Symptom Identification and Control Methods of Spruce Rust Disease

Spruce rust disease is distributed only in the **Tianshan region. The disease has a high incidence rate, but few diseased cones. Infected cones stop growing and quickly die.

Symptoms: The disease affects the scales of both female and male cones. Infected female cones are slender and small, curved, with open scales; the bracts become lanceolate, and the cones turn yellow and stop growing. The scales are small, yellow, and bear orange-red protruding telial pustules.

Pathogen: The pathogen is Chrysomyxa deformans (Diet.) Jacz., a fungus belonging to the phylum Basidiomycota, class Teliomycetes, order Uredinales, genus Chrysomyxa.

Disease pattern: The pathogen has only the teliospore stage. In early summer each year, spores produced from overwintered diseased buds infect female or male cones, producing yellow lesions and telial pustules. In rainy weather, the teliospores germinate to produce basidiospores, which are spread by air currents onto newly produced buds of spruce, where they invade and overwinter.