What to Do When Aphids Appear on Bok Choy? A Few Effective Control Methods

Bok choy is a vegetable we commonly eat in daily life. It is cultivated in all provinces across northern and southern China, especially widely in the Yangtze River basin. Bok choy is very rich in nutritional value; eating it regularly can lower blood lipids, promote bowel movements, and relieve toxicity and swelling. A bok choy plant must endure many hardships during its growth, so what should be done when bok choy gets aphids?

I. Main Pests of Bok Choy and Their Control Methods

The main pests harming bok choy include aphids, diamondback moths, cabbage caterpillars, cabbage webworms, and flea beetles. After a pest outbreak, the pest species should be identified as early as possible so the right treatment can be applied. The aphids that harm bok choy include the turnip aphid and the green peach aphid. Both the 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. For control, spray with 40% dimethoate emulsifiable concentrate 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.

The diamondback moth larva, commonly known as “two-pointed ends”, is another major pest harming bok choy. First-instar larvae bore into plant tissues and feed on the leaf mesophyll; from the second instar they begin chewing the mesophyll on the underside of leaves; after the third instar they eat the leaves into holes or a net-like skeleton. They generally begin activity when the weather warms in early spring. For control, spray with 90% crystallized trichlorfon at 800 times dilution or 25% Zhongke Meiling at 1500—2000 times dilution.

The cabbage caterpillar, also called the green worm, has an adult form known as the cabbage white butterfly, also called the cabbage butterfly. Its larvae damage leaves, eating them into holes or notches, and in severe cases consuming the entire leaf so that only the petiole and veins remain. Its control method is the same as that for the diamondback moth.

The larva of the cabbage webworm is commonly known as the heart-boring worm. Newly hatched larvae spin silk webs inside the heart of seedlings, feeding on the young leaves; after the third instar they can bore downward from the heart leaves through the stem pith to the roots, causing root rot. Seedlings are most severely damaged at the 3—4 leaf stage. For control, first clear weeds and dead plant debris from the field and destroy pupae and cocoons. During the seedling stage of the vegetable, that is, before the larvae spin silk and form clusters, spray with 90% crystallized trichlorfon at 800 times dilution or 25% Zhongke Meiling at 1500—2000 times dilution.

Both the adults and larvae of flea beetles can cause damage. The adults mainly eat leaves and can also harm tender stems, flower buds, and pods. The larvae strip and feed on the root epidermis or bore into the root epidermis or into the roots, forming tunnels that cause the plant to wither. After autumn, clear weeds and dead leaves and plant debris from the field to eliminate overwintering adults. In early spring, after weeds grow, they should also be cleared promptly so that overwintering adults have no suitable food. When adults are found, immediately spray with 90% crystallized 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.

II. How to Choose Bok Choy

Bok choy is very tender and loses water and shrivels easily. Once it has lost water, even if it is sprayed with water again, the shriveled tips of mature leaves cannot recover. Therefore, do not buy any with wilted leaf tips; those with water droplets at the cut end indicate the highest freshness. At the same time, do not buy those that look old; dark color means old, light color means tender. Those with a long growth period also have long petioles; generally speaking, short ones are better.