The Harmful Characteristics and Control Methods of the Cabbage Moth, a Pest of Mustard Greens

Mustard greens (Brassica juncea) is an annual or biennial herbaceous plant of the genus Brassica in the family Cruciferae (crucifers). It is a famous specialty vegetable of China, originating in China, and is a commonly cultivated vegetable throughout the country, mostly distributed in the provinces south of the Yangtze River.

Mustard greens (original variety) is an annual herb, 30-150 cm tall, usually hairless, sometimes with bristles on young stems and leaves, covered with a powdery bloom, and having a pungent taste; the stem is erect and branched. The basal leaves are broadly ovate to obovate, 15-35 cm long, with a rounded-obtuse apex and cuneate base, lyrately pinnatifid, with 2-3 pairs of lobes, or undivided, with margins always incised or toothed, and the petiole 3-9 cm long, bearing small lobes; the lower stem leaves are smaller, with incised or toothed margins, sometimes with rounded-obtuse serrations, not clasping the stem; the upper stem leaves are narrowly lanceolate, 2.5-5 cm long and 4-9 mm wide, with margins having inconspicuous sparse teeth or being entire.

The raceme is terminal and elongates after flowering; the flowers are yellow, 7-10 mm in diameter; the pedicels are 4-9 mm long; the sepals are pale yellow, oblong-elliptic, 4-5 mm long, erect and spreading; the petals are obovate, 8-10 mm long and 4-5 mm wide. The silique is linear, 3-5.5 cm long and 2-3.5 mm wide, with the valves having 1 prominent midvein; the beak is 6-12 mm long; the fruiting pedicel is 5-15 mm long. The seeds are spherical, about 1 mm in diameter, and purple-brown. The flowering period is March-May, and the fruiting period is May-June.

What is the cabbage moth, a pest of mustard greens, and what harm does it cause?

The cabbage moth is commonly known as the square moth, diamondback moth, small green worm, hanged ghost, two-pointed tip, and so on. It belongs to the order Lepidoptera and the family Plutellidae.

1) Damage status The cabbage moth is a worldwide pest, distributed throughout China, with more severe damage in the south, and is one of the important pests of vegetables. The cabbage moth mainly harms cruciferous vegetables and other cruciferous hosts, as many as 40 species. In China it harms cabbage, radish, cauliflower, Chinese cabbage, mustard greens, turnip, rapeseed, and so on. In addition, it can also harm tomato, potato, ginger, onion, and so on.

The young larvae of the cabbage moth mine leaves, boring into and eating the leaf mesophyll, leaving the upper and lower layers of epidermis. Or they bore and feed inside petioles and veins. After the 2nd instar they feed on the leaf surface, leaving only one layer of epidermis, commonly known as "opening a skylight." Larger larvae bite the leaves into small holes. The larvae prefer to cause damage on the heart leaves of seedlings, affecting vegetable development. When causing damage on seed plants, they can feed on tender leaves, tender stems, tender pods and tender seeds, affecting seed yield. Control Methods for the Cabbage Moth, a Pest of Mustard Greens

① Rational layout In vegetable fields, continuous year-round cropping of cruciferous vegetables should be avoided. Early, middle and late varieties should be planted in combination with other vegetables, or separated by a certain distance. This prevents the pest from occurring continuously and causing severe damage.

② Clean the field After harvest, promptly remove residual branches and fallen leaves, carry them out of the field and bury them deeply or burn them, to eliminate larvae or pupae and reduce the insect population density in the field.

③ Light and sex pheromone trapping of adults During the adult occurrence period, black light lamps can be installed in the field to trap and kill adults. Sex pheromone lures can also be used: that is, take female moths that emerged the same day, remove the end of the abdomen, and use solvents such as dichloromethane and alcohol for crude extraction; apply the crude extract to strips of paper and hang them in the field to attract male moths for trapping and killing.

④ Chemical control Spray promptly during the young larval stage. Commonly used agents include Bacillus thuringiensis 500-1000 times dilution, or BT emulsion, with 100 grams used per mu, or diflubenzuron No. 1 or No. 3 500-1000 times dilution, or 40% fenvalerate-malathion emulsifiable concentrate 2000-3000 times dilution, or 40% fenvalerate-malathion emulsifiable concentrate 2000-3000 times dilution, or 10% cypermethrin emulsifiable concentrate 2000-3000 times dilution, or 20% fenvalerate emulsifiable concentrate 2000-3000 times dilution, or 5% chlorfluazuron 3000 times dilution, or Jinan-79 strain (Pieris rapae granulosis virus agent) 5000 times dilution, or 50% cartap wettable powder 1000-1500 times dilution, etc., or 10.8% lambda-cyhalothrin emulsifiable concentrate 10000-20000 times dilution.