Juniper shrubs are all about consistent color, stunning texture, and a hands-off care regimen. New plants need time to acclimate, but established plants only need a little care. However, certain fungal and bacterial infections can wreak havoc on juniper plants. Early detection is critical to helping shrubs recover from a disease, and prevention is possible. Learn how to spot the signs of a diseased juniper and how to help a sick plant recover.
Juniper Phomopsis Tip Blight
Phomopsis tip blight is a fungal infection caused by Phomopsis juniperovora. This disease impacts new growth and causes the tips of branches to die. Warm and wet conditions are more conducive to this fungus and encourage its spread.
Identifying Phomopsis Tip Blight
Phomopsis tip blight impacts new growth found at the end of branches. The light green foliage loses its vibrancy and turns a rusty reddish-brown hue before dying. Dark green established growth doesn’t fall victim to Phomopsis tip blight, and there is often a clear delineation between the healthy part of a branch and the infected, dead part.
Treating Phomopsis Tip Blight
Prevent Phomopsis tip blight by planting the shrubs far enough apart in an area with good drainage. Avoid watering juniper during the spring when new growth emerges unless necessary. Remove damaged branches at the first sign of a problem. Pruning is often effective at containing the problem, but spray the juniper with a fungicide as an extra step to address the issue.
Juniper Cercospora Twig Blight
Cercospora twig blight is a fungal infection that impacts old growth and does not damage new growth. Wet conditions and close proximity are more likely to encourage fungal diseases and can bring about a case of Cercospora twig blight.
Identifying Cercospora Twig Blight
Cercospora twig blight targets the older greenery on the lowest branches. Needles turn brown and die, and this progresses outward; however, new growth is often spared and remains a bright green color. Cercospora twig blight kills the foliage in the plant's crown, creating bare branches in what should be the most dense area.
Treating Cercospora Twig Blight
Improve air circulation to reduce the risk of Cercospora twig blight. Ensure plants have plenty of space, remove overlapping branches, and only water when necessary. Remove infected growth as soon as possible to contain the spread and burn, or responsibly dispose of infected branches. Spray the plant with a fungicide to prevent a future outbreak.
Juniper Disease Chart
| Disease | Identifying | Treating |
|---|---|---|
| Phomopsis Tip Blight | Dead leaf tips | Prune/discard stems & apply fungicide |
| Cercospora Twig Blight | Dead foliage in the crown | Prune/discard stems & apply fungicide |
Sources: "Juniper Diseases & Insect Pests." Clemson University Cooperative Extension Service. hgic.clemson.edu
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Author Alison Cotsonas - Published 12-22-2023 |