Bur Oak Blight
What is Bur Oak Blight?
Bur Oak Blight is a fungal disease affecting the leaves of bur oak trees in Midwestern states. The disease can begin gradually and build in severity until it kills the tree. The symptoms of Bur Oak Blight might look similar to those found with other conditions of oak trees. High value oaks should be inspected by a Kinnucan Certified Arborist for accurate diagnosis.
Infected Trees Require Treatment for Control
Bur oaks with Bur Oak Blight can be treated with fungicidal treatments. Additional treatments may also be necessary if other conditions affect the tree at the same time. Kinnucan Tree Care is conducting research aimed at improving the success rate for treatment of Bur Oak Blight.
What to Look For
•Purple–brown lesions along middle vein of leaf
• Wedge-shaped areas of leaf yellowing or dieback
• Leaves turning brown and curling
• Black pustules at the base of leaf stalk
• Dead leaves remaining on the tree through the winter
Life Cycle of Bur Oak Blight
- In spring, spores are released from the black pustules that developed on leaf stalks the previous fall and winter.
- Rain and wind disperse the spores onto new leaves, and the new infection begins.
- Leaves appear healthy in the early part of the season. Symptoms become visible in late July, August and September.
- Dead leaves and leaf stalks form black pustules and remain on the tree to begin the cycle again the following spring.
- Secondary infections continue throughout the growing season during wet periods.
Treatment and Prevention of Bur Oak Blight
- Increase plant vigor and disease resistance using:
– Root zone or soil injections of insecticide
– Fertilization with oak-specific fertilizer
– Application of Cambistat® tree growth regulator - Proper/sufficient watering
- Our Kinnucan Certified Arborist may prescribe early season fungicide sprays and a trunk injection
- Affected Bur Oaks should also be treated against Two-Lined Chestnut Borer and other conditions as warranted by the situation
Possible Reactions to Bur Oak Treatment
Trees treated for Bur Oak Blight with Alamo fungicide will occasionally react to the treatment with a scorched appearance on their leaves, typically on leaf sprouts along the main trunk. While this may appear disconcerting, it does not cause permanent harm to the tree. It is a sign that the product has moved through the tree and the dosage used is appropriate to perform its work successfully. Continue to water your tree and provide other supportive care after treatment, following the advice of your consulting arborist.
FAQs about Oak Trees
Why are the oak trees dying?
This question is most asked these days in the Northern suburbs of Chicago. Resident's tree awareness is especially keen these days since the area has lost hundreds of thousands of Ash trees due to the Emerald Ash Borer. So, what is causing the death of so many Oak trees? The answer is complex, number of factors. The comprehensive answer is a combination of diseases, weather phenomena and insects.
Are there diseases that affect only one species of Oak trees?
Yes, Bur Oak Blight (BOB).
What diseases affect other Oak species, such as White Oaks and Red Oaks?
Oak Wilt, a vascular fungus disease that kills many White and Red Oaks. This disease is very similar to Dutch Elm disease since it’s primarily spread by bark beetles and /or adjacent trees roots grafting. It appears that the Red Oaks are more susceptible than the White Oak varieties. There is no cure for Oak Wilt.
What is the best prevention for this deadly disease is frequent inspection of suspect Oaks.
If disease is identified and confirmed, remove the infected tree. Root pruning adjacent trees may prevent root grafting of diseased trees to healthy trees.
Are there other factors / insects / diseases afflicting Oak trees?
Yes, the extreme weather the Midwest has experienced over the last decade, combining excessively wet, dry, hot and cold weather spells has caused significant stress on the Oak species.
How do I properly diagnose the condition of my Oaks?
Contact a Kinnucan Certified Arborist that is trained and experienced in dealing with the various Oak diseases.