Relative susceptibility of northern and southern provenances of Pinus greggii to infection by Sphaeropsis sapinea.
Sphaeropsis sapinea is a well-known pathogen of Pinus spp. that causes severe dieback, in South Africa. In this study, 65 families representing both the northern and southern populations of Pinus greggii were evaluated for their tolerance to infection and subsequent die-back caused by S. sapinea. Families were evaluated for tolerance following natural infection after hail damage, as well as through inoculation. Variation in tolerance of trees after natural infections, occurred amongst families of both the northern and southern provenances, but highly significant differences in tolerance were observed between the two provenances. P. greggii trees of the southern provenances were significantly more susceptible to natural infection after hail damage. Artificial infection was not suitable for prediction of susceptibility to natural infection after hail damage. These observations have significant practical implications for plantation establishment in South Africa.