Differential responses of Central American and Mexican pine species and Pinus radiata to infection by the pitch canker fungus

Seedlings from a wide array of 23 species, varieties, and geographic races were screened for resistance to pitch canker using artificial inoculation i n a greenhouse. Seed to represent these taxa were generally collected in na tural stands. In addition, seedlings from 79 families of P. radiata from co mmercial populations from Chile and New Zealand were screened in a separate experiment. There was little variation in resistance among the commercial P. radiata families, with over 98% mortality. Similar results were obtained with native P. radiata populations. All close relatives of P. radiata (sub -section Patula) were very susceptible. However, a number of closed-cone pi ne species (specifically, from sub-section Oocarpa) were generally very res istant, with survival approaching 100%. In addition, in P. oocarpa, P. jali scana, and P. tecunumanii from low elevation provenances an extremely high frequency of trees suffered no apparent damage from the pathogen (92%, 85% and 80%, respectively).