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I have tall thin Junipers in my backyard. They resemble a Hollywood Juniper but I am not sure of their species. They are 25 years old and have begun to look like they are dying, the needles are turning brown and falling off. Is there anything I can do to save them?

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A

  Junipers are some of our most hardy landscape plants, but can develop problems when the weather is very hot (such as it has been this summer!)   I suspect your junipers need more water. They are mature trees now,
and their root systems are probably quite extensive. Realize that they may have extended their roots outwards at least 25 feet (same as their height).So, if you have be watering only as much as usual, and these trees are
surrounded by lawn, they are probably heat stressed and need more water. 

I usually recommend watering trees extra during the hot summer months, making sure to deliver the water over most of the root zone, applying the water slowly enough so that the soil is wet 12 to 18 inches deep. This deeper soil moisture will be available to the trees but not to the lawn grass, so you can be sure that the trees will be able to take it up. Soaker hoses are great for this purpose, since they emit water very slowly and the water can percolate down into the soil without running off down grade.    

When junipers are stressed, they are very attractive to spidermites. You can check for spider mites by holding a white piece of paper under a branch, striking the branch sharply, and catching the "dust" onto the paper.  Watch the dust a moment. If pieces of "dust" start crawling around, the tree is infested with spider mites.    To control spider mites without significantly harming the beneficial mites and insects that prey on them, try spraying the trees with a sharp stream of water every few days. This, plus the extra water you will provide, will probably help the trees regain their vigor. A shot of nitrogen fertilizer over their root zone would probably help, too. Apply the fertilizer before doing the deep watering so that it reaches the deeper tree roots (and won't be "stolen" by the lawn grass).

Posted on 15 Aug 2007

Maggie Wolf
Horticulture Agent, Salt Lake County

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