Trees do a lot more than just look pretty in our yards. They give us shade, clean air, and even raise our property value. But like all living things, trees can get sick. If you live in Warren or Hunterdon County, New Jersey, and you notice something strange about your trees — brown leaves, odd spots, dying branches — you might be dealing with a tree disease. Working with certified tree care experts can help diagnose issues early and protect your landscape before minor problems turn into costly damage.
Let’s walk through the most common tree diseases we see here in NJ, how to spot them, and what you can do about them.
Why Tree Health Matters in Warren & Hunterdon County
Trees are a big part of what makes our neighborhoods in New Jersey beautiful. But our local climate — with its humid summers, cold winters, and stormy springs — makes trees more vulnerable to fungal infections, bacterial diseases, and pest attacks.
Sick trees can be dangerous. A weakened tree can lose limbs, fall during a storm, or even spread disease to other plants in your yard. That’s why early detection and expert care are so important.
What Causes Tree Diseases in NJ?
Tree diseases often come from a mix of things:
- Fungal spores spread by wind and rain
- Insect infestations that carry bacteria or viruses
- Stress from poor soil, drought, or root damage
- Bad pruning or storm injuries
Even one unhealthy tree in your yard can turn into a problem for the whole landscape if left untreated.
Common Tree Diseases in Warren and Hunterdon County
Here’s a breakdown of the tree diseases we deal with most often as arborists in this area.
- Anthracnose
This one’s a fungal disease that targets hardwood trees like maple, oak, sycamore, and dogwood.
What to look for:
- Brown or black spots on leaves
- Curled or wilted leaves
- Premature leaf drop in spring or early summer
What causes it: Cool, wet spring weather creates perfect conditions for the fungus to grow.
What to do: Prune infected branches, clean up fallen leaves, and improve airflow through the tree canopy. In severe cases, we might recommend a fungicide treatment.
This disease attacks a tree’s vascular system — the part that moves water and nutrients.
Common victims:Maples, ash, smoke trees, and redbuds
Symptoms:
- Yellowing or wilting leaves on one side of the tree
- Dead branches
- Discolored wood when cut
The science: It lives in the soil and enters through the roots. Once inside, it’s hard to get rid of.
Best action: Remove affected branches, avoid overwatering, and mulch the base to reduce stress. Sometimes, we’ll suggest replacing the tree with a resistant species.
Even if you don’t grow fruit trees, your ornamental crabapples can get this.
Signs:
- Olive-green to black spots on leaves and fruit
- Early leaf drop
- Ugly, deformed apples (if fruiting)
Treatment: Prune to open up the canopy for better air movement. We often apply a preventative fungicide in early spring.
This disease shows up as a soft, white powder on leaves, especially in shady spots.
Commonly affected:Dogwoods, maples, lilacs, and oaks
Symptoms:
- White coating on leaves
- Twisted or stunted leaf growth
Caused by: High humidity and poor airflow
Fix: Thinning crowded branches helps. If it keeps coming back, we might use a fungicide made for powdery mildew.
This is a bacterial infection, not a fungus, and it spreads fast.
Targets:Apples, pears, and crabapples
Look for:
- Blackened tips of branches that look scorched
- Sticky, milky sap on bark
- Rapid dieback of shoots
Spread by: Rain, insects, and pruning tools
Control: Prune infected branches well below the damage and sterilize tools between cuts. Avoid high-nitrogen fertilizers which can make things worse.
This is a group of diseases caused by different fungi — like Cercospora or Septoria — and they affect tons of tree species.
What you’ll see:
- Tiny black, brown, or purple dots on leaves
- Leaves turning yellow or falling off early
It’s more cosmetic than deadly, but repeated infections can weaken the tree.
What helps: Rake and dispose of fallen leaves, avoid wetting the leaves when watering, and prune for better airflow.
Root rot is serious. It lives in poorly drained soils and attacks from underground.
Signs:
- Slow growth
- Yellow leaves
- Mushy roots or foul smell near base
Affected trees: Almost any species, especially if the soil is heavy clay or stays soggy
What to do: Improve drainage with proper grading or aeration. In some cases, tree removal may be the only option.
Tree Pest Problems That Worsen Disease
Many tree diseases in NJ come hand-in-hand with pests. Here are a few we see a lot:
- Emerald Ash Borer – Devastates ash trees by boring under the bark
- Spotted Lanternfly – Feeds on sap and spreads disease through wounds
- Scale Insects – Weakens trees and attracts fungus
- Bark Beetles – Invade trees that are already stressed or dying
We often use integrated pest management (IPM) to handle these — a combo of natural predators, tree treatments, and safe insecticides.
Signs Your Tree Might Be Sick
Keep an eye out for:
- Leaves turning brown or falling too early
- Cracks in bark or peeling trunk
- Fungi or mushrooms near the base
- Dead limbs or thinning canopy
- Leaning or sudden tilting
If something feels “off,” it probably is.
How We Diagnose and Treat Tree Diseases
At Midstate Tree, we take a science-based approach to tree health. Every tree is different, so we:
- Do an on-site inspection
- Check soil, roots, bark, and leaves
- Test for fungi, bacteria, or pests
- Offer treatment options that fit your budget
Sometimes the best solution is pruning. Sometimes it’s treating the roots. And sometimes — if the tree’s too far gone — we recommend safe removal to protect the rest of your property.
Prevention Tips for Homeowners
The best way to avoid tree disease? Stay ahead of it.
Here’s how:
- Get annual check-ups from a certified arborist
- Mulch properly (but don’t pile it against the trunk!)
- Prune during the right season
- Water deeply, not too often
- Avoid lawnmowers or string trimmers near the tree base
Choose native or disease-resistant tree species whenever possible — they’re better adapted to our local conditions.
FAQs
Q: Can tree diseases spread to other trees?
Yes — especially fungal and bacterial ones. Wind, rain, and even your own tools can carry the disease.
Q: Will a diseased tree always need to be removed?
Not always. Many infections can be managed with early treatment.
Q: Is it safe to treat trees with pets or kids around?
We use eco-friendly treatments whenever possible and always follow safe application practices.
Q: When should I call an arborist?
At the first sign of trouble. The sooner we catch it, the more likely we can save the tree.
Need Help? Call Midstate Tree for a Free Tree Health Check
If your trees aren’t looking their best, don’t wait until they become a hazard. Whether it’s fungus on your maples, wilting branches, or early leaf drop, expert help makes all the difference.
We proudly serve homeowners and businesses across Warren and Hunterdon County — and we’re available 24/7 for emergency service.
Call us at 908-283-5755
Email: midstatetreemanagement@gmail.com
Trust your trees to certified professionals who care about health, safety, and the beauty of your landscape — from root to crown.
