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Water trees deeply when high temperatures hit
FOR IMMEDIATE RELEASE -- Major Media Distribution
July 17, 2009
09- 27

Contacts: Paul D. Ries, 503-945-7391
Cynthia Orlando, 503-945-7421

When temperatures in Oregon soar into the 90's or triple digits, it can take a toll on trees as well as people. This is especially true if, in conjunction with high temperatures, there's been little recent rainfall.

The Oregon Department of Forestry suggests a few tips for keeping your trees healthy during times of heat stress.

“High summer temperatures can be hard on trees, especially the landscape trees in our urban areas," said Paul Ries, an urban forester with the Oregon Department of Forestry. "Hot weather and prolonged drought can make trees more susceptible to insect and disease problems," adds Ries.

Symptoms of drought
One of the first signs that a deciduous tree (i.e., trees that lose their leaves in the winter) needs water is that its leaves begin to look dull.

Advanced symptoms of needing water are yellowing of leaves, wilting, and curling at the edges. Leaves may also develop a scorched or burned look - turning brown on outside edges, or between leaf veins. Leaves may also appear smaller than usual, drop prematurely, or turn  brown, but remain on the tree. Evergreen needles may turn yellow, red, purple or brown.

Watering tips
During prolonged dry periods with higher temperatures, remember the amount of water required to keep a lawn green is not enough for a tree. Given the benefits and longevity of trees, trees should be given higher watering priority over lawns.

If trees are only provided with shallow water, every day, they're probably only getting a fraction of what they need. Watering trees for short periods of time encourages shallow rooting, which can lead to future health problems for the tree. To make sure your tree gets the water it needs, saturate the soil within the drip line – that’s the circle that could be drawn on the soil around the tree directly under the tips of its outermost branches. Using a regular hose or a soaker hose, water deeply and slowly – slowly is important, so the water doesn’t run-off.

For conifers, water 3’ – 5’ beyond the drip line on all sides of the tree. Also, if you have a choice, water during the cooler part of the day for all trees.

Another way to water trees slowly is to put a 1/8" nail hole in the bottom (near the edge) of a five gallon bucket. Fill the bucket with water, and leave the slowly leaking bucket under the canopy of the tree. Do this twice or three times per tree moving the bucket each time.
Other tips: mulch can help
Using mulch is a helpful way to care for trees in hot or dry climates, since mulch helps the soil below trees retain moisture and stay cool. Mulch can be made of bark, wood chips, leaves and evergreen needles. Apply mulch within the drip line, at a depth of four inches, leaving a six-inch space between the mulch and tree trunk.

Do not plant annual flowers or other groundcovers under the canopy of your tree. Remove lawn and replace it with a ring of mulch. Any plants below a tree’s canopy compete with the tree’s roots for moisture and, since they are often closer to the surface than the tree’s roots, will get any limited water before the tree does.

Lastly, do you know what kinds of trees surround your home or business? Some trees, especially fruit trees, need extra water in a heat spell, whereas trees adapted to drier climates – like elms and pines - need far less irrigation than other species.

Tree care - always a good investment
Trees and forests enhance quality of life in many ways, including by providing wildlife habitat, shade, wood and other products, raising property values, and providing clean, healthy streams.

Remember that proper tree care - including deep watering of trees during hot summer months - pays big dividends in the long run.
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For more information about trees and  tree care:

About urban forestry:

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