Tree problems · Disease
White pine blister rust: signs and what to do
White pine blister rust is a tree disease, often seen on eastern white pine, sugar pine, western white pine, whitebark pine and other five-needle pines. Look for: yellow or orange-bordered patches on branches or the trunk, often swollen.
General information, not a diagnosis. A certified arborist or your county extension office can confirm.
- Disease
- Eastern white pine
- Sugar pine
- Western white pine, whitebark pine and other five-needle pines
- Currants and gooseberries (Ribes), which are the alternate host
Signs to look for
Tick what you see. More ticks make it more likely, but only an on-site look can confirm.
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Season
Spores from currant and gooseberry leaves blow to pine needles in late summer and fall. The fungus then grows slowly into the branch. Cankers can take a few years to show, and the blisters appear in spring.
How it spreads
The fungus needs two hosts: a five-needle pine and a currant or gooseberry (Ribes). Spores from the pine infect the Ribes leaves, and spores from the Ribes leaves blow back to the pine needles on the wind.
Where it is found
White pine blister rust is an introduced disease from Asia. It has spread through much of the range of five-needle pines in the United States. Check your state official map; ranges change.
Official sources
What to do
- 1
Look closely at the branches of white pines for swollen, orange-bordered patches and flagging branches. Take clear photos.
- 2
Contact your county extension office or state forestry agency to ask for confirmation and local advice.
- 3
On small, young trees, ask a pro whether a branch with an early canker can be pruned off well away from the trunk.
- 4
Sterilize pruning tools between cuts and prune in dry weather.
- 5
If a canker is on the trunk, the tree usually cannot be saved. Ask a certified arborist about removal if it is near a target.
- 6
Ask your extension office about local advice on currants and gooseberries before removing any plants.
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
Healthy white pines in open, airy sites do better. Avoid planting white pines in cool, damp spots where the disease is common. Ask your state forestry agency or nursery about rust-resistant planting stock where it is offered. Researchers also note that little can be done to control the disease in forests, so plan for diversity: plant a mix of species.
When to call a pro
Call a certified arborist if a white pine has dying branches, oozing patches or a dead top, or stands near a house, driveway or line. Pruning cankers off and removing a dying pine are jobs for a trained and insured crew.
Not sure who to call? Read how to hire a tree service or check is my tree dangerous?
Trees it affects
Usually seen on: Eastern white pine, Sugar pine, Western white pine, whitebark pine and other five-needle pines, Currants and gooseberries (Ribes), which are the alternate host.
See all species in our tree library, or pick a tougher tree with the tree picker.
For tree companies
How to explain white pine blister rust to a customer
Be honest that no spray cures this disease. Explain the signs you see, say that a trunk canker usually means the tree will not recover, and offer a plain plan: prune early cankers on small trees, watch, or remove. Do not sell fungicide as a cure.
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 white pine blister rust?
It is a fungus that grows in the bark of five-needle pines. It forms cankers that can kill branches and, if it reaches the trunk, the whole tree.
Why does it need currants or gooseberries?
The fungus lives on two hosts. It spreads from pines to Ribes plants and then back to pines. Without one of the two, it cannot finish its cycle.
Which pines get it?
Five-needle pines, including eastern white pine and sugar pine. Other pines are not affected by this rust.
Can I save an infected tree?
Sometimes, if the canker is on a branch and can be pruned off well away from the trunk. A canker on the trunk usually means the tree will die.
Is there a spray that cures it?
No. Researchers say little can be done to control it in forests, and a spray does not cure a canker. Ask your extension office before paying for any treatment.
Should I pull out my currant bushes?
Not without local advice. Ask your state forestry agency or extension office whether it makes sense in your area.
Is a dying white pine dangerous?
It can be. Dead branches and tops can fall without warning. Keep people and vehicles away and have a qualified pro assess any dying pine near a building or road.
Can Lirevon diagnose white pine blister rust 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.
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