Troubleshooting
Bigcone Douglas Fir problems — and how to fix them
Bigcone Douglas Fir (Pseudotsuga macrocarpa) is generally forgiving once you match its basics, but a few issues come up again and again. Here is what each one looks like, why it happens, and the fix.
Root rot in heavy soil
Poorly drained clay soils cause Phytophthora root rot. Always plant on slopes or raised, amended ground; never allow standing water around the root zone.
Douglas fir tussock moth
Orgyia pseudotsugata caterpillars can defoliate branches. Monitor in late spring; biological controls (Bacillus thuringiensis) are effective if applied early.
Bark beetle attack under stress
Drought-weakened or injured trees are susceptible to bark beetles (Dendroctonus spp.). Maintain plant vigour through correct siting and avoid wounding the bark.
Prevent bigcone douglas fir problems before they start
Most bigcone douglas fir issues are care-mismatch, not bad luck. Dial in the basics:
Bigcone Douglas Fir problems — FAQ
Why is my bigcone douglas fir root rot in heavy soil?
Poorly drained clay soils cause Phytophthora root rot. Always plant on slopes or raised, amended ground; never allow standing water around the root zone.
Why is my bigcone douglas fir douglas fir tussock moth?
Orgyia pseudotsugata caterpillars can defoliate branches. Monitor in late spring; biological controls (Bacillus thuringiensis) are effective if applied early.
Why is my bigcone douglas fir bark beetle attack under stress?
Drought-weakened or injured trees are susceptible to bark beetles (Dendroctonus spp.). Maintain plant vigour through correct siting and avoid wounding the bark.