Troubleshooting
Danica Globe Arborvitae problems — and how to fix them
Danica Globe Arborvitae (Thuja occidentalis 'Danica') 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.
Thuja blight (Didymascella thujina)
A fungal disease causing browning of inner foliage and shoots, especially prevalent in wet, humid conditions; compact forms with dense foliage are particularly susceptible. Improve air circulation by spacing plants adequately and avoid overhead irrigation.
Bagworms (Thyridopteryx ephemeraeformis)
Caterpillars create distinctive silk-and-foliage bags that hang from branches, consuming foliage from inside and causing dieback. Hand-pick bags during dormancy in winter and treat active infestations with Bacillus thuringiensis (Bt) spray in late spring when caterpillars are small.
Winter bronzing and desiccation
Foliage naturally bronzes in cold weather (considered ornamental), but in exposed positions drying winds can cause permanent browning and dieback. Protect newly planted specimens with a hessian windbreak for the first 1–2 winters.
Prevent danica globe arborvitae problems before they start
Most danica globe arborvitae issues are care-mismatch, not bad luck. Dial in the basics:
Danica Globe Arborvitae problems — FAQ
Why is my danica globe arborvitae thuja blight (didymascella thujina)?
A fungal disease causing browning of inner foliage and shoots, especially prevalent in wet, humid conditions; compact forms with dense foliage are particularly susceptible. Improve air circulation by spacing plants adequately and avoid overhead irrigation.
Why is my danica globe arborvitae bagworms (thyridopteryx ephemeraeformis)?
Caterpillars create distinctive silk-and-foliage bags that hang from branches, consuming foliage from inside and causing dieback. Hand-pick bags during dormancy in winter and treat active infestations with Bacillus thuringiensis (Bt) spray in late spring when caterpillars are small.
Why is my danica globe arborvitae winter bronzing and desiccation?
Foliage naturally bronzes in cold weather (considered ornamental), but in exposed positions drying winds can cause permanent browning and dieback. Protect newly planted specimens with a hessian windbreak for the first 1–2 winters.