True Fir: Rust (Pucciniastrum)

Biology

Pucciniastrum rusts are fungal diseases. Yellowish spots or blotches appear on the upper side of infected needles. White, tube-like structures are typically found on the underside of last season’s needles in early summer or on current-season needles in late summer or fall. Yellow fungal spores are found inside these structures. Severely infected needles drop from the trees. Alternate hosts for Pucciniastrum goeppertianum include wild blueberry, cranberry, and huckleberry. The berry bushes develop witches’ brooms with thickened stems and few leaves when infected. A reddish-brown layer forms around the infected stems. Alternate hosts for P. epilobii are fireweeds. Pucciniastrum rusts affect grand, Pacific silver, noble, balsam, white, red, and subalpine firs. Rust diseases are favored by cool, moist springs. This disease is often confused with Uredinopsis rust.

Management Options

Use Integrated Pest Management (IPM) for successful plant problem management.

Non-chemical Management

Select non-chemical management options as your first choice!

• Remove alternate hosts within approximately 1,000 feet of susceptible trees.

Chemical Management

IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.

• None recommended

Additional Images