Seedling inoculation distinguishes lodgepole pine families most and least susceptible to gall rust

Resistance of lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) to western gall rust (Endocronartium hrknessii (J.P. Moore) Y. Hi ratsuka) was compared between 21-year field infection trials and inoculatio n of 2-month-old seedlings. The seedlings were produced from seed stored si nce the original field plantings. Virtu ally all of the seedlings from fami lies identified as susceptible in the field produced galls in the inoculati on trial, only 1% of seedlings from these families did not develop galls. N early half the seedlings in families classed as resistant in the field tria ls did not form galls 13 months after inoculation. Only one of these seedli ngs developed galls in the following 2 years. Seedling inoculation provides a simple early test to assess field resistance to gall rust of lodgepole p ine seedlots, and an efficient way to cull at least the most susceptible on es.