Polyphenols as fungal phytotoxins, seed germination stimulants and phytoalexins

This review deals with the sources and chemical and biological characterization of phytotoxic polyphenols produced essentially by pathogenic fungi of forest and crop plants and of weeds. Their potential use as natural herbicides and fungicides is discussed. The use of some polyphenols which could be applied as an alternative method to control parasitic weeds, the so called ``suicidal germination{''}, will be covered. The sources and the isolation and identification of polyphenols produced by some crop plants in consequence of the attack of pathogenic fungi as plant defence compounds (phytoalexins), are also described.