Burrowing into my Grapefruit Tree?

MisterK71May 14, 2014

Hi All,

My first post here and I am in need of some professional advice.

I have a beautiful grapefruit tree in my backyard that we treat very well, over the last few weeks on one of the main limbs i have noticed what appears to be burrowing of some sort? Thought it might be a woodpecker but it is only on this one limb.

I am attaching an image, hopefully you all can tell me what is causing the issue so I can remedy it.

Thanks for your help!


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Wow that must be one beautiful tree . I am no expert at this but do you happen to see any wasps or hornets flying around the tree.


    Bookmark   May 14, 2014 at 1:15PM
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Hi Brian,

It is a great tree, keeps us in grapefruit and juice year round, absolutely love it.

No hornets or wasps around, they are in the neighborhood but not near the tree.


    Bookmark   May 14, 2014 at 1:19PM
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missingtheobvious(Blue Ridge 7a)

Why was the branch cut off (at the extreme top of the photo)?

    Bookmark   May 14, 2014 at 1:26PM
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"Why was the branch cut off (at the extreme top of the photo)?"

It was broken off (2ft out) when we moved in the house, the tree was not maintained for numerous years and was kind of a mess, we did some pruning and trimming to get the grapefruit to grow, they were being starved of water due to "leach" branches and untrimmed overgrowth.

    Bookmark   May 14, 2014 at 1:49PM
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gregbradley(Upland, CA USDA 9b Sunset 19)

Looks like Phytophthora to me. You are going to need some advise by someone with more knowledge than I have. You might want to order some Agri-Phos to get you started. You need to work on this ASAP if you want to save it.

This post was edited by GregBradley on Wed, May 14, 14 at 20:39

    Bookmark   May 14, 2014 at 8:23PM
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Thanks for the insight Greg, I am going to run by a local nursery today and show them images and see what they say.

Will post back with an answer in case anyone else encounters this problem.


    Bookmark   May 15, 2014 at 10:00AM
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I appreciate you taking a look.

Went to a local tree nursery and they confirmed it is a worm burrowing into the wood, the heavy sap running is a good sign as well as the perfect circular holes that the wounds start as.

Thanks for the effort, hope this post helps someone in the future.


    Bookmark   May 16, 2014 at 9:44AM
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Looks to me like Ambrosia Beetle damage. Useful link here: http://edis.ifas.ufl.edu/hs1179



    Bookmark   May 16, 2014 at 10:40AM
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gregbradley(Upland, CA USDA 9b Sunset 19)

Need better pictures. I missed the round holes completely.

I would guess that something is burrowing but that is secondary problem, not primary. Unless the nursery is a citrus specialist, they are probably not up to the task of diagnosis.

Do you have sprinklers that hit the trunk of the tree? Do you have mulch that touches the trunk at the base?

Hopefully someone will come along here with more info and that you have posted some pictures with more detail.

If it was my tree, I would be applying Agri-Phos.

Insecticide for whatever is burrowing might be a good idea also.

    Bookmark   May 16, 2014 at 10:40AM
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Thanks for the responses, to answer a few questions.

No sprinklers hitting the bark, I irrigate, the damage is above my head.

No mulch touching the tree, the bark is perfect except this one branch, no direct sun on the bark either.

Ambrosia Beetle - this is a possibility as well, the people at the nursery, a very well respected tree nursery here in az mentioned that it was a worm OR beetle.

I have included more images for you all, I have knocked a lot of the sap off to reveal the actual wound, should have taken images with all the sap hanging off the tree.

I have a large wood pile close to this tree, found a lot of perfectly round holes in the wood pile last night as well... think it is in the wood pile as well.

I hit it with nursery recommended insecticide, wont be eating any grapefruit for a year... ;-(

Hopefully this helps someone else.


    Bookmark   May 16, 2014 at 12:48PM
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BarbJP CA 15-16/9B

What insecticide did they recommend?

Bark beetles are tough to spray for as once they're inside the tree, the bark is a really good protection. Usually you will need to use a systemic to get it into the sap to kill them from the inside.
Either injected under the bark,(which I think only arborists with a spray licence can apply,) or one applied to the soil so the tree can take it up through the roots, which anyone can apply.

Once you kill the beetles larvae inside the tree, you can use a surface type spray to keep the adults from laying eggs on the surface of the bark again. You'll need to read up on their life cycle to see when the adults are laying eggs in your area, so next year you'll know when to spray the surface protection spray. This kind protection spray may need to be done every year.

The biggest problem with bark burrowing beetles isn't the small holes they make, most trees can deal with that much small damage. It's that a lot of them carry fungus and/or bacteria on their bodies and that can infect the trees. Like a malaria infected mosquito with people.

I wish you luck! I think with an older tree like that, if it's generally pretty healthy, even if it gets an infection, with good care it may live with it for a long time without killing it.

    Bookmark   May 16, 2014 at 1:29PM
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Thanks for the additional information, I will find when to spray to stop them doing this again.

Would you recommend applying Agri-Phos on top of the insecticide? As a secondary precaution that they might be carrying a fungus?

The nursery sold me "Bayer Tree and Shrub Insect Control" which I did a fair amount of reading on and from what I read it seems to work well... don't worry, I don't have any bees near my house ;-)

Look forward to your response,


    Bookmark   May 16, 2014 at 3:42PM
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BarbJP CA 15-16/9B

It sure couldn't hurt to try the Agri-phos too. I think it would be good insurance. Plus it's a pretty useful product for lots of other fungal problems on lots of plants, so not a bad idea to have some on hand. And if it already has Phytophthora it will help the tree.

The "Bayer Tree and Shrub Insect Control" is a very good product and what I was hoping they sold you.
It does take a few days to weeks for the product to be absorbed throughout the tree, depending on the trees size and age; older and larger trees will take longer. I'm pretty sure it lasts almost all year, check the label to be sure.

So you'll have protection for quite a while, but eating the fruit during this time isn't a good idea, as you mentioned before.
In future years, surface sprays when the adults are laying eggs again, may be all you need to do, if you get the timing right. That timing will be different in different areas; your local ag agency may know when to spray.

Sounds like you have a good plan in place, good luck!

    Bookmark   May 16, 2014 at 11:09PM
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gregbradley(Upland, CA USDA 9b Sunset 19)

The first pic clearly shows a burrower ejected by the sap. The other two look a bit less like Phytophthora than your original pic but there isn't any downside to treatment.

Bark Beetles don't, or aren't able to successfully attack a healthy limb. That is why you found them in your woodpile. Weakened branches from Phytophthora or other disease give them a way to successfully attack.

The Bayer product is Imidacloprid and is absorbed through the roots into the system. It will kill insects after they have eaten lots of the plant with the systemic poison. It can be absorbed through the bark with an absorption agent or applied into those holes where it will kill the larvae quickly and be absorbed into the tree to protect as a systemic.

My friends with a commercial grove actually drill a hole down at an angle into the trunk of trees with Phytophthora and pour in the commercial version of Agri-Phos to be absorbed into the tree. They do Imidacloprid the same way.

    Bookmark   May 16, 2014 at 11:44PM
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Thank you all for your help and insight, I will be adding the Agri-Phos this weekend.

Mucho Appreciated!


    Bookmark   May 28, 2014 at 10:38AM
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