Factors associated with the decline of Euphorbia ingens in the Limpopo Province of South Africa

Abstract

The genus Euphorbia consists of a group of plants with a diverse morphology occurring all over the world. In South Africa species of the succulent Euphorbia trees are mostly found in the Northern provinces with Euphorbia ingens being the largest. In the last 10 years, symptoms of the disease have been reported on E. ingens trees in the Limpopo Province, which led to mass mortality. Pilot studies did not reveal a specific abiotic or biotic factor as the primary cause of the decline and the problem seems to result from a combination of these factors. The genus Euphorbia and specifically E. ingens is reviewed revealing the limited information known of insects and pathogens and the associated death of these trees. Climate change is also addressed in this review with examples from other countries as a possible factors leading to the deaths of E. ingens. To gain a better understanding into the deaths of E. ingens all factors will be investigated by expanding on the previous pilot studies done in the Limpopo Province and conducting comparative studies in areas where the trees are not as severely affected.