Pathogenicity of Phytophthora species to ornamental plant Plectranthus scutellarioides

Abstract

Pathogenicity of seven Phytophthora species (P. plurivora, P. citricola, P. lacustris, P. gonapodyides, P. chlamydospora, P. pseudocryptogea and P. hydropathica) to ornamental plant Plectranthus scutellarioides was evaluated. Susceptibility of the tested plant to the selected pathogens was analyzed by a baiting technique with detached leaves and an infection of cuttings. P. pseudocryptogea was determined as the most aggressive pathogen to the coleus plant according to the results of both methods. P. lacustris, P. gonapodyides, P. chlamydospora and P. hydropathica induced comparable disease symptoms on tested leaves as well as cuttings. P. plurivora and P. citricola demonstrated less aggressiveness to leaves of P. scutellarioides, but strongly inhibited the growth of the roots of the cuttings. All tested Phytophthora species were recognized as a real threat for coleus plants in their natural habitat, but they could also compromise its cultivation in greenhouses, nurseries and parks. In addition, the ability of the fungicide azoxystrobin for an effective control of Phytophthora species was proved.