Crab apple bark issue - Ask Extension
Concern with the bark, deer, fungus, other disease and what to do about it?
Knowledgebase
Crab apple bark issue #857958
Asked January 27, 2024, 2:52 PM EST
Concern with the bark, deer, fungus, other disease and what to do about it?
Macomb County Michigan
Expert Response
Hello,
Based on what I see in your images:
Fungus issue:
From the MSUE article - Crabapples Can be a Star in your Landscape at this link:
https://www.canr.msu.edu/news/crabapples_can_be_a_star_in_your_landscape
The most common problem among wide crabapple varieties is a fungus disease called attacks leaves and fruit called “Apple Scab,” Venturia inaequalis. Apple scab on crabapples can leave plants looking fairly bare as the leaf spot disease causes leaves to drop from the tree throughout the summer. Some very susceptible varieties will often have only leaves at the tips of branches by early August. Cultivars selected as landscape specimens and planted to be a focal point of the site can end up being a huge eyesore. This disease is treatable with fungicides but often requires repeated applications from bud break through petal fall to prevent leaf drop. An Extension publication from Purdue University, Apple Scab of Flowering Crabapples, provides an in-depth review of apple scab and cultivar resistance. Check out this link:
https://www.extension.purdue.edu/extmedia/BP/BP-39-W.pdf
If you currently struggle with a crabapple that drops leaves each year due to apple scab, you have the choice to protect the plant yearly with multiple fungicide applications, do nothing and live with the unsightly leaf drop, or remove the plant and replace it with a resistant variety. Sanitation can help reduce the presence of the disease from year to year by picking up and removing fallen crabapple leaves from the site. Visit MSU’s Integrated Pest Management (IPM) website for more information on apple scab. Check out this link:
https://www.canr.msu.edu/resources/apple_scab
If you decide to replace this tree, I am attaching a guide to crabapple trees to help you decide. It also provides information on the care of the tree.
https://www.canr.msu.edu/uploads/files/e2177.pdf
Bark Issues on Trunk (addresses deer damage, too)
According to Michigan State University, the bark on a crab apple tree can peel due to several reasons, including normal aging, winter injury, fire blight, and pest infestation. If the peeling bark is due to normal aging, it is not a cause for concern. However, if it is due to other reasons, it is important to take appropriate measures to prevent further damage. Here are some steps you can take:
Wildlife damage: A common cause of bark problems is wildlife damage, such as deer. They will strip and eat the bark of crabapple trees. Here is a link with more information:
https://www.canr.msu.edu/resources/smart_gardening_to_deter_deer
Winter injury: If the peeling bark is due to winter injury, it is important to protect the tree from further damage. You can do this by wrapping the trunk with a protective material such as burlap or tree wrap.
Fire blight: If the peeling bark is due to fire blight, it is important to prune the affected branches and dispose of them properly. You should also avoid using nitrogen-rich fertilizers, which can promote the growth of fire blight. Please Note: I don't see fire blight in your branches from your images.
Pest infestation: If the peeling bark is due to pest infestation, it is important to identify the pest and take appropriate measures to control it. You can use insecticides or other pest control methods to get rid of the pests. I can't really tell by the images provided.
Option 1 – To help identify the pest (if there is one)
You should get a confirmed diagnosis from the MSU Diagnostic Plant & Pest Lab - Please email your digital images prior to bringing or sending physical samples. It can be sent to <personal data hidden>.
MAKE SURE IN THAT E-MAIL YOU INCLUDE YOUR NAME, ADDRESS, AND PHONE NUMBER!!
Be prepared. The lab may ask for more images - THE LAB WILL LET YOU KNOW IF A SAMPLE NEEDS TO BE SENT - There is a $20-25 dollar fee (if they need a sample sent).
Lab email: <personal data hidden>
Lab phone:<personal data hidden>
Hours of operation: Monday through Friday, from 8:00 AM to 5:00 PM.
PLEASE READ BELOW ON PREPARING YOUR SAMPLE (if the lab needs a sample)
From the lab: Please do not ship samples on Fridays. They thank you for your patience and understanding.
Every sample must be accompanied by a completed submission form. Please place the form in a separate resealable bag to prevent it from getting damp or soiled. The form is at this link: https://www.canr.msu.edu/pestid/uploads/files/General_Sample_Submission_Form_May2022.pdf.
Complete details of submitting a sample are at this link: https://www.canr.msu.edu/pestid/submit-samples/
Option 2: You have an arborist do an onsite visit. To find an arborist in your zip code, please go to this direct link: https://www.treesaregood.org/findanarborist/arboristsearch
I hope this helps! Please let me know if you have any other questions - Thanks
Based on what I see in your images:
Fungus issue:
From the MSUE article - Crabapples Can be a Star in your Landscape at this link:
https://www.canr.msu.edu/news/crabapples_can_be_a_star_in_your_landscape
The most common problem among wide crabapple varieties is a fungus disease called attacks leaves and fruit called “Apple Scab,” Venturia inaequalis. Apple scab on crabapples can leave plants looking fairly bare as the leaf spot disease causes leaves to drop from the tree throughout the summer. Some very susceptible varieties will often have only leaves at the tips of branches by early August. Cultivars selected as landscape specimens and planted to be a focal point of the site can end up being a huge eyesore. This disease is treatable with fungicides but often requires repeated applications from bud break through petal fall to prevent leaf drop. An Extension publication from Purdue University, Apple Scab of Flowering Crabapples, provides an in-depth review of apple scab and cultivar resistance. Check out this link:
https://www.extension.purdue.edu/extmedia/BP/BP-39-W.pdf
If you currently struggle with a crabapple that drops leaves each year due to apple scab, you have the choice to protect the plant yearly with multiple fungicide applications, do nothing and live with the unsightly leaf drop, or remove the plant and replace it with a resistant variety. Sanitation can help reduce the presence of the disease from year to year by picking up and removing fallen crabapple leaves from the site. Visit MSU’s Integrated Pest Management (IPM) website for more information on apple scab. Check out this link:
https://www.canr.msu.edu/resources/apple_scab
If you decide to replace this tree, I am attaching a guide to crabapple trees to help you decide. It also provides information on the care of the tree.
https://www.canr.msu.edu/uploads/files/e2177.pdf
Bark Issues on Trunk (addresses deer damage, too)
According to Michigan State University, the bark on a crab apple tree can peel due to several reasons, including normal aging, winter injury, fire blight, and pest infestation. If the peeling bark is due to normal aging, it is not a cause for concern. However, if it is due to other reasons, it is important to take appropriate measures to prevent further damage. Here are some steps you can take:
Wildlife damage: A common cause of bark problems is wildlife damage, such as deer. They will strip and eat the bark of crabapple trees. Here is a link with more information:
https://www.canr.msu.edu/resources/smart_gardening_to_deter_deer
Winter injury: If the peeling bark is due to winter injury, it is important to protect the tree from further damage. You can do this by wrapping the trunk with a protective material such as burlap or tree wrap.
Fire blight: If the peeling bark is due to fire blight, it is important to prune the affected branches and dispose of them properly. You should also avoid using nitrogen-rich fertilizers, which can promote the growth of fire blight. Please Note: I don't see fire blight in your branches from your images.
Pest infestation: If the peeling bark is due to pest infestation, it is important to identify the pest and take appropriate measures to control it. You can use insecticides or other pest control methods to get rid of the pests. I can't really tell by the images provided.
Option 1 – To help identify the pest (if there is one)
You should get a confirmed diagnosis from the MSU Diagnostic Plant & Pest Lab - Please email your digital images prior to bringing or sending physical samples. It can be sent to <personal data hidden>.
MAKE SURE IN THAT E-MAIL YOU INCLUDE YOUR NAME, ADDRESS, AND PHONE NUMBER!!
Be prepared. The lab may ask for more images - THE LAB WILL LET YOU KNOW IF A SAMPLE NEEDS TO BE SENT - There is a $20-25 dollar fee (if they need a sample sent).
Lab email: <personal data hidden>
Lab phone:<personal data hidden>
Hours of operation: Monday through Friday, from 8:00 AM to 5:00 PM.
PLEASE READ BELOW ON PREPARING YOUR SAMPLE (if the lab needs a sample)
From the lab: Please do not ship samples on Fridays. They thank you for your patience and understanding.
Every sample must be accompanied by a completed submission form. Please place the form in a separate resealable bag to prevent it from getting damp or soiled. The form is at this link: https://www.canr.msu.edu/pestid/uploads/files/General_Sample_Submission_Form_May2022.pdf.
Complete details of submitting a sample are at this link: https://www.canr.msu.edu/pestid/submit-samples/
Option 2: You have an arborist do an onsite visit. To find an arborist in your zip code, please go to this direct link: https://www.treesaregood.org/findanarborist/arboristsearch
I hope this helps! Please let me know if you have any other questions - Thanks
