Clark Asks: Drought affects conifers

Just about every day, arborist Greg Richardson and his crew are out dealing with trees suffering damage from the same problem.

“There’s one main culprit that will weaken the tree, or leave them in a stressed state, and then some damaging agent, or some environmental factor, comes along and basically finishes them off,” said Richardson, owner of Cascade Tree Works LLC in Orchards, on a job site late January.

It’s a lack of water.

A Columbian reader — through our Clark Asks website feature, where readers can suggest and vote on questions for further coverage — anonymously noted their neighborhood’s conifers appeared to be in distress. Other readers choose that entry as the top one for more investigation.

That reader, and the voters, aren’t mistaken. The Northwest has seen repeating, on-and-off drought conditions for the past several years, and that kind of stress can lead to serious problems for already sensitive trees.

Drought conditions

Hunter Decker, the county forester, said he’s seen many conifers showing the telltale top-down die-off of dehydrated trees. Charles Ray, the city of Vancouver’s urban forester, said the city has seen a steady number of residents calling with concerns about the health of trees in their neighborhood or on their property.

While drought can affect any tree, conifers seem to be getting a lot of attention from worried residents.

Usually, Ray said, people calling him are concerned their trees are sick or infested with harmful insects. That might be the case, he said, but when bugs or disease show up it’s often a secondary problem.

“The primary issue is really the drought stress,” Ray said, adding the stress has been repeating over the past several years.

In fact, much of Southwest Washington is currently experiencing a moderate drought, according to the U.S. Drought Monitor, and 48 percent of Washington, primarily east of the Cascades, is considered at least “abnormally dry.”

All of Oregon is at least abnormally dry, according to the drought monitor, and 62 percent of the state is considered in a “severe drought.”

Karin Bumbaco, assistant state climatologist of the Office of the Washington State Climatologist at the University of Washington, said three of the last four summers have been significantly more dry than usual.

The region’s trees aren’t exactly in crisis, said Patrick Shults, a forester with the Washington State University extension service, but the cumulative effect of dry weather is making some trees more vulnerable than they might be otherwise.

“That stress is cumulative on the trees,” Shults said. “It can be really, really hard on some of those trees, especially those tress that are in urban settings.”

The symptoms are usually the same, especially among conifers: trees turning brown and appearing to die off from the top down, or on the far end of longer boughs.

“Trees dying from the top down. That’s how people describe it to me a lot,” Shults said. “This is just the inability of the tree to get water to those extremities.”

People he talks to also often say their trees are full of cones. Conifers in crisis will often produce cones in a last-ditch effort to reproduce.

“It’s kind of like a going out of business sale, you might say,” Shults said.

The effect of the drought might be more pronounced in urban areas, he said, considering those trees also must contend with the added heat of urban and suburban environments. Then there are insects, diseases and other pests, or physical damage.

Combine those stressors with a lack of water, and it might be too much for a given tree.

“Trees have a natural immunity to damaging agents,” Richardson said. “When they’re dehydrated and thirsty, their immunity is one of the first things that they lose, so it makes them extremely vulnerable to different types of infection, infestation, and things like that.”

‘Right tree for right spot’

High temperatures and low precipitation can damage trees on their own, whether they’re contending with the stresses of a suburb or in the middle of the woods, said Dan Omdal, forest pathologist with the state Department of Natural Resources.

That can make attributing the cause of death for any tree a challenge: Was it dry weather, or the beetle that knew to burrow into a weakened tree, that killed the tree?

Failing big-leaf maple trees, he said, appear to be suffering not because of bugs or disease, but purely heat and lack of water.

East of Clark County into the Columbia River Gorge, there are ample examples of struggling maple alongside healthy Oregon white oak. The oak seem to be doing better, he said, despite sunny southern slope aspects or rocky, hot terrain.

Both are native to the region, but the maples generally do better west of the Cascades.

Even though his work is on forests, he’s seen, in urban landscapes, more clear-cut examples of what happens when homeowners try to raise non-native trees or trees maladapted to the climate.

When he moved to the region from North Carolina in the early 1990s, he tried bringing along a small white birch tree.

“It just melted,” he said. It couldn’t take the relatively less humid weather and longer, drier summers.

“In the urban forest, they say pick the right tree for the right spot,” he said. “Pick those trees that are native to the forest and the landscapes around here. It doesn’t mean they will be immune to some of these extremes, but they will most likely be best adapted to tolerating these climates that we have out here.”

Tree care tips

The city and county foresters, Shults and Richardson all repeated every tree, and any problems they might have, can vary, and they didn’t want to pin a blanket cause to anyone’s tree problem without seeing it.

Still, Richardson, who’s been an arborist for 20 years, said homeowners can keep their trees healthy by being proactive.

He recommended taking pictures of the trees every spring and fall, and keeping an eye out for discoloration of thinning in the top 10 percent of the tree over time. In addition, a photo record will help out any arborists who come to inspect the site, should it come to that.

Homeowners should also make sure to keep the base of the tree, where the roots flare out as it meets the ground, clear of debris. Raking or blowing out the organic material — pine needles, branches, other dead plant matter and the like — around the trunk annually helps prevent disease and other problems.

Clearing the base is also a good time to check for holes or cavities around the root flare, and for fungal growths, called conks, up the trunk.

Still, he said, many tree problems start as water problems, either from lack of water or inadequate drainage. Even both.

“That one simple evaluation on their own, of every tree that’s within striking distance of their home, once a year, they’re going to be way ahead of the game,” he said.

He estimates 75 percent of fallen tree incidents, trees into cars and homes and the like, can be prevented with a bit of vigilance.

Calling an expert

Ultimately, however, serious tree care will likely involve a professional at some point.

Richardson said most arborists will offer free initial consultations, and he recommended shopping around and talking to multiple people before settling on a service, and to make sure they’re both experienced and appropriately certified with the International Society of Arboriculture.

And, like with any contractor, would-be customers should know they’ll likely have to wait in line, Richardson said. He’s often booked out weeks or months in advance.

“You gotta get this stuff early,” he said. “If you want something done next week, you should be talking to the arborist six weeks ago.”

Ray, Vancouver’s urban forester, agreed, likening hiring an arborist to building a relationship.

“Having a good arborist is like having a good mechanic or accountant,” Ray said. “You wouldn’t necessarily want to rush out and find one at the last minute.”