Field Tour Stop 3: Testing Resistant Western White Pine: MGR Field Trial Stefan Zeglen, FLNRO, Nanaimo Despite prodding by geneticists and forest pathologists, foresters have been reluctant to reintroduce white pine into new plantings due to the historic unreliability of the species. To demonstrate that planting white pine will not be a futile endeavour forever, a trial was started in 2001 using some of the first major gene resistant (MGR) seed available in BC. Three sites were selected (Slesse Creek (DCK), Beavertail (DCR) and Eagle Heights (DSI)), in roughly decreasing order of rust pressure. Five seedlots (three MGR and two “controls” from Texada Island) were planted in random rows across five plots on the three sites. Figure 1 shows the health status of the seedlots across all sites after 15 growing seasons. Note the percent of uninfected Texada white pine is much lower than any of the Dorena seedlots. Culling out the trees killed by causes other than rust and averaging over all the sites, the percentage of uninfected Texada trees is about 12% vs 60% for the Dorena trees. Currently infected trees are 40% vs 14%, respectively. Survival of white pine depends on the risk of infection which is driven primarily by the abundance of Ribes sp on or near a site. More Ribes means more mortality. The trial also showed differences in the amount and timing of infection and mortality by site (Figures 2a and b). Survival at Eagle Heights (moderate) is 63% and just over 50% at Slesse (Valley of Doom). Currently available MGR material should convey at least 50% survival. Figure 2. Trends in infection and mortality of MGR trees at two sites. Figure 1. Tree survival by seedlot after 15 growing seasons. Coastal Silviculture Committee – Summer Field Tour Campbell River, BC June 2018