Question about what disease is affecting Crabapple

Question: Hi ! I recently moved into a home with an established Crabapple tree in the front ( I would guess around 20 years old). It was fine the first year we moved in but this year it is almost completely defoliated with dead branches and leaves that turn yellow and then die.  I'm leaning towards Apple Scab but I'm not sure. Thank you for any information you may have.

responder: Weld County Colorado Master Gardeners Replied August 19, 2024, 2:03 PM EDT
response: Hi, this is Steve and thank you for your Ask Extension question concerning your crabapple. It seems that the tree has had issues for a number of years prior to your ownership as I see dead branches which were cut long ago.  Do you see any issues with the trunk from the lowest branches to the soil line or on any of the lower branches such as dead looking areas? I can’t be sure from your pictures (which are good) as to what the exact disease/issue could be. Are there any evergreens nearby which have orange growths on their branches? The branches on your crabapple which appear dead, most likely are and should be removed. Considering the size, you would probably want a Certified Arborist to perform that work and can be found at: https://wwv.isa-arbor.com/publicOutreach/treesAreGood/index In addition, should you need to apply a chemical to manage the infection, considering the size, it might be difficult for a homeowner to get good coverage. I will attach information concerning care of crabapples. https://extension.colostate.edu/topic-areas/yard-garden/flowering-crabapple-trees-7-424/ Older crabapples can have a host of issues, among which are environmental as Colorado has such wide swings in weather temperature and moisture which are very difficult for many trees to endure.  If you can answer the questions I posed along with any more pictures of trunk/limb issues or growths on evergreens, I might be able to provide more guidance. Again, thank you for your question and don’t hesitate to contact us with any landscape issues.

responder: The Question Asker Replied August 19, 2024, 8:12 PM EDT
response: Hi again , thank you so much for your response. I will try to answer all of your questions. There are no evergreens nearby. The trunk looks okay to me ( but I'm not an expert). There are a couple of lower branches that were previously removed but for the most part the lower branches look healthier than the rest of the tree. All of the branches have at least some leaves that are yellowing and dropping early. I attached a photo of the trunk to this email. Let me know if you need more information or photos. I greatly appreciate it. Have a good day!On Mon, Aug 19, 2024, 12:03 PM Ask Extension <<personal data hidden>> wrote:

responder: Weld County Colorado Master Gardeners Replied August 20, 2024, 2:32 PM EDT
response: Thanks Kimberly, for the response and new picture. I have asked another Master Gardener who is expert in tree issues to take a look but have not heard back from her yet, if she is available.  In the meantime, from your latest picture with a close up of the leaves, I am fairly certain you have a hawthorn tree and not a crabapple. That being the case, we are likely dealing with a fungus issue. I'll attach information from Penn State about diseases. With that, it appears we may be dealing with a rust caused by a fungus. Information on control is listed in the publication and the fungicide should be found at any larger nursery. It is too late in the year to apply any this year. As I said before, I believe this tree has been under stress for many years and it would likely take a certified arborist to assess what to do going forward.  Also, from you latest picture it looks like the tree was planted too deep which can cause trunk rot and the stones piled around can also hold moisture which promotes rot.  I'll let you know if I learn any more, regards, Steve

responder: Weld County Colorado Master Gardeners Replied August 20, 2024, 4:52 PM EDT
response: Our tree specialist did get back with me and believes the first picture of the leaf is damage done by a Japanese Beetle, which would not cause the tree to be in decline. She does not believe the overall damage was from a fungus, but we can't know for sure what the causes are - root problems, extremes in weather or just "old age" in the tree. We hate to bear this news but we both believe the tree will continue to decline for the next 2-3 years and there is nothing to be done to prevent that happening.  If you have further questions about anything in the landscape don't hesitate to contact us and hopefully the news will be better in the future.

responder: The Question Asker Replied August 20, 2024, 7:02 PM EDT
response: Thank you so much for your response! I had feared that it might just be old age or something that is difficult or impossible to reverse. I appreciate you and your tree specialist giving what advice and information you have. We will get it pruned and treated for a fungal infection and if that doesn't seem to help we will likely get it removed and place a new tree. I put one more picture of the flowers , to confirm whether it's a crabapple or Hawthorne. Thank you for what you do , it's greatly appreciated!! On Tue, Aug 20, 2024, 2:52 PM Ask Extension <<personal data hidden>> wrote:

responder: Weld County Colorado Master Gardeners Replied August 20, 2024, 7:49 PM EDT
response: That bloom would lead a person to believe it is a crabapple, but some varieties of hawthorn also have this look. The tree specialist agreed it is a hawthorn from the leaf and trunk picture. As always, get several bids to care for the tree and then weigh that against the likelihood of a good outcome.  Best regards, Steve