Northern Corn Leaf Blight Disease Pathogen Identification And Its Control In Qingdao City

Maize（Zea Mays L.）is an important crop and is widely cultivated worldwide.It plays an important role in protecting food security in China.Northern corn leaf blight（NCLB）is a serious disease infecting maize in northern corn-producing regions in China,causing serious losses in maize quality and yield.Qingdao is one of the important corn-producing regions in Shandong Province.However the occurrence of NCLB is unclear.In this study,we investigated the incidence of NCLB in Qingdao city,isolated and identified the pathogens causing NCLB,determined their mating type,screened maize varieties and high efficiency and low toxicity chemical agents against NCLB.The main results are as follows:（1）NCLB incidence in Qingdao city was investigated.We investigated NCLB incidence in West Coast New Area,Jimo,Jiaozhou,Pingdu and Laixi,by a five-point sampling strategy.The results showed that the incidences among different regions are different,in which a field in Jiangshan town of Laixi city has the highest disease index（34.00）.（2）11 strains of pathogens causing NCLB was isolated and identified and their mating types were determined.We isolated and identified the pathogens from the samples displaying typical symptoms of NCLB and obtained 11 strains.It showed that the morphology of the colony and conidium of the strains from different sampling sites are varied.The mating-type analysis showed that five belong to Type A（45.45%）and six strains belong to Type a（54.55%）,respectively.（3）In total 15 maize varieties showing high resistance to NCLB was obtained.The resistance of 24 maize varieties against NCLB was screened by artificial inoculation.Results showed that 15 maize varieties,including Zhengdan 7137,Longxin 100 and Hongda11,etc.,showed high resistance to NCLB;Qingnong 1 is resistant to NCLB;Four maize varieties,including Zhongnongdan 78 and Liyu 16,etc.,showed moderate resistance to NCLB;Ludan 9169 and Denghai 605 showed susceptible to NCLB.（4）Two high efficiency and low toxicity fungicides for controlling the NCLB was obtained.We compared six chemical agents on controlling NCLB.Results showed that18.7% propiconazole·azoxystrobin（SE）and 32.5% difenoconazole·azoxystrobin（SC）showed the best effect,with the control efficacy above 90%.The control efficacy of 25%propiconazole（EC）and 70% thiophanate-methyl（WP）was 88.92% and 83.38%,respectively.The control effects of 80% mancozeb（WP）and 50% carbendazim（WP）were77.68% and 77.20%,respectively.