Tree problems · Disease

Sudden Oak Death: signs and what to do

Sudden Oak Death is a tree disease, often seen on northern red oak, pin oak, coast redwood. Look for: bleeding cankers on the lower trunk: dark, sticky or tar-like sap oozing from the bark.

General information, not a diagnosis. A certified arborist or your county extension office can confirm.

Disease
Northern red oak
Pin oak
Coast redwood (carries the pathogen, rarely dies)
Bigleaf maple (carries the pathogen, rarely dies)

Signs to look for

Tick what you see. More ticks make it more likely, but only an on-site look can confirm.

Bleeding cankers on the lower trunk: dark, sticky or tar-like sap oozing from the bark
Bark around the bleeding spot may look reddish-brown or dark under the surface
Leaves on a susceptible oak turn brown quickly, often over a short time
Twig dieback and leaf spots on host plants such as rhododendron, camellia and bay laurel
Beetle holes and fungus on the trunk of a tree that is already weak (a later stage, not the cause)
A dead oak that still has brown leaves hanging on in a known quarantine area

0 of 6 signs ticked. Ticks stay in this browser only.

Season

Spread is linked to cool, wet weather. Symptoms on host plants often show in spring and fall rain. Dead oak crowns are most obvious in late spring and summer.

How it spreads

The pathogen (Phytophthora ramorum) moves in rain splash, wind-blown rain, and in infected plants, soil and water. People spread it by moving infected nursery plants, soil, and plant material.

Where it is found

Sudden oak death is best known on the West Coast, and it has also been found in nursery stock in other parts of the country. Check your state official map; ranges change.

Official sources

What to do

1
Do not move wood, soil, mulch or plants out of a known quarantine area. Rules can apply by law.
2
Take clear photos of the bleeding area and the leaves, and note the species.
3
Call your state department of agriculture or your local extension office before you cut or haul the tree.
4
Lab testing is the only way to confirm it. Many other problems look similar, so do not guess.
5
Clean tools, boots and truck tires between jobs, and keep chips and logs on site if officials ask you to.
6
Follow the disposal instructions of your state agency for any confirmed tree.

Safety first: do not climb, do not cut near power lines and do not use a chainsaw on storm-loaded wood. Call the utility for downed lines and 911 if anyone is in danger.

Prevention

Buy nursery plants from trusted growers, avoid moving soil and plant debris between sites, and clean tools and tires after working in a wet, infested area. In known areas, follow the local rules for green waste and firewood.

When to call a pro

Call a certified arborist when an oak has bleeding trunk cankers or sudden crown browning, or when the tree is near a house, road or play area and may be hazardous. If you suspect the disease, also tell your state agriculture office or extension service.

Not sure who to call? Read how to hire a tree service or check is my tree dangerous?

Trees it affects

Usually seen on: Northern red oak, Pin oak, Coast redwood (carries the pathogen, rarely dies), Bigleaf maple (carries the pathogen, rarely dies).

See all species in our tree library, or pick a tougher tree with the tree picker.

For tree companies

How to explain sudden oak death to a customer

Be calm and clear with the homeowner: many oak problems look alike, and only a lab test can confirm this one. Tell them you will take photos, call the right agency, and follow any local rules for hauling wood. Do not promise a cure or say it is confirmed before a lab says so.

Send this page to the customer after your visit so they can read the signs in plain words. See also selling plant health care and the job photo checklist.

Questions

What is sudden oak death?

It is a disease caused by a water mold called Phytophthora ramorum. It kills some oak species and also harms many shrubs and trees without killing them.

Does every oak with bleeding sap have sudden oak death?

No. Many things can make an oak ooze sap, such as other cankers, borers and wounds. A lab test is the only way to know.

Can I save an infected oak?

Some products may protect healthy, high-value oaks in affected areas, but they do not cure a tree that is already sick. Ask a certified arborist and your local extension office.

Can I take firewood from an affected area?

Not if a quarantine applies. Rules vary by place, so check with your state agriculture department before moving wood, soil or plants.

Why are plants like rhododendron and bay laurel mentioned?

They can carry the pathogen on their leaves and help it spread to oaks, even when they do not die from it.

Is it safe to be near an infected tree?

The disease does not harm people or pets. The danger is a weak or dead tree that can drop limbs or fall, so have it checked by a pro.

Can Lirevon diagnose sudden oak death on my tree?

No. Lirevon is a remote marketing team for tree service companies and does not do tree work. This page is general information, not a diagnosis. A certified arborist or your county extension office can confirm what is wrong with your tree.

How do I find a good local pro for this?

Search Google Maps for certified arborists or tree services near you, read their reviews and ask for proof of insurance. Get two or three written quotes. Our guide on how to hire a tree service lists the questions to ask.

When customers spot sudden oak death, they call

Make sure someone answers. Missed-call text-back, lead follow-up, booking and review requests, set up for you. See our services and pricing.

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