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.
