Troubleshooting
Nootka Cypress problems — and how to fix them
Nootka Cypress (Cupressus nootkatensis) 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.
Cypress canker (Seiridium cardinale)
Causes bark lesions, resin bleeding, and branch dieback, particularly in warm, dry conditions. Prune out infected branches promptly, sterilising tools between cuts. No curative fungicide is available; improve site conditions and avoid drought stress.
Bagworm (Thyridopteryx ephemeraeformis)
Caterpillars construct silk-and-foliage bags on branches, defoliating sections over time. Hand-pick bags in winter; apply Bacillus thuringiensis (Bt) spray in early summer when caterpillars are small.
Heat and drought stress in warm zones
In USDA Zone 8 and above, prolonged summer heat causes browning of inner foliage and tip dieback. Site in a cool, north- or east-facing aspect; mulch heavily and irrigate during dry spells.
Prevent nootka cypress problems before they start
Most nootka cypress issues are care-mismatch, not bad luck. Dial in the basics:
Nootka Cypress problems — FAQ
Why is my nootka cypress cypress canker (seiridium cardinale)?
Causes bark lesions, resin bleeding, and branch dieback, particularly in warm, dry conditions. Prune out infected branches promptly, sterilising tools between cuts. No curative fungicide is available; improve site conditions and avoid drought stress.
Why is my nootka cypress bagworm (thyridopteryx ephemeraeformis)?
Caterpillars construct silk-and-foliage bags on branches, defoliating sections over time. Hand-pick bags in winter; apply Bacillus thuringiensis (Bt) spray in early summer when caterpillars are small.
Why is my nootka cypress heat and drought stress in warm zones?
In USDA Zone 8 and above, prolonged summer heat causes browning of inner foliage and tip dieback. Site in a cool, north- or east-facing aspect; mulch heavily and irrigate during dry spells.