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The Garden Guru: An expert advises on how to treat our trees

When the guy's ringtone is of a chain saw revving, he might be an arborist.

I had a chance to visit with Steve Houser, owner of Arborilogical Services, a few days ago as his crew worked 50 feet up in my trees. Houser is highly respected by his crews, his clients and even his competitors. He has been instrumental in bringing tree issues to the attention of thousands of local residents. He's an advocate for North Texas trees, and he's good at it.

So, there he was in my landscape. What a golden chance to get tree-management tips from one of the top guys in town. He had the time, and I had the tablet. Here are some of his feelings on local trees and how they fared after last summer's brutal weather.

In Houser's mind, it wasn't just the high daytime temperatures that did damage. Evenings when temperatures never dropped below 85 degrees were perhaps even more harmful. The trees were under stress all day and all night, and they never really got a chance to recover. Trees that aren't especially suited to high temperatures struggled most.

From Houser's observations, silver maples were among the most impacted. "High-water-use trees like cottonwoods and willows were hurt, and many bald cypress trees went into self-induced dormancy," he said.

The effects of summer 2011 will continue to be felt for five or 10 years, Houser predicts. Root systems of many trees were damaged. As temperatures rise this spring and summer, those trees will find it hard to get enough water to their foliage, and some will begin to decline. The more time that passes, the more difficult it will be to convince people that this ties back to the record summer. Local soils developed cracks 2 and 3 inches across, and that contracting of the clays did serious damage to trees' roots. Rural native trees that are not part of urban landscapes were especially hard hit. Houser said as many as 10 or 15 percent of those trees may have been lost.

The best thing we can do for our trees this spring and summer will be to water them attentively, according to Houser. He encourages deep soaking, almost to the point of runoff, then waiting until the soil is relatively dry before watering again. Most of all, he suggests not rototilling and planting flowers near the trunks of trees.

"People water their flowers way too much, and that is not good for their trees," he said. "I'd much rather see them put mulch or a low-water-consumption ground cover near the trees' trunks."

He said he prefers purple wintercreeper euonymus or mondo grass in such settings, but that mulch is still his first choice.

On feeding our trees, Houser says we need to be patient with them after last year, and that we shouldn't try to promote strong new growth too quickly.

He recommends fertilizing healthy trees twice per year. His company uses organic fertilizers, so timing is not as critical, since the organics work over longer periods of time. For people using inorganic products, he suggests feeding once the trees are fully leafed out in the spring, with the second feeding in early fall. However, he says that if the trees are growing in a landscape setting, nutrients supplied to the turf will also be taken up by the trees, so special applications just to the trees may not be required.

Neil Sperry publishes Gardens magazine and hosts Texas Gardening 8-11 a.m. Sundays on WBAP AM/FM. Reach him during those hours at 800-288-9227 or 214-787-1820.

In disclosure: Mr. Houser's business, Arborilogical Services, advertises with Neil Sperry's radio program, magazine and website.

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