sulfate, or a 100- to 150-fold dilution of 3% agricultural antibiotic 120 aqueous solution, applied once every 10 to 15 days for 3 to 4 consecutive times.

2. Root-knot Nematode Disease

(1) Damage and symptoms: This disease damages the roots of Salvia miltiorrhiza. The affected main roots, lateral roots and fibrous roots all bear tumor-like galls; the main and lateral roots become thinner, and the fibrous roots increase in number. Fine hairy roots grow on the galls. After the nematodes parasitize the plant, the function of the root system is disrupted, causing the above-ground part of the plant to be markedly stunted, the leaves to turn yellow, and growth to be weak, affecting yield.

(2) Control measures

① Crop rotation: Rotate with gramineous crops for more than 3 years, which can reduce the density of nematodes in the soil. The longer the rotation period, the better the effect. Note that rotation must not be with host plants of root-knot nematode disease.

② Chemical treatment: Use 1.5 to 2 kg of 3% Miral granular formulation per mu, mix with 50 kg of dry fine soil, apply it 20 cm deep into the soil 10 days before sowing, and immediately cover and level the soil. Alternatively, use 5 to 6 kg of 98% dazomet (Basamid) granular formulation per mu, mix well with an appropriate amount of dry fine soil, and apply it into the sowing furrows at sowing time.

3. Leaf Blight

(1) Damage and symptoms: This disease mainly damages the leaves of Salvia miltiorrhiza. The lower leaves of the plant are affected first, and it gradually spreads upward. In the early stage, small brown, round spots appear on the leaf surface; afterward the spots continue to expand, and the center turns grayish brown. Finally the leaves scorch and the plant dies, seriously affecting the yield of Salvia miltiorrhiza.

(2) Control measures

① Select robust seeds and soak them in 1:1:100 Bordeaux mixture for 10 minutes before sowing.

② Apply more phosphorus and potassium fertilizers to strengthen the plants' disease resistance; open ditches promptly after rain to drain water and lower field humidity.

③ Chemical control. In the early stage of the disease, spray with agents such as a 600-fold dilution of 50% carbendazim, a 600-fold dilution of 65% zineb, or a 500-fold dilution of 50% zineb, at intervals of 10 to 15 days, for 2 to 3 consecutive sprays.

4. Southern Blight

(1) Damage and symptoms: This disease mainly damages the roots of Salvia miltiorrhiza. In the early stage, white silky sclerotia appear from the stem base to the main root near the topsoil, the roots suffer wet rot, and later the branches and leaves of the above-ground part of the plant wilt and die. When the weather is humid, white mycelium and sclerotia resembling mouse droppings often appear at the stem base of diseased plants. In years when it occurs severely, the yield of Salvia miltiorrhiza drops substantially.

(2) Control measures

① Select robust, disease-free seeds; practice paddy-upland rotation or rotate with gramineous crops.

② In the early stage of the disease, promptly dig out diseased plants, remove them together with the soil, and compost them centrally; drench the diseased holes with a 600-fold dilution of 50% carbendazim or a 1500-fold dilution of 50% procymidone; or scatter Trichoderma preparation at 10 to 15 g per sq m and then loosen the soil.

5. Dodder Dodder is a parasitic weed.

(1) Damage and symptoms: Because dodder has very strong vitality, spreads rapidly, and is a rootless vine, it twines around Salvia miltiorrhiza plants with haustoria and survives by absorbing nutrients from within Salvia miltiorrhiza. Therefore, it can cover Salvia miltiorrhiza plants in patches within a relatively short period, seriously affecting plant growth and causing hindered root growth and reduced yield. After the young stems of dodder twine around Salvia miltiorrhiza, they continuously produce branches that spread to surrounding plants, and in severe cases cover the entire patch of Salvia miltiorrhiza, causing the leaves to turn yellow or die.

(2) Control measures

① In conjunction with deep plowing, bury dodder seeds deep, or practice paddy-upland rotation; when dodder damage is found, remove it as early as possible to prevent its spread and seed production.

② Scatter the biological herbicide "Lubao No. 1" powder at 2 to 2.5 kg per mu, or spray 3 to 5 kg of the bacterial liquid.