Black rot causes black spots in cabbage how to control black rot in cabbage

Black rot seriously harms cabbage, which can occur from seedling stage to heading stage. After harming leaves and flower heads, cabbage loses its commercial value, resulting in yield reduction and loss. Therefore, cabbage black rot must be controlled in time to cure early, small and well.

Black rot of cabbage

Symptom identification: black rot mainly harms cabbage leaves, bulbs or bulbs. The disease occurred at the seedling stage, the cotyledons were immersed in water and died rapidly or extended to the true leaves. In the early stage of the disease, the "V"-shaped yellow-brown spots appeared at the apex of the leaf vein, which gradually extended to the whole leaf margin, forming a yellow-brown band. If the disease occurred in 5 to 10 true leaves, the lowest leaves of cabbage now began to wilt and turn yellow, and then the whole cabbage gradually withered; if it occurred in the rosette stage, there were black spots on the flower bulb, the heading was soft and unsolid, and it was of full value. Once cabbage black rot occurs, the infected area is large and the incidence rate is fast, which will lead to a reduction in yield.

Occurrence regularity: the pathogen of black rot overwintered on the seeds of cabbage or in the soil with the disease residue, invaded from the leaf edge of cotyledons or true leaves of cabbage seedlings by water pores or wounds, and quickly entered the vascular bundle to cause the disease at the base of the leaves. Germs can be spread through farm tools and Rain Water. High temperature and humidity, continuous cropping, poor soil drainage function, large amount of nitrogen fertilizer, low application amount of organic fertilizer, potassium fertilizer, trace elements such as zinc, manganese and molybdenum, and imbalance of soil microbial environment are all beneficial to the survival and reproduction of cabbage black rot and disease pathogen.

Prevention and control methods: (1) agricultural control. The cabbage seeds were soaked in 50 ℃ warm water for 20 minutes or 0.1% copper sulfate solution for 15 minutes. In the plots with serious black rot disease, the rotation of cruciferous vegetables was carried out for 2 to 3 years. Improve soil supply and drainage conditions, increase the application of organic fertilizer, phosphorus and potassium fertilizer and micro-fertilizer. (2) Pesticide control. The seedbed was disinfected and watered with 50% benzoammonium 800-fold solution to wet the soil or 50% carbendazim 800-fold solution to irrigate the cabbage seedbed. At the initial stage of the disease, 14% ammonia copper solution, or 77% copper hydroxide wettable powder, or 72% agricultural streptomycin soluble powder 5000 times, once every 10 days, was sprayed 2 times 3 times.