Like many varieties of hardwood, red oak (Quercus rubratends) leaves tend to change color during autumn. The deep red-colored leaves may transition to a brown or yellow. But what if you notice this change occurring during the spring or summer?

Yellowing of red oak leaves isn’t normal during these months, which is why it’s important for homeowners to diagnose and treat the problem.

Iron Chlorosis

One of the most common causes of yellowing oak leaves is an environmental condition known as iron chlorosis. Often found in USDA zones four through eight, this condition is characterized by an iron deficiency. When a red oak tree is unable to consume enough iron, its leaves may turn yellow or even fall off and die.

Iron chlorosis is most often associated with a lack of iron in the soil, or the tree’s roots simply can’t reach the iron-rich areas of the soil. You can often fix problems associated with iron chlorosis by maintaining a proper pH level and adding nutrients to the soil when needed.

Fungal Disease

Another possible cause of yellowing red oak leaves is fungal disease. There are hundreds of different plant/tree-based fungal diseases out there, some of which are more severe than others. Certain types of fungi may latch on to the tree, reproducing and spreading while simultaneously causing yellowing of the leaves.

So, what can you do to protect your red oak tree from fungal disease? Keep the area surrounding the tree clean and free of debris. If there’s a large pile of fallen leaves and tree limbs, it may promote the formation of fungal disease, offering an ideal environment for fungi to grow and spread.

Lack of Water

Red oak – like all living organisms on this Earth – require water to live. If a red oak tree doesn’t consume enough H2O, the leaves may turn a different color, such as yellow for instance. Rather than relying strictly on mother nature to keep your trees hydrated, set up a sprinkler or irrigation system.

If you have a long drought spell in which little-to-no drain is falling, this will allow you to keep your trees healthy and hydrated throughout the year.

Sudden Oak Death

Sudden oak death (Phytophtora ramorum) is a type of root rot disease that affects red oaks. When a tree succumbs to this disease, the leaves will turn yellow and fall off. You can reduce the risk of sudden oak disease by planting your oak tree in an area with proper drainage (e.g. water doesn’t pool up around the base), and only supplying your tree with the water it needs.

The Woodsman Company offers tree planting, tree pruning and shrub trimming, tree removal and stump grinding as well as a tree wellness program.

If we can help with any of your tree care needs give us a call at 512-846-2535 or 512-940-0799 or

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