The Temperature Sensitivity And Fungicide Resistance Of Two F.Asiaticum Spp.and Fungicide Screening Against Fusarium Head Blight

Fusarium Head Blight caused by Fusarium spp.is a worldwide disease in wheat producing areas,not only reduce wheat production,but also produce toxins that affected food quality and the health of human and livestocks.Fusarium graminearum and F.asiaticum were two predominant pathogens of Fusarium Head Blight in China.In order to explore the corelation between the population distribution of F.graminearum and F.asiaticum and temperature,and the effect of temperature and fungicide as selective pressures on pathogen populations,the results in this study are as follows:1.The growth rate and temperature sensitivity of F.asiaticum and F.graminearum were measured using mycelial growth rate method at 22,25,28,30 and 32℃.The optimum growth temperature of two species was25℃,followed by 22℃and 28℃,decreased by about 40%at 30℃,and significantly inhibited at 32℃.There was no significant difference on growth rate between F.asiaticum and F.graminearum except at 30℃.The population of F.graminearum was more adaptable to high temperature compare with F.asiaticum populations.2.The sensitivity of F.asiaticum and F.graminearum to tebuconazole was measured by mycelial growth rate method at 25℃and 30℃.The mean EC₅₀values of F.asiaticum and F.graminearum were（0.76±0.26）μg·m L^-1and（0.37±0.14）μg·m L^-1 at 25℃,and were（2.42±0.82）μg·m L^-1and（2.03±0.97）μg·m L^-1 at 30℃.The sensitivity of F.asiaticum and F.graminearum to tebuconazole was significantly decreased at 30℃.Although the tebuconazole sensitivity of F.asiaticum was significantly lower compare to F.graminearum at both 25℃and 30℃,the sensitivity of F.graminearum to tebuconazole was significantly influenced by high temperature.3.The CYP51s gene sequencing showed that Fa CYP51s genes included11 genotypes,and Fg CYP51 gene included 5 genotypes,but there was no correlation between point mutations on genotypes and fungicide sensitivity.4.Using the distinguishing dosage method,only two F.asiaticum isolates were resistant to carbendazol with a resistance frequency of 2%,and there was no F.graminearum resistant isolate.5.F.asiaticum isolates are mainly included 3ADON chemotype,also included 15ADON and NIV chemotype,while F.graminearum isolates are only included 15ADON chemotype in Hubei Province.6.There was no correlation between genetic diversity and temperature sensitivity and fungicide sensitivity of F.asiaticum and F.graminearum.7.The control efficiency of 6 fungicides against wheat powdery mildew and yield production showed that 25%phenamacril SC and 3%prothioconazole SC had higher control efficiency with 95.4%and 94.3%in diseased head rate,and 96.3%and 94.4%in disease index.The highest yield was 631.2 kg·667 m^-2 when treated with 3%prothioconazole SC.These results will provide the basis for the population distribution of Fusarium spp.under the climate change,the theoretical guidance for the occurrence and epidemic prediction of Fusarium head blight.The fungicide efficacy in the field trials provides technical support for reducing pesticide application in wheat.