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UC publication helps city folks living with oaks

The oak is a common symbol of strength and endurance, but some of the majestic trees in California are buckling under the pressure of urbanization, reported the Sacramento Bee this week.

The Bee's feature about the care and feeding of California native oaks was centered around the new UC publication "Oaks in the Urban Landscape," written by retired UC Cooperative Extension environmental horticulture advisor Laurence Costello, and co-authors Bruce Hagen and Katherine Jones. The 265-page book is available in the UC ANR Catalog for $55.

In most cases where urban environments are shaded by oaks, the trees towered over the landscape long before humans moved in. Costello said witnessing the heartbreaking decline of urban oak trees was a catalyst for writing the book.

"It's just a shame; they're such a beautiful tree and the symbol species of California," Costello was quoted in the story.

Costello provided reporter Debbie Arrington with basic tips for protecting oaks in urban environments:

  • Know what kind of species you have. "Is it a California native or imported? It makes a huge difference."
  • Don't surround a valley oak with lawn; irrigation three times a week can cause fungus problems in the root and crown.
  • Know where the oak roots are before installing a swimming pool or an irrigation line. Oak roots are very sensitive.
  • Use a layer of mulch – preferably bark – to keep oak roots comfortable.
  • Fertilizer is usually unnecessary and pruning can weaken trees.

Oak trees may seem needy, but Costello says they are worth the extra effort. California's oaks are difficult to regenerate and it can take centuries for trees to develop the massive canopies and enormous trucks found on the most highly valued oaks.

Although shade-tolerant turf can be used under oaks, it is best to replace the turf with mulch.
Although shade-tolerant turf can be used under oaks, it is best to replace the turf with mulch.

Posted on Thursday, August 18, 2011 at 6:05 AM
Tags: Laurence Costello (1), oak (2)

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