Troubleshooting
Atlantic White Cedar problems — and how to fix them
Atlantic White Cedar (Chamaecyparis thyoides) 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.
Cercospora needle blight
A fungal disease causing reddish-brown needle discolouration and premature needle drop, particularly in humid conditions with poor air circulation. Improve spacing for airflow; remove infected material; apply copper-based fungicide if severe.
Cypress tip moth (Argyresthia cupressella)
Larvae mine into shoot tips causing branch tips to turn brown and die. Damage is most visible in spring. Remove and destroy affected shoot tips; spray with pyrethrin or spinosad in early spring targeting adult moths.
Alkaline soil chlorosis
Atlantic White Cedar is an obligate calcifuge. In soils above pH 6.0, iron and manganese become unavailable, causing interveinal chlorosis and stunted growth. Acidify soil with elemental sulfur and use acidifying fertilisers; avoid liming nearby.
Prevent atlantic white cedar problems before they start
Most atlantic white cedar issues are care-mismatch, not bad luck. Dial in the basics:
Looking for atlantic white cedar in general rather than its problems? Read the full atlantic white cedar care guide — light, water, soil and feeding.
Atlantic White Cedar problems — FAQ
Why is my atlantic white cedar cercospora needle blight?
A fungal disease causing reddish-brown needle discolouration and premature needle drop, particularly in humid conditions with poor air circulation. Improve spacing for airflow; remove infected material; apply copper-based fungicide if severe.
Why is my atlantic white cedar cypress tip moth (argyresthia cupressella)?
Larvae mine into shoot tips causing branch tips to turn brown and die. Damage is most visible in spring. Remove and destroy affected shoot tips; spray with pyrethrin or spinosad in early spring targeting adult moths.
Why is my atlantic white cedar alkaline soil chlorosis?
Atlantic White Cedar is an obligate calcifuge. In soils above pH 6.0, iron and manganese become unavailable, causing interveinal chlorosis and stunted growth. Acidify soil with elemental sulfur and use acidifying fertilisers; avoid liming nearby.