A Complete Guide to Scientific Control Methods for Chinese Cabbage Soft Rot

Chinese cabbage, of the genus Brassica in the family Brassicaceae, originated in northern China and is a traditional Chinese vegetable. Chinese cabbage was first called song, but song is not entirely the same as today's Chinese cabbage. Modern Chinese cabbage is generally divided into Chinese cabbage and baby bok choy; northerners generally call Chinese cabbage “baicai” while baby bok choy is called “youcai”.

Types of Chinese Cabbage

Botanically, Chinese cabbage belongs to the Chinese cabbage subspecies of Brassica rapa in the genus Brassica, family Brassicaceae.

The Chinese cabbage subspecies can be divided into 4 horticultural varieties: the loose-leaf Chinese cabbage variety, the semi-heading Chinese cabbage variety, the flowering-heart Chinese cabbage variety, and the heading Chinese cabbage variety.

The heading Chinese cabbage variety can be divided into 3 basic ecotypes according to the central cultivation region and ecology: the cylindrical type, the oval type, and the flat-head type. From the three basic ecotypes come 5 secondary types: flat-head cylindrical, flat-head oval, round cylindrical, cylindrical flowering-heart, and flowering-heart oval.

In addition to classification by ecotype, Chinese cabbage varieties can also be divided into different types according to head traits and growth period.

According to the number and weight of head leaves, they can be divided into leaf-weight type, leaf-number type, and intermediate type. According to the heading form of the leaf head, they are divided into closed-heart, flowering-heart or turning-heart, upright-heart, and semi-closed-heart types. According to the type of head top, they are divided into flat-head, round-head, and pointed-head types. According to the way the inner leaves clasp together, they are divided into overlapping, folded, twisted, and clasping types. According to growth period, they are divided into extremely early-maturing, early-maturing, mid-maturing, and late-maturing types.

Scientific Control of Chinese Cabbage Soft Rot

Bacterial soft rot of Chinese cabbage is also called “rotten lump”. This disease is a devastating disease; if control is inadequate and measures are improper, it can bring great economic losses to vegetable growers. So how should Chinese cabbage soft rot be scientifically controlled?

Damage symptoms of Chinese cabbage soft rot:

Chinese cabbage mostly begins to show symptoms at the heading stage. Diseased plants start to develop symptoms from the base of the petiole. The diseased part is initially water-soaked and semi-transparent, then expands into pale grayish-brown wet rot. The diseased tissue is sticky and slippery, and after water loss the surface sinks in, often exuding a dirty-white bacterial ooze and giving off a foul odor, sometimes causing the pith to rot. In the early stage of disease, the outer leaves of the diseased plant droop and wilt under strong sunlight, but can recover in the morning and evening, later gradually failing to return to their original state; the outer leaves of the diseased plant lie flat on the ground, and the leaf head is exposed. In some cases, rot also starts from the leaf margin of the outer leaves or from the leaf head, and the diseased leaves become thin and papery after drying. Diseased plants are easily kicked over by foot. During storage of Chinese cabbage, the disease continues to develop, causing the storage cellar to rot.

Pathogen transmission routes and disease conditions of Chinese cabbage soft rot:

The pathogen overwinters on carriers such as infected diseased residues, soil, undecomposed farmyard manure, and diseased plants that survive the season, becoming an important source of primary infection, and can move between different hosts to cause damage. The pathogen can be transmitted through many routes such as rain, irrigation water, fertilizer, soil, and insects, and mostly enters through wounds or natural cracks in the plant to cause infection. According to survey results: because pests can carry the pathogen both inside and outside their bodies, and pest feeding on leaves creates a large number of wounds, this becomes an important channel for pathogen entry, so fields with severe pest outbreaks are more likely to have soft rot occur, and if disease occurs, it also spreads faster; high temperature and frequent rain favor pathogen reproduction and spread, and after Chinese cabbage heads, long drought followed by rain favors the occurrence of soft rot, and the disease is also more severe; fields with long-term standing water and high soil water content also have more severe disease.

Scientific control methods for Chinese cabbage soft rot:

Select disease-resistant and disease-tolerant varieties. Generally choose varieties with strong wound-healing ability, tall-cylinder type, upright type, and green-petiole type, such as: Beijing Xin No. 3, Jincai No. 3, Taiyuan Erqing, etc. From the seedling stage, control leaf-eating and boring pests such as imported cabbageworm, cabbage moth, beet armyworm, diamondback moth, cabbage webworm, root maggot, striped flea beetle, etc. In addition, diseases such as viral disease, downy mildew, and black rot may all aggravate the damage of soft rot. Therefore, these diseases must be well controlled. Do a good job of disinfecting the pathogen; when diseased plants are found, dig them out promptly, and scatter lime in the diseased holes for disinfection.

Chemical control: seize the key period and apply pesticides at the right time. After Chinese cabbage is planted, 72% agricultural streptomycin 3000-4000 times liquid or 20% jinggangmycin water-soluble agent can be used, with each 25 g bag diluted in 50 kg of water for spray prevention. 45% amobam 900 times liquid; 77% copper hydroxide wettable powder 800 times liquid can also be used for spraying. The chemicals should be used alternately, sprayed once every 7-10 days, for 2-3 consecutive sprays; spraying should be thorough. In addition to spraying the whole field, focus should also be placed on spraying the petioles and stem base near the ground and the root base, with about 100 g of spray liquid per plant, so that the liquid flows into the heart of the cabbage and penetrates into the soil around the cabbage roots.