Browning Oak leaves around Corvallis

[flowerfiend]

What is happening with the Oak leaves browning suddenly at tips? I’ve just noticed this within the past 2 weeks.

[olin...@earthlink.net]

If I was back East I’d say that was cicada damage from them slitting open the ends of branches to lay their eggs – that’s exactly what it looks like.  Not sure that’s the case here in OR with our relatively uncommon annual cicadas.

 

Olin

 

From: 'flowerfiend' via Mid-Valley Nature <mid-vall...@googlegroups.com>
Sent: Wednesday, June 25, 2025 2:04 PM
To: Mid-Valley Nature <mid-vall...@googlegroups.com>
Subject: [MidValleyNature:7841] Browning Oak leaves around Corvallis

 

What is happening with the Oak leaves browning suddenly at tips? I’ve just noticed this within the past 2 weeks.

 

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[Bill Gerth]

Hi, 

That looks like the branch tip damage that occurs after cicadas insert their eggs into small branches. When they do this, the leaves on the branches beyond the oviposition sites wilt & die. This type of damage is called flagging. Luckily, it seems not to affect the health of the trees in the long term.

Cheers,

Bill

On 06/25/2025 2:03 PM PDT 'flowerfiend' via Mid-Valley Nature <mid-vall...@googlegroups.com> wrote:

 

 

What is happening with the Oak leaves browning suddenly at tips? I’ve just noticed this within the past 2 weeks.

 

 

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[Bill Gerth]

Looking into this a little further, I found that squirrels & gall wasps might also interact to produce similar damage. Here is a link about that...

https://ask.extension.org/kb/faq.php?id=769144

Cheers,

Bill

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[Marge Alig]

Here's another info sheet from the Oregon Department of Forestry about a few oak issues, including the scattered brown patches. 

https://www.oregon.gov/odf/Documents/forestbenefits/oak-pests.pdf

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[Lisa Millbank]

I agree that these are probably caused by tree squirrels going after twig gall wasp larvae. This is seen periodically, and doesn't seem to cause any serious harm to the trees.

Lisa Millbank 

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