How to control the main pests of bok choy? Detailed explanation of the latest methods

The main pests of bok choy include aphids, diamondback moths, cabbage caterpillars, cabbage webworms and striped flea beetles. Effectively controlling these pests is a necessary guarantee for high yields of bok choy. How should we control these pests? Below, the editor of Qiannong Network will introduce the control methods for these pests of bok choy!

Aphids

1. Damage: The aphids harming bok choy include the turnip aphid (radish aphid) and the green peach aphid, which are the main pests of bok choy. Both adult and nymph stages of these two cabbage aphids suck plant sap, causing leaves to curl and turn yellow and plants to become stunted, and they can also transmit viral diseases. The turnip aphid produces 10—20 generations a year, overwintering as wingless aphids in the host's heart leaves or on the underside of leaves. In March—April of the following year, they reproduce and produce winged and wingless aphids, and throughout the year they alternate among cruciferous vegetables and cause damage. However, the damage is most severe in autumn. The green peach aphid produces 20—30 generations a year, overwintering as wingless aphids in the host's heart leaves or on the underside of leaves, or as eggs. They hatch in March—April of the following year, and by May large numbers of winged aphids are produced and migrate to cause damage. This continues until winter. Male aphids can reproduce parthenogenetically and produce 10—100 or more offspring. When the climate is suitable, they can lay eggs once every 4—5 days, and the damage is more severe in dry years.

2. Control method: Spray with 40% dimethoate emulsion at 1500 times dilution, or 4.5% beta-cypermethrin at 3000 times dilution, or Ke Ya Bao produced by Shenzhen Ruidefeng at 1500 times dilution.

Diamondback moth

1. Damage: The diamondback moth larva is commonly known as “pointed at both ends” and is another major pest harming bok choy. First-instar larvae bore into tissues and feed on the leaf mesophyll; from the second instar they begin gnawing the mesophyll on the underside of leaves; after the third instar they eat the leaves into holes or a network pattern. The diamondback moth produces 9—10 generations a year, and adults, pupae and larvae can all overwinter. When the weather warms, adults begin activity, and eggs are mostly laid on the underside of leaves near the veins. A single female moth can lay an average of up to 300 eggs. Generally, diamondback moth damage occurs from April—October, with more frequent and severe damage in April—May and August—September.

2. Control method: Spray to kill with 90% crystalline trichlorfon at 800 times dilution, or 25% Zhongke Meiling at 1500—2000 times dilution.

Cabbage caterpillar

1. Damage: The cabbage caterpillar is also called the green worm; the adult is the cabbage white butterfly, also called the cabbage butterfly. The larvae damage leaves, eating them into holes or notches, and in severe cases eat the entire leaf, leaving only the petiole and veins. The cabbage caterpillar produces 8—9 generations a year and begins overwintering as pupae in November. The first-generation adults begin to appear in mid-March. Adults are active during the day, feeding on nectar, and like to lay eggs on cabbage and cauliflower. Each female moth can lay 100—200 eggs, and the egg stage lasts 3—8 days. The larvae have five instars in total; before the third instar they eat relatively little and have poor pesticide resistance.

2. Control method: Chemical control is the same as for the diamondback moth.

Cabbage webworm

1. Damage: The larva of the cabbage webworm is commonly known as the heart-boring worm. Newly hatched larvae spin silk and form webs inside the heart of young seedlings, feeding on the heart leaves. After the third instar, they can also bore downward from the heart leaves through the stem pith to the roots, causing root rot. Seedlings are most severely damaged when they have 3—4 leaves. The cabbage webworm produces 6—7 generations a year, overwintering as larvae in the soil, where they spin silk to bind soil and dead leaves into a nest and overwinter in the cocoon. In the following spring, they form cocoons and pupate in the soil or on fallen leaves and plant debris on the ground. After adults emerge, they are active at night, and eggs are laid singly on leaves, mostly on the heart leaves. The larvae have the habit of moving to alternate hosts to cause damage, and mature larvae spin cocoons and pupate on the soil surface or in the soil near the cabbage roots.

2. Control method: Remove weeds and dead plant residues in the field, and eliminate pupae and cocoons. At the seedling stage of the vegetables, that is, before the larvae spin silk and form clusters, spray with 90% crystalline trichlorfon at 800 times dilution or 25% Zhongke Meiling at 1500—2000 times dilution.

Striped flea beetle

1. Damage: The striped flea beetle is commonly known as the flea, and its larva is commonly known as the white maggot. It is also one of the main pests harming vegetables. Both adults and larvae of the striped flea beetle can cause damage. Adults mainly eat leaves, and can also damage tender stems, flower buds and pods. Larvae peel and feed on the root epidermis or bore into the root epidermis or into the roots to form tunnels, causing plants to wilt. The striped flea beetle produces 5—6 generations a year, overwintering as adults in soil crevices, on the underside of cabbage leaves on the ground, and in plant residues and weeds. When the temperature is warmer, they continue to move and feed. Each overwintering female adult can lay about 600 eggs. After hatching, the larvae feed on cabbage roots, and mature larvae pupate at a depth of 3—7 cm below the soil surface.

2. Control method: After autumn, remove weeds and residual leaves and dead plants in the field to eliminate overwintering adults. In early spring, after weeds grow, they should also be removed promptly so that overwintering adults have no suitable food. When adults are found, immediately spray to kill with 90% crystalline trichlorfon at 800 times dilution or 25% Zhongke Meiling at 1500—2000 times dilution. For larvae, the above pesticides can be sprayed on the soil surface to eliminate them.