How should cutworms be controlled in Angelica sinensis
Cutworms, also known as "ground silkworms" and "black ground silkworms." They belong to the order Lepidoptera, family Noctuidae. The cutworms affecting Angelica sinensis are mainly the black cutworm and the yellow cutworm, and their damage and control measures are the same.
1. Damage: The larvae damage Angelica sinensis seedlings, hiding by day and emerging at night; at the young instar stage they mostly damage tender leaves and tender growing tips, biting through the root crown and causing missing plants and broken rows.
2. Morphological characteristics: The adult black cutworm has a body length of 16-23 mm and a wingspan of 42-54 mm. The female moth's antennae are filiform, and the male moth's are bipectinate. The forewing is dark brown between the costal margin and the outer transverse line. Between the inner transverse line and the outer transverse line there are distinct kidney-shaped markings, ring-shaped markings and rod-shaped markings. The hindwing is grayish white, with the veins and margins dark brown. The abdomen is gray. The egg is hemispherical, initially milky white, later turning yellow, and grayish purple just before hatching. Mature larva: body length 37-47 mm. The head is yellowish brown, the body is yellowish brown to dark brown, with pale longitudinal bands on the back. The body surface is rough, covered with small round black granules. The anal plate is yellowish brown, with two dark brown longitudinal bands. Pupa: body length 18-24 mm. Reddish brown and glossy.
3. Occurrence pattern: Adult black cutworms hide during the day and are active at night, being most active around dusk, and are strongly attracted to blacklight lamps and sugar-acid-alcohol substances. Adults lay eggs on low weeds below 5 cm, preferring to lay eggs on the undersides of leaves or tender stems close to the ground. The larvae have 6 instars in total. Before the 3rd instar, the larvae mostly gather on the host's heart leaves and tender leaves and on field weeds, and can feed day and night without entering the soil. After the 3rd instar, the larvae hide in the surface soil layer during the day and come out at night to bite through seedlings and drag them into their burrows. Mature larvae have a death-feigning habit, immediately curling into a ring shape when disturbed.
The black cutworm prefers warmth and moisture. At a temperature of 18°C-26°C, a relative humidity of about 70%, and a soil moisture content of about 20%, conditions are favorable for its growth, development and activity, and the damage is severe.
4. Control measures: First, promptly clear field weeds to reduce transitional hosts and eliminate eggs and young larvae. Second, set up sugar-acid-alcohol liquid in the field to trap adults, use palm fiber and burlap pieces to attract moths for egg-laying, and use Paulownia leaves to attract larvae. Third, apply 50% phoxim emulsifiable concentrate at 1000 times dilution and 2.5% deltamethrin at 1000 times dilution at the root zone of the seedlings to kill the pests.