The Action Mechanism Of Prothionazole Against Rice Sheath Blight

Prothioneazole is a broad-spectrum triazole fungicide developed by Bayer Company in the United States and marketed in the United States in 2004.Triazole fungicide has high bactericidal activity,wide action range and good compatibility with the environment.It is a widely used fungicide at present.In this paper,the effects of prothionazole on rice sheath blight were studied systematically.The effects of prothionazole on the activity of rice sheath blight were studied by field experiment and virulence determination.The mechanism of action of prothioneazole was preliminarily confirmed by morphological observation,DNA and protein content determination,ergosterol content change,induced disease resistance and pathogenic mechanism study.The main conclusions are as follows:1.Control effect of prothionazole on rice sheath blightThe results of field efficacy experiment showed that 4.8×10⁵mg/L prothionazole suspension of 400 mg/L,480 mg/L and 560 mg/L had good control effect on rice sheath blight,and the control effect could reach 90.40%,96.29%and 98.17%,respectively,7 days after treatment.The control effects were 89.11%,92.57%and 96.87%after 14 days,respectively.The control effect was similar to that of the control agent,thiofuramide.2.Sensitivity of rice sheath blight to prothionazoleThe results of virulence test showed that prothionazole had high antibacterial activity against 94 strains of rice sheath blight,and the inhibitory effect was enhanced with the increase of concentration.The best inhibitory effect against rice sheath blight strain AHGD1 was EC₅₀value of 0.1365 mg/L.The EC₅₀value of AHFT6 was 4.6692 mg/L.The average EC₅₀value of these strains was 1.0629±0.7959 mg/L.Propyrithiazole indirectly inhibits sclerotia formation by inhibiting mycelium growth.There was no significant difference in resistance levels among the strains,and the distribution of resistance levels was relatively concentrated.There was no resistance population with reduced sensitivity.All the 94 strains were prothioxazole sensitive strains.The average EC₅₀value of these strains（1.0629±0.7959 mg/L）could be used as the baseline of the sensitivity of rice stripblight bacteria to prothioxazole in this area,and the difference of EC₅₀value was independent of geographical location.3.Safety of prothionazole on riceThe safety evaluation of prothionazole on rice showed that different concentrations of prothionazole had no significant effect on the normal germination,emergence and growth of seeds.There is no risk of harm.4.Inhibitory effect of prothionazole on rice sheath blightThe changes in DNA content,soluble protein content,and ergosterol content in the hyphae of Rhizoctonia solani treated with different concentrations of prothioconazole showed that prothioconazole was mainly reduced by the content of sterols,and at the same time it would lead to the osmotic pressure of mycelial cells,The degree of mycelial lipid peroxidation increased,while the DNA content and soluble protein content decreased.5.Effect of prothionazole on defense enzyme activity in riceThe results showed that the activities of POD,CAT,SOD and PAL showed an increasing trend under the action of a series of insecticides,and had certain inductive disease resistance.Compared with Jinggangmycin which had the ability of inducing resistance,prothiomycin had the stronger ability of inducing resistance.6.Effect of prothionazole on cell wall degrading enzyme activity of rice sheath blight fungusThe results showed that the overall activities of PG,PMG and CX cell wall degrading enzymes were lower than those of the control group,and the activities of all cell wall degrading enzymes were lower,and the chemical agents had the strongest effect on the activities of PG and PMG.The results indicated that the concentration of a series of agents had a good inhibitory effect on the infection of the pathogen.Combined with the induced resistance experiment of prothionazole,it was concluded that prothionazole had not only therapeutic effect but also preventive effect on the control of rice sheath blight.