Susaintable Management For Cruciferous Clubroot

Brassicae Woron is a worldwide soil-borne disease caused by Plasmodiophora.Brassicae Woron,which causes severe economic loss to cruciferous crops.However,the traditional method to reduce the occurrence of clubroot,such as agricultural,chemical,biological and other prevention and control technologies,usually have problems of low efficiency and high cost,this area still need to be improved and enhanced.This study aims to establish a quantitative inoculation system of clubroot,explore comprehensive prevention and control measures based on the density of clubroot spores in soil,optimize existing prevention and control technologies,and provide reference for the following studies of clubroot.The results are as follows:1.Quantitative assessment system of clubroot.The quantitative system of clubroot spore is established as the follows y=0.6ln(x)+7.8(R~2>0.97)to achieve quantitative assessment of clubroot spores.The model can quantitatively analyze the spores of different hosts(including rapeseed and Chinese cabbage)in different states(fresh and dacay).At the same time,the inoculation method of clubroot was optimized,and it was found that homogenate inoculum(HI)has higher efficiency.Furthermore,this study provided theoretical basis and technical support for the standardization of inoculation of clubroot.2.Soil mulching in sunlight is one of the physical control for clubroot.The temperature affected the activity of Plasmodiophora.Brassicae,and the lethal temperature of Plasmodiophora.Brassicae was 55oC,and the spore germination rate was less than 2%at this temperature.After mulching the diseased soil,through monitoring the weather and the temperature of different soil layers,it was found that drying can improve the temperature of shallow soil,while mulching can increase the soil temperature to reach the lethal temperature of Plasmodiophora.Brassicae.The density of spores in the mulching soil was found lower and lead to the reduction of the clubroot occurrence.3.The antagonistic strains of Bacillus MCNB19 can be used in clubroot control.Bacillus12 strains were isolated from plant root tissue,after the confront culture and screening of antagonismand,the result shows that MCNB19 had a better inhibitory effect.To further explore the influence of the MCNB19 on clubroot spore germination,the results show that the strain has better inhibitory effect.Pot and field experiments showed that MCNB19 has better inhibitory effect when the density of clubroot is low in soil,the control effects reached 52%and54.6%respectively.4.Chemicals flurazine and cyanostole are applied in order to effectively improve the effect of clubroot prevention and control.Both flurazine and cyanostole had inhibitory effects on spores germination in different spore density.When the spore density was 10~3,the inhibitory rate of flurazine and cyanostole reached 72.1%and 73.9%respectively.And the inhibitory effect decreased when the spore density gets higher.The greenhouse and field experiments showed that when the spores density is low,the effect is more ideal;Root irrigation control works better than that of spraying control;The effect was better when the chemicals applied at the plants earlier growth stage;Chemical applying twice has better effect than once.