Structure-activity Relationships of N-Methyl-2′-methoxybenzanilides against Rice Blast: Fungicidal Activity of N-Methylbenzanilides (Part 2)

The thirty-four N-methyl-2′-methoxy (substituted) benzanilides were synthesized and their preventive activities against rice blast were studied by the pot test. The substitution at the para-position of benzoyl moiety varied the activity to various extents. The inhibitory activity of N-methyl-2′-methoxy-4-substituted benzanilides on the penetration of infection pegs from appressoria of Pyricularia oryzae were also measured by using cellophane film as a model of plant cell walls and the structure-activity relationships were analyzed using the physicochemical parameters and regression analysis. The inhibitory activities were related to the bulkiness and electronic effect of the substituents and parabolically to the hydrophobicity of the molecules.