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what is this?

Posted by sluice z6a CO (My Page) on
Tue, Jun 12, 12 at 12:08

Saw a Juniperus osteosperma a few days ago with some of these things growing on it. Any ideas? Thanks.

J. osteosperma

J. osteosperma

J. osteosperma


Follow-Up Postings:

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RE: what is this?

Looks like a witch's broom - That's where most funky conifer selections originate. Try grafting it onto a rootstock and see what it turns into!


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RE: what is this?

mistletoe ?

Keith


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RE: what is this?

kbguess,

Mistletoe was my first thought, too. I tried finding pics, but they don't look quite like that. The growth seems too different to be a broom. I hope it's not mistletoe.

Barb


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RE: what is this?

Hmm, maybe it is a broom, or some sort of disease.

Here are a couple of pics of juniper mistletoe from a J. monosperma in New Mexico, which looks like Phoradendron juniperinum.

Phoradendron juniperinum (?)

Phoradendron juniperinum (?)

I had thought about trying to root that small rosette, and even brought one home with me.


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RE: what is this?

Well of COURSE you brought it home, lol! It will be interesting to see how that comes out.


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RE: what is this?

I've enjoyed reading some of the threads in this forum, as I'm a fan of conifers.

I was curious about the cute little growth on the juniper, so I went to Google. Here's what I found:

It appears to be a gall, the home of the larvae of juniper tip midge (Oligotrophus betheli).

You can look for mining and exit holes "found at the junction between living and dead tissue or at the base of the swollen portion". This is from the Pacific Northwest Insect Management Handbook: http://insects.ippc.orst.edu/pnw/insects?16LAND10.dat

This midge lays its eggs in Juniperus occidentalis, J. scopulorum, J. virginiana, but is especially common on J. osteosperma in Colorado and Utah according to the book 'Forest Entomology' by William Ciesla.

Although from western N America, the juniper tip midge is also an expat in Serbia; it was first identified there in 2007 on J. virginiana.

The number of rosettes in the gall is between 5 and 20. A photo of galls is on p.59 in www.aspensite.org/FTP/Colorado_insects_Feed_Trees.pDf

And finally, people who study galls are called cecidologists!

BTW Sluice, nice pics. Your third photo looks like that of a beautiful christmas tree ornament.


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RE: what is this?

I've enjoyed reading some of the threads in this forum, as I'm a fan of conifers.

I was curious about the cute little growth on the juniper, so I went to Google. Here's what I found:

It appears to be a gall, the home of the larvae of juniper tip midge (Oligotrophus betheli).

You can look for mining and exit holes "found at the junction between living and dead tissue or at the base of the swollen portion". This is from the Pacific Northwest Insect Management Handbook: http://insects.ippc.orst.edu/pnw/insects?16LAND10.dat

This midge lays its eggs in Juniperus occidentalis, J. scopulorum, J. virginiana, but is especially common on J. osteosperma in Colorado and Utah according to the book 'Forest Entomology' by William Ciesla.

Although from western N America, the juniper tip midge is also an expat in Serbia; it was first identified there in 2007 on J. virginiana.

The number of rosettes in the gall is between 5 and 20. A photo of galls is on p.59 in www.aspensite.org/FTP/Colorado_insects_Feed_Trees.pDf

And finally, people who study galls are called cecidologists!

BTW Sluice, nice pics. Your third photo looks like that of a beautiful christmas tree ornament.


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RE: what is this?

Whoops! Didn't mean to send this twice.


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RE: what is this?

Thanks IshCountryGal!

Tomorrow I'll inspect it for mining and exit holes.


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RE: what is this?

So here is the gall, there were 10 small rosettes.

After pulling apart each rosette, I noticed the juniper tip midge larvae were still in the gall.

Oligotrophus betheli larva in Juniperus osteosperma gall rosette

A close up of the juniper tip midge larva


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RE: what is this?

What amazing photos! It makes me so happy when folks are curious enough to really explore. What a great learning experience, thanks for sharing!


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RE: what is this?

Thanks greenhaven!

To complete the story, this is Glenwood Springs, CO where the gall was found. That's the Roaring Fork river coming down the valley, from Mt. Sopris in the background.
A nice mix of J. osteosperma, J. scopulorum, P. menziesii and P. edulis along this canyon.


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RE: what is this?

Really nice work sluice! That's a mighty little midge to provoke that response from its host.

I envy you the beautiful blue sky in the last photo. We're in the midst of "June gloom" here in the pacific NW.

-m


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RE: what is this?

Yep, Juniper gall midge. I remember seeing them on J. osteosperma in the White Mts in California. This species seems particularly prone to them, though I've read they occur on some other junipers too.

Resin


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