Tree problems · Disease
Cedar-Apple Rust: signs and what to do
Cedar-Apple Rust is a tree disease, often seen on eastern red cedar, apple and crabapple, hawthorn. Look for: round, brown, woody galls on cedar twigs, from the size of a pea to a golf ball.
General information, not a diagnosis. A certified arborist or your county extension office can confirm.
- Disease
- Eastern red cedar
- Apple and crabapple (not on our species list)
- Hawthorn (not on our species list)
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
Orange jelly-like horns show on cedar galls in spring after warm rain. Leaf spots on apples appear in late spring and early summer.
How it spreads
The fungus (Gymnosporangium juniperi-virginianae) needs two hosts. Spores from cedar galls travel on the wind to apples and crabapples, and spores from the apples travel back to cedars later in the year.
Where it is found
Cedar-apple rust is common in the eastern United States, where red cedars and apples grow near each other. Check your state official map; ranges change.
Official sources
What to do
- 1
Prune off and bin cedar galls in winter if the tree is small and easy to reach.
- 2
Rake and remove fallen apple leaves in fall.
- 3
Pick resistant apple or crabapple varieties for new plantings.
- 4
If you have apple trees you care about, ask your extension office about fungicide timing from the pink bud stage.
- 5
Do not worry about the cedar itself in most cases. Galls rarely harm it much.
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
Plant resistant apple and crabapple varieties and keep new apples away from red cedars where you can. A good gap helps, but spores travel far, so it does not fully stop the disease.
When to call a pro
Call a pro when the cedar is large, covered in galls with a lot of dead twigs, or when apple trees lose their leaves year after year and you need a treatment plan.
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 red cedar, Apple and crabapple (not on our species list), Hawthorn (not on our species list).
See all species in our tree library, or pick a tougher tree with the tree picker.
For tree companies
How to explain cedar-apple rust to a customer
Tell the homeowner that the orange horns look scary but are a normal part of the life cycle and rarely hurt the cedar. Offer gall removal or advice on resistant plants. Do not sell removals of healthy cedars for this.
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 cedar-apple rust?
It is a fungal disease that needs both a red cedar (or related juniper) and an apple, crabapple or related tree to complete its life cycle.
Are the orange blobs on my cedar dangerous?
They are the fungus fruiting after spring rain. They do not harm people or pets, and they dry up in a few days.
Will it kill my red cedar?
Usually not. The galls can cause some twig dieback, but healthy cedars normally live with them.
Should I cut down my cedar to protect my apple tree?
Generally no. Spores travel far, so removing one cedar rarely solves the problem. Resistant apple types work better.
Can I spray?
Fungicide on apples may help when applied at the right times. It does not help the galls on the cedar. Ask your extension office.
When is the best time to remove galls?
Winter, before spring rain, when galls are dry and easy to see.
Can Lirevon diagnose cedar-apple 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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