Black Streaks & Green Fuzz on Douglas Fir Firewood: Stain Fungi, Not a Threat

Identification

Black streaks in wood grain + bright greenish-white surface fuzz = stain fungi, not decay fungi. Two common types:

• Black stain root disease (Leptographium wageneri): Narrow bands following growth rings in cross-section.
• Blue stain (Ophiostoma spp.): Wedge-shaped pattern across rings.

Canadian Forest Service comparison photos.

No Spread Risk

• Stain fungi require beetle vectors to infect living trees.
• Spores on firewood/gear cannot infect healthy forest trees.
• Burning the wood is completely safe.

When to Worry

If the wood is soft, stringy, or crumbly (brown/white rot), it's decayed—burn it promptly. Stain fungi only discolor; structural integrity remains.

USFS can confirm ID if desired, but no action needed. Your gear and the forest are safe.