Forest Health News 2018

PLANTING TREES TO CONSERVE GENETIC RESISTANCE to White Pine Blister Rust in Southwestern White Pine

By Greg Reynolds, USDA Forest Service

April 2018

Planting trees to conserve genetic resistance to white pine blister rust. Photo by: Greg Reynolds.

Region 3 Forest Health Protection continued a partnership with New Mexico State University’s (NMSU) John T. Harrington Forestry Research Center in Mora, NM; the US Forest Service Dorena Genetic Resource Center (DGRC; Cottage Grove, OR); and Northern Arizona University to conserve genetic resistance to white pine blister rust (WPBR), caused by the introduced fungus Cronartium ribicola, in southwestern white pine (SWWP). In 2017, the first of two regional plantings was established on the Mescalero Apache Reservation in the Sacramento Mountains of New Mexico. Families of SWWP identified at DGRC as having some level of resistance to WPBR were planted along with known susceptible families to monitor for durability of resistance and the efficacy of the resistance mechanisms against local races of the pathogen. These seedlings will be monitored over time for WPBR symptoms and associated mortality. Scion material was also collected from several trees in New Mexico identified by DGRC as resistant to WPBR. The material is being grafted into a seed orchard by NMSU that will eventually be able to provide WPBR-resistant seed for replanting SWWP in areas devastated by the disease or catastrophic fires.

For more information contact: Greg Reynolds, Forest Pathologist