Douglas Fir: Armillaria root rot Categories: Conifers Douglas Fir Douglas Fir Diseases Ornamentals Last review date: 2026-04-26 10:43 White fungal mat of Armillaria root rot infecting trunk Photo by: C.R. Foss Biology Armillaria root rot is a fungal disease transmitted between plants by root contact. Armillaria is often found in newly cleared soils or ones […]
Douglas Fir: Laminated root rot Categories: Conifers Douglas Fir Douglas Fir Diseases Ornamentals Last review date: 2026-04-27 10:12 Staining in wood (James) and wind-thrown tree (Wallis) R.L. James (wood), G.W. Wallis (tree); Bugwood.org Biology Laminated root rot is a fungal disease of conifers throughout the Pacific Northwest. Douglas-fir, grand fir, and mountain hemlock are highly […]
Douglas Fir: Rhabdocline needle cast Categories: Conifers Douglas Fir Douglas Fir Diseases Ornamentals Last review date: 2026-04-27 10:28 Douglas-fir Rhabdocline needle cast Photo by: R.S. Byther Biology The first symptoms of this fungal infection are many tiny yellow spots on the current season’s needles appearing in late summer or fall. By spring, these spots have […]
Douglas Fir: Rust Categories: Conifers Douglas Fir Douglas Fir Diseases Ornamentals Last review date: 2026-04-27 11:09 Douglas-fir Melampsora rust Photo by: G.A. Chastanger Biology Rust is a fungal disease infecting the needles of Douglas fir. Wind-blown spores infect the new needles in the spring. Yellow to orange bumps, or pustules, are found on the underside […]
Douglas Fir: Stem cankers Categories: Conifers Douglas Fir Diseases Ornamentals Last review date: 2026-04-28 08:20 Douglas-fir stem canker Photo by: Unknown Biology Stem cankers on Douglas fir are sunken and oval, occurring on branches or new shoots. Each canker is typically centered around a dead twig and can be small or up to 30″ long […]
Douglas Fir: Swiss needle cast Categories: Conifers Douglas Fir Douglas Fir Diseases Ornamentals Last review date: 2026-04-28 08:25 Douglas-fir Swiss needle cast Photo by: R.S. Byther Biology This fungal disease causes infected needles to become off-color and mottled yellow or brown. The needles may turn completely brown and are usually dropped prematurely, often in early […]
Douglas Fir: Upper stem canker Categories: Conifers Douglas Fir Douglas Fir Diseases Ornamentals Last review date: 2026-04-28 12:10 Douglas-fir upper stem canker Photo by: R.S. Byther Biology Upper stem cankers are caused by fungi in the soil. Seedling Douglas fir trees are affected, with the tops of infected trees turning yellow. By fall, the tops […]
Douglas Fir: Yellow-green mottle syndrome Categories: Conifers Douglas Fir Douglas Fir Diseases Ornamentals Last review date: 2026-04-28 12:13 Douglas-fir yellow-green mottle syndrome Photo by: G.A. Chastanger Biology The cause of yellow-green mottle syndrome is unknown but may be genetic. Needles of all ages are affected by yellow-green mottle syndrome. Yellow-green blotches may be small or may […]