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Pest SolutionsPESTS + WEEDSUSING PESTICIDES OR HERBICIDES?
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Apple and Pear Fire Blight
Erwinia amylovora
Updated Dec 17, 2024
Make a Positive Identification
- Fire blight is a bacterial infection that causes leaves and shoots to die, appearing “scorched”.
- Fire blight may be very serious some years but rare in others.
- Cankers can girdle and kill tree limbs. Trees may die without any sign of dead leaves in the canopy.
- The younger the tree, the more likely the tree will die from fire blight infection.
Species: Fire blight
Mary Ann Hansen, Virginia Polytechnic Institute and State University, Bugwood.org
Bacteria enter through injuries to leaves and shoots. These may be caused by wind, hail, or insects. At first infected twigs and flowers appear water-soaked.
Species: Fire blight
Don Hershman, Bugwood.org
Shoots may wilt, forming a distinctive “shepherd’s crook” shape.
Species: Fire blight
Penn State Department of Plant Pathology & Environmental Microbiology Archives, Penn State University, Bugwood.org
Infected tissues quickly turn brown to black and die. They stay on the tree and appear scorched.
Species: Fire blight
William Jacobi, Colorado State University, Bugwood.org
Fire blight is spread to nearby blossoms or young shoots by splashing rain or insects.
Infected blossoms are often distorted.
Species: Fire blight
William Jacobi, Colorado State University, Bugwood.org
Cankers develop on trunks, limbs, stems, and the graft union. The first sign is a watery, light tan bacterial ooze that exudes from cankers. Cankers may start purplish. Later they turn brownish red, then dark brown or black. There may be reddish-brown streaking beneath the bark. Severe cankers girdle and kill infected limbs.
Species: Fire blight
University of Georgia Plant Pathology, University of Georgia, Bugwood.org
Infected fruits show sunken black spots up to 1" in diameter and 1/4" deep. There may be bacterial ooze exuding from the diseased areas.
LOOK-ALIKES
Species: Pseudomonas blight
Joseph Postman, Oregon State University, 2008
Pseudomonas blight, blossom blast
Wilted blossoms may resemble fire blight. There is no bacterial ooze. On European pears dead tissue doesn’t extend much into the spur. On Asian pears it may kill entire branches.
Species: Nectria canker
Jay Pscheidt, Oregon State University
Nectria canker
Canker grows in a series of concentric calluses. There is no bacterial ooze.
Apple and Pear Fire Blight Benefits
- Fire blight is a plant disease that harms susceptible apples, pears and other trees. It doesn’t have any benefit for people or the environment.
Apple and Pear Fire Blight Risks
- Fire blight causes damage to leaves and fruit.
- Cankers can kill whole limbs.
- Once a tree has fire blight the only way to get rid of the infection is to prune out all infected wood. This can disfigure trees.
- Fire blight can kill trees, especially young ones.
Risk Card
Does it cause harm?
Adults & Children
None
Property
Some
Pets
None
Annoyance
Some
Environment
None
Action Recommended
Cankers can girdle and kill tree limbs, and trees may die.
Take Action?
Fire blight can cause serious orchard losses.
Do I need to take action?
Yes. Remove and burn all traces of wood infected with fire blight as soon as it is seen.
What if I do nothing?
Fire blight can kill trees, especially young ones.
Prevent Fire Blight
Signe Danler, Oregon State University
Plant Fire Blight Resistant Varieties
- Apple: 'Liberty', 'Prima', ‘Red Delicious’, ‘Redfree’, ‘Spur Delicious’, and ‘Stayman Winesap’ are resistant.
- Pear: ‘Bradford’ and ‘Seckel’ pears are somewhat resistant to fire blight. Most others are very susceptible to it.
- Asian Pear: ‘Seuri’, ‘Shinko’, and ‘Ya Li’ are most resistant to fire blight.
- Crabapple: Many cultivars are resistant to fire blight. See the Crabapple Resistance Chart.
- Root stocks: M9, M26, M27, Mark, and Ottawa 3 are very susceptible.
Signe Danler, Oregon State University
Prevent Succulent Growth
- Avoid excess nitrogen fertilization and heavy pruning. These cause rapid, succulent shoot growth. These shoots are most susceptible to infection.
- In general, young trees are more susceptible to fire blight infection.
"20150722-NRCS-LSC-0093" by USDAgov is licensed under CC PDM 1.0
Reduce Infection Spread in Flowers
- Fire blight is spread to nearby blossoms or young shoots by splashing rain or insects.
- Remove late blooms during fruit thinning to reduce re-infection.
- Don’t irrigate trees during bloom.
- Avoid overhead watering, or irrigate in the morning to allow drying time.
"afrc.mc.9.10.14 (23)" by Rural Matters is licensed under CC BY-NC 2.0
Remove or Avoid Sources of Infection
- Remove nearby trees or hedgerow plants, such as hawthorns. These can be a source of infection.
- Check new nursery trees for any symptoms of fire blight.
Solutions for Fire Blight
Non-chemical Methods
- Prune out and destroy infected tissues.
- Use multiple methods to control and prevent fire blight.
Chemical methods
- If fire blight has been a problem in the past, apply preventative blossom sprays.
NEED HELP?
Consider a licensed pest control company. Learn How to Hire a Pest Control Company.
Your local Extension Specialist in Oregon and other states can suggest other methods.
Jump to
| Method | Does it work? | Is it safe? | Recommendation |
|---|---|---|---|
A Remove Diseased Wood |
Effective |
Low risk |
Recommended |
B Scrape out cankers on trunks or large limbs |
Effective |
Low risk |
Recommended |
C Control with Fungicides |
Somewhat effective |
Moderate risk |
Use if Necessary |
|
D If Using Fungicides, Protect Yourself & Minimize Risks
|
A
Remove Diseased Wood
Non-Chemical Method
William M. Ciesla, Forest Health Management International, Bugwood.org
Remove Diseased Wood
Recommended
Prune out and destroy infected tissues.
| Does it work? | Effective Pruning out all diseased wood can remove the infection. Trees may be re-infected if there are nearby sources. |
| How much effort? | Moderate effort |
| What's the risk? | Low risk |
| Possible risk of exposure or harm from chemicals | NONE |
University of Georgia Plant Pathology, University of Georgia, Bugwood.org
John Hartman, University of Kentucky, Bugwood.org
B
Scrape out cankers on trunks or large limbs
Non-Chemical Method
William Jacobi, Colorado State University, Bugwood.org
Scrape out cankers on trunks or large limbs
Recommended
Fire blight infection may occur on a trunk or major limb. In winter, look for infections extending beyond the margin of the canker. Scrape out all discolored tissue plus 6 to 8 inches more beyond the infection.
If more than half the limb is girdled by canker, remove the limb.
| Does it work? | Effective Pruning out all diseased wood can remove the infection. Trees may be re-infected if there are nearby sources. |
| How much effort? | Moderate effort |
| What's the risk? | Low risk |
| Possible risk of exposure or harm from chemicals | NONE |
C
Control with Fungicides
Chemical Method: Use with caution
iStock
Control with Fungicides
Use if Necessary
Fungicides can prevent new infections but won’t eliminate existing wood infections. These must be pruned out.
| Does it work? | Somewhat effective Fungicides can prevent new fire blight infections when used according to label directions. They must be applied before plants develop disease symptoms to work. |
| How much effort? | Moderate effort |
| What's the risk? | Moderate risk Using fungicides comes with real risks. ALWAYS read the entire label front to back. Review instructions even for brands you know. |
| Possible risk of exposure or harm from chemicals | El uso de fungicidas conlleva cierto grado de riesgo. El riesgo más bajo se produce sin el uso de fungicidas. You may be exposed to a fungicide if you:
Follow directions closely to reduce risk. |
Some products are available for home use. A few are listed below. These active ingredients are suggested chemical treatments to control apple scab. Look for these chemical names in the “Active Ingredients” section of product labels.
- Bacillus amyloliquifaciens strain D747
- Streptomycin sulfate
- Mono- and Di-Potassium Salts of Phosphorous Acid
- Copper Sulfate
Suggested pesticides are from the Pesticide Information Center Online (PICOL) Database. They are permitted for HOME use in Oregon. Read the label for application directions and effectiveness information.
ONLY professional pesticide applicators can use Restricted-Use Pesticides (RUP) that may be more effective. If you need further support, contact a licensed pesticide applicator.
Fungicide Application Tips
- If fire blight has been a problem in the past, apply preventative blossom sprays.
- They must be applied before plants develop disease symptoms to work.
- Consult a licensed pesticide applicator for treatment of trees over 10 ft. tall.
If Using Fungicides, Protect Yourself & Minimize Risks
Chemical Method: Use with Caution
Weston Miller, Oregon State University
Why Is It Important to Read Fungicide Product Labels?
- They have detailed information on how to use the product correctly and legally.
- They contain information on potential hazards of the product.
- They provide instructions you should follow for poisonings and spills.
- Following label instructions helps you to minimize the risks and maximize the benefits.
Key Fungicide Safety Tips
- Read the entire label front to back.
- Follow the instructions.
- Review the instructions even for brands you know.
- Only apply the product where the label says it can be applied.
- Keep all fungicides in their original container.
The Label is the Law
ALWAYS read the label before using fungicide products. The label is a legal document that provides information on how to safely use the fungicide. This helps avoid harm to human health and the environment. Using a fungicide in off-label ways is illegal. It can result in legal enforcement actions.
READ THE LABEL & Follow Instructions
It has instructions to protect you and the environment.
- Labels are different for every product and they often change over time.
- Use a magnifying glass for small print.
- Pay attention to CAUTION, WARNING, and DANGER statements.
- Pay attention to the PRECAUTIONARY STATEMENTS.
- The law states you must read and follow fungicide instructions.
Protect Yourself
Eye, skin & lung irritants
- Wear the correct personal protection equipment. The right gear often includes chemical-resistant gloves, safety glasses, a long-sleeve shirt, pants, socks, and shoes.
- Mix fungicide products outdoors or in a well-ventilated area.
- Wash hands after you mix or apply fungicides and before smoking or eating.
- Wash clothes worn while mixing and applying fungicides separately from all other laundry.
Protect Children & Pets
Children and pets are at risk if they eat or touch the plant before fungicides dry.
- Keep them away during and after applying fungicides (read label for how long).
- Remove toys and pet dishes from yard before applying.
- Don’t track fungicide products into home on shoes or clothes.
Protect Pollinators
- Apply early morning or evening when bees are less active.
- Avoid spraying flowering plants, if possible.
- Don’t spray on bees or insects.
Storage & Disposal
- Store out of the reach of children and pets.
- Store in a cool and dry place.
- Never pour down any drain.
- If you mix too much, apply it rather than storing it.
- Don’t put fungicide containers in the trash unless instructed by the label.
- Take unused fungicides to a hazardous waste facility.
Call 1-800-CLEANUP (1-800-253-2687) to find out where to dispose of pesticides.
For the Portland metro region in Oregon, contact Metro’s Recycling Information. Call 503-234-3000, email or visit Metro’s website
More about:
About Using Pesticides on School Grounds in Oregon
If using pesticides on school grounds, there are special rules in Oregon. See School Integrated Pest Management (Oregon Department of Agriculture).
NEED HELP?
The National Pesticide Information Center (NPIC) can answer questions about pest control chemicals.
1-800-858-7378 or npic@ace.orst.edu
Consider using a licensed pest or weed control company. Learn How to Hire a Pest Control Company.
Your local Extension Specialist in Oregon and other states can suggest other methods.
Content provided by Weston Miller, Signe Danler and Jeremiah Mann. Pesticide safety information edited by Kaci Buhl.
Peer review facilitated by OSU Department of Horticulture.
APPLE FIRE BLIGHT REFERENCES
Fire Blight of Apple and Pear
PNW Pest Management Handbooks
Apple: Fire Blight
Washington State University Hortsense
Pear: Fire Blight
Washington State University Hortsense
Pests in Gardens and Landscapes Fire Blight
University of California IPM
Apple Cultivar Susceptibility
PNW Pest Management Handbooks
Pear Cultivar Susceptibility
PNW Pest Management Handbooks
Asian Pear Cultivar Susceptibility
PNW Pest Management Handbooks
Crabapple Cultivar Susceptibility
PNW Pest Management Handbooks
Fire Blight Annual Management Guide (pdf)
Utah State University Cooperative Extension
Managing Diseases and Insects in Home Orchards
Oregon State University Extension Service