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

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