Study On The Biological Characteristics And Variety Resistance Of Exserohilum Turcicum In Shanxi Province

Northern corn leaf blight disease is an important disease for corn and seriously restricts the development of corn industry.The incidence,epidemic and damage characteristics have been greatly changed with the planting pattern change and resistance variety popularization in recent years.Northern corn leaf blight disease has heavily aggravated and seriously affects the quality and yield of corn in Shanxi Province.In order to prevent and control more effectively its occurrence and prevalence,pathogen distribution,biological characteristics and disease resistance identification combinated with morphological identification were studied in the study based on the samples collected from the north,the center,the south in Shanxi Province.It aims to provide a theoretical basis for the identification and breeding of northern corn leaf blight in Shanxi Province.The results are as follows:1.180 Exserohilum turcicum pathogens strains were isolated and purified from 36 counties and cities from 2017 and 2018 in Shanxi Province.The results showed that there are some differences in the morphology and cultural characters of pathogens collected from the south to the north in Shanxi Province,especially the pathogen strain collected from Yuncheng City.It showed that there is a significant difference and variation of Exserohilum turcicum in different districts of Shanxi Province.2.Biological characteristics of northern corn leaf blight in different geographical districts of Shanxi Province was studied The results showed that nitrogen sources,carbon sources,p H value and temperature had significant effects on mycelial growth and colony morphology of Exserohilum turcicum in different districts.Among them,the best results were potassium nitrate,p H 6.5 and 25 °C,but carbon source has no significant difference.3.Field resistance identification of 210 varieties in 2017 and 243 varieties in 2018 were tested.The results showed that most varieties generally have high resistance to northern corn leaf blight,but no immune species are found,and the ratio of high-sensitivity varieties is very low.The resistance of corn varieties to northern corn leaf blight is middle-resistant(MR)or above.In general,varieties with longer growth period have higher resistance to northern corn leaf blight than those with shorter growth period.