Bur Oak Blight in Southern Maryland


Bur Oak Blight is very harmful to your trees. Click here to learn everything you need to know about treating this tree disease in Southern Maryland.

Your oak trees have thrived for years. But now, with rain and humidity, your oak trees have begun showing signs of bur oak blight.

The bad news is that Southern Maryland is especially susceptible due to high ambient humidity in the warmer months. How do you treat this tree disease? Here’s a quick and easy guide—and when it’s time to call an expert arbor care tree service.

What is the Threat?

Bur oak blight is an infection caused by Tubakia iowensis, a relatively new fungal pathogen from Europe or Asia with a localized mutation that first occurred in the Midwest. There are five species of Tubakia known to cause oak leaf diseases, but Tubakia iowensis is the only strain that causes bur oak blight.

It is a serious, progressive disease that causes leaf blight, branch dieback, and even death of the tree in severe cases.

The good news is that while this is serious, it is not necessarily fatal for the tree. A bur oak can lose up to 50% of its foliage to blight and still remain relatively healthy. The larger issue is susceptibility to secondary complications, typically Armillaria root disease. If the tree loses too many leaves to defoliation over several years and does not regrow leaves normally, bur oak blight may kill the tree.

Where is the Threat?

Bur oak blight is found throughout the Midwestern United States but has seen increased severity in Illinois, Missouri, Kansas, Nebraska, and Minnesota in recent years, likely the result of climate change and increasingly frequent rain. It has also been observed in Maryland, where the high ambient humidity creates moist conditions allowing the fungus to flourish.

As the name implies, bur oak blight exclusively affects bur oaks. It is most prevalent in Quercus macrocarpa var. oliviformis, a type of bur oak characterized small, olive-shaped acorns, though the blight is seen in many bur oak species with small acorns. It is not known whether bur oak hybrids are also susceptible to infection.


Bur oak blight is characterized by small, wedge-shaped brown pustules on the leaves. These are visible as small black fruiting bodies on the petioles and veins of affected leaves. Unfortunately, these initial lesions are best seen through a magnifying glass.

As the disease progresses, leaves become fully brown as lesions coalesce, creating a scorched appearance. Eventually, the wind will carry away leaves, but the petioles remain attached, allowing the infection to spread and intensify. It typically takes several years of progression to see tree mortality.

What to Do About It

The best way to treat and prevent this disease is with the help of expert tree care services.

An arborist can treat and prevent this disease by injecting fungal treatment into the trunk between partial leaf emergence and the first week of June. This can supplement treatments made in the previous fall to protect the tree in early spring months.

If a tree already has it, an arborist can apply fungicide treatments to keep infection manageable so that the tree can recover.

Turn to a Tree Disease Expert in Southern Maryland

Looking for an expert arborist in Southern Maryland? When it comes to tree diseases, Southern Maryland trusts us to protect trees.

We offer expert tree services with more five-star reviews than any other service in the region, because our customers know we deliver the best experience no matter what. So if you need help, get in touch today to schedule a free on-site estimate.


Contact us for a free quote.

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