Juniperus with yellowing foliage : help !

Hi there,
We have a beautiful 35 ft juniperus in our garden, probably a red cedar, that dangerously becomes yellow. Spring has been moderately warm but very dry, and I have noticed a lot of red spider mites one month ago in the garden. I have not seen a big quantity around the tree and along the trunk (two or three), so I was not worried. But now, I am...
I am a complete newbie to gardening. I keep it moist at the moment, and try to wash red spider mites with my hose, as high as I can. Is this a good idea ? I plan to buy some pesticide for red mites but wonder how I am going to reach the top ! Could a treatment at the bottom be sufficient ?
Is the jupinerus likely to die and will dead foliage be replaced in the future ?
I'm in New Zealnad. Thank you for you help.
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"............and I have noticed a lot of red spider mites one month ago in the garden. I have not seen a big quantity around the tree and along the trunk (two or three), so I was not worried. But now, I am ........."
I have my doubts about them being Red Spider. If they are bright red, about half the size of a pin head and moving fairly fast then they are red mites, and are in fact a predator of the red spider. Red spider are a dull brick red and very hard to see with the naked eye, they are mostly found by the presence of their web.
--
David Hill
Abacus nurseries
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Well I have no proof they are the cause of the problem. They are bright red and move fast. Some plants in the garden seem to be eaten quite a lot too(photinia for example).
My tree is dying. In a park nearby, I saw a couple of similar trees with the foliage turning yellow too, but not as much. Both older and younger trees seem to experience the problem, and moreover at different places.
Looks like a pest problem to me, a weather-related problem would not cause that much damage. Can't think about any other reason with regards to the information I gathered so far.
Any recommendation before it is too late ?
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Spider mites can certainly decimate a number of coniferous species in warm, dry climates. Keeping the plants well hydrated and increasing humidity will certainly help. You might want to inquire at a good, local garden center what their diagnosis and recommendations may be. A systemic miticide may be in order.
Dead foliage will not be replaced on a juniper, however new growth may emerge from branch tips and serve to dsguise bare areas. Whether or not the plant will die is impossible to suppose from this distance and through this forum.
pam - gardengal
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Today by shaking the foliage and holding a white sheet of paper underneath, I saw two tiny insects, really smaller than the bright red little spider moving very fast. They did move slower, too. Darn, are they small !
My vision being far from perfect and having no magnifying lens, as far as I can tell those two insects - mites, probably - were dark brown (black ?), and yellow for the second one. I did the test two or three times, but only found two of these.
By keeping looking for information on the web, I read that they were sucking out the plant fuild by piercing into it, leaving yellow or brown holes on the scales of conifers. I didn't manage to recognize those holes.
One thing that I did not understand well was what happens to yellow foliage. One web page on the net seemed to state yellow foliage could recover from the fuild being sucked out, would somebody be kind enough to shed some light on this ?
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- Tallahassee, FL - Only to the white man was nature a wilderness -- Luther Standing Bear (Ogallala Sioux Chief)
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Today by shaking the foliage and holding a white sheet of paper underneath, I saw two tiny insects, really smaller than the bright red little spider moving very fast. They did move slower, too. Darn, are they small !
My vision being far from perfect and having no magnifying lens, as far as I can tell those two insects - mites, probably - were dark brown (black ?), and yellow for the second one. I did the test two or three times, but only found two of these.
By keeping looking for information on the web, I read that they were sucking out the plant fuild by piercing into it, leaving yellow or brown holes on the scales of conifers. I didn't manage to recognize those holes.
One thing that I did not understand well was what happens to yellow foliage. One web page on the net seemed to state yellow foliage could recover from the fuild being sucked out, would somebody be kind enough to shed some light on this ?
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John, I envy you your 35' Juniperus specimen but not your problem. Once a conifer's foliage starts to yellow it is usuaully too late to do much about halting the folaige loss that has already begun. You have to correctly identify the cause. I heartily concur with those who have written about the red spider mites. With your size tree the problem has most likely had upwards of a year or more to establish before showing any signs and dealing with your tree with a anti-mite spray will be a problem in itself. A couple of observations though: Do beware cutting into old wood unless the circumstances are dire because most conifers will not grow back and the result is very, very unsightly. Red spider mite may be ONE cause but there may be others. I had your same problem several years back, fortunately my tree was small enough to spray liberally for several weeks. But when you spray you must significantly increase water availability to the roots. In my case it was not until I discovered the main roots were in an airlock underground and was able to fill it that the plant eventually came back. But checking the roots on your tree is not practical I'm afraid. All you can do is spray for mite as best you can, water liberaly if it's not already near a water source and hope a plant that size has enough natural defences to pull itself through! Regards Mike Gilmore WinsfordWalledGarden, SW England, USDA Zone9a

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Hi Mike, and thanks all of you for the replies.
The tree is in fact a monterey cypress. From what I could hear, there is apparently no real evidence that mites damaged it, at least that badly.
The drought we had during spring could therefore be the cause of the problem. Sounds weird to me since the monterey is said to be drought tolerant, according once again to the info I got off the web. I imagine you guys in the US know what a real drought is !
I think what I can do now is to water it every day, which leads me to two additional questions.
Is it sufficient to water the tree just below the end of the branches (encouraging the tree to extend further its root network I've been told) or is it necessary to water the whole covered area ?
Watering such a tree uses heaps of water, I thought maybe you guys might have a piece of advice or two to make my efforts efficient.
Also, is it possible to give too much water for a tree that big ?
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Is it sufficient to water the tree just below the end of the branches (encouraging the tree to extend further its root network Yes. A short-term (2-3months) drought will be no problem. Seems because of size/costs involved you should give nature more time to recover her equilibrium. Regards Mike Gilmore WinsfordWalledGarden, SW England, USDA Zone9a

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snipped-for-privacy@hotmail.com (John Doe) writes:

fungual disease when it is grown away from cool, coastal conditions: coryneum canker fungus. Symptoms are yellowing foliage, which turns dark reddish brown, and then slowly falls off. There is no cure. ( from Sunset Western Garden Book)
I would not water this tree every day (adding root rot to its problems) deep watering no more than once a week would be better. MC is native to the rocky Calif coast, where the soil would be very well-drained. But better yet, I would consult an arborist very soon.
Good luck Emilie NorCal
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Sure. But I have no idea how much is too much. .
Jim Lewis - snipped-for-privacy@nettally.com - Tallahassee, FL - Only to the white man was nature a wilderness -- Luther Standing Bear (Ogallala Sioux Chief)
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John, I work part time for a friend who owns 3 junipers that were about 6 ft tall. The first one was yellow when I started working for him, and with a little pushing around was able to pull it out of the ground. I get a College Extension Agent to come over and look at all the trees on the property. He said that once they are brown they are dead. He showed me some holes in one that was remaining, but turning yellow. He indicated that some kind of borer may have been the problem. The second one has since died and will need to be taken out next spring.
Spraying might have helped before the problem started, and he suggested getting something that you spray or sprinkle on the ground that will eventually come back up through the roots and into the trees. Too late now for the yellow ones, but may help with any you have left.
Dwayne

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