Bur Oak Blight

Bur oak blight, (Tubakia iowensis sp. nov.  –  a subspecies of Tubakia) is a  disease that causes petiole and leaf necrosis. The pathogen may have come from Europe or Asia but is potentially a localized mutation of Tubakia to the Midwest. This pathogen is a long term pest (the disease intensifies year after year) that requires many growing seasons to build a strong enough pathogen population to cause tree death. The pathogen has been positively identified in Iowa, Minnesota, Missouri, Arkansas, Illinois, and many other states believe they have the pathogen. However, the movement of the pathogen to new areas is relatively slow. It is possible that Bur Oak Blight requires a highly specific environment to develop and survive; which may prevent widespread pathogen distribution.

Treatment Strategy

Due to the limited trial research available regarding this pest, much of this is based upon preliminary studies and the treatment of similar pathogens. A root flare injection to control the infection occurring in the petioles and leaves using Alamo fungicide is the most effective known treatment for Bur Oak Blight.   Only 2/3 of Bur Oaks have shown a response to treatment with Alamo, the reason for this is not understood. Monitoring is crucial as much of the management is yet unknown. Bur oaks should also be treated preventively with Xytect insecticide to prevent against two-lined chestnut borer.

Cultural practices such as mulching trees in turf grass environments, regular watering, fertilization, or use of Cambistat to promote tree health can also help increase tree vigor and mitigate the impacts of Bur Oak Blight.

Purchase Bur Oak Blight Treatments Now!

Bur Oak Blight Treatment Option 1

Alamo® Application 

Alamo® treatment involves injecting the fungicide directly into the root flares of your oak using the Low Volume Macro-Infusion Pump equipment.

For complete instructions see the Low Volume Macro-Infusion Application Guide or view the application video.

Find out more about quick tips on oak wilt treatments.

Application Type Low Volume Macro-Infusion

DIY Product/Equipment Needed:

Alamo®

Low Volume Macro-Infusion Kit

• Shovel and hand trowel

• Gloves

• Stiff bristled hand brush

Bur Oak Blight Treatment Option 2

Cambistat®, a growth hormone regulator, has been shown to increase drought tolerance and vigor in trees with compromised root systems, a common predisposing factor for tubakia infections.  By slowing top growth, energy is directed to roots, encouraging the development of an extensive, fibrous root system.  In addition to increased drought tolerance, leaves are often smaller, greener and have a thicker waxy covering.  Not only are these leaves more efficient in making “food”, they are less prone to foliar infections because the coating is more difficult to penetrate.  Cambistat® is a soil applied product that lasts for three years in the tree.

Application Type – Soil drench

DIY Product/Equipment Needed:

• Cambistat®

• Measuring or diameter tape

• Graduated cylinder measuring in mL

• Shovel

• Bucket or watering can

• Cambistat Soil Drench Kit

Bur Oak Blight DIY Kit

Option 1

Application Type – Low Volume Macro-Infusion

DIY Product/Equipment Needed:

Alamo®

Low Volume Macro-Infusion Kit

• Shovel and hand trowel

• Gloves

• Stiff bristled hand brush

How Is It Spread?

Black fruiting bodies develop in leaves that have been killed and remain on tree. They will develop in the fall/winter at the base of the petiole. In spring they are mature and spores from them will be splashed through rain onto new leaves. This makes the disease very severe  because re-infection is so common

Susceptible Trees

Bur Oaks (Quercus macrocarpa)

Symptoms

Leaves when they first leaf out appear healthy each year.

This is a late season disease with symptoms appearing in late July, August, and September. Veinal browning occurs in late summer. Leaves initially have brown spots that eventually coalesce resulting in complete leaf browning and leaf curling. New flushes of growth in September will be killed by the fungus as well. Leaves stay hanging on the tree through the winter, which is unusual for Bur Oaks. Petioles will hang on through summer. Infections typically start in the lower portion of the crown and spreads higher up in subsequent years.

Black fruiting bodies develop at the base of the petiole in the fall and infected leaves will hang on throughout the winter and early spring months. The black fruiting bodies (spores) are on the petioles that overwinter and hang on to the tree and these spores become the overwintering inoculum to infect the tree the following year in May/June.

Lookalikes

Two-line chestnut borer can cause dieback in limbs, and is found in stressed trees; therefore, it may be in bur oak blight infected trees, along with the Tubakia pathogen.

Anthracnose looks similar, but works from the bottom up, and leaves do not persist like bur oak blight.  Bur oak blight infected trees show browning on most leaves on entire branches.  Leaves hanging on bur oak in winter are very distinctive of bur oak blight.

Related/Similar Problems

Two-lined Chestnut Borer (TLCB)

Timing

Spring through Summer

Urgency

High

Risk of Spreading

High

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