Mayhem Among The Madrones

FIRE RENEWS. It's true for Valhalla at the end of "The Ring of the Nibelungs," and it's true for Pacific madrones, one of the Northwest's most beloved native trees.

Without fire, these fire-adapted trees can suffer. So in suppressing fire, we've contributed to a slow-motion catastrophe.

Blackened trunks, denuded branches and large cankers sadden madrones up and down the Puget Sound basin. "People come in here all the time and say, madrones have all these diseases. Is it OK to grow them?" says Deb Ferber, nursery manager at the MSK Rare Plant Nursery of the Kruckeberg Botanic Garden in Shoreline.

The short answer is yes, it's OK to grow them, and yes, it's possible to have them thrive. Madrones, also known as madrona or arbutus, are a defining icon of the region, like salmon. They are the state's only native broadleaf evergreen, a seemingly exotic anomaly compared to the familiar needled trees. Perched on bluffs like those north of downtown Seattle in Magnolia, around Lake Washington, in forests and throughout the San Juan Islands, they cling to fast-draining slopes and stretch out to the sun like weight lifters doing bench presses. The white flowers in spring and red berries in fall nourish wildlife, from bees to band-tailed pigeons and hummingbirds. The paper-thin bark — an extraordinary red-orange as eye-catching as any San Juan sunset — peels and exfoliates to reveal on younger stems a pistachio-green face as smooth as a newborn's cheek.

Visitors from other parts of the country are routinely amazed and inquire about those "strange and beautiful" trees. What's primarily harming and killing such special trees is Fusicoccum, a fungal organism, according to Marianne Elliott, a forest pathologist who recently completed her doctorate at the University of Washington with madrones as her focus. Elliott suspects this organism has always been around, but environmental conditions are stressing the madrones and making them vulnerable.

Virtually every tree in Seattle is infected. Among the most damaged are some of the city's grandest and most visible, like those in the highlands of Magnolia overlooking Puget Sound, and along scenic Lake Washington Boulevard. The fungus invades the xylem tissue just below the bark, interrupting the flow of water and nutrients, and resulting in something akin to starvation and ultimately death.

The problem was not noticed until the early 1970s, when summers started getting drier and springtime wetter. Damp springs are ideal for fungal growth, and drought summers tax the trees. "It's the perfect conditions for the fungus," observes Elliott.

In the wild, relatively frequent fires help rejuvenate madrones. Fire kills pathogens, and the tree resprouts using starchy food stored in the roots. But lack of fire isn't the only problem in Seattle. As people remove big leaf maples and Douglas firs for expansive views, madrones are suddenly left in isolation to bear harsh wind and sun. Such exposure damages bark and gives the blight an entry. Elliott says wherever the trees are stressed, by not only wind and sun but soil compaction, pollution and so on, they are hammered by the disease.

Elliott has several recommendations for worried tree owners. The most basic is to keep trees as healthy as possible, for example by removing competing vegetation such as grass, by mulching with wood chips, and by making sure the soil remains uncompacted. She advises avoiding sudden changes, such as major pruning around the tree, allowing a lot of sun and wind. Make changes gradually over several years, she suggests.

Mark Mead, the Seattle Parks and Recreation Department's senior urban forester, says removing dead wood is a good idea, but be sure when pruning to stay within the dead stuff; otherwise, you risk accelerating spread of the disease. Thoroughly grooming away blighted leaves is also helpful for smaller trees. Overwatering is another common problem. Adapted to our dry Mediterranean summers, madrones suffer from the abundant water that lawns and gardens typically receive. A more drastic approach for infected trees is to cut them down to mimic the effect of fire. The tree can resprout lushly if it's not so far gone that resources stored in the roots are depleted.

Valuable large trees can also receive emergency medical aid, but unfortunately such palliatives are labor intensive and expensive, and far from guaranteed.

Not every urban madrone tree is on death row. There are a few gorgeous healthy stands, especially in southwest Seattle. Much of the parks department's madrone emphasis is keeping these from harm. The department is also working with the group Save Magnolia's Madrones to replant madrones. Launched in the 1990s, the group has sponsored path-breaking research into madrones over the past 10 years. Unfortunately, much remains unknown. The group's funding, supplied by a settlement over a sewage-plant expansion at Discovery Park, is now mostly gone. And the success rate for newly planted trees is less than 50 percent.

Despite the challenges, madrones are such a fabulous tree, they are absolutely worth growing. Nurseries are increasingly sophisticated with propagating techniques and cultural advice. Look for a sunny, well-drained site with low-nutrient soil and no supplemental water (though a little summer water can be needed till established). Try to duplicate the natural conditions of madrones that may be growing successfully in your neighborhood. Choose young plants and transplant gently; madrones don't like their roots disturbed. And if half the seedlings die, that means half will live. So plant with abandon. This distinctive Northwest native more than repays the effort.

David Berger is a Seattle freelance writer.