Toxicity And Field Control Effects Of Three Fungicides To Pathogens Causing Fusarium Crown Rot In Huanghuai Wheat Area

Fusarium crown rot is a worldwide fungal disease,caused by Fusarium graminearum species complex,infecting the base of wheat stems.The disease reduces wheat production,and the toxins produced affect crop quality and threat human and animal health.To clarify the dominant pathogen of Fusarium crown rot in Huanghuai wheat area and their toxin chemotype,this thesis applied primers of EF-1α gene to identify the pathogens of Fusarium crown rot in Huanghuai wheat area and determine its dominant species.To compare the susceptibilities differences of the dominant pathogens to three different fungicides（98% phenamacril,97% tebuconazole and 98.5% fludioxonil）,susceptibilities of 142 strains of F.pseudograminearum and 15 strains of F.graminearum were measured in vitra using the mycelium growth rate method.The sensitivities difference of Fusarium spp.of 3ADON and 15 ADON toxin chemotype to different fungicides were compared.The candidate fungicides for preventing and controlling Fusarium crown rot and their optimal application concentration were screened through the field test.The results are as follows: 1.The main pathogens of Fusarium crown rot in Huanghuai wheat area are F.pseudograminearum and F.graminearum,with F.pseudograminearum as dominant.Toxins chemotypes of the pathogens include 3ADON and 15 ADON.75 F.pseudograminearum were 3ADON,and 67 were15 ADON,8 were 3ADON,and 7 F.graminearum were 15 ADON.2.The sensitivities of F.pseudograminearum and F.graminearum causing Fusarium crown rot in Huanghuai wheat area to phenamacril,fludioxonil and tebuconazole were determined using mycelium growth rate method.The EC50 values of F.pseudograminearum and F.graminearum to cyanostrobin are 0.0881～0.9299 μg·m L^-1 and 0.1618～0.5688 μg·m L^-1,respectively,and the EC50 values of F.pseudograminearum and F.graminearum to fludioxonil the ranges are 0.0291～0.3544 μg·m L^-1 and 0.1332～0.2073 μg·m L^-1 respectively.The EC50 range of F.pseudograminearum to tebuconazole is 0.0146～0.9607 μg·m L^-1.3.The control effect in field of the three fungicides showed that the 25% phenamacril suspension had a higher control effect on Fusarium crown rot than 30% prothioconazole suspension and 6% tebuconazole suspension for seed dress.It is recommended to use 25% fenvalerate suspension concentrate that medium concentration is 6.67 ml·kg-1 for seed dressing can obtained the best control effect.The result of this thesis could provide technical support for the prevention and control of Fusarium crown rot.