Troubleshooting
Blue Rug Juniper problems — and how to fix them
Blue Rug Juniper (Juniperus horizontalis 'Wiltonii') 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.
Juniper blight (Phomopsis tip blight)
Brown, dead shoot tips appear in spring after wet weather; most damaging on new growth. Remove infected material, improve air circulation, and apply copper or mancozeb fungicide preventively during wet periods.
Bagworms (Thyridopteryx ephemeraeformis)
Camouflaged silk-and-foliage bags hang from branches, with caterpillars defoliating stems from inside. Hand-pick bags in late autumn and winter; treat active infestations with Bacillus thuringiensis (Bt) in late spring.
Juniper scale (Carulaspis juniperi)
White, waxy scales on stems and foliage cause yellowing and dieback. Apply dormant horticultural oil in late winter or systemic insecticide during the crawler stage in early summer.
Prevent blue rug juniper problems before they start
Most blue rug juniper issues are care-mismatch, not bad luck. Dial in the basics:
Blue Rug Juniper problems — FAQ
Why is my blue rug juniper juniper blight (phomopsis tip blight)?
Brown, dead shoot tips appear in spring after wet weather; most damaging on new growth. Remove infected material, improve air circulation, and apply copper or mancozeb fungicide preventively during wet periods.
Why is my blue rug juniper bagworms (thyridopteryx ephemeraeformis)?
Camouflaged silk-and-foliage bags hang from branches, with caterpillars defoliating stems from inside. Hand-pick bags in late autumn and winter; treat active infestations with Bacillus thuringiensis (Bt) in late spring.
Why is my blue rug juniper juniper scale (carulaspis juniperi)?
White, waxy scales on stems and foliage cause yellowing and dieback. Apply dormant horticultural oil in late winter or systemic insecticide during the crawler stage in early summer.