Development Of 20% Pyraclostrobine·Metconazole Supension Based On Fusarium Head Blight Control

Wheat is an important grain crop in China,and fusarium head is one of the main diseases that affect wheat.Fusarium head blight is a global disease,the pathogen is mostly Fusarium graminearum,which can produce a mass of fungaltoxin and damage to the human health.In the production of chemical agents used to control fusarium head are mainly carbendazim,tebuconazole etc,but due to the perennial single use of these agents,resulting in fusarium head on these traditional agents have produced resistance.The combination of agents with different mechanisms of action is an effective way to improve the effectiveness of Fusarium head blight and delay the development of resistance to the agent.Based on this,this paper conducted laboratory activity determination,compound and synergia study,preparation of suspension,performance index testing of suspension,and field efficacy tests of fungicides etc.The main results obtained in this thesis are as follows:1.The indoor activity of nine commonly used fungicides agaist Fusarium graminearum was measured by the mycelial growth rate method,and based on the indoor activity,the binary combination of pyraclostrobin and metconazole were selected for this experiment,with EC₅₀of 0.65μg/m L and 0.13μg/m L,respectively.The combined virulence of pyraclostrobin and metconazole were determined by the Wadley method,and the most obvious synergistic effect was observed when pyraclostrobin:metconazole was7:3 and the synergistic coefficient was 2.39.2.According to the optimal compounding ratio obtained from the screening,the wetting and dispersing agent types and dosage ratios were screened using the controlled variable method and orthogonal tests,other auxiliary types and dosages were screened,and the final formulation of 20%pyraclostrobin·metconazole suspension was determined as follows:14%pyraclostrobin,6%metconazole,2%SC wetting and dispersing agent,1%500LQ wetting and dispersing agent,1%D-425 wetting and dispersing agent,1%magnesium aluminum silicate thickener,0.26%xanthan gum thickener,5%ethylene glycol antifreeze agent,0.2%AF1501 defoamer,0.2%kathon preservative,0.2%citric acid p H regulator.3.According to the national standard to detection all control items of 20%pyraclostrobin·metconazole suspension,and its active ingredient concentration,suspension rate,particle size,lasting foaming,pouring,storage stability,and p H value all conformed to the standard.4.Select and use 20%pyraclostrobin·metconazole suspension to conduct field efficacy trials,the results showed that the efficacy of the 20%pyraclostrobin·metconazole suspension was 79.65%and 75.36%at the dosage of 135g a.i./hm²and 105g a.i./hm²of active ingredient,respectively.In this paper,the indoor biological activity of nine fungicides against Fusarium graminearum was measured,and the more active pyraclostrobin and metconazole were selected for compounding and synergistic study.20%pyraclostrobin·metconazole suspension was successfully developed according to the optimal ratio,and the formulation was verified in field trials to provide a candidate agent for later chemical control of Fusarium head blight.