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Hearty trees can survive drought Mail Tribune / Jim Craven Native oak trees in the old Odd Fellows cemetery in Medford can survive drought for years. But non-native trees, especially young ones, need particular attention this dry summer. By BILL VARBLE You say that big old tree in front is looking a little bedraggled? Oaks and birches dropping leaves? Pines and firs with brown needles? It could be drought, all right, but you'd better look around. "Established trees, bigger than 6 inches, it's not typically going to affect them that much until the second year," says Ken Marshall, maintenance supervisor for the Medford Parks and Recreation Department. "It has more impact on smaller trees." On the other hand, some trees just look different this year. Keep trees healthy Here are some things you can do to help backyard trees live with drought: Plant drought-resistant or drought-tolerant trees. If possible, use native trees that like hot summers but stand wet winters. ("But all trees need water to get established," warns Medford tree program coordinator Gwendolyn Scott.) Look for trees that are happy west of the Cascades, including such evergreens as Western juniper, deodar cedar, Leyland cypress, knobcone and Jeffrey pine, or broad-leafed trees such as various oaks, madrone, crabapples, upright flowering cherry, some locusts and myrtle. Don't just assume drought is the problem. Is the soil compacted from heavy use or construction equipment? Is pavement keeping water from reaching the roots? Has soil been added above ground level (just a few inches can kill a mighty oak)? Have roots been damaged by soil removal or digging (they can reach horizontally beyond the canopy). Mimic the seasons. Water trees in spring and fall and taper off for summer. Don't put lawn under oaks. If you're convinced a big tree is suffering from drought, put a soaker hose around the edge of the canopy (trees have most of their roots reaching out far from the trunk but concentrated in the first two or three feet of earth, creating a saucer-shaped system). Leave it on low two or three days. Do this several times in the fall and check the tree in the spring to see how it leafs out. Even if you don't see improvement, it may stop the decline. "I've been doing this 22 years," says arborist Tom Myers, of Ashland, "and I've never seen native oaks go dormant this early." There are those Autumn Blaze pears near the fountain by Medford City Hall which, as city tree program coordinator Gwendolyn Scott notes, already look like it's fall. The same with those maples behind the Medford Police Department. Southern Oregon has had one dry winter after a string of wet ones. Trees vary widely in how they show the effects of drought. An oak or locust, for example, typically reacts more slowly than a cottonwood, birch or willow, which need lots of water. Maples fall in the middle. At the old Odd Fellows cemetery in Medford, after an irrigation system was removed years ago, a drought killed ornamental trees almost to a specimen. But the old oaks there are relatively OK and host thriving bird communities each spring. Oaks go dormant to conserve water by shutting down their leaf system as a survival strategy. That means the tree is not conducting photosynthesis. A healthy tree may be OK with that. But for a stressed tree, that can mean compromised defense systems the following year and a weakened tree for insects or fungi to attack. Trees in city parks present a special problem in that people don't want soaked ground. "If there's turf, we end up inundating it," Marshall says. "The idea is to build the moisture earlier in the year and not allow it to dry out." Sunset's Western Garden Book notes that the concept of "drought" makes more sense on the East Coast or in the Midwest in the sense of a temporary condition that has an end. Communities in the arid West don't have enough water and depend for the most part on distant winter snows or rains. It's standard advice to not put lawn around an oak because the watering will kill it. But Myers says many oaks around the valley that have been getting supplemental water this summer are green and holding their leaves. He says if you do water an oak to water it deeply and slowly, in a trickle, and then be sure to let the ground dry out. Birches - an eastern tree - require watering all summer. Myers predicts dead walnut trees next summer. "They can handle about a year of drought," he says. But people often blame drought for something that happened years earlier, Marshall says. Accidentally cutting some tree roots in a yard project may cause dead limbs two or three years later. And no amount of water will fix that. Finally, don't panic at a stressed tree. "Just because it's dormant doesn't mean it's dying," Scott says. "They do the best they can." Reach reporter Bill Varble at 776-4478 or e-mail [email protected] Mail Tribune Home | Ottaway Newspapers, Inc. | Dow Jones & Co., Inc. | Privacy | Contact Us Copyright � 2001 Mail Tribune, Inc.