The soluble phenolic acids of the stems of three Capsicum annuum culti
vars associated with differing resistance to Phytophthora capsici show
ed qualitative and quantitative variation after inoculation, notably a
n increase in the total phenolic acid content in the resistant and int
ermediate varieties. The soluble phenolic acids also retarded mycelial
growth of P. capsici in culture. The most pronounced inhibitory effec
t was produced by t-cinnamic acid, followed by p-hydroxybenzoic, vanil
lic and salicylic acids. Colonization and necrosis spread throughout t
he stem of the susceptible cultivar whereas the stem of the resistant
cultivar was only partially invaded. In the latter, invasion of the ti
ssue adjacent to necrosis occurred in only 20% of the plants.