Tree Health

Common Tree Health Issues

Tree pests and diseases can vary massively between regions, which is why it can be difficult to diagnose the problem a tree is suffering from. Below is some basic information about the most common tree health issues, and we recommend consulting an arborist if you are in need of further assistance.

Take a look at the Pests and Diseases page of the USDA Animal and Plant Health Inspection Services Website to learn more about specific tree health problems.

Drought

Drought is a common problem affecting trees all across the country. Not having enough water causes a range of problems for plants including:

• Wilted leaves
• Scorched leaves
• Stem dieback
• Increased risk of diseases and pests

Keep your trees safe from draught by choosing a species that will survive well where you live and following basic tree watering guidelines.

Disease

The diseases that affect trees can vary between trees and regions. We’ve listed the most common tree diseases to watch out for:

• Dogwood Anthracnose

This affects flowering and Pacific dogwoods

• Dutch Elm Disease

This affects different elms to different degrees including American, winged, September, slippery, rock, and cedar elms.

• Eastern Filbert Blight

This affects hazelnut trees

• Oak Wilt

This affects most oak species

• Pine Wilt

This will primarily affect non-native pines including Austrian, Scot, and Japanese red and black pines

• Sudden Oak Death

Sudden oak death will fatally affect coast live oaks, tanoaks, California black oaks, Shrew’s oaks, and canyon live oaks. It may also affect coast redwoods, Douglas fir trees, madrones, and other kinds of trees

• Thousand Cankers Disease

Primarily affects black walnut trees

Pests

Much like with diseases, the pests that can damage trees can vary between trees and regions. Here are some of the more common tree pests that you may encounter:

• The Asian Longhsorned Beetle

These pests affect paper birches, green ashes, cedar elms, horse chestnuts, golden rain trees, hackberries, London planetrees, mimosas, sugar maples, poplars, willows, and mountain ashes.

• Bark Beetles

These pests affect a variety of different trees depending on the type of beetle

• Emerald Ash Borers

These primarily affect ash trees

• Gypsy Moth

These affect hundreds of different plant species, but will commonly attack aspens and oaks

• Hemlock Woolly Adelgid

These affect eastern/Canadian and Carolina hemlock

• Japanese Beetle

These can affect hundreds of different plant species

• Periodical Cicada

These will occasionally affect shrubs and small trees

Invasive Species

An invasive species is a kind of plant, animal, or pathogen not native to the region that will – or already has – caused damage. Learn more about invasive species’ through the National Invasive Species Information Center.

Improper Planting