Hello Renee,

Research from Michigan State University shows several potential causes for your boxwood's brown leaves, with winter injury being the most common culprit in Michigan.

Here are the main possibilities and their treatments:

Winter Injury:

Most common in Michigan, especially when temperatures drop below -10°F

Typically affects uppermost or outermost leaves

The growth below the previous snowline often remains green. Treatment: Prune out damaged foliage if the damage isn't too severe

Pesticide/Herbicide Damage: It looks a lot like this—if pesticides or herbicides were sprayed in the area, this could be the likely culprit.

Volutella Blight:

Leaves turn tan to straw-yellow or bronze in spring

Pink to salmon-colored spores appear in wet conditions

Dead branches have loose bark. Treatment:

Remove and destroy infected branches

Improve air circulation through proper pruning

Keep plants healthy to prevent infection

More information at this link:

Boxwood Diseases

Boxwood Blight

Causes rapid defoliation

Shows round, dark, or light brown leaf spots with darker borders

Leaves drop quickly, leaving bare branches. Treatment:

Remove severely affected plants

Don't compost infected material

Sanitize pruning tools between cuts

More information at this link:

Browning of boxwood: Is it boxwood blight? - Landscaping

Your image IMG_6636.jpg looks a lot like - Boxwood leafminer

More information at this link:

Boxwood insect pests - MSU Extension

To determine the exact cause and best treatment, I'd recommend:

Check if the damage pattern matches winter injury (damage above snowline)

Look for any fungal growth or specific spotting patterns

Consider sending your images to the MSU Plant & Pest Diagnostics for precise diagnosis.

Their email is <personal data hidden> - Please include your first and last name.

The experts there can also provide you with the best treatment options.

The lab will let you know if they need a sample sent.

The lab may also ask for additional images. So be prepared.

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 the MSU Plant & Pest Diagnostics Lab:

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

I hope this helps!