Leaf Neoplasia Pathogen on Euryale ferox:Biological Characteristics and Fungicide Screening
Leaf neoplasia was one of the important diseases affecting aquatic vegetables such as Euryale ferox.To clarify the optimal conditions for the preservation of the pathogen causing Euryale ferox leaf neoplasia,a method based on the rate of mycelial growth was employed to investigate the effect of the temperature,pH,carbon source and nitrogen source on the growth of the pathogen's mycelial.To screen out fungicides for the control of this disease,laboratory toxicity tests were conducted to determine the inhibitory rate of single and mixed fungicides against the pathogen,followed by field efficacy trails to assess the control effects of single fungicides on Euryale ferox leaf neoplasia.The results indicated that the optimal temperature for mycelial growth was 30℃,and the most favorable pH 7.The preferred carbon and nitrogen sources were glucose and ammonium nitrate,respectively.The laboratory toxicity assays revealed that the EC50 values for the tested fungicides against the pathogen were 0.8992 mg/L for tebuconazole,0.6531 mg/L for pyraclostrobin,0.1650 mg/L for prothioconazole,1.8751 mg/L for difenoconazole,0.9227 mg/L for epoxiconazol,2.3432 mg/L for propiconazole,and 6.0517 mg/L for azoxystrobin.Among these,tebuconazole,pyraclostrobin and prothioconazole exhibited strong inhibitory activities.The field efficacy trials demonstrated that the control effect of tebuconazole,pyraclostrobin and prothioconazole against Euryale ferox leaf neoplasia were 94.36％,85.64％,and 82.56％,respectively.In door joint toxicities test,tebuconazole and pyraclostrobin were combined in a ratio of 1∶1,1∶2,1∶3,1∶4,1∶5,5∶1,4∶1,3∶1 and 2∶1 by weight.The combination of 5∶1 showed synergistic effect,with the synergistic ratio(SR)of 1.5029,indicating that this formulation could be effectively used for the control of Euryale ferox leaf neoplasia in agricultural practices.
Euryale feroxleaf neoplasiapreservation condition of the pathogenbiological characteristicsfungicide screeninggrowth rate methodtoxicity testfield efficacy trial
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