Licorice Pest Control Methods and Technical Key Points

(1) Leafhoppers: mainly the elm leafhopper, the small green leafhopper, etc. They occur throughout the entire growing period of licorice, with the most severe damage from late June to mid-August. Nymphs or adults suck the sap of licorice leaves, buds, young branches and young shoots, first showing silvery-white dot-like spots, then the leaves lose chlorophyll and turn pale yellow, and finally fall off.

Control methods: Clear the elm trees and other overwintering hosts of leafhoppers around the licorice field. At the peak of infestation, spray with 2.5% deltamethrin at 1000-1500 times dilution. Use natural enemies such as cotton aphid parasites and ladybugs for biological control.

(2) Short-haired weevil: a small green weevil that feeds on licorice rhizomes. This pest has a long damage period, and can generally be seen in licorice fields from May to September. The peak damage period is from July to early August. It mainly feeds on leaves, and after feeding the leaf margins become notched. It occurs two to three generations per year, overwintering as adults or early-instar larvae in bark crevices and at the roots of licorice and weeds.

Control methods: In autumn, combine with mowing to destroy its overwintering sites and reduce the overwintering population. Spray 2.5% deltamethrin at 1000-5000 times dilution, using 45 kg of spray solution per mu.

(3) Leaf beetles: mainly the elm leaf beetle and the yellow-spotted leaf beetle, which are the main leaf-eating pests of licorice in the Hetao floodplain and lake silt areas. Both adults and larvae feed on licorice leaves, leaving the leaves riddled with holes after damage; the remaining leaves of the damaged licorice turn yellow and fall off, seriously affecting photosynthesis and causing poor plant growth. The main damage period is from mid-July to late August. It occurs two to three generations per year, overwintering as adults among weeds, under plant debris, and in clods and soil crevices.

Control methods: Before overwintering, clear the field of residual branches and fallen leaves, and use irrigation and other methods to kill overwintering pest sources. When pest numbers are relatively high from May to June, control with 4.5% jiadi powder or 2.5% trichlorfon powder, using about 2.5 kg per mu. At the peak of occurrence, spray with 2.5% deltamethrin at 2000-4000 times dilution.

(4) Licorice seed chalcid: adults lay eggs on the seed coat during the green fruit stage, and after the larvae hatch they bore into and feed on the seeds, and pupate inside the seeds. After the adults emerge, they bite through the seed coat and escape, and the damaged seeds are hollowed out by feeding, with small round holes left on the seed coat and pods. This pest has a great impact on seed yield.

Control methods: Treat the seeds, remove insect-bored seeds, or mix the seeds with carbaryl powder. During the occurrence period, especially the larval stage, spray with 40% dimethoate emulsifiable concentrate at 1000 times dilution.

(5) Ningxia ground pearl: a piercing-sucking pest on licorice roots. In addition to severely damaging wild licorice, cultivated licorice in Inner Mongolia, Ningxia, Gansu and other places has also suffered devastating damage from this pest.

This pest has one generation per year, overwintering as newly hatched nymphs in the rhizosphere of the host. In its life cycle, only the adult stage briefly lives above ground, while the other stages all live underground. The main damage period is from early May to early August each year. During the damage period, waxy spider-shaped red spheres can be seen on the rhizosphere of the host.

Control methods: The best control period is from late March to early May, when overwintering nymphs are seeking hosts, and from early to late August, before the adult mating and egg-laying period. In the earlier stage, systemic insecticides can be applied by furrow irrigation; in the later stage, dusting or spraying can be used for contact killing.

In addition, during the seedling emergence stage there are also mole crickets and Hosie's oriental crab beetle, and during the adult plant stage there are also underground pests such as the black wrinkled chafer, the yellow-brown anomala beetle, wireworms and darkling beetles. There are also pests such as the licorice bean weevil and the licorice clearwing moth, which can be controlled with conventional pesticides, and attention should be paid to mowing before winter, eliminating overwintering pest sources, and timely removing damaged plants.