Control Effects on Two Pathogenic Fungi of Pepper(Capsicum annuum)by Biological Fungicides
To ascertain the efficacy of various biocides as a means of biological control for diseases affecting Guizhou pepper,the pathogenic fungi Botrytis cinerea and Fusarium graminearum were selected as the research subjects,and the inhibitory efficacy of four biocides on the growth of hyphae,the virulence in an indoor environment,their conductivity,and the leakage of nucleic acids were determined.A propidium iodide solution(PI)staining test was carried out to further investigate the effects of the biocides on the cell membranes of the fungi to ascertain their effectiveness.The results demonstrated that among the four biofungicides,0.5%picrasidine aqueous solution exhibited the most significant inhibitory effect on Botrytis cinerea,with a half-maximum effect concentration(EC50)of 156.675 1 mg/L.This was followed by 10%polymyxin wettable powder,4%kasugamycin aqueous solution and 28%validamycin soluble powder,with EC50 of 598.681 4,1 485.473 9,2 449.178 1 mg/L,respectively.0.5%picrasidine aqueous solution exhibited the greatest inhibitory effect on Fusarium graminearum,with an EC50 of 162.536 8 mg/L.This was followed by 10%polymyxin wettable powder,28%validamycin soluble powder,and 4%kasugamycin aqueous solution,with EC50 of 577.307 7,1 833.176 6,1 963.849 1 mg/L.The mycelial conductivity of pathogenic fungi increased following biocide treatment,with the absorbance value at OD260 of the treated group exhibiting a significantly higher level than that of the control(untreated with biocide)at 8 h(P<0.05).The results of the PI test indicated that the biocides had an obvious damaging effect on the cell membrane of pathogenic fungi,exerting their inhibitory effect by destroying the integrity of the cell membrane.In conclusion,the results demonstrate that both 0.5%picrasidine aqueous solution and 10%polymyxin wettable powder inhibit the mycelial growth of both Botrytis cinerea and Fusarium graminearum.The two biofungicides can be employed as biocontrol agents for pepper diseases caused by Botrytis cinerea and Fusarium graminearum.
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