Pest and Disease Control Methods and Technical Key Points for the Chinese Medicinal Herb Lotus Seed

The lotus has strong adaptability and can still resist common pests and diseases, but if there are many pests and diseases, it will affect the growth and development of the lotus.

Diseases

Rot disease (root rot): In the early stage, dark brown spots appear on the leaves, which gradually expand and eventually cause rot, followed by successive rotting of the leaf stalks, lotus root nodes, and rhizomes. Control method: Spray with 800-fold dilution of thiophanate-methyl solution or 600-fold dilution of 65% zineb solution; at the same time, remove diseased leaves and burn them, keep the water clean, and practice rotation between paddy and dry cultivation.

Black spot disease: In the early stage, irregular brown spots appear on the leaf surface, slightly zonate; in the later stage, black mold-like growth appears on the spots, often several spots join together to form large lesions, and in severe cases the entire plant dies. Control method: Spray 500-800-fold dilution of 50% carbendazim or 75% chlorothalonil in a timely manner at the early stage of the disease for control.

Pests

Bagworm (large bagworm): Also called bagworm, the larvae hatched in mid-June crawl on nearby branches and leaves, spin silk and hang down, spread with the wind to lotus leaves, spin silk to make bags, and bite leaves into pieces to stick on the outside of the bag; they carry the bag and crawl, extend their heads to bite and feed on lotus leaves and bud stalks. In severe cases, they can eat all the lotus leaves bare. Control method: Spray-kill with 1500-2000-fold dilution of 90% trichlorfon plus 800-fold dilution of Bacillus thuringiensis; the best control effect is before the second-instar larvae in early July.

Lotus aphid (Rhopalosiphum nymphaeae): Nymphs or adults gather on the leaf buds, leaf undersides, and flower buds of floating leaves and standing leaves to suck sap and cause damage. It mainly occurs from May to September. Control method: Spray-kill with 2000-2500-fold dilution of 40% dimethoate emulsion or 500-fold dilution of 2.5% derris extract.

Copper green chafer (Anomala corpulenta): Adults fly onto lotus leaves at night to bite and feed, causing the most severe damage in summer. Control method: Taking advantage of its phototaxis and death-feigning behavior, set up lights to trap and kill, manually capture and kill, or spray-kill with 1500-2000-fold dilution of 90% trichlorfon.

Yellow stinging moth (Thosea sinensis): The larvae damage lotus leaves. The larvae's stinging hairs are toxic, and skin contact immediately causes redness, swelling, and severe pain. Control method: Spray-kill with 1000-1500-fold dilution of 90% trichlorfon plus 800-fold dilution of Bacillus thuringiensis; also remove infested leaves and eliminate overwintering cocoons attached to the lower parts of branches and trunks around the lotus.

Spodoptera litura: Newly hatched larvae gather on the underside of leaves and nibble the leaf mesophyll, leaving the epidermis and veins; the damaged leaves look like window screens and appear grayish-white. After the larvae grow slightly larger, they disperse to feed, biting the leaves into notches and also biting flower buds and flowers. The damage is most severe from June to October each year. Control

method: Remove infested leaves in a timely manner and destroy them; at the same time, when the larvae are gathered and causing damage, spray 1000-fold dilution of methamidophos in the evening for control.

Rice root leaf beetle: The larvae are water maggots, which suck the sap of stems, leaves, and stalks, causing lotus leaves to turn yellow; lime can be used to drive them away and kill them.