NOVELTY - (4E)-4-(Methoxymethylidene)-3,4-dihydro-1H-2-benzopyran-3-one (II) is dissolved in methanol, inert solvent (S3) and halogenating agent, and reacted, to obtain (E)-2-(2-halo-methylphenyl)-3-methoxy acrylate (III). The compound (III) and 6-(trifluoromethyl)pyridin-2-ol (IV) are reacted under alkaline condition, to obtain picoxystrobin. Predetermined amount of water is added to obtained reaction mixture, extracted, solvent is separated by distillation, and obtained crude picoxystrobin is purified, to obtain picoxystrobin as agricultural fungicide.    USE - Synthesis of agricultural fungicide (claimed).    ADVANTAGE - The method enables economical and efficient synthesis of agricultural fungicide with high yield, excellent external appearance and external standard content of more than 98%, under mild reaction conditions, by simple and environmentally-friendly process.    DETAILED DESCRIPTION - 3,4-Dihydro-1H-2-benzopyran-3-one of formula (I) is dissolved in an inert solvent (S1), alkoxide anion source is added at -10 degrees C to 100 degrees C, alkyl formate or aryl formate is added, and resultant mixture is reacted at -10 degrees C to 60 degrees C for 1-12 hours. The reaction mixture is acidified, extracted using an inert solvent (S2), aqueous phase is separated from the extract, base (B1) and methylating agent are added to organic phase, and reacted at -10 degrees C to 60 degrees C for 1-12 hours. The reaction mixture is washed with water, extracted, and distilled, to obtain (4E)-4-(methoxymethylidene)-3,4-dihydro-1H-2-benzopyran-3-one of formula (II). The compound (II) is dissolved in methanol, inert solvent (S3) and halogenating agent, and reacted at -10 degrees C to 120 degrees C for 2-12 hours, to obtain (E)-2-(2-halo-methylphenyl)-3-methoxy acrylate of formula (III). Alternately, the compound (II) is dissolved in inert solvent (S3) and halogenating agent, reacted at -10 degrees C to 120 degrees C for 1-12 hours, halogenating agent is distilled from the reaction mixture, methanol is added to resultant reaction mixture and distilled, to obtain compound (III). The compound (III) and 6-(trifluoromethyl)pyridin-2-ol of formula (IV) are reacted at 20-120 degrees C for 3-12 hours under alkaline condition in an inert solvent (S4), to obtain picoxystrobin. Alternately, the compound (IV) is reacted with a base (B2) in presence of inert solvent (S5) at 50-120 degrees C for 5-10 hours, and distilled, to obtain 6-trifluoromethyl-2-pyridinol salt of formula (V). The compound (V) and compound (III) are reacted at 20-120 degrees C for 3-12 hours in presence of inert solvent (S6), to obtain picoxystrobin. Predetermined amount of water is added to obtained reaction mixture, extracted, solvent is separated by distillation, and obtained crude picoxystrobin is purified, to obtain picoxystrobin as agricultural fungicide.    X=not defined;and    M=metal atom.    N.B: X is not defined.