A Detailed Guide to the Latest Control Measures for Pests and Diseases of Choy Sum

During the growth of choy sum, it is highly prone to certain pests and diseases, which have a huge impact on the yield and quality of choy sum and bring huge economic losses to farmers. So what are the common pests and diseases of choy sum? How should they be controlled? Let's find out together with the editor.

1. Viral disease

Choy sum viral disease mainly occurs at the seedling stage. Because of differences in variety and pathogen source, two types of symptoms appear after infection: one is the deformed mosaic type, and the other is the necrotic spot type. After the plant is infected, it forms fewer pods, has a low seed-setting rate, and a low germination rate.

Control measures: For the control of viral disease, comprehensive control measures should be adopted, with prevention as the main approach. Choose varieties with strong disease resistance; generally, early-maturing varieties have stronger disease resistance than late-maturing varieties. Before sowing, clean up leftover plant residues and weeds, avoid continuous cropping, promptly pull out diseased plants and burn or deeply bury them, regularly spray fungicides to sterilize, increase the application of phosphorus and potassium fertilizers, and cultivate robust plants. At the same time, aphids must be controlled to cut off the transmission route.

2. Downy mildew

Downy mildew mainly harms the leaves of choy sum. The symptoms are irregular spots on the leaves, grayish green, and in the later stage a downy mildew layer appears on the diseased spots.

Control measures: You should also learn to choose varieties with strong disease resistance, do a good job of field cleaning to eliminate pathogens, and promptly remove diseased leaves to prevent the spread of pathogens. In the early stage of the disease, spray 75% chlorothalonil wettable powder at 600-800 times dilution, once every 10 days, for 2-3 consecutive times.

3. Black spot

Black spot mainly harms leaves, leaf stalks, and flower stalks. When leaves are infected, nearly round chlorotic spots first appear, and after expansion the edges become light green to dark brown. In severe cases, multiple diseased spots merge into large spots, causing the entire leaf to die, and finally the leaves of the whole plant dry up from the outside inward.

Control measures: Seeds can be treated by soaking in warm water or by chemical seed dressing. When the disease occurs, spray pesticides such as chlorothalonil, mancozeb, and anilazine. Generally, control once every 15-20 days, and for anilazine, apply 1-3 times according to the condition of the disease.

4. Cabbage caterpillar

The main pest is the cabbage caterpillar. In severe cases, it often eats the leaves completely, leaving only the leaf veins. Cabbage caterpillars generally appear easily when harvesting from the medium seedling to large seedling stage. If control is not timely, it will have a huge impact on yield.

Control measures: Spray BT powder at 1200-2000 times dilution once at the seedling stage, 20-25 grams per mu. After fertilizing and watering, you must apply the pesticide, but note that pesticide application is prohibited half a month before harvest to avoid pesticide residues.

The above is an introduction to control measures for pests and diseases of choy sum. We hope it can help you. To learn more related knowledge, please stay tuned to us.