Sensitivity And Resistance Analysis Of The Pathogen Of Maize Ear Rot To Fungicides

Maize ear rot is one of the important diseases in maize production,which will cause huge economic losses every year.Fusarium graminearum Schw is one of the pathogens causing maize ear rot,chemical control is also the most effective control measures to control maize ear rot at present,so it is of great significance to screen out fungicides with good control effect on Fusarium graminearum,control maize ear rot and effectively control the loss caused by the disease.In this paper,the selection of effective fungicides,the compound effect of fungicides and the resistance of fungicides were studied.The main results are as follows:Six effective fungicides were screened out from 22 fungicides by indoor virulence test.They were triadimefon,prochloraz,difenoconazole,tebuconazole,pyraclostrobin and propiconazole.The inhibition rates of each fungicide on the mycelia of corn ear rot fungus were over 70%at the concentration of 1 mg/L,71.35%,70.01%,72.44%,72.89%,70.71%and100%respectively.Five concentration gradients were set up to measure the inhibitory effect of each fungicide on the mycelial growth of maize ear rot fungus,and the EC₅₀value of each fungicide was calculated.The results showed that the six fungicides were sensitive to maize ear rot,and the EC₅₀values of triadimefon,pyraclostrobin,difenoconazole,tebuconazole and pyrazoleside were 0.3308 mg/L,0.3152 mg/L?0.2617 mg/L?0.2448 mg/L and 0.2356 mg/L,respectively.The toxicity of tebuconazole and difenoconazole,pyraclostrobin,prochloraz and triadimefon to the tested pathogens was measured by five concentration gradients.The results showed that EC₅₀of tebuconazole and difenoconazole,tebuconazole and triadimefon,tebuconazole and prochlorazole,tebuconazole and pyraclostrobin to the tested pathogens The average values were 0.0843 mg/L?0.0790 mg/L?0.0823mg/L and0.0837 mg/L,respectively,The average value of the co-toxicity coefficient of each compound was 296.87?353.74?330.05 and 282.81 respectively,which had obvious synergistic effect compared with the single agent.The resistance of maize ear rot fungus to triadimefon was studied by mycelium block mutagenesis.The results showed that the resistance of maize ear rot fungus was easy to produce at high dose.