QUANTITATIVE STRUCTURE-ACTIVITY-RELATIONSHIPS FOR THE ANTI-RICE BLASTACTIVITY OF O,O-DIARYL DICHLOROMETHYL PHOSPHONATES

The relationships between the structures of a series of O,O-diaryl dic hloromethyl phosphonates and their activity against Pyricularia oryzae Cav., the causal organism of blast disease of rice, have been analyse d by means of multiple regression analysis using physico-chemical subs tituent parameters for hydrophobic, electronic and steric properties. The anti-rice blast activity of these compounds has an inverse parabol ic relationship with hydrophobicity of the compounds; it increases wit h electron-withdrawing character of the substituents and decreases wit h the bulkiness of para-substituents in the benzene ring.