Key Technical Points for Pest and Disease Control in the Chinese Medicinal Herb Ophiopogon japonicus

Diseases

Black spot disease: The pathogen is a type of imperfect fungus (Deuteromycete), which damages the leaves. The pathogen overwinters on seedlings, begins to cause disease in mid-April, and under suitable temperature and humidity develops rapidly, causing patches of plants to wither and die.

Control methods: Select seedlings with green leaves that are robust and disease-free; in the early stage of disease, when the morning dew has not yet dried, scatter 100 kg of plant ash per mu; drain standing water promptly during the rainy season to reduce field humidity; soak seedlings for 5 minutes in 1:1:100 Bordeaux mixture or 800-fold 65% amobam wettable powder, or spray over a large area. In Zhejiang production areas, when the disease is severe, cut off the above-ground parts of affected plants to allow them to regrow.

Black spot disease of Ophiopogon japonicus

Anthracnose: The pathogen overwinters as conidia and mycelium in soil-borne diseased residues and diseased tissues, and conidia spread and infect via airflow and water droplets. The disease is more severe when plants are planted too densely, and in years with heavy single rainfall events or concentrated rainfall. Because conidia can enter and reinfect, anthracnose of Ophiopogon japonicus in southern regions has multiple peak periods of disease incidence. In the early stage of disease, small circular spots from withered yellow to brown appear on leaves; as the spots gradually expand, they develop into semicircular shapes or irregular shapes at the leaf tip. The center of the spot is chlorotic white, the edge is pale red, and within the pale red edge there is also 1 brown-black line. In the late stage of disease, the tissue at the spot may fall off, causing concave defects on the natural edge of the leaf, and the entire leaf from the diseased area to the diseased leaf tip turns orange-yellow prematurely. Apply 800-fold 80% thiophanate-methyl plus thiram wettable powder continuously 2-3 times.

Control methods: (1) In winter and early spring, promptly clean up diseased residues, prune diseased leaves, and disinfect plant foliage with 1-2 degrees Baume lime sulfur mixture or 200-fold 18% copper polycarboxylate wettable powder. (2) Prevent plants from being planted too densely, and promptly thin branches to let light through. (3) Starting from the beginning of the rainy season, spray foliage every 7-10 days with 400-fold 75% zineb wettable powder, or 800-fold 50% carbendazim wettable powder, or 70% chlorothalonil wettable powder.

Anthracnose of Ophiopogon japonicus

Root-knot nematode disease: Root-knot nematodes can occur throughout the year in Guangxi. They mainly damage the roots. Control methods: practice crop rotation; where conditions permit, practice paddy-upland rotation, and avoid rotation with crops such as flue-cured tobacco, Chinese milk vetch, yardlong bean, taro, sweet potato, Trichosanthes kirilowii, monk fruit, Atractylodes macrocephala, Salvia miltiorrhiza, and belladonna; select disease-free seedlings and prune off all old roots; select disease-resistant varieties; carry out soil disinfection.

Pests

White grubs, mole crickets, cutworms, click beetles, and others damage the rhizomes. Control methods: rotate with rice; after flooding in paddy fields, they can all be eliminated in one season; or use conventional pesticide methods to kill them.