How To Identify & Treat Fall Leaf Diseases In Southeast Michigan

Fall in Michigan is pure magic—crisp air, cozy layers, cider mill runs, and trees bursting into brilliant shades of red, orange, and gold. But while you’re soaking in the seasonal beauty, your trees might be quietly battling leaf diseases beneath the surface. The good news? You don’t have to be a tree expert to fight back. We’re here to help you spot the signs and treat them like a pro!

What Are Fall Leaf Diseases?

Fall leaf diseases are typically caused by fungi, though some bacterial infections can also sneak in. These diseases thrive in Michigan’s cool, damp autumn conditions and target the leaves of trees and shrubs. The result? Premature leaf drop, unsightly spots and discoloration, and in some cases, long-term damage to your landscape if left untreated. But with a little know-how, you can catch them early and keep your trees looking their best.

Let’s break down the most common culprits in Southeast Michigan right now:

1. Anthracnose

Trees affected: Maple, Oak, Ash, Sycamore

Anthracnose Symptoms And What To Look For:

• Dark blotches along leaf veins: These spots often appear brown or black and may spread outward from the veins.
• Twisted or curled leaves: Infected leaves may become misshapen or crinkled.
• Premature leaf drop: Trees may shed leaves earlier than usual, even while others are still turning color.
• Twig dieback (in severe cases): If the infection spreads, small branches may begin to die off, especially in younger trees.

How to Treat Anthracnose

• Rake up fallen leaves: Infected leaves can harbor fungal spores that spread the disease. Bag and dispose of them—don’t put them in the compost!
• Prune branches for airflow: Thin out crowded branches to improve air circulation, this helps keep moisture levels down and discourages fungal growth.
• Consider fungicide (if recurring): For trees that get hit year after year, a preventative fungicide treatment in early spring can help stop Anthracnose before it starts.

2. Apple Scab

Trees affected: Apple, Crabapple, Pear, Hawthorn

Apple Scab Symptoms And What to Look For

• Spots on the leaves and fruit: Look for olive-green to dark brown blotches, often with a velvety texture. These spots may start small but can grow, spread, and merge over time.
• Early leaf drop: Your tree might start dropping leaves before fall really kicks, specifically in late summer or early fall.
• Misshapen or cracked fruit: Infected apples or crabapples may appear deformed, cracked, lumpy, or blemished, or just plain weird. Making them less appealing and more prone to rot.
  

How to Treat Apple Scab

• Clean up all the fallen leaves and fruit: Infected debris can spread the disease, so rake it up and toss it—don’t compost it!
• Use fungicide if needed: Apply a fungicide in early spring to protect new growth, and again in fall if the problem keeps coming back.
• Plant resistant varieties: If you’re adding new trees, choose types that are naturally resistant to Apple Scab to avoid future issues.
  
  

 3. Needle Cast (Rhizosphaera)

Trees affected: Colorado Blue Spruce

Needle Cast: What to Look For

• Needles that are turning yellow or brown: The inner needles that closer to the center of each branch, start to turn yellow, then brown and fall off.
• Thin or bare branches: As needles drop, branches may look sparse or bare—especially on the lower part of the tree.
• Tiny black dots on needles: These are fungal spores. You’ll usually see them on the underside of the affected needles.

How to Treat Needle Cast

• Trim infected branches: Prune away affected areas to stop the spread and help the tree breathe better, this will improve the air circulation. 
• Improve airflow: Remove nearby plants or trim surrounding trees to give your spruce more space and reduce moisture buildup.
• Use fungicide: Apply a fungicide in spring when new needles are growing, and again in fall if the problem continues.
  

 4. Leaf Spot Diseases

Trees affected: Many deciduous trees

Leaf Spot Diseases: What to Look For

• Spots on leaves: You’ll see small, round spots in shades of brown, black, or yellow. Depending on the type of tree, these spots might be spread out or clustered together.
• Leaves falling early: Infected leaves often fall off earlier than they should, making your tree look bare before fall is even in full swing.
• Less energy for the tree: When too many leaves are damaged or fall off early, the tree loses its ability to make food through photosynthesis. Over time, this can weaken the tree and affect its overall health.

How to Treat Leaf Spot Diseases

• Rake and remove fallen leaves: Fallen leaves that are infected can carry and spread the disease to healthy parts of your yard. To prevent this, rake them up regularly and throw them away—don’t compost them, or you’ll risk reintroducing the problem later.
• Water the right way: Avoid watering your tree from above, wet leaves create the perfect environment for fungus to grow. Instead, water at the base of the tree to keep the leaves dry and reduce the risk of disease.
• Use copper-based fungicide if needed: If leaf spot keeps coming back year after year, a copper-based fungicide can help control the spread. Be sure to follow the label instructions carefully and apply it during dry weather for best results.

Pro Tips for Prevention

• Rake regularly: Fallen leaves are a fungal playground. Keep your yard tidy!
• Mulch smart: Use disease-free mulch and avoid piling it against tree trunks.
• Water wisely: Water at the base, not the leaves. Watering in the morning is the best.
• Prune properly: Fall is a great time to remove dead or diseased branches.
• Call the pros: If you’re unsure, Safari Tree’s certified arborists can diagnose and treat tree diseases before they become a bigger problem.

Why It Matters

Ignoring leaf diseases can lead to weakened trees, increased pest problems, and costly removals down the road. A little TLC now means a healthier, happier landscape come spring.

We've Got Your Back! 

Fall leaf diseases may be sneaky, but with a sharp eye and a few smart moves, you can keep your trees thriving. 

Need help identifying a problem in your yard? Safari Tree is here to help! Our experts treat your landscape like family—because healthy trees make happy yards.