Distribution And The Pathogen Identification And Control Technology Of Blackleg Disease On Oilseed Rape In China

Aimed to control the stem canker/blackleg on the oil seed rape(Brassica napus)in China,the pathogenicity and the damage degree of several unknown pathogenic bacteria types have been investigated and identified,which contribute to analyze the relationship among yields of single plant with different damage level and plant agronomic characters,so as to clear and definite their distribution in China.Yield loss has been evaluated and the management strategy has been established in this study.Base on the goal above,disease surveying,samples collecting,pathogenic separating and purifying,morphological characteristics observing,biological identifying and pathogenicity evaluating were conducted.Single plant with different disease level has been obtained by artificial inoculation.The plant high,branch number,pod number and pod seeds number,thousand seed weight(TKW)and yield have been recorded after harvest,indicating that the chemical control have positive effect on controlling this disease comparing to the control group.Blackleg survey of oilseed rape were conducted in 70 locations of 16 provinces in China,covering both of winter and spring oilseed rape production regions during 2011~2014,which exhibited universality and diversity of blackleg in the field.The disease level in Anhui,Hubei etc Provinces where the incidence was up to 90%,was more serious than otherprovince.Both cultural identification and DNA detection were conducted to identify the selected isolates samples.Results demonstrated that Leptosphaeria biglobosa wereless aggressive while L.maculans were no aggressive.Pathogenicity of 22 L.biglobosa isolates(collected from 11provinces)was evaluated by in vivo cotyledon inoculation method using pycnidiospore suspension.Results illustrated that all the 22 isolates were pathogenic to B.napus.Almost all the tested isolates displayed higher pathogenicity than the control,Polish L.biglobosa isolate PL-Lb,.Fourteen isolates were considered highly pathogenic and eight isolates were moderately pathogenic.Yield losses among the different damage level were evaluated in this study,which exhibited that the disease with 4-5 grade have heavier damage than others,causing yield losses up to about 50%.Infections of pathogens not only caused the yield loss,but also directly affected the plant's characters,such as plant height,branch number,pod number and TKW(Thousand Kernel Weight).According to the disease propagation prevalence and their characters,the comprehensive control technology were suggested.