Symptoms and Control Methods
Symptoms
Bacterial soft rot of Chinese cabbage usually occurs at the
heading stage.
Infection starts at the base of the petioles.
Initially, infected tissues show water‑soaked, translucent lesions, which later expand into light grayish‑brown wet rot.
Affected tissues become slimy, and the surface shrinks when dehydrated, often exuding off‑white bacterial ooze with a foul odor.
In severe cases, the pith becomes rotten.
At the early stage of infection, outer leaves wilt under strong sunlight but recover in the morning and evening.
Gradually they fail to recover, and outer leaves collapse to the ground, exposing the head.
In some cases, rot starts from the margins of outer leaves or the head itself.
Diseased leaves become thin and papery when dry.
Infected plants are easily knocked over.
The disease continues to develop during storage, causing rot in storage pits.
Infected seed plants will continue to develop symptoms after transplanting and may die completely.
Conditions for Disease Development
The pathogen mainly overwinters on infected plants or in storage pits with seed plants, and is carried to the field in the following year.
It spreads via irrigation water, rainwater, and insects.
The use of manure containing undecomposed diseased residues can also spread the pathogen.
The bacterium invades the host through wounds and natural openings, and multiplies in parenchyma tissues.
The pathogen can infect Chinese cabbage seedlings at the root hair zone and lie latent in vascular tissues.
The infection rate of seedling roots in the field can reach
95%.
Disease outbreaks occur under anaerobic conditions caused by irrigation.
Crops planted on
raised beds are less affected than those on flat beds.
Rotation with gramineous crops also reduces disease severity.
Early sowing, low‑lying fields, poor drainage, heavy clay soil, and flood irrigation all increase the incidence.
Control Methods
Use resistant varietiesResistant varieties include Lübao, Zhongbai No. 1, Beijing Xiaozha 50, Jindong Zhongqing No. 1, Longxiebai No. 2, Lianbai No. 1, Ji Baicai No. 4, Xinza No. 1, Lu Bai No. 7, Luguang 18, Lu Bai No. 10, Lu Bai No. 11.
Localities may select suitable varieties according to local conditions.
Sow at the proper timeThe occurrence of soft rot is closely related to sowing date.
The optimal sowing date for controlling downy mildew and virus disease is also suitable for controlling soft rot.
Treat 150 g of seeds with 100 g of
Caifengning B1.
Prepare land thoroughly, plant on raised beds, and improve field managementSoft rot can spread via running water through wounds.
Poor land preparation and waterlogging are major causes of soft rot.
Planting on raised beds can significantly reduce soft rot in non‑saline‑alkali soils.
Avoid excessive hardening off in dry years.
Prevent root and leaf injury during field operations.
Water evenly after heading to avoid physiological wounds.
Remove and discard diseased plants before irrigation.
Apply lime or fungicide in the diseased holes before watering.
Control insects to reduce infection courtsFrom the seedling stage, control leaf‑eating and boring pests, including cabbage caterpillar, cabbage armyworm, beet armyworm, diamondback moth, cabbage webworm, cabbage maggot, and striped flea beetle.
Virus disease, downy mildew, black rot, and other diseases may also aggravate soft rot, so their control is also necessary.
Chemical control in the fieldRemove diseased plants immediately when found.
Sprinkle lime in the diseased holes.
Spray the whole field with
- Agricultural streptomycin 4000× dilution, or
- Neomycin 4000× dilutionevery 10 days for 2–3 consecutive applications.
Alternatively, apply 300 g of Caifengning B1 mixed with 250 L of water per 667 m² for root irrigation.
