Juniper tip blights occur on upright, spreading, and prostrate junipers. Juniper tips die back and turn gray or brown when small twig and branch cankers develop following foliage and twig infection. When cankers girdle the branch, distal tissues are killed. In extreme cases, tip dieback can become branch and limb dieback, which results in unsightly or dead junipers. Juniper tip blights are caused two different fungi, Kabatina juniperi and Phomopsis juniperovora. Kabatina tip blight symptoms develop in the spring on growth made the previous season and Phomopsis tip blight symptoms appear in early summer on new growth. Since Kabatina tip blight symptoms appear in early spring, it is suspected that the actual infection occurred the previous fall. The fungus may enter through wounds such as insect feeding sites. Phomopsis tip blight begins as a foliar infection which then spreads to and kills stem tissues. Newly developing needles in the yellowish-green stage are especially susceptible, while more mature, darker green needles are not. Phomopsis blight can occur during the growing season anytime there is new shoot growth. Symptoms are evident a week or two after infection. When the fungus invades young stem tissue, terminals and branches distal to the point of infection become light green, reddish-brown, and finally ashen-gray. Small branches up to 1 cm in diameter are generally girdled by tip blight disease. When a side shoot is infected, Phomopsis may progress to a main branch. Lesions on larger branches develop into cankers which seldom girdle the branch.
Tip blight disease management:
- When buying plants, select only those that are healthy and that do not have dead or dying branch tips.
- Space new plantings to allow for good air circulation.
- Avoid wounding when transplanting, mowing, or working near the shrubs.
- Provide good growing conditions; maintain adequate fertility, but do not over fertilize as this makes the plant more susceptible to Phomopsis.
- Water plants in early morning so the foliage will dry as the day progresses. Avoid watering at night.
- During dry weather, prune out diseased branch tips and destroy them; Phomopsis can survive and produce spores for up to two years on dead branches. Pruning to shape the plant could encourage development of new growth which is highly susceptible to infection. Prune as little as possible.
- Protect plants from insect attack.
- Choose to grow disease-resistant cultivars.
- For Phomopsis tip blight, apply recommended fungicides whenever new growth begins and conditions are wet. Spring and fall growth must be protected. Sprays are not required during dry weather. Fungicide applications are not known to be very effective for Kabatina blight. Contact your local Cooperative Extension office for fungicide recommendations.
