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Serving small woodland owners and managers in the Willamette Valley and northwest Oregon
Updated: 4 hours 9 min ago

Summer 2015, DROUGHT! And Heat. A Forest Health Report

Wed, 09/02/2015 - 7:23pm

By David Shaw, Forest Health Specialist, OSU Forestry and Natural Resources Extension

Douglas-fir killed by drought

The summer of 2015 is shaping up as a big year for drought and drought related forest health issues throughout Oregon, but especially in the Willamette Valley, SW Oregon, and in Eastern Oregon.

In late summer, it can be very difficult to discern whether insects, disease, or drought and heat are causing tree dieback and deaths, but we are becoming pretty confident that drought and heat together are influencing much of what we see.  In this report I outline and describe some of the more common problems we are seeing with conifers and hardwoods as of early September.

Drought related issues

In severe drought, trees may die with no associated biotic agents such as bark beetles or canker diseases. However, it is very common to find dead trees with these agents too.


Douglas-fir in the oak zone of western Oregon (the drier area of the Valley and on heavy clay and shallow dry soils at lower elevations) is having an especially hard summer, with some sites outside the oak zone also showing drought effects. The general symptoms are top dieback, branch flagging, and whole tree mortality. These symptoms may or may not be directly related to a biotic organism. The major ones are branch cankers, bark beetles, and twig weevils. All these organisms seem to do well on Douglas-fir during drought, and this year is no exception. We also believe root diseases are exacerbating the issue, but it can be difficult to discern. Twig weevils and branch canker diseases are very common on young Douglas-fir during drought, and both are known to increase attacks on drought stressed trees.

Douglas-fir twig weevil damage. Whitney Schmike photos.


Left: Douglas-fir branch flagging, likely from dought and canker interaction. Right: Douglas-fir canker. Note the brown dead bark area and green live bark. Branch is flagging.

Bark beetles

Douglas-fir beetles initiating an attack this spring. The tree had a red crown already, likely from drought. Photo Kara Shaw.

Bark beetle attacks on conifers increase during drought. This is the case for Douglas-fir, grand fir and other true firs, as well as pine. In these conifers it often results in top dieback, but can also result in whole tree mortality. We do not have the results from this year’s the statewide survey yet, but it appears that bark beetle activity is going to be really up. However, symptoms of bark beetle attack vary with beetle type and drought effect. For example, typically when a Douglas-fir is attacked by Douglas-fir beetle in April or May, the tree crown does not go red for many months, perhaps not until late fall or even early the next spring. However, this year many trees that were attacked in the spring were turning red right away, by mid-summer. This may be because they were already dying from drought, and this may also be exacerbated by existing root diseases.

Group mortality of Douglas-fir in May. Douglas-fir beetle was found in all these trees. Photo Kara Shaw

Many declining Douglas-fir trees have an associated stress cone crop, a smaller than normal abundant cone crop that is hypothesized to be related to the last gasp of the tree to reproduce before death. For a stress cone crop to hang on a tree in early 2015, means they likely formed in 2014, indicating many of the trees with top-dieback this summer have been suffering for two years or more.

Douglas-fir with stress cone crop. These cones formed in the previous year, therefore indicating stress beginning in 2014 or earlier. Photo Kara Shaw.

True fir/Grand fir

The fir engraver bark beetle attacks all true fir, but is especially important on grand fir and white fir during drought. We anticipate a lot of grand fir mortality this summer, but it will not become evident until fall, as the trees may take a few months before showing red foliage. Throughout the range of grand fir, the species has expanded its site occupancy with fire suppression, even in the Willamette Valley.   During drought, many of these sites are not suitable for fir and mortality may become very common. Root diseases may also exacerbate the mortality.

Foliage loss in conifers

Many conifers lose foliage in a drought, theoretically as an adaptation to reduce water loss through leaves. Although this is poorly understood, this summer it is quite common to see conifers like Douglas-fir or ponderosa pine losing two-year-old foliage and older. There may be interactions with foliage fungi/diseases, but it is very difficult to differentiate what is happening during mid-summer.

Foliage browning in hardwoods

Foliage browning in hardwoods is becoming more and more common throughout the region as drought intensifies this summer. Partial tree crown and whole tree crown foliage browning is already present in big leaf maple, Oregon ash, and cottonwoods. We anticipate Oregon white oak will also begin showing symptoms within the next month. We believe this is an adaption to prevent whole tree mortality, a type of early season senescence, and next spring most these trees will flush and be healthy if rains return this winter. Significant foliage browning is also being reported in California black oak in southern Oregon already this summer.


And, a few NON-drought issues…

Oregon white oak with branch flagging from Cynipid wasp and squirrel interaction.

Oregon white oak has had a big year for small branch dieback in some areas of the Willamette Valley. This is associated with a complex which involves a twig gall wasp (Bassettia ligni)(Hymenoptera: Cynipidae) in which the grubs develop under the bark of small twigs. The western gray squirrel is attracted to these areas with gall wasp grubs and the squirrel debarks the twig. If you see branch dieback in oak (red-dead foliage in clumps), check just below the dead foliage and see if you see the twig debarked. It is very characteristic and easy to see generally. This issue is common in the Valley, but year-to-year it varies in locations and intensity. This year it is particularly common in the Corvallis area and along the west side of the valley.

Bigleaf maple also begins showing branch dieback this time of year. This often is associated with western gray squirrel feeding damage, but no gall wasp is involved, the squirrels just like young maple bark. Again, to verify this is squirrel damage and not drought or other issue, check to see if the branch has been debarked below the dead leaves.

Bigleaf maple with dead branch flagging (left) and showing debarking by squirrels (right)

Swiss needle cast along the coast is still persisting and the aerial survey again showed over 500,000 acres of visible disease symptoms from the air. This was restricted to sites within about 20 to 30 miles from the coast. Occasionally young stands also show symptoms along the Cascade foothills. However, in the Willamette Valley and SW Oregon in general, the foliage loss we are seeing this summer is likely not caused by Swiss needle cast. See the Swiss Needle Cast Cooperative website.

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Fri, 08/21/2015 - 11:28am

By Amy Grotta, OSU Forestry & Natural Resources Extension – Columbia, Washington & Yamhill Counties

Like just about any small woodland, the Matteson Demonstration Forest has its share of invasive weeds. Besides familiar and ubiquitous foes such as Scotch broom and thistles, one of particular concern is knapweed.

Meadow knapweed, photo by Eric Coombs, OR Dept of Ag,

With purple flowers emerging from roundish bases at the top of a tall stalk, knapweeds superficially resemble a sort of spineless thistle, and in fact they are relatives of thistles, botanically speaking. They are biennial (2-year life cycle) to perennial plants and reproduce by seed. Fairly inconspicuous in the winter and spring; at this time of year, their purple flowers betray their location on and along roadbeds and other disturbed areas.

There are several species of knapweeds (Centaurea spp.) in Oregon, and all are classified as noxious weeds. Meadow knapweed, actually a hybrid of two other species, seems to be the most prevalent in the Willamette Valley.   Spotted knapweed is more of a problem on the eastside though has been documented on the westside too.

These two species can be tricky to tell apart, but we think we have meadow knapweed at Matteson, based on its wider distribution on the westside, the shape of the foliage and the color of the bracts (the tiny scale-like leaves at the base of the flowers).

So why are knapweeds a problem in forestlands? The biggest concern is their impact to native plant communities. They are tough competitors that can crowd out other desirable herbaceous plants, posing particular challenges to pasture or grassland managers, or those trying to restore meadows or oak savannahs. Even for those that do not have those particular objectives for their property, knapweeds are “road runners” in that they are easily spread by foot and vehicle traffic along roads and trails. So if you find that you have a knapweed infestation on your property, you can do surrounding property owners a favor by keeping it in check.

On the Matteson tract, knapweed is largely confined to gravel roads and open areas along the roads. Our main concern is limiting the spread of the weed, not only on this property but also to other College Forests and to other properties. For that reason, we are trying to keep OSU College Forest vehicles off the property as much as possible, so that tires and vehicle undersides do not pick up the seeds.  Multi-year herbicide treatments will also likely be necessary to reduce knapweed on the property; although because the weed is also prevalent along the county road ringing Hagg Lake, we may be fighting an uphill battle. We will be regularly surveying where our access roads join up with county roads and neighbors to contain and prevent its spread.

Roadbed infestation of knapweed with flowers and maturing seed heads, August 2015. Same road last October, showing mature seeds.

For more on knapweed management, consult these fact sheets: Invasive Weeds in Forestlands: Knapweeds from OSU Extension and Meadow Knapweed Best Management Practices from the King County Noxious Weed Program.

Thanks to Michelle Delepine from West Multnomah SWCD for her helpful expertise on this subject.

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Speaking of the weather…

Fri, 07/31/2015 - 3:00pm

By Amy Grotta, OSU Forestry & Natural Resources Extension – Columbia, Washington & Yamhill Counties

I don’t need to tell you it’s hot out there today. (Oops! I just did. Sorry.)

Between the extreme heat and the very real fire danger, it’s not a good afternoon to be working in the woods.  Rarely do I say I’d rather be in the office than in the field, but today is one of those days that I’m appreciating the air conditioning.

Since everyone is talking about the weather anyhow, it seems appropriate to share some reading material that relates to it, which you can enjoy in the comfort of whatever cool spot you’ve found today.  Oregon Forests and Climate Change is the subject of a little writing project which a number of my Extension colleagues have taken on as a group.

Why this project?  OSU Forestry & Natural Resources Extension strives to provide objective, science-based education to help forest owners succeed in forest stewardship. The growing body of climate science means that a basic understanding of climate and climate variability are needed to guide key aspects of stewardship of managed forests, such as:

  • selecting appropriate tree species and types of forest,
  • determining the timing of management actions such as planting and thinning,
  • estimating rates of growth and productivity, and
  • anticipating climatic stress and threats to forest health.

We realize there are still a lot of unknowns that go along with all this, so our intention is not to be prescriptive but rather to explore what some of the key issues might be. We’re learning as we go and sharing what we learn through a series of short articles.  The first set of these stories are available to read now over on the Oregon Forests & Climate Change blog. To set the stage, we get some perspectives on the subject of climate change from a woodland owner who also happens to be a forest geneticist working in the timber industry.

Crater Lake snowpack in July circa 1915. Photo credit:

The next three articles address some of the basic principles of climate science. One looks at Oregon’s weather and climate as we’ve experienced it in our lifetimes vs. what is projected for the future. The next uses snowfall at Crater Lake as an example, in analyzing long term trends vs. year-to-year fluctuations in our weather. Finally, we look at some of the underlying factors that create these fluctuations, such as the El Niño cycle we are in right now.

These articles lay the foundation for the next phase of our project, in which we’ll be exploring how our forests respond to climate variability, extremes, and long-term change, and how we as managers can respond in turn. Stay tuned over the next year or so as we continue.

Of course, climate change can be a loaded subject and discussions about the topic can quickly grow rather heated. (I could not resist that pun…) We will be staying above the fray and look objectively at what anticipated changes may – or may not – mean on the ground, here in Oregon. So grab another icy drink and click here for more.

Thanks to the USDA Pacific Northwest Climate Hub and the Oregon Forest Resources Institute for providing financial support for this ongoing project.

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Reflections from the Trail

Fri, 07/10/2015 - 10:36am

Brad Withrow-Robinson, OSU Forestry & Natural Resources Extension agent, Benton, Linn and Polk Counties.

I recently did a backpacking trip with my daughter, about a 12 year long summer tradition. This year we did a section of the Pacific Crest Trail starting at the California border, travelling “north” to Howard Prairie Reservoir. We actually travelled much farther east than north, ending up only about 10 miles north of California after 55 miles on the trail.
This was really the first time I spent much time in the Siskiyous. I have always heard great things about that landscape from friends and colleagues who have worked or played down there.
The landscape, geology and soils of that region are quite diverse and often quite different from other parts of the state. We spent time hiking through very interesting and diverse mixed conifer forests and meadows with many familiar as well as unfamiliar shrubs and flowers. We really enjoyed the chance to experience the Siskiyous for ourselves. On this dry year, we saw no snow and had pretty long stretches between water. But mosquitos were scarce.
Another rather unusual characteristic of this section of the PCT is the relatively large amount of private lands traversed. Much of the Oregon PCT travels through National Forest lands. In Southern Oregon we were in part of the checkerboard of BLM and private lands. It turns out that I know a few of those private family landowners who have long been encouraging us hike that section.
Jud Parsons met us at his gate at the end of our second day on the trail with a smile and jug of fresh water. He then gave us a tour of the family’s property near Mount Ashland. Jud has a great knowledge and deep connection to this land, most of which was purchased by his grandfather over a hundred years ago. We rumbled around in the old Chevy looking at a recent selective harvest, visiting some favorite trees, talking about history and a century of family ties to the land in southern Oregon. That history included the establishment of the ski road and also the PCT, of which the family hosts about two or three miles as it passes back and forth between their property and the BLM. Just a couple of weeks earlier, he had hiked his section of the trail with a chainsaw to clear the trail of a tangle of snags that came down in a winter storm. The trail is now part of that land and its stewardship.
I imagine some of you are beginning to feel sorry for me, or certainly my daughter, for interrupting a perfectly good wilderness experience for a busman’s holiday to a family forestland. Don’t be. Visiting a place, woodland or other, with somebody so familiar with and having such deep roots to a place has always been a cherished experience for me, and for my daughter too. We loved the visit with Jud on his property, and already look back at it as one of the highlights of the trip due to all the new dimensions it added.
The visit gave us a perspective that is inaccessible to most hikers on the PCT who often dash along the trail unaware of the ecological, social or historical context of the land they pass through. This is understandable since they have to rely on a sparse, landscape-impoverished guidebook, much to their loss. I am once again grateful for the chance to work with the landowner community, which affords me so many pleasures and benefits – including a jug of water and patch of cherished ground to camp on.



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Put down those pruning shears

Wed, 07/08/2015 - 11:56am

Brad Withrow-Robinson, Forestry & Natural Resources Extension Agent, Benton, Linn and Polk Counties

I recently got a call from a fellow whose Douglas-fir trees were covered with globs of pinkish pitch. It looked kind of like candle wax drippings on a Chianti bottle in some Italian restaurant, except it was on the trunks of his trees. As we talked I discovered that it was not an old stand, and the landowner had been out during the nice weather last summer and pruned his trees up six or eight feet to make it easier to get around and to reduce the risk of fire down near the County road. The pitch blobs were at the pruning scars.

Pitch moth evidence on off-site ponderosa pine

The culprit here is the Sequoia pitch moth (Synanthedon sequoia), a common clear-winged moth that attacks many conifer species.

Although commonly seen in town in people’s shore pine and other ornamental pine species, it is not generally a problem on Douglas-fir, or native Valley ponderosa pine except when the tree is wounded. A common and very attractive wound is easily created by pruning live branches during the summer months (April thru September) when the bark is soft and the adult moth is active. Although unlikely to kill your trees it is unsightly and generally avoidable.

Prevention is the best cure.

So this summer, put down those pruning shears. Save that job for the winter months.


Have an image of pitch moth on Douglas-fir you would like to share? email

Fresh pitch moth evidence on an ornamental pine

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Mapping your forest with Google Earth and a GPS phone app

Tue, 06/09/2015 - 11:56am

By Amy Grotta, OSU Forestry & Natural Resources Extension – Columbia, Washington, & Yamhill Counties

This must be the end of the road…

One of the first orders of business on the Matteson Demonstration Forest is getting to know the lay of the land.  180 acres is a lot to get to know!  As is the case with any new woodland owner, we need a map to help orient ourselves while on the property, and to keep track of where different roads and trails lead.

Eventually, the OSU College Forests staff will create a GIS map of the Matteson Forest with various spatial layers – property boundaries, roads, forest types, culverts, and so forth.  In the meantime, I’ve been using Google Earth to create my own map, adding information as I continue to explore the tract.  While in the woods, I’ve been using a GPS app on my smartphone to keep track of where I am and to record points and paths. In this article I’ll describe how I’ve been using these two applications, which I think would be useful to most woodland owners who don’t have GIS at their fingertips.

Some woodland owners are already familiar with Google Earth. For those that are not, Tristan Huff (OSU Extension Forester on the south coast) has developed a useful tutorial for landowners.  I recommend the Pro version of Google Earth, which is now available for free (a recent change).  In addition to all the standard features of Google Earth, the Pro version shows tax lot boundaries and allows you to calculate the area of a polygon that you draw.  This enabled me to draw the Matteson property boundaries on my map with reasonable accuracy, by tracing the taxlot lines.

Yellow polygon approximates the property boundary. Google Earth Pro

On a recent visit to the Matteson Forest my goal was to map the roads and trails in the southern half of the property.  Major roads stand out on the aerial photo, but walking the tract we’ve come across numerous secondary roads, trails and a small pond that are obscured by the canopy when looking at  the aerial image.

Mature timber in the southwest section obscures roads and trails in this aerial view. My iPhone GPS proved to be at least as precise as this handheld GPS receiver.

A GPS receiver can be used to map them. GPS receivers vary widely in their accuracy, especially under tree canopy; the most accurate systems are quite costly.  Even a consumer-grade GPS receiver, which might be accurate to around 50 ft under tree canopy, can cost several hundred dollars.  But, if you are one of the two-thirds of American adults that has a smartphone, you already have a GPS receiver built in.  Why not use it?

Doing some research I came across Motion X-GPS, an iPhone app available for the bargain price of 99 cents.  Motion X-GPS uses your phone’s GPS receiver to track your location.  This works in places where you don’t get a phone signal.  You can record tracks and points as you move about. You can even take photos and associate them with a place or track.

Motion X-GPS has good tutorials on their website, so I won’t go into much detail here on how to the app in the field.  Below are two screenshots from my phone, showing a waypoint and a track that I recorded.

After I was done for the day, the next step was to get these features from my phone into Google Earth.  In Motion X-GPS you can share locations, tracks and waypoints to an email address.  I simply emailed the tracks to myself.

Opening up the .kmz attachment automatically opens the feature in Google Earth.  From there I could save it to my map of the property.  Here is my Google Earth map now, with all the features that I mapped in the field imported and saved.

In summary, I give Google Earth Pro and Motion X-GPS two thumbs up.  I’ve been using the latter for biking and running as well.  To conserve my phone’s battery charge while in the field, I turned off the cellular receiver (there’s little to no cell signal on the Matteson Forest anyhow).  Using the GPS app for 90 minutes consumed about 40% of my battery.  Unfortunately, Motion X-GPS is not available for Android devices, but there are other GPS tracking apps that function similarly and are Android compatible.

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