Screening for plant extracts to control potato late blight

Abstract

Six extracts from plant material (Galla chinensis, Potentilla erecta, Rheum rhabarbarum, Salviae officinalis, Sophora flavescens, and Terminalia chebula) were tested for controlling effects against the infection of Phytophthora infestans on detached potato leaves, seedlings, and tuber slices. On detached leaves, G. chinensis (2%), R. rhabarbarum (rhizome, 2%) and S. flavescens (2%) extracts showed a significant control effect, with a control efficacy of 96.67%, G. chinensis was the best. On seedlings R. rhabarbarum (rhizome, 2%) showed the best inhibiting effect, followed by S. flavescens (2%), T. chebula (1%), and G. chinensis (2%). The control efficacies were 91.67%, 75.00%, 70.24%, and 64.29%, respectively on the seventh day after inoculation. However, on potato slices, none of the plant extracts showed effective protection against infection and sporangia production by P. infestans. The reason was analyzed and the potential for developing a natural fungicide based on these plant materials was discussed.