How to prevent and cure the purple feather disease of tea

Distribution and symptoms: distributed in all tea-producing areas, but more common in North and East China. The disease mainly occurs in the seedling stage and adult stage, causing damage to the root or root neck. At first, the fibrous root is rotten, brown or dark brown, and then it spreads to the lateral root. After decay, it is purple-brown, and the surface of the disease spot is covered with purplish-brown filaments. On the surface of the diseased root, there are hemispherical granular wormwood nuclei and centimeters of nitrate, which is often surrounded by purplish red filaments. It is easy to peel off, and the root cortex is also easy to peel off. In severe cases, the aboveground part wilts, the new shoots sprout less, and the diseased plants die.

Occurrence regularity: generally, the disease is more serious at the turn of high temperature and rainy spring and summer or between summer and autumn, and it is easy to occur in tea gardens with high groundwater level, poor drainage and over-dry soil. This pathogen can survive in the soil for many years, with agricultural operations; Rain Water, underground pests and root contact and spread, the transfer of infected seedlings and soil can also be transmitted over a long distance, continuous cropping and pre-cropping susceptible crops are also prone to disease.

Prevention and control methods:

Select sterile healthy seedlings, dig and burn the diseased seedlings in time, wash the tools after use, and then soak the roots of the remaining healthy seedlings with 20% lime emulsion for 1 hour, or 50% carbendazim 1000 times dilution for half an hour before planting. Tea gardens with poor drainage and high water level should pay attention to drainage and dig drainage ditches before waterlogging. The land that had previously planted sweet potatoes, potatoes and fruit trees and had the disease should be disinfected with 70% pentachloronitrobenzene, disinfected with 2.5kg fine soil per mu, or irrigated with formalin 30 times dilution, and the root neck was watered with potassium permanganate or doinling 1000 times dilution at the initial stage of the disease.