NOVELTY - Agricultural fungicide synthesis involves dissolving 3-isochromanone as raw material in inert solvent under stirring condition, and then adding alkoxide anion source and acid alkyl ester or acid aryl ester at -10-60 degrees C. The resulting mixture is reacted for 1-12 hours to give 4-( alpha -hydroxy)methylene-2H-benzopyran-3-(4H)-one after performing acidification, extraction and distillation. The obtained 4-( alpha -hydroxy)methylene-2H-benzopyran-3-(4H)-one is dissolved in another inert solvent with base and methyl reagent at -10-60 degrees C for 1-12 hours.    USE - Method for synthesizing agricultural fungicide (claimed).    ADVANTAGE - The method synthesizes agricultural fungicide in a simple, cost-effective and eco-friendly manner on industrial scale in a reduced process.    DETAILED DESCRIPTION - Agricultural fungicide synthesis involves dissolving 3-isochromanone as raw material in inert solvent under stirring condition, and then adding alkoxide anion source and acid alkyl ester or acid aryl ester at -10-60 degrees C. The resulting mixture is reacted for 1-12 hours to give 4-( alpha -hydroxy)methylene-2H-benzopyran-3-(4H)-one after performing acidification, extraction and distillation. The obtained 4-( alpha -hydroxy)methylene-2H-benzopyran-3-(4H)-one is dissolved in another inert solvent with base and methyl reagent at -10-60 degrees C for 1-12 hours, where the reaction mixture is extracted and washed with water to give 4-(methoxymethyl)-3-benzopyran-one. The obtained 4-(methoxymethyl)-3-benzopyran-one is dissolved in methanol with halogenating agent in an inert solvent at -10-120 degrees C for 2-12 hours to give (E)-2-(2-halo-methylphenyl)-3-methoxy-acrylate. The obtained compound (E)-2-(2-halo-methylphenyl)-3-methoxy-acrylate and 2-hydroxy-6-trifluoromethyl pyridine are dissolved under basic conditions in an inert solvent at 20-120 degrees C for 3-12 hours. The resulting mixture is treated at 50-120 degrees C for 5-10 hours to give 6-trifluoromethyl-2-pyridinol salt. The obtained 6-trifluoromethyl-2-pyridinol salt is dissolved in inert solvent at 20-120 degrees C for 3-12 hours to obtain picoxystrobin crude product. The obtained crude product is added in appropriate water, and then purified to give pure product.