Fungicide for Juniper Tip Blights

Causal Agent

• The disease is caused by two different fungi that infect host trees at different times of the year and are referred to by different names. Phomopsis juniperovora, causing phomopsis tip blight, infects tree during mid spring and Kabatina juniperi that causes kabatina tip blight infects tree during late winter or very early spring but symptoms are not evident until fall. Fungicides are effective in controlling only the phomopsis fungi.

Symptoms

• Both fungi that cause juniper tip blight produce similar symptoms on infected trees. However the control method with fungicides and disease cycles differ. Disease is characterized by the appearance of small, yellow spots on younger, succulent foliage. Infected needles turn brownish red or brown and eventually ash gray. Small, gray lesions girdle the tips of branches with tiny, black fruiting structures visible within the lesions. It is best to confirm disease prior to the use of fungicides.

Recommended Fungicides

• The use of chemical control options is only recommended on younger trees and not for older, established plants or windbreaks. The Ohio State University recommends the use of products containing mancozeb or thiophanate-methyl for controlling phomopsis tip blight. Copper based fungicides labeled for use on phomopsis tip blight are also effective for disease control. There are no fungicides labeled for use on kabatina tip blight.

Fungicide Use Suggestions

• Start applying the recommended fungicide at a seven- to 14-day interval to phomopsis affected trees as soon as symptoms are seen during early spring. Chemicals are most effective when used during the rapid plant growth stage. Using resistant juniper varieties and providing adequate cultural care help to minimize infection and the use of fungicides. Select a well-ventilated and sunny site for plants, avoid overhead irrigation and try not to wound plants unnecessarily especially in fall and spring.