Fusarium circinatum and pitch canker of Pinus in Colombia

Abstract

Pitch canker, caused by the ascomycete fungus Fusarium circinatum, infects a wide range of Pinus species. The pathogen has a global distribution and limits plantation productivity wherever susceptible Pinus species are commercially cultivated. During 2005-2007, symptoms typical of those associated with F. circinatum were observed in Colombia on nursery seedlings of P. maximinoi, P. tecunumanii and P. patula, as well as established P. patula and P. kesiya trees in plantations. Symptoms on seedlings included collar and root disease while shoot dieback and resinous stem cankers were found on trees in plantations. The aim of this study was to isolate and identify the causal agent of these symptoms and to evaluate the relative tolerance of various families of Pinus species commonly grown in Colombia. By making use of morphology and DNA-based methods, as well as pathogenicity tests on P. patula seedlings, it was possible to show that the symptoms observed in the nursery and field were caused by F. circinatum. Furthermore, the results of pathogenicity tests with two virulent isolates of the pathogen indicated that P. tecunumanii from lowelevation sources and P. maximinoi are significantly more tolerant to infection by F. circinatum than P. tecunumanii from high-elevation sources and P. patula. These results show that there is substantial opportunity to avoid losses due to infection by F. circinatum through deployment of resistant planting stock.