Phytotoxicants from microorganisms and related compounds

Phytotoxic compounds produced by microorganisms are reviewed. Their utilisation as leads to new herbicides is explored in three chemical classes : 2-aminoalk-3-enoic acids, ether derivatives of 3-hydroxycyclobut-3-ene-1,2-diones, and 2-(acylaminooxy)acetic acid derivatives. It is concluded that some bacteria and fungi yield compounds possessing sufficient herbicidal activity to be valuable as herbicides as such, or as leads for chemical optimisation.