| Benziothiazolinone is a compound invented by Professor Song Disheng of Northwest University in 1984,and currently being used in the field of plant production to control plant diseases.In this study,nine kinds of plant pathogens with different classification status were used as indicator bacteria,and the antibacterial activity of benziothiazolinone was determined.The results showed that benziothiazolinone not only had a strong antibacterial activity against plant pathogenic fungi,but also had a good inhibitory effect on the reproduction of plant pathogenic bacteria.The EC50 value of benziothiazolinone for Acidovorax citrulli which cause bacterial fruit blotch of watermelon was 48.77 mg/L,while the EC50 value of streptomycin was 822.75 mg/L,and the relative toxicity index was 1687.The EC50 values of benziothiazolinone for Erwinia amylovory,Dickeya fangzhongdai,Xanthomonas oryzae pv.oryzae,Pectobacterium carotovorum subsp.brasiliense,Clavibacter michiganensis subsp.Michiganensis were 34.87,5.07,25.93,32.65 mg/L,respectively.and their relative toxicity indices were 2525.68,1492.92,431.38,400.70,151.48,respectively.Bacterial fruit blotch of watermelon is a seed-borne disease,in order to study the control effect of benziothiazolinone on the disease systematically,five chemical agents were selected for indoor toxicity test and seed soaking treatment experiments in the study.The results showed that benziothiazolinone had the best antibacterial effect among the tested chemicals,the EC50 value was 67.41 mg/L;the inhibition effect was better by soaking the inoculated seeds with 250 mg/L benziothiazolinone for 1 h before sowing,and the growth of roots was promoted during germination,the control effect and root length were 95.94%and 13.54 mm respectively.In order to further understand the control effect of benziothiazolinone,commercial chemicals of benziothiazolinone were selected for seed dressing test and foiar spary trial,the results demonstrated that contaminated seeds dressing treament with 10 times solution of BanShengYuan（4%Fludioxonil·Benziothiazolinone）can effectively improve germination and significantly reduce diasese incidence,it was only 0.06%;foliar spary with 1000 times solution of XiSha（3%benziothiazolinone）can effectively control bacterial fruit blotch of watermelon,and the control effect was 71.35%.Pear fire blight is a devastating disease on pear trees,although streptomycin can control the disease to a certain extent,but it was banned in 2016.In order to screen out effective agents that can replace streptomycin,the study conducted indoor toxicity test on 15 kinds of bactericides including benziothiazolinone.The results showed that the seven agents had a certain inhibitory effect on the growth of Erwinia amylovora,of which tetramycin,shenqinmycin,zhongshengmycin,benziothiazolinone and streptomycin have better inhibitory effects,the EC50 values were 0.39,42.69,219.11,233.25,359.40 mg/L,respectively,but Bordeaux mixture+Mancozeb and Chlorobromoisocya-nuric acid had poor antibacterial effects.In addition,Tetramycin,zhongshengmycin,benziothiazolinone and streptomycin with highly toxicity were selected for filed control trials in this study.The results showed that the four bactericides had good control effects on pear fire blight.The control effect of benziothiazolinone is the best,each trial was above 80%,which was significantly higher than the other three bactericides.There are many antagonistic bacteria in the rhizosphere soil and plants,which can effectively inhibit the growth of plant pathogens and can be developed into an ideal biocontrol agent.In this experiment,95 strains of bacteria were isolated from the fruits,branches,leaves,bark,and rhizosphere soil of the pear tree.By indoor plate confrontation experiments,four types of bacteria（numbers C,XX2,19,21）were screened,these bacteria had a good inhibitory effect against Erwinia amylovora which cause pear fire blight,of which strains C was best,the average bacteriostatic diameter was 9.33 mm.Based on morphological observation,16S rDNA sequence and gyrA gene sequence analysis,strain C was identified as Bacillus amyloliquefaciens.In addition,strain C was made into two kinds of biocontrol agents with water-soluble starch and maltodextrin as filler,and the number of live bacteria and their antagonist effect were measured indoors.The results showed that after making into biocontrol agents,strain C can maintain its activity for a long time.Moreover,biocontrol agents can effectively inhibit the growth of Erwinia awylovora after being diluted 100 to 1600 times.The inhibitory effect was the best when 400 times solution,the average bacteriostatic diameter were 13.83,13.08 mm,respectively。... |
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