Lasiodiplodia species associated with dying Euphorbia ingens in South Africa

Abstract

Various species of Euphorbia occur in South Africa, including herbaceous, succulent and woody types. The largest of the succulent Euphorbia spp. in South Africa is Euphorbia ingens. These trees have been dying at an alarming rate in the Limpopo Province during the course of the last 15 years. Investigations into the possible causes of the death have included the possible role of fungal pathogens. Amongst the most common fungi isolated from diseased trees were species in the Botryosphaeriaceae. The aim of this study was to identify these fungi using morphology and DNA sequence data of two gene regions (TEF-1α & ITS). Results showed that Lasiodiplodia theobromae and Lasiodiplodia mahajangana were present. Pathogenicity studies showed that these Lasiodiplodia species can cause infections on healthy E. ingens trees, implicating them as contributors to the decline of E. ingens.