| The rot root of tomato caused by Fusarium oxysporum.f.sp.radicis-lycopersici is a destructive soilborne disease throughout the world,which impairs the production of tomato seriously.In recent years,the occurrence of root rot of tomato in China increase with the development of protected area.However,few reports about the measures for effective management on the root rot of tomato,growers are still using conventional fungicides excessively by flood irrigation,leading to a low efficiency,fungicides wasting,and serious environmental pollution.The author found that pyraclostrobin has a high level efficacy against the root rot of tomato through in vitro and field experiments,but using high concentration of pyraclostrobin EC by irrigating root results in slight phytotoxicity.This article is ready to explore the safety dose of pyraclostrobin in vitro experiment,and to evaluate the efficacy of different formulations of pyraclostrobin and different fungicides-applying ways in controlling root rot of tomato by pot experiment,as well as to determine the adsorption,leaching ability of different formulations of pyraclostrobin and explore the distribution of these compounds in soil and its efficacy in management the disease under the drip irrigation.The main contents are as follows:1.Under the root-irrigation by 100 m L water,the three formulations of pyraclostrobin at 30 mg/plant and 60 mg/plant were safe for tomato plants.At the 7 days after treatment,there were no obvious effects on tomato's plant height and stem diameter in three formulations.At 15 days after treatment,pyraclostrobin at 60 mg/plant obtained the highest plant height for 9.03 cm,which was significantly higher than that of other treatments.The effect of different dosage of the same formulation on tomato plant growth was same.There was no significant difference in stem growth between treatments.2.The efficacy of different fungicides-applying ways in controlling root rot of tomato were studied in pot experiments.At 7 days after treatment,there were no significant differences in the control efficacy of the three formulations of pyraclostrobin.At 45 days after treatment,pyraclostrobin CS has the highest efficacy,while pyraclostrobin EC 30 mg/plant had the lowest efficacy(43.38%).The control efficacy of pyraclostrobin CS was the highest at 45 days after treatment by once treatment,which was significantly higher than that of pyraclostrobin EC.Under the condition of twice treatment,the control efficacy of pyraclostrobin CS was 86.65%,82.05% and 74.91%,respectively at 45 days after treatment,but no significantly difference was observed between treatments.The control efficacy of pyraclostrobin 60 mg/plant by root irrigation was 73.72% at 45 days after the treatment.The efficacy of soil treatment and drip irrigation was lower,which are both 71.15%.3.The adsorption and leaching characteristics of pyraclostrobin in soil were studied by indoor oscillation balance,soil leaching and soil thin plate chromatography,and the distribution of pyraclostrobin in soil were studied under different drip irrigation conditions.The results showed that the ability of adsorption capacity,leaching and distribution of pyraclostrobin are SC>EC>CS,CS>EC>SC and SC>EC>CS,respectively.4.In field experiment,we studied the effects of different formulations of pyraclostrobin as well as the distribution of soil in different soils and different drip water.The results suggested that different formulations and treatment times exhibited different efficacy in controlling root rot of tomato.The efficacy of pyraclostrobin CS was higher than that of EC and SC at 90 days after the treatment,and the control efficacy was 85.18% and 88.63%,respectively.The efficacy of pyraclostrobin CS of twice treatment on the root rot of tomato was higher than that of other treatments.Root irrigation had the highest control efficacy was 78.25% and 87.21%,respectively.Next was drip irrigation method,the control efficacy was 73.89% and 84.53%,respectively.At 150 days after treatment,the control efficacy of drip irrigation was the highest has no obviously difference with root irrigation,and the efficacy of flood irrigation was the lowest.The amount of dripping water and the formulations of fungicides has impact on the distribution of the pyraclostrobin in the soil.In field expriments,the amount of dripping water is the main factor influencing the migration and diffusion of fungicides in the soil.The leaching and migration ability of fungicides may be changed by the amount of drip water,but the control efficacy increasing with the amount of dripping water increased,but difference was not significant.In the early stage of tomato growth,the three formulations of pyracolatrobin showed a high level effect on the rot of root rot.However,with the prolongation of time,the control efficacy of the three formulations decreased,but pyraclostrobin CS showed a favorable effect. |
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