Archive for the ‘Urban & Community Forestry’ Category

Timely tree tips — drought damage dynamics

August 12, 2015
Drought tree

Trees in Washington state are showing the damage caused by dry conditions. Photo: DNR.

When the rainforest in Olympic National Park catches fire, you know that Washington is dry. However, increased fire risk is not the only summertime threat to trees and forests. Drought conditions can cause cell and tissue dieback in trees and can also give pests and diseases a leg up in the battle for forest health.

According to DNR’s recently published Forest Health Highlights in Washington–2014:

“Trees experiencing drought stress can become more susceptible to insect and disease attacks and are less likely to recover from damage. In eastern Washington, trees growing in dense or overstocked stands have a higher likelihood of experiencing drought stress.”

Trees in urban landscapes that may be disproportionately affected by drought are those that are newly planted, victims of root damage, or growing in tough planting sites that are heavily compacted, poorly irrigated, or space limited.

In some cases, such as with water-dependent diseases like Sudden Oak Death, drought can hinder the growth and spread of disease organisms. However, many pests and diseases are more resilient in drought conditions than their host tree species.

For example, bark beetles thrive on drought stressed trees. In recent years, pine bark beetle populations have been exploding throughout the western U.S. as a result of drought and other complicating factors. Many types of tree diseases may also worsen in drought conditions including root rots, cankers, and wilts such as Dutch elm disease.

Check out this recent story from King5 News about the effects of drought on Seattle’s elm tree population.

For more information on this topic, consider reviewing the following resources:

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Homeowners can learn from the pros about wildfire prevention

August 3, 2015
Keep a close eye on lawnmowers and yard tools after use. They stay hot for at least an hour. Photo Frank Boston/Flickr/CC/Cropped

Keep a close eye on lawnmowers and yard tools after use. They stay hot for at least an hour. Photo Frank Boston/Flickr/CC/Cropped

Those who work day-in and day-out in the forest have plenty of know-how about taking extra precautions to prevent wildfires. With these dry days in Washington state, residents can take a page out of the professionals’ rulebook while performing yard work at home, too.

DNR currently has restrictions, called Industrial Fire Precaution Levels (IFPL), in place for people who work out in the woods, such as loggers or foresters, to help reduce the risk of wildfires. While these restrictions only apply to pros and their equipment, certain home yard tools, such as mowers, edgers, trimmers, saws and chainsaws, can also cause a spark that could start a fire in your yard, causing havoc in your neighborhood, or spread to any nearby wildland areas.

Instead, homeowners can apply these common-sense tips when using such tools at home.

  • Work in the mornings or late evenings to avoid the hottest parts of the day, and postpone your work when the weather calls for low humidity or high wind.
  • Keep a water hose or bucket or fire extinguisher on hand.
  • Use a nylon or plastic weed whacker line instead of metal.
  • Be careful not to set a hot tool down on dry grass or leaves.
  • Allow power engines to cool before refueling, and make sure the hot exhaust is kept away from dry grasses, weeds, and shrubs. Only use such equipment that’s in good repair and has spark arresters installed when applicable.
  • Stay home for an hour after finishing your work. This way you’d be around to notice if anything begins to smolder and smoke.

For more information on how to prevent wildfires, visit DNR’s Wildfire Preparedness webpage.

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Have you watered your trees lately?

July 16, 2015

TreeThe dog days of summer are upon us, so it’s a good thing we have trees to help keep us cool! Summer is a great time to kick back, relax, and enjoy the nice weather. But this month and next can be hard on trees, and they can use our help. Don’t be fooled by cloudy weather, because it does not necessarily mean moisture.

In Washington, most of the annual accumulation of moisture comes in three seasons, fall, winter and spring. Summer is typically very dry. This weather pattern is great for vacations and back yard barbecues, but difficult for trees – particularly newly planted trees.

When we do get moisture, it may not be enough for our leafy friends, especially those planted within the last year or two. Even if you are watering your lawn on a regular basis, your trees might not be getting enough to drink. Grass roots, after all, only grow to a depth of several inches. In contrast, trees roots are deeper, from about 18” to 24” deep.

Long, slow watering under the drip-line of a tree with a soaker hose or even a bucket with small holes drilled into it will ensure that moisture seeps down into the root zone.

Or build a low ring of dirt about 1 foot from the trunk of the tree to create a soil dam. With your hose turned on to a slow trickle, fill the tree ring with water (this will take about 30 minutes). Keeping the hose on a trickle will allow the water to soak in rather than run off, while the dam will keep the water directly over the roots of the tree.

Remember that a 2-4 inch thick layer of bark mulch around the base of a tree will maintain soil moisture and help control weeds, (but keep the bark about a hands-width away from the trunk).

There are many factors involved when considering how much and how long to water. Check out this article by Oregon State University Extension (OSUE) about watering trees and shrubs the right way, and how watering needs differ depending on soil texture.

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Ehhh, what’s up doc? Diagnosing plant health problems

May 27, 2015
Tree Doctors can come in all ages. Photo DNR

Tree Doctors can come in all ages. Photo DNR

The term “Tree Doctor” implies that such a professional can effectively diagnose a plant health problem and offer advice or prescriptions for resolving it.

Although not known as tree doctors these days, arborists are often called upon by their clients for exactly this service, since diagnosing plant health problems takes specialized knowledge and experience. Some diagnoses are straight-forward when dealing with common problems; however, other plant health issues can be frustrating to diagnose in cases when symptoms are elusive or when circumstances conspire to obscure the signs that something might be wrong.

The best plant health diagnosticians out there will tell you that it takes decades of study and diligent practice to get really good at it – and even then, the most experienced will still consult textbooks and research articles to help verify their conclusions.

So whether you’re a professional looking to beef up your skills on how to triage a tree issue or a homeowner with general concerns about the plants in your yard, consider consulting the following sources that outline the process of plant problem diagnosis:

  1. Article: “Plant Disease Diagnosis” from the American Phytopathological Society (APS).
  2. A companion PowerPoint presentation to the above APS article.
  3. “Diagnosing Plant Problems” as excerpted from the University of Kentucky’s Master Gardener Manual.
  4. “Diagnosing Tree Disorders” from the Colorado State Extension Master Gardner program

“As any doctor can tell you, the most crucial step toward healing is having the right diagnosis. If the disease is precisely identified, a good resolution is far more likely. Conversely, a bad diagnosis usually means a bad outcome, no matter how skilled the physician.”

~Andrew Weil, Director of the Arizona Center for Integrative Medicine at the University of Arizona.

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Hurray for Arbor Day; do you live in a ‘Tree City USA’?

April 8, 2015
It takes all kinds of help to plant trees in celebration of Arbor Day. Photo: Linden Lampman/DNR

It takes all kinds of help to plant trees in celebration of Arbor Day. Photo: Linden Lampman/DNR

Today is Arbor Day, a celebration of trees and all the great things they do for us in “The Evergreen State.” Washington State Arbor Day is always celebrated on the second Wednesday, April 8 this year as proclaimed by Governor Jay Inslee.

However, Arbor Day is more than just a celebration of trees. It’s a celebration of responsible natural resource management.

Salmon streams that DNR protects in native forestlands flow out of the foothills, across the landscape, and ultimately through one or more of Washington’s cities. Urban areas are where streams, shellfish beds, and fragile nearshore habitats are most threatened by stormwater runoff, erosion and sedimentation, toxic pollutants, low oxygen levels, and climate fluctuations.

As foresters we recognize that trees are erosion reducers, pollution mitigators, water purifiers, climate stabilizers, and carbon sinks. The practice of forestry in cities offers practical, low-cost, natural resource-based solutions to many environmental problems that affect our daily lives in Washington. Planting a tree in a city is an act restoration. Caring for urban trees is an act of stewardship. Cultivating an urban forest is natural resource management.

Sixty percent of Washingtonians live in an incorporated municipality, and approximately 90 percent of the State’s population lives in an area identified as “urban” by the 2010 census. There are 86 Tree City USA Communities in Washington and nearly 50 percent of Washington’s population lives in a Tree City USA.

Tree City USA is a national award from the Arbor Day Foundation that recognizes cities and towns for making a commitment to plant, protect, and maintain their trees. At DNR we celebrate Arbor Day in partnership with local communities across the state that have earned the Tree City USA® award. Find out if your city is a Tree City USA, as there may be special programs to celebrate trees in your community this month.

If your city isn’t part of the Tree City USA Program, contact your city officials to help them plan Arbor Day celebrations next year. Sponsored by the Arbor Day Foundation in cooperation with the US Forest Service and the National Association of State Foresters, Tree City USA® provides technical assistance and national recognition for urban and community forestry programs in thousands of towns and cities.

DNR provides assistance and support to many forest landowners, including Washington’s cities and towns. The agency’s work in urban forestry helps protect natural resources, engage urban residents in forest stewardship, and preserve the environmental character of our state.

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Diversify your yard with a different type of tree

March 12, 2015
The Japanese pagodatree isn't fussy about soil or water.

The Japanese pagodatree isn’t fussy about soil or water.

Looking for a tough, unusual tree to diversify your yard or woodland? One with character and multi-season interest? Give the Japanese pagodatree, sometimes called the Chinese scholar-tree, a look. Japanese pagodatree has been extensively planted near temples and shrines in eastern Asia for centuries. It is native to China and Korea, but—oddly enough, considering both its common and botanic names—not Japan. The tree was introduced to the western nursery trade in 1747.

Those of us who know the tree as Sophora japonica should be aware that botanists have recently renamed the tree Styphnolobium japonicum to differentiate it from trees of the genus Sophora. The roots of Sophora species form associations with soil bacteria to fix nitrogen like most members of the Fabaceae family. Recent scientific studies, however, show that Japanese pagodatree is one of the few trees in the extensive Fabaceae family that does not fix nitrogen in the soil. Who knew?

The Japanese pagodatree produces large, very showy panicles of creamy white pea-like flowers over several weeks in mid to late summer, a time when most other flowering trees are done with their show. Dark green compound leaves provide dappled shade through summer, becoming yellow in fall. Bark develops a rugged look similar to oak as the tree matures, offering winter interest. Bean-like pods are 3 to 8 inches long, and are retained on the tree through winter, an additional seasonal texture. The roots tend to be fibrous and deep, unlikely to affect nearby hardscape. (more…)

You can’t top a healthy tree

February 23, 2015


The practice of topping trees creates large wounds that are susceptible to disease and decay. Remember to always prune responsibly.

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Planting for success

February 9, 2015

Here are six tips from a DNR urban forester on how to properly care for your trees. Well-cared-for trees provide a lifetime of benefits.

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Guide your tree’s life: prune as it grows

February 2, 2015
Learn how to prune properly by taking a class.  Photo to DNR

Learn how to prune properly by taking a class.
Photo to DNR

If you want your trees to live long, healthy, sturdy lives, pruning is the way to go. Good pruning practices act as structural training, which develops strong ‘bones’ as trees grow and mature. In other words, less work for you and more safety for everyone.

Simply put, structural pruning helps your tree keep its ‘head’ – its leader – and develop strong branches. You can start by identifying the central leader, the straightest stem in the middle of the tree. Then prune away the 3Ds:

  • Dead
  • Diseased
  • Damaged

Next, support that central leader by removing any branches that look like they will grow higher than the central leader.

Prune with care. Over-pruning reduces a tree’s ability to feed itself and may stress a tree enough to encourage insect or disease problems. Never remove more than 25 percent of a tree’s live crown in a single year.

If you’d like to see structural pruning in action, take a drive to the City of Shoreline. Throughout the month of February, the City will work with a Puget SoundCorps team to prune young street trees to help them develop a strong, sound structure that will keep them healthy and safe as they mature. To conduct this work, the City received an Urban Forestry Restoration Project (UFRP) grant, which is administered by DNR’s Urban and Community Forestry Program.

The UFRP provides Puget SoundCorps crews to assist communities with urban forestry maintenance and restoration tasks, such as structural pruning and invasive plant removal. For more information about the UFRP, visit our webpage or contact Micki McNaughton at (360) 902-1637 or

Well-cared for trees provide a wide variety of environmental services, such as cleaning the air, while contributing to the health, beauty and economic vibrancy of a community. Give your trees the right care to help them grow up to be healthy, safe, beautiful citizens of your community!

Learn more about good pruning practices with these resources:

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Timely Tree Tips; suggestions for bare-tree season

January 15, 2015
Don't forget to check often any structural support cables or stakes used on your trees.  PHOTO DNR

Don’t forget to check often any structural support cables or stakes used on your trees.

Winter is often regarded as a slow time for working with trees; even the hardiest of Northwesterners don’t exactly enjoy working outside in freezing cold, pouring rain, or blowing snow. Any volunteer coordinator will tell you that it’s much harder to coax would-be volunteers out of their cozy abodes for a mid-morning ivy yank on a gray day in January.

Nonetheless, this season of leafless trees sets the stage for work that might be easier – yes, easier, to do now than in the warm days of summer.

Here are some activities particularly suitable to our leafless deciduous trees in winter:

  • Tree Inspections. Leaves send us important signals about tree health; however a dense summer canopy may obscure other signs of tree distress such as dead wood, broken limbs, cracks, cavities, included bark, and decay fungi. Binoculars are a great tool for performing ground-based inspections of tree canopies in the leaf-off season.
  • Cable Inspections. Many tree owners make the mistake of installing structural support cables and never following up with regular inspections. Cable inspections are easier in the winter as there are no leaves to interfere with visual inspections. Cabling systems should be periodically inspected by an ISA Certified Arborist to ensure they are still performing as intended and no causing harm to the tree(s).
  • Invasive Species Control. Remove perennial invasive plants in the winter to reduce the abundance of seeds come spring. Where English Ivy is flourishing out-of-reach in tree canopies, winter is a great time to cut a “lifesaver” ring in the ivy around trees. Doing so means you’ll witness the dieback of treated ivy before tree leaves re-emerge, and you will be assured your hard work was effective.
  • Tree Removal. No leaves means less mess. Frozen ground also means less damage to turf from heavy equipment and other impacts of large tree removal.
  • Structural Pruning.  If January brings a lull in your maintenance schedule, fill it with structural pruning to “pay it forward” and you won’t regret it. Structural pruning is easier in winter when you can clearly see the structure of the tree. Pruning to encourage good tree structure in young trees can significantly reduce the need for costly tree maintenance in the future. This work is best done by those with the experience and skill to recognize the difference between dead limbs and live ones in the absence of leaves.

If tree work entices you outside this winter, stay warm, stay dry, stay hydrated, and stay positive. Remember that you’re doing important work for a good cause. The busy days of spring will be here before you know it, and you’ll be grateful to have made the most of your time and maintenance opportunities this winter.

From DNR’s January Tree Link Newsletter

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