Fuente: WIPO "tomato" The present invention provides a compound which exhibits an excellent effect as an agricultural and horticultural chemical agent, especially as an agricultural and horticultural bactericide. The present invention provides, as an active ingredient, a hydrazone derivative represented by formula (1) or a salt thereof. In the formula, R1 represents a hydrogen atom, a C1-6 alkyl group, or the like; R2 represents a formyl group, or may form a group represented by formula (2) together with R1; and R5 represents OR6 or NR7R8, wherein R6 represents a C1-6 alkyl group, R7 represents a hydrogen atom or a C1-6 alkyl group, and R8 represents a C1-6 alkyl group, or R7 and R8 may bond to each other and, together with the nitrogen atom to which R7 and R8 are bonded, form a saturated 4- to 7-membered ring.