Hello,

The pale green and spotty leaves on your White Oak (Quercus macrocarpa) trees could be caused by several factors. Here are some possibilities based on information from educational sources:

Oak Lace Bug: This pest can cause white or yellow speckled discolorations on the upper side of the leaf, which may lead to defoliation in severe cases. More information at these links:

What's wrong with my plant? : Garden : University of Minnesota Extension (umn.edu)

How To Recognize Common Diseases of Oaks in the Midwest: A Quick Guide (iastate.edu)

Oak Leaf Blister: This disease causes raised blister-like spots on leaves that are initially pale green to orange but turn brown with age. Heavy infestation can make leaves curl after the blisters have merged. More information at these links:

What's wrong with my plant? : Garden : University of Minnesota Extension (umn.edu)

How To Recognize Common Diseases of Oaks in the Midwest: A Quick Guide (iastate.edu)

Iron Chlorosis: This condition occurs when leaf blades that should be green turn yellow, but the leaf veins remain green. It’s common on pin oaks and can lead to poor growth and undersized leaves. More information at these links:

What's wrong with my plant? : Garden : University of Minnesota Extension (umn.edu)

How To Recognize Common Diseases of Oaks in the Midwest: A Quick Guide (iastate.edu)

Powdery Mildew: This fungal disease produces white or gray powdery mats on leaves, which can cause leaves to curl or distort. It’s more common on lower shaded leaves and in small understory trees. More information at these links:

What's wrong with my plant? : Garden : University of Minnesota Extension (umn.edu)

How To Recognize Common Diseases of Oaks in the Midwest: A Quick Guide (iastate.edu)

Oak Slug Sawfly: The larvae of this pest feed on the underside of leaves, creating a lace-like appearance. They are dark green to black and covered in slime. More information at these links:

What's wrong with my plant? : Garden : University of Minnesota Extension (umn.edu)

How To Recognize Common Diseases of Oaks in the Midwest: A Quick Guide (iastate.edu)

To treat these conditions, it’s important to correctly identify the cause. For example, iron chlorosis can be treated with iron supplements, while fungal diseases like powdery mildew may require fungicides. However, it’s crucial to use the right treatment for the specific issue.

Remember, proper identification is key before applying any treatment, as the wrong treatment can sometimes exacerbate the problem. Additionally, consider the environmental impact of any treatment and follow the instructions carefully.

Since you’ve been using a 3-in-1 control spray without success, it might be a nutrient issue or a disease not covered by the spray. It’s recommended to consult with a local arborist or use the MSU Plant and Pest lab for an accurate diagnosis and treatment plan. They can provide advice tailored to your local conditions and the specific needs of your trees.

HERE ARE YOUR TWO (2) OPTIONS

OPTION 1:

For a confirm and precise identification of the problem, I recommend you send all your images by e-mail to the MSU Plant & Pest Diagnostics Lab. The experts there can also provide you with the best treatment options. Their email is <personal data hidden> - Please include your name – The lab will let you know if they need a sample sent. FYI – The lab may also ask for additional images too.

Their website is at this link:

Plant & Pest Diagnostics (msu.edu)

Their Contact Information is at this link:

Contact Us - Plant & Pest Diagnostics (msu.edu)

This link will explain the details on submitting a sample to MSU Plant & Pest Diagnostics Lab:

Submit Samples - Plant & Pest Diagnostics (msu.edu)

OPTION 2:

You can consult with a local certified arborist for a more detailed onsite assessment and personalized advice. To find a certified arborist in your Zip Code go to this link:

Find an Arborist (treesaregood.org)

I hope this helps!