Screening Of Efficient Fungicides And Field Efficacy Trials To Control Main Diseases Of Sesame

Sesame is one of the traditional oil crops in China.Sesame products are loved by people.In recent years,the demand for sesame is increasing.Because the whole growth period of sesame is in the environment of high temperature and humidity in summer,it is easy to be infected by pathogenic bacteria,and the disease is more serious in the sesame planting area of China,which is caused by Fusarium oxysporum Fusarium Wilt of sesame caused by Fusarium oxysporum f.sp.sesami(Xaprometoff)Castellani and stem spot blight of sesame caused by Macrophomina Phaseolina are common and difficult to control diseases on sesame,which seriously affect the yield and quality of sesame.There are few reports on the screening of soil borne diseases of sesame at home and abroad.At present,only the fungicides of difenoconazole and nuclear polyhedrosis virus have been registered in sesame in China,and there are no registered fungicides to control stem blight and Fusarium Wilt of sesame.In this study,the fungicides with high activity to Fusarium oxysporum and stem blight of sesame were screened out by mycelial growth rate method,and the safety of the fungicides to the growth of sesame was evaluated.The field test verified the field control effect of the high activity fungicides.The main results are as follows:1.The inhibition toxicity of pyrrolidin,difenoconazole and azoxystrobin to the growth of Fusarium oxysporum was the highest.The EC50 values were 0.176 mg/L,0.463 mg/L and 0.719 mg/L,respectively,which were 45.16,17.17 and 11.06 times of carbendazim.The EC50 of prochloraz was 3.9481 mg/L,and its toxicity was slightly higher than that of carbendazim.Amino oligosaccharide had no direct inhibitory effect on Fusarium oxysporum.The inhibition toxicity of fipronil,difenoconazole and prochlorazole to the mycelial growth of Macrophomina Phaseolina was the highest,EC50 was 0.032 mg/L,0.192 mg/L and 0.315 mg/L,respectively,which were 216.22 times,36.04 times and 21.97 times of carbendazim.EC50 of azoxystrobin was 6.919 mg/L,and its toxicity was slightly lower than carbendazim.Amino oligosaccharide had no direct inhibitory effect on the pathogen of Macrophomina Phaseolina.2.In the light incubator,the safety test of six kinds of medicament on sesame seed soaking was carried out.The results showed that prochloraz had obvious inhibiting effect on sesame seed germination,which was not safe.Other medicament had no adverse effect on sesame seed germination.Under the potted plant conditions,5 kinds of spray agents were used to test the safety of sesame seedlings.The results showed that pyrazonitrile,diphenoxazole,amino oligosaccharide,carbendazim and azoxime were safe for sesame growth.The results showed that the seed treatment with clomionitrile and difenoconazole was safe for the emergence and growth of sesame.3.Field efficacy trials showed that the incidence rate of sesame wilt and stem blight was significantly reduced by the mixture of pyrimidine ester and levonitrile suspension seed coating.The effective component dosage of 25 g/L suspension seed coating agent was 12.5 g/100 kg.The control effect of seed dressing treatment on Fusarium Wilt and stem spot blight of sesame was 73.27% and 62.85%,respectively,which was significantly higher than that of 30 g / L suspension seed coating agent of difenoconazole.At the blooming stage of sesame,25% azoxystrobin suspension was used to spray 225 g/ha of effective components on the root and stem of sesame to control Fusarium Wilt and stem spot blight,with an average control effect of 77.44% and 79.37% respectively,significantly higher than that of difenoconazole.4.According to the evaluation of the comprehensive test results,the treatment of seed dressing with fipronil has a good preventive effect on the Fusarium Wilt and stem spot blight of sesame,with a long period of validity.The recommended field dosage is 10~12.5g/100 kg seeds of effective ingredients.The application of pyrimidine ester in sesame growing season,especially at flowering stage,can prevent and control sesame wilt and stem blight effectively.It is recommended that field dosage is 168.75~225.0 g/ha.Both pyrrolizonitrile and azoxystrobin are safe and effective agents for controlling Fusarium Wilt and stem spot blight of sesame.