Key Points of Pest and Disease Control Techniques for the Chinese Medicinal Herb Aconite (Fuzi)

Diseases

Southern blight: The pathogen is a type of imperfect fungus. It mainly damages the junction between the stem and the mother root of aconite, and mostly occurs in summer during hot, rainy seasons. In the early stage of the disease, leaves wilt and droop; in severe cases, the aboveground part lodges, the leaves wither while still green, but the stem does not break, and the mother root remains attached to the stem. Control methods: Select disease-free aconite as seed; rotate with rice; do not use fertilizer from aconite fields or produced during aconite processing; at the second root trimming, mix 1.5 kg of Xilisen or 2 kg of pentachloronitrobenzene powder per mu with 50 kg of dry fine soil or 30 kg of plant ash, apply it around the rhizome, then cover with soil; in the early stage of the disease, dig up diseased plants and diseased soil and bury them deeply, and drench healthy plants near the diseased plants with 5% lime or 50% carbendazim wettable powder at 1000 times dilution to prevent spread.

Downy mildew: It is a type of alga-like fungus. It occurs from March to May and is a relatively common and serious disease at the seedling stage. At the seedling stage, diseased plants have poorly developed fibrous roots, leaves elongate upright, and are narrow, curled, and grayish-white light green, with purple-brown mold layers on the underside of the leaves. After onset, the whole plant gradually dies, which is called "gray seedling" in producing areas. When adult plants are affected, the top leaves turn white, the leaves curl, and become dark red or black and scorched, and the stems split and the plants die, which is called "white tip" in producing areas. Control methods: Promptly pull out diseased seedlings and spray with 1:1:200 Bordeaux mixture or 65% amobam wettable powder at 800 times dilution.

Root rot: The pathogen is a type of imperfect fungus. It occurs from April to July and damages the roots. The upper part of the plant wilts, leaves droop, and in severe cases the diseased plant dies. Control methods: Be careful not to injure the rhizome when trimming roots; do not apply too much alkaline fertilizer; use 0.5 kg of 50% thiophanate wettable powder mixed with 300 kg of water plus 15 kg of lime and 125 g of urea, and drench once immediately after the second root trimming; it can also be applied in manure water according to the ratio, or drenched with 50% carbendazim wettable powder at 1000 times dilution.

Wilt disease: The pathogens are viral soft rot and fungal root rot. It occurs in mid-April. There are dark brown streaks on the stems, the leaves are numb, the veins show black oily streaks, the leaves turn yellow and die, and a black ring can also be seen when the tuberous root is cut crosswise. It is a soil-borne disease. The disease enters the vascular bundle through wounds on the tuberous root, and then enters the next generation of seed roots. Control methods: Be careful not to injure the seed roots during seed collection, transport, planting, and root trimming; immediately pull out diseased plants when found. Powdery mildew: It occurs from May to September. After onset, the leaves first twist upward, and brown oval patches form on the underside of the leaves, gradually becoming scorched. The pathogen overwinters on diseased remnant plants, and the next year the pathogen germinates and produces white powder, spreading with the wind, and it is especially severe in dry weather. Control methods: In the early stage of the disease, spray with Qingfengmycin at 60-80 units or 80% thiophanate-methyl wettable powder at 800-1000 times dilution; lime-sulfur mixture at 0.3 degrees Baume, thiram-sulfur, and other agents can also be sprayed, once every 7-10 days, for 3 consecutive times.

Gray mold: The pathogen is Botrytis cinerea Pers., belonging to Deuteromycotina, Hyphomycetales, Botrytis, a weakly parasitic fungus. It damages leaves, generally starting from the leaf tip or leaf margin, producing brown nearly circular lesions with irregular concentric rings. Under high humidity, sparse gray mold appears on the underside of the lesions; when the disease is severe, the lesions merge with each other and can cause leaf death. Control methods: After harvest, remove diseased remnants in the field to reduce the initial infection source, strengthen management, and increase resistance. No special control is needed. If there is much rainy weather from April to May, broad-spectrum fungicides such as Bordeaux mixture, mancozeb, and carbendazim can be used for prevention.

Aconite mosaic virus disease: The pathogen is a virus, Aconitum mosaic virus, a whole-plant disease. Leaves show mosaic symptoms alternating dark green and light green, and some varieties also show dark green ring patterns on the leaves. Symptoms are most obvious on young leaves at the top. In a survey in Jiangyou, the diseased plant rate in some severely affected fields was above 60%. Virus carried by seed roots is the main infection source in the field. The level of virus-carrying rate is the factor affecting severity. Symptoms can appear at the seedling stage, and new leaves continuously show symptoms. Although the plants do not die, the tuberous roots become smaller. Aphids are the vector insects for disease transmission. Key control points: Use virus-free techniques to cultivate virus-free seed roots; when sporadic disease occurs in the field, pull out and destroy diseased plants; controlling aphids can reduce field incidence.

Root-knot nematode: The pathogen is a type of root-knot nematode in Nematoda. It damages the roots. Affected plants are weak, the seed roots are small, and nodular galls form on the fibrous roots. Control methods: Avoid continuous cropping, choose disease-free land for planting or disinfect the soil, and select disease-free seed roots for planting.

Pests

Stem borer: Also called stalk borer, it damages stems, bites and destroys tissues, causing the upper part of the plant to gradually wilt and droop, which is called "hooked head." In severe cases, the plant dies. Control methods: When harvesting aconite, gather stems and burn them; promptly remove "hooked heads" and compost them centrally; spray with 90% crystalline trichlorfon at 1000 times dilution; use black light traps to kill adults.

Red aphid: It damages the tender stems at the top of the plant. It begins to occur in late March or early April, and May to June is the peak period of infestation. Control methods: Spray with 40% dimethoate emulsifiable concentrate at 800-1500 times dilution.

Silver Y moth: It occurs in early April. The larvae bite and feed on leaves, creating holes or notches. Control methods: Spray with 90% crystalline trichlorfon at 600-800 times dilution.

Leafhopper: It damages leaves. From early April to late June, with the peak from mid-April to early May. Affected leaves first turn red, gradually turn purplish red, and finally rot into black scorched spots and die. In severe cases, the whole plant dies. Control methods: Spray with 40% dimethoate emulsifiable concentrate at 1000-2000 times dilution.