Oak tree issue

Question: I am attaching photos that I took of our oak leaves. We have a swamp white oak. It has been treated in the past for Oakleaf blister but this didn’t seem to look the same. The tree is huge and we would hate to lose it. Thank you for your time.

responder: The Question Asker Replied June 19, 2023, 5:40 PM EDT
response: I was talking to Blair at American Turf and Tree Care (he gave a talk at CSU last week) and he said you might want a sample of our oak leaves.  Do you have a phone number I can call to find out and where I would bring a sample if you want one?  I'm seeing this in different areas on the tree (north, south, east, west).  I've also seen some aphids, but not on the leaves I took photos of.  Blair wants me to keep him in the loop on this. He is very interested to know what I find out. He's not seen this before. Thank you again for your time. Pamela Madigan <personal data hidden> Cell In a message dated 6/19/2023 2:32:32 PM Mountain Standard Time, <personal data hidden> writes:   Dear PAMELA, Thank you for using Ask Extension. A request for support has been created and a representative will follow-up with you as soon as possible. Questions are usually answered within two business days. You can view this question's progress online. YOUR QUESTION #0106411: Oak tree issue   I am attaching photos that I took of our oak leaves. We have a swamp white oak. It has been treated in the past for Oakleaf blister but this didn’t seem to look the same. The tree is huge and we would hate to lose it. Thank you for your time. Ask Extension offers one-to-one expert answers from Cooperative Extension/University staff and volunteers within participating Land-Grant institutions across the United States. If you wish to provide additional comments or information regarding the issue, please login to your account for a complete archive of your prior questions and answers.  This message for informational purposes only. It is not intended to be a substitute for personalized professional advice. For specific local information, contact your local county Cooperative Extension office or other qualified professionals. eXtension Foundation does not recommend or endorse any specific tests, professional services, products, procedures, opinions, or other information that may be mentioned. Reliance on any information provided by eXtension Foundation, employees, suppliers, member universities, or other third parties through eXtension is solely at the user's own risk. All eXtension content and communication is subject to the Terms of Use which may be revised at any time.

responder: The Question Asker Replied June 19, 2023, 5:44 PM EDT
response: These leaves do not have bugs on the underside.  I did see some aphids on other leaves, but not these affected ones. I've seen this damage on all sides of the tree but the worse branch is on the north side.  Blair from American Turf and Tree Care (he gave a talk at CSU last week) is very interested in what I find out from you.  He said you may want a sample.  If so, what would you want and where would I bring it?  This tree is HUGE and about 16 years old.  I sure hope you have some ideas.  This does not look like the Oak Leaf Blister which was treated with Cambistat last July.  Unless it's taken on another form.....  Thank you again for your time.  Pamela Madigan

responder: Alison O'Connor, PhD  Replied June 20, 2023, 4:59 PM EDT
response: Hi Pamela,  This is oak leaf blister and we're seeing it on a lot of oaks this year - even red oaks, which is more unusual. The inoculation occurs when the leaves are just emerging and there is nothing curative that can be sprayed - there are only preventative fungicides.  Fungicides can be applied late in winter dormancy, before bud break, to kill overwintering spores before they can infect the newly developing foliage in the spring. Fungicides labeled for use include copper-based products and mancozeb.  Fortunately the damage is cosmetic and it usually doesn't harm the overall health of the tree. As the season progresses the blisters will turn brown.

responder: The Question Asker Replied June 20, 2023, 9:11 PM EDT
response: Alison,  We had our tree treated with Cambistat last July for Oak Leaf Blister, recommended by Blair at American Turf and Tree. It's supposed to stimulate root growth for better overall plant health. The treatment is supposed to last 2-3 growing seasons. However, I believe the blister can show up in year two.  I knew about spraying before bud break, 2 years ago, but could not find someone who would do it.  We used to have our trees sprayed every year with dormant oil and never had this problem with the oak until we stopped dormant oil because it was told to us by another tree company that it is a waste... I'm beginning to believe it may not be. Although I know dormant oil is not a fungicide.  And the down side is, fungicides are quite toxic.  If it was your tree, what would you do?  I'm feeling a bit conflicted and frustrated when all of these blisters begin to turn brown (again).  What is your feeling about dormant oil.  I realize we're talking apples and oranges here.   Thank you for your time.  I really appreciate it.   Pamela In a message dated 6/20/2023 2:59:10 PM Mountain Standard Time, <personal data hidden> writes:

responder: Alison O'Connor, PhD  Replied June 21, 2023, 11:19 AM EDT
response: Hi Pamela,  Cambistat is a plant growth regular, which would reduce overall growth - I don't know if it will promote root growth. But Cambistat will not prevent the infection from oak leaf blister, unless they sprayed something else?  Dormant oils don't generally control disease - though there is some very limited research that it can help with some fruit tree issues (research done in California). Dormant oils are generally used for insect pressure.  Oak leaf blister is a very common disease, and again, is aesthetic. It doesn't affect the overall health of the tree. If you want to try to prevent infection next year, then consider using the fungicides I mentioned in my first response and work with Blair and his company to apply them at the right time.   Because of all the rain, humidity, and moisture, we're having an increase in overall disease and insect pressure. It's a strange year!