| Corn is an important food crop in the Northeast and an important source of feed.Corn ear rot caused by Fusarium is common in the main corn producing areas of Northeast China,especially in Jilin Province,and the occurrence is relatively serious in some areas.Fusarium ear rot causes large yield losses in production and reduces corn quality,which seriously threatens production safety in spring corn areas.Therefore,the research and prevention of corn Fusarium disease is particularly important.In this experiment,different concentrations of Fusarium graminearum conidia suspensions were inoculated at the base,middle and tip of corn ears at different periods to study the rate of infection and expansion of Fusarium graminearum on the ears and the soluble sugar and sugar content of the infected grains after inoculation.The relationship between the water content of ears,and the screening of agents through indoor antibacterial tests to study the effect of the first inoculation time and spraying time for the control effect of Fusarium ear rot of corn grits.The main research results are as follows:(1)From the early silking stage to the end of grain filling,10~4-10~6 conidia suspensions of Fusarium graminearum were inoculated at three different positions at the base,middle and tip of the corn ear.The results showed that 10~6 spores/m L was inoculated in the middle of the corn ear.The disease index of the spore suspension was higher than that of the base and tip of the inoculation.The disease index showed a downward trend with the delay of the inoculation time,indicating that the inoculation of the middle part of the ear is beneficial to the expansion of the disease,and the inoculation time decreases with the mature ear.(2)The expansion of pathogenic bacteria inoculated with Fusarium graminearum conidia suspension in different parts of corn ears was detected by PCR and Taq man-PCR,and the changes of soluble sugar content and grain water content of corn ears at inoculated and uninoculated parts were measured by microplate reader.The results showed that with the increase in the number of diseased kernels of the ears,the pathogen content increased,and the rapid growth time of the diseased kernels was the rapid increase time of the soluble sugar content of the inoculation site and the decrease time of the water content of the kernels.The change of soluble sugar content is positively correlated with the change of grain moisture content is negatively correlated.(3)In laboratory,four pesticides for six pesticides have screened were selected for their inhibitory effects on Fusarium graminearum.According to their antibacterial effects and characteristics,by spraying fungicides before inoculating Fusarium graminearum or inoculating Fusarium graminearum before spraying.Two methods were used to test the control effect of Fusarium graminearum ear rot.The results showed that the EC50 values of 30%pyraclostrobin,43%tebuconazole,25%bromothalonil,20%coumoxystrobin and 2%Phenazine alpha-2 carboxylic acid inhibiting the growth of Fusarium graminearum colonies were 3.906μg/m L,0.956μg/m L,5.978μg/m L,149.2μg/m L,9.472μg/m L.The disease index after spraying 1000 times of 20%coumoxystrobin,5000 times of 43%tebuconazole and 1000times of 30%pyraclostrobin before inoculation is lower than that of the control,and the prevention and treatment of inoculating Fusarium graminearum and then spraying treatment relatively poor.It shows that spraying syringomycin,tebuconazole and pyraclostrobin before the pathogen infects corn ears can effectively control the occurrence of Fusarium ear rot.It is recommended that preventive application in production is more conducive to reducing corn sickle. |
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